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 Front Cover
 Table of Contents
 Acknowledgements and productio...
 Preface
 Introduction
 Topography
 Water resources
 Geology
 Mineral resouces
 Engineering geology
 Energy resources
 Land use
 References
 Back Cover


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r . --. -... . REFERENCE OVERSIZE REF FGS SP 19 C 2 I I II I I ENVIRONMENTAl GEOlOGY AND HYDROlOGY II I I ., TAMPA AREA, FlORIDA I

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STATE OF FLORIDA DEPARTMENT OF NATURAL RESOURCES Harmon Shields, Executive Director DIVISION OF INTERIOR RESOURCES Robert 0. Vernon, Director BUREAU OF GEOLOGY C. W. Hendry, Jr., Chief SPECIAL PUBUCATION NO. 19 ENVIRONMENTAL GEOLOGY AND HYDROLOGY TAMPA AREA, FLORIDA by Alexandra P. Wright Prepared by the BUREAU OF GEOLOGY DIVISION OF INTERIOR RESOURCES FLORIDA DEPARTMENT OF NATURAL RESOURCES TALLAHASSEE, FLORIDA 1974 Geologicar :. Llbrary 903 West Tennessee Street l'.anahaasee,. Florjda 32304

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CONTENTS ACKNOWLEDGEMENTS AND PRODUCTION PREFACE, Charles W. Hendry, Jr. INTRODUCTION Population .. Recreation . . . . . . . . . itansportation, Carleton J. Ryffel, A. P. Wright TOPOGRAPHY Topographic Maps ...... Topo!lraphy of the Tampa Area Physiography . . . . . Topography and land Use Planning WATER RESOURCES Water Cycle Rainfall and Evapotranspiration Drainage ... Water Quality lakes ..... Streams Hillsborough River Water Table and Swamps Floridan Aquifer and Springs Water Use Flooding .......... GEOLOGY Geologic History General Geology Sinkholes ... Structure ... Geology and Urban Planning .iv v 2 3 4 8 9 12 13 16 17 18 19 20 22 24 26 28 30 32 36 38 40 42 43 MINERAL RESOURCES,. C. Pirkle, W. H. Yoho, Fredric L.Pirkle, A.P. Wright Phosphate Sand ... Clay limestone Cement, Oyster Shells and Peat Concluding Remarks . ENGINEERING GEOLOGY Foundations, A.P. Wright, James F. Orofino Sands .................. Sand Suitability as a Foundation Material Clays ...... Organics .... Potential Collapse Soil Associations Soil Relationships in Urban Planning ENERGY RESOURCES Primary Energy Sources, W. B. Simonds Electric En ergy, W. B. Simonds Energy of the Future, W. B. Simonds Oil and Gas, W. R. Oglesby . . . LAND USE Current land Use Future Land Use Transportation Planning and Geology Geologic Factors Affecting Construction Geologic Factors and Sanitary landfills REFERENCES ............. 46 51 54 56 58 59 62 64 65 66 67 68 69 70 74 76 79 80 86 87 89 90 92 93 iii

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iv ACKNOWLEDGEMENTS Gratitude is expressed to Dr. Robert 0. Vernon, Director of the Division of Interior Resources, Mr. Charles W. Hendry, Jr., Chief of the Bureau of Geology and Mr. Steve R. Windham, Assistant Bureau Chief, for making this publication possible. Appreciation is expressed to the staff of the Bureau of Geology for encouragement throughout the project and assistance in reviewing the text. Special thanks are due J. W. Yon, Jr. who gave generously of his time to assist in the preparation of this publication. Sincere thanks are extended to Dr Joseph S. Rosenshein, Subdistrict Chief of the U.S Geological Survey's Tampa office and to his staff for generously providing data and helpful suggestions for the Water Resources chapter. Assistance from Mr. Gerald Parker, Chief Hydrologist, and other staff members of Southwest Florida Water Management District and from staff members of the Tallahassee District U S. Geological Survey office is also gratefully acknow ledged. Mr. Samuel R Lockwood, past Superin tendent of the City of Tampa Water Department also provided invaluable data. Special thanks is expressed to James F Orofino, Orofino and Company whose extensive assistance made possible the Engineering Geology chapter of the study. Appreciation is also due William B. Forney, past District Conservationist, Soil Conservation Service who kindly gave of his time to assist with the soils sections of the study. Gratitude is expressed to the following people for assisting in the preparation and review of the Mineral Resources chapter: T. Walter Herbert, Bobby J. Timmons, J. S. Weaver, Thomas J. Patterson, Bruce Congleton, Allen C. Edgar, L B. Carnes, James L. Eades, Walter W. Rowe, and Edward Medard. The Department of Physical Science and the Department of Geology, University of Florida and the Florida Phosphate Council are also acknowledged. Sincere appreciation is expressed to Xiomara Ortiz for typing and lay-out of materials. Sincere appreciation is extended to Timothy Varney, past Environmental Planner, Hillsborough County Planning Commission. William Ockunzzi and other staff members of the Tampa Bay Regional Planning Council provided much useful information with regard to land use. Thanks are expressed to both planning agencies for extending encouragement and sincere interest during the study. Thanks are also due the following people for providing vital information and assistance with various parts of the study; Peter McPhee, Division of Recreation and Parks, Thomas Griepentrog, Depart ment of Transportation, Dr. Daniel P. Spangler, University of South Florida, H. J. Woodard, Bureau of Water Resources, S. Melodie Oleson, Southwest Florida Water Management District, Robert W. Johnson and Bishop Beville, Soil Conservation Ser vice, and Philip Linn, Hillsborough County Planning Commission. Genuine thanks are extended to the many people too numerous to mention who have taken an interest in the project and cooperated throughout the preparation and production of this publication. PRODUCTION Coordinator Technical Assistant Graphic Consultants Photography Drafting Art-text -chapter title pages Typing and Type Setting Printing Alexandra P. Wright Carleton J. Ryffel Juanita D. Woodard Donald F. Tucker Simmie L. Murphy Stephen J. Wharton D. E. Beatty Robert M. Grill Dorothy P. Janson Philip R. Shaw Harry Whitehead Dorothy P. Janson Anne M. Prytyka Gloria Monk Xiomara Ortiz Janis Roberts Juanita Woodard Stephen J. Wharton

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( PREFACE "Environmental geology The collect ion, analysis, and application of geologic data and principles to problems created by human occupancy and use of the physical environment, including the maximization of a rapidly shrinking living space and resource base to the needs of man, the minimization of the deleterious effects of man's intraction with the Earth, and the accommodation of the exponentially increasing human population to the finite resources and terrain of the Earth. I t involves studies of hydrogeology, topography, engineering geology, and economic geo logy, and is concerned with Earth processes, Earth resources, and engineering properties of Earth materi als. It involves problems concerned with construction of buildings and transportation facilities, installation of utility facilities, safe disposal of solid and liquid waste products, development and management of water resources, evaluation and mapping of rock and mineral resources, and overall long-range physical planning and development of the most efficient and beneficial use of the land." So states the Glossary of Geology, published by the American Geological Institute, and to this end this publication is pre sented. To accommodate the exponentially incrasing human population to the fin ite resources and terrain of the earth has become the foremost responsibility of government officials, planners and technical researchers within the last two decades. I n the not too distant past, it seemed we had inexhaustible supplies of clean air, potable water, energy and other mineral resources, but such excesses are no longer assured. We have entered the era of shortages and recycling which has resulted i n the reestablishment of priorities and the sequential uses of our resources in order to insure our surv i val. This publication is presented not as the answer to any of the monumental problems facing those with the responsibility of planning for the future, but as a tool to help those with such responsibilities. Charles W. Hendry, Jr. v

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INTRODUCTION LLLLLL LLLLLL LLLLLL LLLLLL ,_______. L L L L l_L I ----........ ....____

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POPUlATION Although Tampa's first incorporation occurred in 1849 with a population of 185, Tampa officially became a city after a second incorporation in 1855. Since that time Tampa and its surrounding suburbs have experienced a population explosion To put Tampa's growth into perspective, the following table provides a summary of census facts: % 1870 pop. 1970 pop increase u.s. 38,558,371 203,184,772 427 Florida 187,748 6,789.443 3,516 Hillsborough County 3,216 490,265 15,144 Tampa 796 277,767 34,795 Population figures alone have little environmental significance The statistic that probably relates most directly to the physical setting is population density, or the number of people per acre of land. Based on 1970 census data, figure one shows population densities within the Tampa area. Obviously, the individual requires a certa i n minimal space for life, work and leisure and it seems reasonable to assume that creature discomfort and environmental damage can result from overcrowding. Establishing an optimum space requirement for the individual is an interdisciplinary problem and no reliable estimate can be given here. Attention can be paid, however, to future growth patterns and specific areas in which accelerated population increases are anticipated. For this 1970 2000 purpose, the graphs below exhibit population projections through the year 2000 for the areas outlined on figure one. These graphs indicate that the population of some areas will increase by many times during the next 30 years It is these areas which are prime candidates for the environmental damages that have historically accompanied indiscriminant development. Prudent planning must keep pace with development in these areas and such planning must be based on thorough knowledge of both physica l and biological environ. It is the job of scientific agencies to provide planners with such information if environmental cri ses are to be avoided as more and more people popu fate the Tampa area. POPULATION PROJECTIONS BY CENSUS AREA (SOURCE: TAMPA BAY REGIONAL PLANNING COUNCIL) (1.3X) Number of times by wh ich the population will increase. V'l-350 0 z 20 PERSONS per ACRE I 2 TAMPA AREA POPULATION DENSITY 3 4 8 9 k--JMiles 7

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RECREATION Recreational facilities are a significant asset to any area in both the intangible enjoyment they provide and the role they play in the local economy. Due to the great influx of tourists to the area as well as the accelerated resident population increases, Tampa's recreational demands are especially high. In fact, according to the Division of Recreation and Parks, current and projected demands for recreational facilities in the Tampa region1 are the highest in the state Fortunately, the area is tmdowed with many natural resources which are the crux of outdoor recreation. Geologic features frequently provide the focal point for recreational facilities in the Tampa area. Springs, for example, are a main attraction of many local parks. Another example of a unique natural feature can be found in Hillsborough River State Park where the occurrence of a rock outcrop in the river provides a scenic stretch of rapids. A primary natural asset of the Tampa Bay area is the Bay itself. Although the Bay has not been as significant a recreational resource as it might have been, several proposed recreation sites are located on the Bayfront. 2000 (J) 1,000,000 w a: u <( 1970 500,000 D D LAND ACREAGE NEEDED FOR CAMPING, PRIMITIVE CAMPING, BEACH, HIKING TRAILS, NATURE STUDY, PICNICING SALT AND FRESH WATER ., SURFACE ACREAGE NEEDED /J&.. : .:;?' FOR BOATING, FISHING, v /itGf!l''"'"SWIMMING WATER SKIING The map shows existing and proposed recreational facilities within the Tampa area. The status of proposed facilities varies from the "drawing board stage" to "development near completion". Tampa's current and projected recreational demands are great, and the proposed recreation areas will not meet all of the needs The task of the recreation planner, however, is simplified by the fact that any site distinquished by its natural or historical elements has potential for recreational development. The important point is that the creation of a list of potential recreational lands and acquisition of those lands should be done now. This is necessary for two reasons: the rising costs of real estate, and the need to preserve the lands' natural resource assets until such time as the sites can be developed for recreation. The fact that demands for water related recreation are greatest further emphasizes the necessity of properly managing the regional water resources. 1 includes Hillsborough, Pinellas, Pasco, Polk, Manatee, Hardee, DeSoto, Sarasota and Highlands counties. RECREATIONAL NEEDS OF THE TAMPA AREA CONTRASTED WITH THOSE OF THE MIAMI AREA (DATA SOURCE; DIVISION OF RECREATION AND PARKS, 1971) ( I PASCO COUNTY POLK CO. -------------,---------------______ l...!: _____ l 1 B I >-I f- zl ol Uo I I I I i LAKE PARK I EXISTING and PROPOSED RECREATIONAL I 11/.JI' \ FACILITIES in HILLSBOROUGH COUNTY f I I I j I I EXPLANATION E XISTING PROPOSED I ) / SOURCE S : / / / TAMPA BAY R EGIONAL P LANNI NG COUNCIL FLORIDA DEPARTM E NT ol TRA N SPORT A T I O N MANATEE LOWER HILLSBOROUGH RIVER' RESERVOIR PARK B BLACKW ATER fREEK RESERVOIR PARK PLEASANT GROVE RESERVOIR PARK "' "T'f.?,qiL LITHIA S P RINGS PAR K ':>::: 1-' '0 a. I I I ------------cou-NTY _____ -----------+-3

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TRANSPORTATION Historically, transportation in the Tampa area has been vitally linked with the expanding population of the area. The existence of the natural estuary (ideally suited for the development of a port), played an important role in the location and subsequent growth of the City of Tampa. Tampa channel was initially dredged in the late 1800's, and has since been deepened several times to accomodate larger ships and cargo. The port was first used for shipping cattle to Cuba in the 1800's. Later, with the discovery of phosphate in the area, a prosperous future for the port was assured. Currently, phosphate is the leading product shipped from Port Tampa, and many area residents depend directly or indirectly on the port for their livlihood. Whereas the port is a key to the economy of the Tampa area, the supporting role of the railroads for carrying goods to the port cannot be ignored. Like the shipping industry, the rail industry was initiated in Tampa during the late 1800's. In 1883, the railroad stretched eastward toward Plant City and by 1885 it was linked with the north. With the expansion and diversification of industry in the area, rail trade continued to grow. A benchmark in transportation history was the completion of Gandy Bridge in 1924, then the world's longest auto toll bridge. Today's impressive network of highways reflects local and regional growth patterns in the Tampa area. Tampa is served by U.S., state and interstate highways. T he airline industry was born in 1914 in the Tampa area when Tony Janus made the first regularly scheduled flights from St. Petersburg to Tampa in an airboat. Tampa's new International Airport is a monument to the spectacular growth of air travel. Tampa's transportation facilities are an important asset to the area. They provide convenience to residents, in addition to facilitating the flow of tourists to the area. Many transportation planning studies, now underway, incorporate environmental considerations to insure that future development of transportation facilities will have minimal environmental repercussions. 4 1 I G ) GULF I I I I \ TAMPA \ \ \ I \ I I BAY J I /1971 AVERAGEfDAILY TRAFFIC I I I G Hillsborough Bay Data from FLORIDA DEPT. of TRANSPORTATION r' Bs @ VANDENBERG ) EXPLANATION < 5000 Vehicles 5000-15000 Vehicles --15000-50000 Vehicles > 50000 Vehicles

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WATER In 1971, Port Tampa handled over thirty six million tons of cargo. This is the largest tonnage handled by any port in Florida. Further, the port ranks eighth in the nation in total tonnage handled, and fourth in export tonnage. With the proposed deepening of the channel, the projected tonnage may reach sixty million tons by 1985, and one hundred million tons by the year 2000. At the present time, the U. S. Geological Survey and the Tampa Port Authority have undertaken an estuarine hydrology and environmental study of Tampa Bay, to insure the wisest environmental and commercial management of the Bay The present status and the fate of Tampa Bay have long been subjects of heated controversy. The comprehensive Bay study will provide a plethora of data including: --the quality of Bay waters and sediments --the quality of inflow to the Bay --flushing mechanisms -circulation patterns --characteristics of bottom and sub-bottom deposits. Among the most sophisticated estuarine investigations ever undertaken, the Tampa Bay study will entail development of a computer model which will provide accurate predictions of changes in the Bay environment so that improvements in the ship channel can be planned and designed to minimize environmental effects The deepening project is necessary to accommodate the larger new ships which the phosphate industry (the largest user of port facilities) will be using. The dredging operation will increase the channel depth to forty-seven feet. The actual desired depth is forty-three feet, but two foot allowances must be made for error and for slumping of the sediment after dredging is completed. It is expected that fifty million cubic yards of sediment will be removed under the supervision of the Army Corps of Engineers, which is the agency responsible for maintenance of the channels. Some sediments removed from the Bay will be used for construction purposes. The remainder will be used in spoil areas. Photo by R.C. Reichenbaugh 1-0:: 0 0.. 0:: 4 ..J < z z 0:: UJ 1-7< 0.. :::!! f! 6(f) 0:: UJ 5" z UJ en en < 40.. a:: 4 0 3UJ z < ..J (L z UJ "-0 (f) z ..J =:! 90-1a:: 0 (L 80-< (L ::;: <{ 1-70-.... <{ 0 UJ 60-c5 z < I 50-g a:: <{ u "-40-0 (f) z 0 1-30-c.. 0 (f) z 20-3 ..J :::!! 10-:::!! 0-7"'5--;;' a""o,---,s""5,----.'""9o:c--,=95 __,'""'2o=o'""oo TRANSPORTATION PROJECTIONS FOR THE TAMPA AREA (DATA FROM: TAMPA BAY REGIONAL PLANNING COUNCIL AND TAMPA PORT AUTHORITY) AIR The new Tampa International Airport has been designated an intercontinental facility and jet terminal by the Federal Aviation Authority, and its runways and terminal complex are designed to accommodate all commercial aircraft including the 747 and SST. Currently, ten major scheduled airlines operate from Tampa International. Completed in 1971, the airport features four levels: baggage claim. ticketing, transfer (landside-airside shuttle), and parking. The multi-level concept and radial design minimize walking distance from automobile to aircraft seat and maximize efficiency. The r emainder of the airports in the area (exclusive of Macdill) are for private use. They offer flight schools, aircraft sales, service and leasing, or some combination of these. SURFACE Hillsborough County is served by interstate highways 4 and 75. On completion, 1 will enable driving from Tampa to Saulte Ste. Marie, Michigan on the Canadian border. Interstate 4 provides easy access to Florida's east coast, and in Daytona Beach it connects with 1 which runs along the entire eastern coast of the United States. With regard to rail transportation, the Tampa area i s served by Seaboard Coastline, the eighth largest railroad in the nation. Seaboard is primarily a carrier of phosphate, and to a lesser degree, citrus products and passengers. Seaboard is also a feeder line to junctions where goods are transferred to other railroads and carried to more distant destinations. 5

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TOPOGRAPHY '''// IUj), fll fll

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8 TOPOGRAPHIC MAPS Topography (or the shape of the land surface) is of great significance to virtually every aspect of land use planning. The relationship of relief to geography and physiography, location and thickness of mineral resources, drainage patterns, climatology, vegetative patterns, occurrence of natural disasters, soil development, physical aesthetics, etc. points up the value of a familiarity with the topography of the study area. The shape of the land, portrayed by contour lines (lines of equal elevation), is the distinctive feature Jxhibited on topographic maps, however, a wealth of information about the area is also shown on the maps. The Tampa area encompasses all, or portions of sixteen quadrangle maps. each showing an area of 7.5 minutes latitude by 7.8 minutes longitude. The scale on these maps is 1 :24,000 -that is, one inch on the map equals 24,000 inches or 2000 feet on the ground. The contours are imaginary lines following the land surface at a constant elevation above sea level. The contour interval (given at the bottom of each map) is the vertical difference in e levati on between adjacent contours on the map. In flat areas such as Tampa, the contour interval is generally small so that contour lines are not far apart. Several characteristics of contour lines are noteworthy: 1) Contour lines never cross or intersect one another, nor do they split 2) Every contour line closes on itself either within or beyond the limits of the map. 3) The closer the spacing of contour lines, the steeper the slope. 4) Contour l ines curve upstream, but cross the stream at right angles to its course. Topographic maps are ideal for pinpointing exact locations, as they are referenced to latitude-longitude, and contain a sectional gridwork within each township. Township is given on the sides of each map, and range on the top and bottom. Each of the 36 sections within a township represents one square mile, and each section number is shown in red on the map. Color coding and numerous map symbols indicate a variety of physical and cultural features. Black is used for man-made features (roads, buildings, etc.), blue for water, brown for contour lines, mines, etc., green for vegetative cover, and r ed for urban areas, section lines, etc. In addition, lavendar is used on photorevised maps to show new features. Cross sections (as shown in the diagram) can easily be constructed from topographic maps and are useful in repres enting cross country relief or slope of the land surface. Topographic maps covering the Tampa area are available through the U. S. Geologrcal Survey in Washington, D. C. CROSS SECTION A I 50' 40' 30' 20' 10' MSL VERTICAL EXAGGERATION X40 J:l. BUILDINGS CONSTRUCTED BETWEEN 1956 AND 1969 CONTOUR LINES ) 28 0' Latitude 82' 30" Longitude ROAD CLASSIFICATION Heavy duty ............ Light duty ........... ==== Medium duty.. ....... Unimproved dirt========= 0 Interstate Route 0 U.S. Route 0 State Route SULPHUR SPRINGS, FLA. N2800-W8222.5/7.5 1956 PHOTOREVISED 1969 AMS 4540 Ill SW-SERIES V847 .5 0 1 KILOMETER CONTOUR INTERVAL 5 FEET DATUM IS MEAN SEA LEVEL

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TOPOGRAPHY OF THE TAMPA AREA The index map on this page shows the boundaries of the sixteen 7.5 minute topographic quadrangles which encompass the Tampa area. Seven of them have been photorevised. Space does not permit reproduction of each quadrangle, however, the Tampa, Gandy Bridge, and Sulphur Springs quads are discussed on subsequent pages. "' r-----T-_____ + __ T __ + ____ R __ 2o_E ____ + R 21 E I ODES-sA WESlEY CHA!PE 1 \ n942 -----------1 I II OlDSM i" R ]943 I I i I + n956 I I I i ]969 I ]956 ]969 BAY SONlO ]956 ]969 TAMPA BAY ]956 ]969/ 0 I 2 3 4 MILES SCALE ( ]955 I + (/) <0 "' + (/) 0 !<) + I I ------...... The simplified contour map presented here portrays the general topography of the Tampa area The interbay peninsula, and the coastal strip (which ranges from about 1 to 3 miles wide) are characterized by elevations rarely exceeding 20 feet above sea level. Low relief extends inland for some distance from the mouths of the river channels. The area gradually slopes upward to the north and east. Highest elevations are found within the Polk Upland (see Physiography Section) in the eastern part of the area. '""-, TAMPA \ \ I \ I HILLSBOROUGH I I BAY I \ I \ I i TAMPA BAY GENERALIZED TOPOGRAPHY of the TAMPA AREA M ll E S SC ALE 9

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1 0 U NI T E D STATES DEPARTMEN T O F THE INTER IOR O EO LOGIC A L S U R V EY i. J. , .. l .. eul<_ro....,loom .. ,olpi>Oiol''O'IO POle<""'< OOO ... IoQIO'"I' "" or>own A"'''""''""""'"""'t : oco..mpo>t>>l"lh S t o toolriO<..,o ao<>< tololol< nHio Oon\%9 '"' "'"'' '"'"not ... t ... ... ._,.,b,o .,,., CuNlOU R IN f(,;l ,., ," ' < ,.., "'"" N"'OON c '""" ccu.oc S,.N ..,,)S I / (' SULPH UR SP R I NGS QUA D R A NGLE FLORIOA-HILLS B O ROUCH C O 7.5 MINUT E SERIES (TOPOGRAP H IC) ... o:., I.,. I 2 6 . 3 4 . /r \ I I Ht; yJu-, -..... .,.,ty "''"'"""Out, ---0 ,,.,., .. , .. ..... u u """ ' 0 !'.ltc SULPHU R SPR IN G S, F LA 19 5 6 PH010R[VISE019fi9 I I Sulphur Springs Quadrangle The southern half of this quadrangle is highly urban i zed. Physically, two distinctive regions are evident -a lake region and a swamp region. T h e western part of the map exhibits a preponderance of lakes, whereas the eastern half co n tai n s almost none. The elevations of most lakes are printed on the map within the surface a r ea of the lake The northeastern quarter of the map is covered by wooded swamp, which accounts for the lack of development in that area With the continued growth of the University of South Florida community, it is conceivable that urbanization may push its way toward the swamps as developers attempt t o overcome the limitations of this hitherto low-priority land Another i n t eresting feature of the map is the cluster o f s i nkholes n ear 1 09th Street and Florida Avenue. T hese appear as ser ies of concentric circular contour Jines w it h h achure marks ind i cating a drop rathe r tha n a rise in eleva t ion Th e b l ue symbo l f or water appea r s in the ce nter of th e sinkholes o n t he origi n a l map but cannot be seen o n th i s r eprod ucti on Lake Ma g dalen e

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UNITED STATES DEPARTMENT OF THE INTERIOR GEOLOGICAL S URVEY 33 0 L D C"""' M '" wt ''""' "'" ""' ';,".:o::' !956 '"'"""""' USC$.G0 '""' t 587 P>IO">< 1921 NoHO '""''<"" O otum !0.000-1..,1 o.,.d on f"'""' ''"''"'"""<"'"" '""' .,.,, .... '"" .. .. The Gandy Bridge quadrangle exhibits the western half of the i nterbay peninsula. Much "made-land" and many alterations of the coast are evidenced by the artificial shape of the shoreline I n the northwest corner of the map, the mangrove symbol appears prominently along the coast. """!' " '" t>'l: MP CO>!Pc< I C MAPS ON0 S>Mf00l$1S .. A>lABlE ON EQUUT ( GANDY BRIDGE QUADRANGLE l]u GAN DY BRIDGE, FLA. NU5< : 5 1955 1%9 1> 1 NE-:ERIU (\ v G H B A Y Almost the entire Tampa quadrangle is urbanized. Man-made land extending into the Bay is characterized by straight shorelines. Many features of the Bay itse l f (water depths, channel boundaries) are found on this quadrangle '1 l"OSMAPCOMPCI(SWI1"NA100NAI.MPCO:VR5T>NO ... OS A ... TAM,:IA QUADRANGLE '"tt.,.H 82 JO TAMPA. FLA. >-12752 5 -W6222 7 J%9

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I .J ........... M [ _..,l .a [A 1 2 I \ I \ I \ I I I I I I / I I HILL RtVER HILLSBO ROUGH BAY 'OGRAPHIC MAP TAMPA BAY v...., UR1 a vERNON 1964 SHORELINE BY J.P MAYS A.P WRIGHT 0 4 MILES SCALE OUGH G e n era l ized L oc atio n s of l andfo r m s mod i fied fro m Puri and V ernon, 1964 POLK UPLAND 60 ) PHYSIOGRAPHY The Tampa area l ies within the major physiographic subdivision known as the Gulf Coastal Plain and in general exhibits litt l e var iation in physiography The terrain is flat and low-ly i ng, reflect ing the relatively low relief of the bedrock I n the eastern part of the area the land surface becomes gently rolling w ith smoothly rounded hills and shallow depressions On the basis of local physiog r aphic f eatures, the area can be divided i nto regions. T hese r egions have been d i sc u sse d i n detail by White ( 1970). Notable physiographic fea t u r es within the area are related to the marine o rigin of the region. Traces of ancient stands of sea level are found in parts of the study area where the landscape has not been greatly altered by fluvial processes GULF COAS T AL LOWL ANDS The western part of the Lowlands is very swampy and many lakes are present Relict marine features, such as bars, barrier islands, etc. formed during ancient stands of sea level are found in the Gulf Coastal Lowlands The area is largely covered by somewhat poorly drained sands with an organic pan and is characterized by flat topography and swamps. Sinkholes are scattered i n the northwest area and will be discussed i n greater detail later Each of the Pleistocene glacial stages was followed by an interglac ial stage during which the ice melted and the seas encroached on the land Each encroachment reached success i vely lower levels and consequently the remnants of interglacial shorelines can still be identified on land. These remnants provide clues to paleogeography. T he Pamlico shoreline represents an advance of the sea to an elevation of about 25 feet above present sea level From the configuration of the P amlico shoreline in the T ampa area, it can be deduced that thi s area was occupied by a large and more open es t ua r y during late P leistocene time. Several isl ands also existe d pr i marily i n the area of what i s now Pinellas County Relict sand dunes are found i n the Temple Terrace area. T he extent of the Pamlico shoreline is shown on the map T his i s t h e only Pleistocene shorel i ne that is w ell preserved in the Tampa area T H E CENTRA L HIG HL ANDS The Central H ighlands comprise a number of upland areas within mid-peninsular Florida Among these i s the Pol k Uplands which is of considerably less elevation and local relief than many of the other Upland features. T he general Central H ighlands also encompasses several lowlands i ncluding the Western Valley T hese lowland and highland features can be attributed to differential e r osion which reduced unprotected solub l e areas to l ower elevations, l eaving r esidual remnants of former regional upland areas T he Hillsborough River Valley: T he Hillsborough R i ver Valley trends northeast-southwest thr ough the central portion of the area and represents the southern end of the Western Valley whic h includes both the Hillsborough and Withlacoochee Rivers There is evidence that the Western Valley may have once held onl y one long st r eam Per iodically, the With lacoochee overflows into the Hillsborough R i ver via a topographic saddle T he Hillsborough River Valley has gently slop i ng to flat relief and is dissected by the Hillsborough River and its numerous tributaries. The size of H illsborough Bay into which the river flows, coupled with the fact that a Pleistocene shore l ine can be traced part way up the r i ver valley suggests that the Hillsborough River has existed for some t i me The river's broad, swampy flood plain is also indicative of an olde r r iver Although well drained, deep sands cover much of the a r ea, portions of the River Valley are swampy, and relatively few lakes are present The Polk Upland : The eastern part of the study area encompasses a small portion of the Polk Upland This area is topographically higher than the surrounding Coastal and River Valley lowlands and attains elevations of 100 to 130 feet. The terrain is gently rolling and bounded on the we s t by a scarp whose slope steepens toward the Hillsborough River. The area is covered by well drained sands which are mixed with phosphatic material in places.

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Because of the detail and accuracy of topographic maps and the relevancy of topography to land use, planners can utilize topographic maps for myriad purposes. Some examples are given below: Locating and Evaluating Mineral Valuable mineral deposits are often associated with physiographic features (arches, relict beach dunes, etc.) that are revealed on topographic maps. In addition, if the elevation of the top of an economic mineral deposit has been mapped, this map can be superimposed on a topographic map of the area and the land surface elevation minus the deposit elevation is equal to the thickness of overburden that will have to be removed prior to mining. Selecting Industrial and Residential Sites Topographic maps provide information that i s useful in selecting industrial and residential sites. Topographic maps can be used as base maps for showmg uttHty lines, access roads and waterways, zoning boundaries, potential water supply and the present i ndustri(!lresidential pattern of the community. Planning Recreation Areas Topographic maps are ideal for locating areas with unique physical attributes that may be suitable as recreation areas. Potential hiking and canoe trails can be sketched on topographic maps, then evaluated in the field. Lack of urbanization is often a primary criteria for recreation areas, and undeveloped land can be spotted at a glance on topographic maps. Defining and Evaluating Water Resources Topographic maps serve as a tool for planning watersheds, recharge areas, well fields, surface water supply sources, flood control structures, reservoirs, etc. Indeed their applications to hydrology are almost limitless. The map illustrates how surface drainage patterns and drainage basin boundaries can be delineated on a topographic map. Such flow nets are used in planning flood control and drainage projects and in correlating climatological conditions with surface water flow. TOPOGRAPHY AND LAND USE PLANNING Incorporating Physical Aesthetics in the Regional Plan In many areas there is an aesthetic quality to the "lay of the land". Creative planners can sometimes capitalize on inherent physical appearances by emphasizing the natural landscape in the land use plan. Topographic maps can be a starting point from which a land use design that is harmonious with natural features can be developed. N FLOW NET SKETCH DRAWN FROM CITRUS PARK QUADRANGLE '"""""" DRAINAGE DIVIDES 13

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WATER RESOURCES ------'D) -----(

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16 One of the consequences of urbanization is an increasing demand upon available water resources for public supply, recreation, industry and other purposes. As the competition for water intensifies, hydrology becomes a more prominent aspect of planning, and sound and equitable water management becomes a necessity. The hydrologic cycle is a fundamental concept in understanding, planning for and managing water resources. Fresh water on land is derived from ocean water evaporated by the sun's heat. Evapor&ted water in vapor form is transported by convective air currents through the atmosphere to inland areas, where part of the vapor condenses and precipitates. Rain that reaches the land returns either to the ocean by gravity flow or to the atmosphere by evaporation from land, water and plant surfaces. Before the basic cycle is completed, however, much interchange of water may take place between lakes, swamps, streams and the ground. Time required for a water particle to complete the cycle may vary from an instant to many years, depending on the path it takes. Once rain reaches the land surface its path depends on the terrain. Two important characteristics are the slope of the land surface and the permeability of the surficial and underlying materials. Steep slopes and low permeabilities 1promote the runoff of rainfall to streams or to lakes, swamps, and sinkholes which may or may not connect to streams leading to the ocean. Gentle slopes and high permeabilities promote the infiltration of rainfall into the ground. Much of the water that infiltrates is stored in a soil zone, serving to supply water for vegetation, but part of it moves down to the water table, ultimately to emerge at some lower level, usually in areas that contain or adjoin streams, lakes and swamps. In Hillsborough County water may also move downward into the Florid a n aquifer, which underlies the water table aquifer and i s generally separated f rom it by a layer of relatively impermeable material called a confining bed. Sinks in the bottoms of some WATER CYCLE streams and lakes may connect directly with the Floridan aquifer. Water in the Floridan aquifer eventually emerges as springflow in streams, lakes, swamps, or the ocean. Recharge to and discharge from the Floridan aquifer are dependent on the relative position of the waters involved and tne fact that water always moves from higher to lower elevations. Because water in the Floridan aquifer is confined, its potential elevation is represented by an imaginary surface, called the potentiometric surface, which is determined by the level at which water freely stands in tightly cased wells that penetrate the aquifer. Given the necessary openings in the confining bed, water can move into the Floridan aquifer from water bodies which stand above the potentiometric surface; conversely, the Floridan aquifer can discharge water into water bodies whose levels stand below the potentiometric surface. It is evident that all components of the hydrologic system are interrelated to form a delicate balance, and when one component of the system fluctuates, other components fluctuate similarly. This can be illustrated by the relationship between streamflow, lake and well levels. These levels respond to both natural and artificial alterations in the quantity of water within the system. Projects involving water withdrawal, addition, or diversion should be evaluated in terms of possible effects on the entire hydrologic system. ) JfMAt.'J,Jt,SOND !97! WATER LEVEL AND STREAMFLOW RECORDS INDICAT ING RELATI ONSHIP BETWEEN COMPON E NTS OF T H E HYDROLOG I C SYST E M SOLAR RADIATION EVAPORATION t t

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Ul w I u z z z 0 i=
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18 On one hand, the Tampa area is facing ever-increasing demands for water, which are difficult to meet with present supply sources ... A critical need exists to retain water on or below the land surface On the other hand, many acres of valuable land are flood prone and many additional acres are swampy and unusable throughout most of the year ... A critical need exists to dispose of, or provide facilities for the disposal of excess water. The polarity of these problems provides the greatest challenge to water management efforts. Ideally, projects which deal with one problem can be planned so as not to intensify the other; or water management can be directed toward alleviating, in part, both problems simultaneously. Water management projects in the Tampa area are currently underway by the U. S. Army Corps of Engineers and the Soil Conservation Service. UPPER TAMPA BAY WATERSHED Soil Conservation Service The watershed includes about 103 square miles in which the two principal problems are flood damage and drainage. The objectives of the SCS watershed project are 1) to protect improved pasturelands, citrus groves and other agricultural developments from flood water damage (2) to provide drainage outlets, and 3) to conserve water during the dry season. GENERALIZED DRAINAGE MAP ....,. DIRECTION OF SURFACE FLOW ----DIRECTION OF GROUND WATER FLOW DRAINAGE These objectives will be accomplished by land treatment measures, channel construction and improvement and installation of channel control structures. The average annual cost of the project ($160,000) compared to the average annual benefits ($212,340) places the benefit : cost ratio at 1.33 to 1. The main objective 6f SCS is to improve agricultural land, however, when lowlying areas are drained, they become suitable for other land uses which may have higher economic priority. Consequently, as land values increase the ownership and use of the land may gradually change Although SCS proposes to retain much of the drainage and flood water, evapotranspiration losses will be high, as all retention areas will be above ground. If the excess water could be rapidly recharged to the Floridan aquifer, more could be conserved and the raised potentiometric surface would reduce the threat of salt water encroachment. (One of the SCS structures can be seen in the soil portion of this study. ) FOUR RIVER BASINS PROJECT U.S. Army Corps of Engineers The objective of the total project is to deal with the following items: flood control, major drainage, navigation, recreational boating, water conservation, pollution abatement, and salt water intrusion. Several works of improvements are slated for the Hillsborough River Of special importance to the Tampa area are the lower Hillsborough River "Detention Area" (discussed previously) and the Tampa Bypass Canal. The Canal, when completed, will lead south from the Lower Hillsborough Reservoir and pass east of urban Tampa. During time of flood, it will divert water from the Hillsborough River directly to the bay It is designed to give urban Tampa maximum protection from floods including one so severe, its likelihood of occurrence is once in about 200 years. The benefit: cost ratio of the entire Four River Basins project is estimated at about 1.5 to 1. UPPER TAMPA BAY WATERSHED SOIL CONSERVAT ION SERVICE ----WATERSHED BOUNDARY CHANNELS AREA BENEFITTED !SOU RCE: PR OJECT MAP-UPPER TAM P A BAY WATERSHED! TAMPA BY -PASS CANAL -U.S. ARMY CORPS OF ENGINEERS --COMPLETED -TO BE COM PLETED !SOURCE : FOU R RIVER BAS INS, FLA. PROJE CT PLAN) TAMPA AREA DRAINAGE PROJECTS Sections of the Canal have been excavated below the top of the Floridan aquifer and below the level of the potentiometric surface. Here, newly made springs are discharging into the canal and the potentiometric surface is being lowered. It is hoped that an adequate number of control structures will be installed to raise the water levels in the Canal and thereby prevent a large decline in the potentiometric surface, excessive drainage from the aquifer, and salt water encroachment. (A view of the Canal can be seen in the Geology section of this study.)

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WATER QUAliTY A variety of chemical and biological constituents are present in water sources in varying amounts, and the quality of any water sample reflects many factors, including: Since all water "used" is actually "borrowed" and will eventually be returned to the environment in some form, a second consideration is important: 1) source of the sample 2) season during which the sample was taken 3) time of sampling --will the use add detrimental constituents to the water in such quantity that treatment will be necessary before the water can be returned to the environment? 4) specific locatioh and depth of the sample 5) nature of soils, rocks and vegetation that the water has contacted 6) kind and amount of matter that has been introduced to the water source by man. Water quality standards have been established for public water supply, shellfish harvesting, recreation, agriculture, industry, navigation and utility In addition, quality standards have been set for specific water uses such as production of carbonated beverages, pulp, canned foods, etc. These standards necessitate the following considerations in planning: Discharge of noxious liquid effluents is only one means of fowling a water body. Alteration of the land surface or landscape may also have detrimental effects on water quality. For example, removing vegetation from a construction site may accelerate erosion and increase turbidity in a nearby stream or lake. Detriment to the water resources may not be readily evident after a project has been completed, but it may be avoided if the possibility is considered during the planning phase of the project. -is the existing quality of the available water source suitable for a given use, or will extensive treatment be necessary? Constituent or property Bicarbonate (HC03l and Car bonate (C03) Calcium (Cal and Magnesium (Mg) Chloride (CI) Dissolved solids (TI:iSI Fluoride IF) Phosphate (P04) Silica (SiOz) Sodium (Na) & Potassium (k) Specific conductance (Kx 106) Sulfate ISO) SOURCE & SIGNIFICANCE OF CHEMICAL CONSTITUENTS IN WATER Source or Cause Produced by reaction of atmospheric C02 with water. Dissolved from carbonate rocks such as limestone and dolomite. Dissolved from most soils and rocks, especially limestone, dolomite, and gypsum. Magnesium is present in large quantities in seawater. Dissolved from rocks and soils. Present in sewage and abundant in ancient, and industrial brines and seawater. Chief mineral constituents dissolved from rocks and soils. Dissolved in small quantities from most rocks and soils. Enters many water from fluoridation of municipal supplies. Decaying organic matter, sewage, fertilizers, and nitrates in soil. Dissolved from many rocks and soils. Some from fertilizers, detergents, domestic and industrial wastes. Dissolved from most rocks and soils, usually in small amounts from 1-30 mg/1. Dissolved from most rocks and soils. Found in ancient brines, seawater, industrial brines, and sewage Measure of the ability of water to conduct electrical current. Dissolved from rocks and soils containing gypsum, irorl sulfides, and other sulfur compounds. Usually present in sewage, mine waters and some industrial waters. Significance. Maximum tolerable concentraiiorl for public water supply is shown in parentheses HC03 and C03 produce alkalinity. In combination with calcium and magnesium, cause carbonate ha r dness. Cause most of the hardness and scaleforming properties of water; consumes soap. About 300 mg/1 in combination with sodium gives salty taste to water. Increases the corrosiveness of water. (250 mg/1). Water containing more than 1,000 mg/1 of dissolved solids are unsuitable for many purposes (500 mg/1 ). Fluoride in drinking water can reduce tooth decay but may cause mottling of teeth depending on concentration and other factors (1 .4 to 1.6 mg/1 depending on air temperature). Concen trations much greater than the local average may suggest pollution. Nitrate encourages growth of algae and other organisms which produce undesi r able tastes and odors. Phosphates stimulate the growth of algae. Excessi'(e amounts may indicate pollution from phosphate mining or domestic wastes. Forms hard scale in pipes and boilers. Inhibits deterioration of zeolitetype water softeners. Large amounts, in combination with chloride, give a salty taste. High sodium content may limit the use of water for irrigation Specific conductance is directly proportional to dissolved mineral content of water. Can also be related to individual constituents in water. Sulfate in water containing calcium forms hard scale in steam boilers. In large amounts, sulfate in combination with other. ions gives bitter taste to water (250 mg/1). Modified: M. E. Beard, 1969, The Florida District Water Quality Laboratory: LAKE MAGDALENE APRIL,I971 = 250 mq/l WATER QUALITY IN THE TAMPA AREA SHOWING RELATIVE PROPORTIONS OF TOTAL DISSOLVED SOLIDS AND CHEMICAL CONSTITUENTS OF TOTAL DISSOLVED SOLIDS. (Data from: U.S.G.S. Provisional records) SHALLOW AQUIFER FEBRUARY, 1970 DISSOLVED SOLIDS CONSTITUENTS CALCIUM (Ca) CARBONATE (C03) MAGNESIUM (Mg) 0 D D D SODIUM PLUS POTASSIUM (Na + K) CHLORIDE, FLUORIDE & NITRATE (CI, F and N03) 19

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LAKES The Tampa area is dotted with numerous lakes which are especially abundant north of the city (see map). Here, lakes are concentrated on a low sandy ridge which is 20 to 40 feet higher than adjacent poorly drained swamplands. Some lakes occupy depressions that intersect the shallow water table. Water levels in these lakes respond to changes in water table elevation. Other lakes occupy partly filled sinkholes or cavities connected to the Floridan artesian aquifer, and fluctuate with the potentiometric surface. A third lake type is found in depressions lined with relatively impermeable material perched above the water table. Although water levels in all lakes are affected by rainfall and evaporation, perched lakes depend almost 65 Llke SteLper vvv 6 57 _J Q) .0 0 -., Starvation Lake /"'--y'\-(\{\-\!"\ FJ" (\[\ kf entirely on rainfall to maintain their levels. It is doubtful that perched lakes in the Tampa area would have any permanence, as such lakes in the Tampa climate would soon be filled with vegetation. Underground movement of water to or from a lake depends on the relationship between lake level, water-table level, potentiometric surface, and the nature of the deposits underlying the lake. J. W. Stewart ( 1968, p 118) has found that the decline in levels of some lakes near the well fields in northwest Hillsborough County was in part due to the cumulative effects of well pumpage. In order to prevent large fluctuation. in water leve l control structures have been i nstalled at many lakes in the Tampa area. WaJ Table lake ('v I 48 a; 1 \ Connected with Floridan Aq uifer, > Q) _J Q) 0 44 :;t 40 20 -1960 61 62 N Round Loke Connected with FloridanAqu i fer, Contcolle d by pu m p m g / gcoun d watec ;nto I\J \J 63 64 65 66 67 6 8 69 7 0 7 1 72 48 56 5 2 HYDROGRAPHS OF S ELECTED L AKES IN THE T AMPA AREA LAKE LEVEL CONTROLLED BY: 0 SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT STRUCTURE) HILLSBOROUGH COUNTY STRUCTURES 0 2 3 SCALE ) East ,!' 'fi)Mango DISTRIBUTION OF LAKES IN THE TAMPA AREA {INFORMATION FROM S.W. FLA. WATER MANAGEMENT DISTRICT} @) .Weeks .Hooker jLong 'Valr7co

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The chemical quality of lake water is an important factor in the continued use of lakes in the area. Although the quality of lake water is generally good, the total dissolved solids in several of the larger, more urbanized lakes in the area are increasing with time. Conductance and turbidity of several local lakes are shown in the graph. A decrease in the quality of lake water may reflect either the direct addition of contaminants to the lake water such as by surface drainage or indirect addition by seepage. Lands with high animal populations, septic tank fields, or receiving high pesticide applications may indirectly contribute contaminants to a nearby lake. Eutrophication is another factor which threatens lakes. This is the enrichment of water with nutrients that promote excessive plant and animal growth. Eutrophication accompanies the natural aging process of a lake, but may be greatly hastened by the activities of man. Study is essential to determine which lakes are under accelerated enrichment before any corrective measures can be employed. During the developments of subdivisions, dredging of lake bottoms is sometimes undertaken to increase the size or depth of a lake and provide fill material to adjacent property. Such projects have the potential to disturb the ecology of the lake basin, change the drainage area, remove impermeable material from the lake bottom with consequent altering of lake level characteristics, and render the lake highly turbid. Extremely fine particles suspended in lake water may not settle for many years. WATER QUALITY AT SELECTED LAKES, 1970 AND 1971 In some areas, new man-made lakes have been created. It is clear that a thorough investigation of the geology and hydrology of the area must precede such a project. With careful planning, some borrow pits may be reclaimed and converted to lakes bordered by attractive landscaping. Lakes in the Tampa area are utilized largely for recreation and residential focal points. Property values usually increase with proximity to a lake. Continued recreational and residential benefits hinge on maintaining adequate chemical quality, and reasonable water level fluctuations. Some range of fluctuation in lake level is conducive to the health of the lake. Some of the potential lake problems which should be considered in developing and managing lakes and adjoining property are: 1) lakefront flooding 2) abnormal recessions in lake levels 3) sedimentation caused by stripping nearby terrain (a special threat during the rainy season) 4) contamination from: a) septic tanks b) outboard motor oil c) storm runoff from urban areas d) runoff from agricultural or farm-lands (pesticides, nutrients) A lake planning and management model is presented on this page. TURBID I TY SPECIFI C CONDUCTANCE 0 MAGDA L ENE CALM HOBBS LIPS E Y STARVAT I ON D A N 10 1 5 20 J ACKS ON TURBIDITY UNIT S I FROM U S G S PROVISIONAL RECORDS ) MMHOS Cost of Preventing Pollut ion from Entering the Lake ,-, I I Runoff-Over land Flow and I I lnterflow 1 I i-1 R unoffStor m D r ainage System I Q_ I L _j Wells (or) Municipal Supply Cost of Inflow Augmentation From U S.G.S Circular 601-G, Real Estate Lokes,D A Rickert and A M Spieker Discharge to Streams URBANI Z E D LAKE Outlet on Flo o d and Drowdown Controls SCHEMATIC DIAGRAM OF A BASIC LAKE PLANNING AND MANAGEMENT MODEL. Shoreline of Lake Thonotosassa (photo by R.C. Reichenbaugh) Typical circular collapse structure. (photograph by J .W. Stewart) "To improve lake quality three major things must be accomplished: 1. The nutrients must be reduced in the lake and future sources of input reduced or stopped. 2. A significant zone of rooted aquatic vegetation must be maintained. 3. The lake must be allowed to fluctuate in a manner similar to the historical natural fluctuation of the lake Southwest Florida Water Management District Hydroscope, Vol 3, No. 11. Cost of Water Q u ality Improvement Cost of O utflow Regulati on 21

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STREAMS Excluding the Hillsborough River, which will be treated separately, there are four major streams within the Tampa area which discharge into Tampa Bay. Streamflow is highly variable seasonally as well as annually due to climatological conditions. Water in the four streams is generally not of the highest quality because of the addition of urban wastes to streams within the Tampa area and contamination from upstream sources which may be outside the County. The ultimate recipient for all streamflow from the area, Tampa Bay, receives 328.400 pounds of suspended solids per year from sewage treatment plants alone. Some important points, regarding streams, that should be land use planning considerations include: Any development which alters the topography will likely alter the drainage pattern in the area. --Any emplacement of contaminants in a stream may endanger the downstream uses of the water. --The lower the flow in a stream, the greater the chances for salty bay water to move upstream. T>JI!O consequences of the movement of bay water inland during low flow are: mineralization of the stream itself, and seepage of brackish water into the aquifer. Competent and effective drainage basin management is mandatory if the effects of drought, flood and pollution are to be minimized and stream channel aesthetics maintained. 22 Land use planning for riverfront areas must be prudent. An assessment should be made of present riverfront land use, and existing physical, chemical, and biological conditions of the stream. In addition, an order of priorities (or a downstream order) for use of the water and waterfront ands should be established. Stream channel segments may be designated as: --sites for historic monuments or archaeological sites, --sites for scenic or 'aesthetic natural areas, --sites for water supply plants, dams, bridges, canals, --recreational sites, --low or high density residential sites; --industrial sites MEAN STREAMFLOW AT GAGING STATIONS 1 /619nO ) HILLSBOROUGH HILLSBOROUGH BAY APPROXIMATED DRAINAGE BASIN BOUNDARIES IN THE TAMPA AREA, and ESTIMATED AVERAGE I FLOW AT MOUTHS OF THE STREAMS. (Source: U.S.G.S. provisional drainage maps) SIXMILE CREEK COASTAL DRAINAGE COASTAL MILES

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Sweetwater Creek Alafia Riv&r R ocky Cr eek ( Stream Alafia River Sixmile Cr. (Palm River) Rocky Cr. Sweetwater Cr. Total Drainage Basin Area 460 mi? 40 mi2 45 mi? 25 mi? Average Discharge at gage1 Period of Record 249 mgd 38 yrs 39 mgd 13 yrs 25.8 mgd 17 yrs. 4 9 mgd 19 yrs STREAM CHARACTERISTICS Estimated Average Maximum Flow at Mouth2 Date 369 mgd 29,651 mg d 9/7/33 56 mgd 833 mgd 9/11/60 33.3 mgd 1835 msd 7 /29/60 16.5 mgd 283 mgd 3/17/60 CHEMICAL QUALITY3 (Samples taken at gage) P04s D a t e Sewage Pla n ts mg/1 Sampl e d Discharging t o Stream Stream Total d i ssolved Chloride pH solids mg/1 4 mg/1 units Alafia River 457 80 7 6 25 4 /26/71 5 Sixmile River 269 17 7.9 0 .21 5 /22/70 2 (Palm Rive r Minimum Flow Date 4 .26 mgd 6/5,6/45 2 8 mgd 5/27/62 NO FLOW 4/7-5/5/67 NO FLOW Often Pollution Loads discharged To Tampa Bay (lbs /day) Total Filte rable NH4 + N02 Total Re sidue + N03 P04 16,760 6870 43.470 3570 170 100 Disc h arge from treatment pl a nts (lbs./ d a ys) Rocky Cr. Sweetwater Cr. 150 138 23 24 7.3 6 6 0.13 5/13/71 0 .94 5 /9/70 1 Gaging station locations shown on may on preced i ng page. 2 Discharge at gage times basin factor (ratio of total drainage area to area above gage) plus any springflow downstream from gage (Data from: 3 4 B O D SUSPENDED SOLIDS 31 38 385 580 3 From U S G S p rovis i onal water quality data 4 Re sidue at 180 C 5 Orthophosphates as P04 2 3

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20,000 10.000 5000 2000 1000 500 Q) Q. E 0 U) 200 E 0 Q 100 Q) a. c: ::l 50 0 E 0 0 20 10 5 2 0 The Hillsborough River rises in the Green Swamp area south of the Withlacoochee River. Crystal Springs, Suiphur Springs and numerous small springs feed the river. The channel is about 54 miles long and flows through Polk, Pasco and Hillsborough Counties. Tampa has acquired the majority of its water supply from the Hillsborough River since the mid twenties. The water treatment plant, located at the dam near twentysecond Street, has a capacity of 60 million gallons a day (mgd). The "firm flow" of the river is estimated to be 50 mgd. During 1971, pu mpage averaged 49 mgd (see figure 1) I I I I I I -1 --I w v v I I \ N rIrrI 1 I 1 l J 1966 67 68 69 70 71 72 Data from City Water Dept. FIGURE 2 COLI FORM CONTENT AT PLANT INTAKE CITY WATER WORKS AT HILLSBOROUGH RIVER OAM 24 HILLSBOROUGH RIVER In 1964, the Tampa water supply was augmented by f low from Sulphur Springs. During periods of low flow in the river, 20 mgd have been diverted from the Spring to the Reservoir Currently, the firm available supply of the Hillsborough Reservoir does not meet the water needs of the City, and plans for deve lopment of well fields are being implemented. The quality of water from the Hillsborough River is not ideal. High values are obtained for turbidity, settleable solids, color, odor, and taste. Treatment by the city water plant includes flocculation, sedimentation, filtration, chlorination, algae control, coagulation, stabilization, clarification, pH control, and taste and odor control. Hillsborough River Total drainage basin area 690 square miles 428 mgd/32 years 485 mgd A notable problem in water quality is the presence of a disturbing number of coliform bacteria1 (figure 2). Only one of 13 samples taken from the swimming area of the H illsborough River State Park between January 1 4 and July 27, 1971 by the Hillsborough County Health Department was found to have less than 1000 bacteria per 100 milliliters (ml) (the upper l imit for public water supply according to state law). 2400 bacter i a per 100 m l were found in water samples collected from the stream from the dam upstream to the Polk County line The effluent of at least six sewage treatment plants f i nds its way to the Hillsborough River-four of these plants are in Polk County. Average discharge at gage/period of record Estimated average flow at mouth Maximum flow/date Minimum flow/date CHEM I CAL QUALITY *9432 mgd/3-21-60 *none/11-30 to 12-2-45 SAMPLED 5/15/69. Total dissolved solids (mg/1) Chloride (mg/1 J pH (units) Nitrate (mg/1) Sewage plants discharging to stream POLLUT I ONAL L OADS discharged TO BAY Total filterable residue NH4 + N02 + N0:3 Total phosphate (Data from U S .G .S. water quality r ecords) 195 16 8.5 1.7 6 (4 in Polk County) 11.470 lbs./day 2501bs./day 630 lbs./day ) Another problem is the presence of water hyacinths, which at times cover Tamps's entire water supply reservoir. Hyacinths a r e treated with a chemical herbic i de (2-4 D) and sink to the bottom of the Reservoir or are discharged downstream. The hyacinths are a h indr ance to recreational uses of the river. Also when they are discharged to Tampa Bay and decompose, each acre of hyacinths can contribute 200 pounds of nitrogen and 26 pounds of phosphate (Florida State Board of Health. 19651. 1 Source-intestinal tract of warm blooded animals; significance--general indicator of pollution. 40 AVERAGE DAILY 35 PUMPAGE (MGD) 30 1100 1000 900 800 700 600 500 400 300 200 100 MEAN DAILY DISCHARGE (MGD) *these figures do not include water div erted for use by the City of Tampa FIG. I DISCHARGE OF HILLSBOROUGH RIVER ( PUMPAGE FR O M RIVER BY CITY O F TAMPA WATER DEPARTMENT. +

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Much of the land adjacent to the Hillsborough River is being acquired for construction of the Lower Hillsborough River Flood Detention area in Hillsborough County and the Upper Hillsborough River Flood Detention area in Pasco and Polk Counties. These areas will be set aside for temporarily detaining flood waters during extreme high flow conditions. The multi-use concept will be employed in the Lower Hillsborough River Detention area. Much of the area is still in a wilderness state and lends itself to recreation and conservation. Exclusive of the primary purposes of the reservoir (prevention of flood damage and improvement of ground water levels), land-use plans for the reservoir area include: 1) development of a well field in the western portion 2) establishment of a high intensity day use recreation area to be leased to local agencies, Th6 University of South Florida, and Tampa University 3) incorporation of a portion of the reservoir in the existing program of Hillsborough River State Park 4) leasing of lands to the Florida Game and Fresh Water Fish Commission for management purposes and limited hunting. PASCO COUNTY ---------Hl LlssoRouGH-------------C-OUNTY----Source= S W Fior ido Management Distri ct ( EXPLANATION STATE OWNED PARKLANDS HIGH INTENSITY DAY USE AREA TO BE INCORPORATED IN L__j HILLSBOROUGH RIVER STATE PARK r--1 WILDLIFE MANAGEMENT and L__j CONTROLLED HUNTING LOWER HILLSBOROUGH RIVER RESERVOIR RECREATION AREA. In addition, over seventeen miles of the r i ver channel in Hillsborough and Pasco Counties has bel!n proposed for designation as a scenic river and canoe trail by the Florida Division of Recreation and Parks This means that the natural environment of this segment of the river will be p r eserved for public enjoyment. The Hillsborough River is a tri-county resource. Regional planning is obviously the basis for successful maintenance and management of the river channel. SCENES AT HILLSBOROUGH RIVER STATE PARK 25

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---------------P..!.!,C EXPLANATION HILLSBOROUGH BAY ABSENT or DISCONTINUES i D o-5' 5'-10' I I TAMPA D 1o'-15' I : BAY DEPTH BELOW LAND SURFACE, IN FEET, OF SHALLOW WATER TABLE I 26 (Stewart and Honan, Mop Series 39,1970). 0 2 3 4 MILES ) WATER TABLE The sandy surface deposits in Hillsborough County generally contain water. The upper surface of the saturated zone is the water table. Water table contours generally follow topographic contours with the water surface lying a few feet below land surface. The level of the water table fluctuates primarily in response to rainfall, which is the principal source of recharge to the shallow aqu iter. Discharge of water from the aquifer is by seepage into lakes and streams, drainage from canals and ditches, evapotranspiration, pumpage from wells, and natural drainage from springs. In some places, the water-table aquifer is hydraulically connected to the underlying artesian aquifer. The primary uses of the shallow aquifer are: 1) as a source of recharge to the Floridan aquifer 2) as a source of water for lawn irrigation. Wells can be driven or drilled into the water table aquifer easily and inexpensively, but because the water produced is small in quantity and of poor quality, it is not useful as a source of public supply. Since the water table lies so close to land surface, the shallow aquifer is suspectible to pollution. Pollution of the shallow aquifer should be carefully avoided in areas where it rapidly recharges the Floridan aquifer, perhaps our most valuable water resource. J THE WATER TABLE

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AND SWAMPS The type and abundance of native vegetation present in an area is in part dependent on the position of the water table with respect to land surface. Where the water table is above land surface, lakes or swamps occur. Swamps, cypress domes or bayheads represent a distinct ecosystem in which the flora and fauna are specifically adapted to the environment. Development in low-lying wetlands is preceded by drainage, filling, or both. Since the swampland biota is dependent on the presence of excessive water, drainage or filling results in a relatively barren landscape. Another limitation of swamps for deve1opmerit is the character of the subsurface material. Many swamps are underlain by thick organic or peaty deposits which form unstable foundation conditions for many types of construction. In addition, low-lying areas are generally flood prone. Despite the limiting factors, many swamplands have been successfu lly developed for a variety of land uses. Prior to developing swamplands, the potential destruction of a unique habitat sho uld be considered. WATER LEVEL IN WATER TABLE WELL NEAR TAMPA, AND ACCUMULATED PRECIPITATION MINUS ACCUMULATED EVAPOTRANSPIRATION AT TAMPA 4 w (.) <( u. cr 5 :::> en 0 0 w z 1<( <( ..J 6 8 ..J ::: :::> 0 ::;! ..J 7 :::> w Urn co Uw 17 6 <(J: UJ cnu UJ :::>Z u. zz -z ..J 8 4 c.: z" UJ -o > (.)_ UJ UJt-..J 3 0:<( a: c. a: UJ 9 o12 we. <( l-en ::: <(z 1 ..J<( ::>a: 10 0 ::>c. (.)<( U> <(UJ J F M A M J J A s 0 N D 1971 ( Unique swampland biota (photo by J W. Stewart) A flourishing swamp (photo by J. W. Stewart) .I 27

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28 FLORIDAN AQUIFER The Floridan aquifer is the principle source of ground water in the state. It includes the Lake City, Avon Park and Ocala Limestones (Eocene age). Suwannee Limestone (Oligocene). Tampa limestone and parts of the Hawthorn Formation (Miocene). It is exposed at the surface in some areas and underlies several hundred feet of sediments in others In the Tampa area, the top of the Tampa limestone can be considered the top of the Floridan aquifer. The aquifer is artesian, and in some places wells that penetrate it flow. An aquifer is artesian when it is confined by an impermeable layer and the water in the aquifer is under sufficient hydrostatic pressure to cause it to rise above the base of the confining bed in wells. The level to which water will rise in wells penetrating the artesian aquifer is called the potentiometric surface. When the potentiometric surface is above land surface, the well is said to be flowing. Water in the Floridan aquifer moves into Hillsborough County from counties and most fresh water discharge from the aquifer occurs inland of Tampa Bay. Currently, the Floridan aquifer produces a large quantity of good quality water from wells in the Tampa area, however, decline in water quality and/or severe reduction of water stored in the aquifer can result from improper land use or shol"t-sighted planning. Recharge or "replenishment" of water to the aquifer takes place where the confining layer is thin or absent and rain water can infiltrate permeable surficial deposits and percolate into the aquifer itself. Recharge occurs also as leakage through the confining layer wherever the altitude of the water table exceeds the altitude of the potentiometric surface of the Floridan aquifer. Recharge areas should be identified and land maintained as "open space". In addition, recharge in these areas can be accelerated by artificial means. When development occurs in recharge areas, the wastes associated with urbanization have ready access to the aquifer and can damage water quality. Likewise, pavement (the ever-present foundation of urbanization) prevents water from infiltrating the soil and greatly reduces the recharge potential of an area. FLORIDAN AQUIFER PERMEABLE LIMESTONES THE AQUIFER Recharge can also take place through sinkholes that breach the confining layer. Great damage to the quality of water in the aquifer can result when sinkholes are used as dumps or waste basins. Another threa.t to the aquifer in any coastal area is salt-water encroachment. At depth saline water underlies the fresh water in the aquifer. Theoretically, the depth below sea level to the top of this saltwater is forty times the height of the potentiometric surface above sea level. Or, for every foot that the potentiometric surface is lowered, salt wat.er moves forty feet upward in the aquifer. During the twenties, public supply wells for the City of Tampa were abandoned due to ever increasing salinity in the watet. This is the result of drilling wells too close to the coast, too deep, or overpumping them. Salt-water encroachment can also take place when canals are dredged inland from the coast. If the aquifer is exposed by the excavation, the potentiometric surface would be lowered as fresh water was drained to the ocean. During periods of low water levels and high tides, salt water ih the canals can move inland and contaminate the aquifer. Construction of dams or water level control structures near the coast can reduce potential salt water encroachment in such canals by maintaining a higher fresh water level. RECHARGE ) POTENTIOMETRIC SURFACE IN FEET ABOVE MEAN SEA LEVEL 0 1 2 3 4 MILES F r om : U.S.Geological Survey Hydrologic Investigations Atlas HA OCEAN 40' eo' FRESH SALT WATER SALT WATER ENCROACHMENT WATER

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APPROXIMATE DEPTH BELOW lAND SURFACE TO THE BASE OF POTABLE" WATER IN THE FLORIDAN AQUIFER EXCEED 250 MILLIGRAMS PEA LITER AND ITS DISSOLVED SOLIDS CONTENT DOES NOT EXCEED 500 MILLIGRAM S PER LITER Wells and a storage tank in a northwest Hillsborough County well field. These wells pump large amounts of potable water from the Floridan aquifer. ( AND SPRINGS Water table springs generally occur where the permeable material in the water table is exposed or crops out in a ditch or along the side of a steeply sloping bank. Artesian springs are found where the limestone aquifer lies at or near land surface and the potentiometric surface is higher than land surface There are five large springs in the Tampa area and these have been studied by the U. S. Geological Survey. In addition, there are innumerable small springs in the area that have been flowing for years. Springs can be used to supplement water supply and are a valuable asset to recreation areas. Continued use of springs for these purposes is dependent on maintenance of water quality through wise management of recharge areas which supply the spring s SPRING D I SCHARGE IU.S.G. SJ SULPHUR BUCKHORN LITHIA JQ 4 llKJd fi/5/70 685 mgd 6/5.'72 7 04 mgd 5 ;21/70 ESTIMATED D I SCHARGES From Mf'nke, CL31.,1961 UNNAMED 1 43 mgd UNNAMED 2 . 03 mgd BLUE S INK TRINITY PURITY 72 mgd RICHARDSON 30 mgd LOWRY 04 mgd UNNAMED 3 02 mgd unnamed UNNAME04 02 mgrl UNNAMED 5 .. 14mgd NORTH PARK 07 mgd EUAEKAI 4 Sprong$1 .6.07 mgd JACKSON . 01 mgd OAK .... 14mgd MAGBEE ... 43 mgd CRAFT MINERAL 22mgd DESHONG . .03rngd PALMA CEIA 07 mgd MESSER . 72 rngd f ; l \ Scenic Lithia Springs, a popular recreation area. V ALRICO 29

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30 WATER USE Water in Hillsborough County is mainly used for irrigation, industry, and public supply. In 1970, about 69 mgd was used for irrigation and 56 mgd for indu stry Most of this water was self-supplied. Twelve of the major public supply systems are shown on figure 1. Their combined pumpage for 1971 (or 1970, as indicated on the map) was 33,933 million gallons o r 93 mgd. About a third of this water was removed from Northwest Hills borough County for use in Pinellas County. There is a vast quantity of fresh water within the Tampa Bay region, however, only a portion of it can be withdrawn from the hydrologic system without creating se ri ous environmental r epercussions (declining lake l evels, parched vegetation, etc.) G. G. Parker ( 1972) states that "If we can capture for our consumptive use more than one-third of runoff, we will be fo rtu nate indeed." For the Tampa Bay region (Hillsborough, Pinellas, Pasco, and Manatee counties), Parker estimates one-third of the runoff to be on the order of 254 billion gallons per year or. 695.4 mgd. Projected water needs for the Tampa Bay region are illustrated on this page. The REGIONAL WATER NEEDS In million gallons per day figures a r e based on population projections in "Florida Land and Water Resources, Southwest Florida, 1966", and the assumption that 300 and 500 gpcd represent reasonable minimum and maximum figures for regional needs Although the picture apparently looks grim (interpolation indicates that water demand will equal water supply in 1973 at the 500 gpcd rate of withdrawal or 1987 at the 300 gpcd rate), two factors should be borne in mind as the illustration is examined: 1) The figures are based on the assumption that the water withdrawn is permanently consumed. They do not take into account the fact that much water that is withdrawn is re-cycled or at some time returned to the hydrologic cycle and therefore, much is not permanently consumed 2) As time goes by, greater sophistication in water management will improve the outlook. A water use projection for Hillsborough County is also shown on this page. This graph applies Parker's per capita water use rates (300 and 500 gallons/day) to the population projections for Hillsborough County published by the Hillsborough County Planning Commission in April, 1972. At 500 GPCD I Gallon s/capita/day! At 300 GPCD From: G. G. Parker ,SWFWMD >
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The water problems of Hillsborough County have been widely publicized. Much of the problem can be attributed to the inadequacy of the facilities rather than the sources. Governmental agencies and private consulting firms have submitted innumerable recommendations for remedial actions to alleviate the City's and County's water problems. Some of the measures suggested include: 1) establish flood retention reservoirs 2) develop the Lower Hillsborough River Reservoir well field immediately 3) establish control structures on dams and streams to reduce salt-water encroachment 4) supplement the water supply by pumping water from sinkholes 5) investigate the possibility of acquiring springs in neighboring counties 6) create recharge facilities for rapid replen ishment of water to the aquifer 7) reduce waste of water by plugging abandoned flowing wells, and encouraging re-use of water by industry and agriculture 8) treat and re-cycle waste waters INDUSTRY AND COWWERCIAL ( P U 8 Ll C S U P P L Y) 2:4% LEC TRIC POWER (PUBLIC SUPPLY) 0.7% HOW FRESH WATER IS USED IN HILLSBOROUGH COUNTY ( Many of these plans are now being implemented. The seriousness of the water situation and the suggested courses of action highlight the role that hydrology must play in land use planning. Hillsborough River dam. (photo by W. M. Woodham) WATER USE FACTS Number of industries in Hillsborough County1 Number of electrical power plants1 Population served by public supply2 Population served by ground water2 Population served by surface water2 Number of acres irrigated2 Saline water (self-supplied)2 Used by industry Used for thermoelectric power Cost of water1 650 3 370,000 65,000 305,000 47,000 86.4 mgd 1899 mgd From Hillsborough River $92.74/million gallons From Lower Hillsborough Reservoir Well Field $31.71/million gallons 11971 Data 21970 Data I .. COSME LJTZ 4,752 fT'Ig : 6,3'59 'T'g .. Hillsborough WATER SUPPLY SYSTEMS and Bay 1971 WATER WITHDRAWAL EXPLANATION mgrni lion ga l lons -!970 Doto -Well "' uTLI E:;, ElRAr-.DON: WATE.R and SEWAGE CO. 681' rng .;6 >I :. JilLlrlES 66 n" HILLSBOROUGH CO. \ IVERVI EW) 224 mg 31

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32 FLOODING "Those of us who work in the water management field know that some of the multimillion dollar public works projects that we are now constructing could have been prevented if the citizens had simply not been allowed to construct their houses, businesses and developments on land that is often flooded by the stream, creek, river or lake that it abuts. Yet, day after day, we see more and more marginal and submarginal land being developed and sold often times to unwary buyers who after the first normal rainy season or two, come to us and demand flood control. We believe that much of their anquish and heartache and l ots of public works money could be saved if the construction process included a requirement for full knowledge of the historic or predictable water conditions at that site so the proposed construction could be accommodated to the conditions, or be prevented altogether." Dale Twachtmann Ex-Executive Director Southwest Florida Water Management District Everyone is aware of the loss of life and property often associated with floods, but unfortunately, not everyone is aware of the flooding potential of the area in which they reside. Many flood prone areas have already been developed, and others are in the path of urban expansion. Now is the time to strengthen controls on flood prone land and provide 1) a zoning classification which would prevent development in these areas, and/or 2) guidelines for construction in flood prone areas where development is allowed. Additional drainage projects could provide even more widespread flood protection, but such projects are costly and may tend to diminish regional water resources. Results of Hurricane Agnes, June, 1972. (photo by Bill Wood) )

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1000 0 1000 2000 3000 4000 5000 6000 7000 FEET The l arge map presented here was constructed by compiling and reducing all the 1:24000 scale flood prone quadrangle maps of the Tampa area which were completed by the U.S Geological Survey. The detail above shows a small area at the actual scale of the 1 :24000 maps. The following explanation appears at the base of each quadrangle map of flood-prone areas, and is quoted verbatim: The purpose of the flood-prone area maps is to show to administrators, planners, and engineers concerned with future land developments those areas that are occasionally flooded The U.S. Geological Survey was requested by the 89th Congress to prepare these maps as expressed in House Document 465. The flood-prone areas have been delineated by the Geological Survey on the basis of readily available information. Flood-prone area maps were delineated for those areas that meet the following criteria: (1) Urban areas where the upstream drainage area exceeds 25 square miles, (2) rural areas in humid regions where the upstream drainage area exceeds 100 square miles, and (3) rural areas in semiarid regions where the upstream drainage area exceeds 250 square miles. This map indicates only areas that may be occasionally flooded, and provides no infor mation on the frequency, depth, duration, and other details of flooding. Larger areas than those shown on the map may be inundated by less frequent floods Flood-hazard reports provide the detailed flood information that is needed for economic studies, for formulating zoning regulations, and for setting design criteria to minimize future flood losses When detailed information, such as that contained in the flood-hazard reports, is required, contact the U S. Army, Corps of Engineers; the U.S. Geological Survey; or the Tennessee Valley Authority in the areas of their jurisdiction. ( BAY ( I I I I FLOOD PRONE AREAS I TAMPA ______________ j BAY 0 2 Miles Scale 33

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.. .. . . -----------------. . :. :: : .. . . .. .. .. . . 0 ----:::.-----( . ...... . .. .. .. .: .. : :. : . . .: .. . -. . ... . . --.l_ I .. GEOlOGY 0 0.: ::: :.. .... -... 0 .. : . . . . 0 0 .... .. .... ... .. ...... -------__ ---;:::::::__ -/ I /

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36 Depending on the depth, temperature, and circulation of the water, varying assemblages of organisms flourished and their skeletal remains make IJP much of the sedimentary sequence. The physical characteristics of the rocks and the fossils they contain enable the geologist to reconstruct a picture of the ancient geography and environment. During Paleocene and Eocene time, the Tampa area was covered by open ocean in which layers of limestone were deposited. Intermittently, the seas regressed and the limestone was subjected to weathering. As sea level fluctuated, the local environment changed and limestones with slightly different physical characteristics and dissimilar fossils were deposited in succession. At the close of Eocene time, the seas retreated from the Tampa area and did not return until later in Oligocene time. The nature of local late Oligocene sediments indicates that they were laid down in a warm, quiet, shallow sea in which mollusks and micro-organisms flourished. The limestones are relatively pure and of economic value in those parts of the state where they are available to surface mining. GEOLOGIC HISTORY The geology of Florida is reflected in the topography of the state, the nature and occurrence of water resources, the character of soils, and the type and extent of valuable minerals. As all of these are important factors in land use planning, the planner should be knowledgeable about what lies the land surface. Beneath the Tampa area, there are several thousand feet of carbonate rocks (chiefly limestones) which were deposited during Cenozoic time. These rocks overlie sandstones, shales and igneous rocks of Mesozoic and Paleozoic age. The thick carbonate sediments were deposited in the warm, shallow seas that covered all of peninsular Florida at one time or another during the Cenozoic era. Accumulation of these sediments was accompanied by subsidence of the land surface with numerous transgressions and regressions of the sea. When sea level was low the emerged land areas were exposed to erosion; consequently, the rock record is not complete. Photo by R.C. Reichenbaugh -CENOZOIC .SHORELINES In FLORIDA From, Bulletin 29, Florida Geological Survey

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Throughout Miocene time, more and more rocks eroding from the highlands north of Florida were washed southward and deposited in the Tampa area Due to the great distance of transport, these minerals were abraded and broken into sand and clay size particles. Considerable quartz sand is found in the last consistent limestone deposit of the area. The Miocene and Oligocene limestones of the Tampa area are generally permeable and yield substantial quantities of water to wells. During late Miocene time, sand and limy, phosphatic clays were deposited in the very shallow, sometimes stagnant seas, estuaries and swamps of the Tampa area. As the shoreline migrated, i slands, lagoons and lakes developed in various, locations. Marine, fresh water and land fossils have been found in Miocene deposits around Tampa. Pliocene sediments similar to late Miocene sediments, are scanty and difficult to differentiate from late Miocene sediment in the vicinity of Tampa. In eastern Hillsborough County, sands and clays containing abundant phosphate nodu l es are presumed to be Pliocene in age and may have been weathered from older deposits. In Polk County, these phosphate-bearing sediments are mined extensively. Tampa By-pass Canal ( Throughout Pleistocene time, the alternate formation and melting of glaciers caused sea level to move back and forth over the Tampa area and seas washed quartz sand over Tampa and much of the state several times. These fluctuations left behind terrace s which are still evident today and record ancient sea level stands. The mantle of quartz sand covering the area served as parent material of many of the soils which later developed. In areas where the sands are thick and pure, they are of economic value. Well developed stream channels in Tampa, and relict dunes on the campus of the University of South Florida reflect the effect that wind and water had on the sandy deposits. Gradually, a land scape with abundant vegetation developed. Throughout the Cenozoic history of Tampa, deposits accumulated essentially as horizontal blankets of sediment which dip slightly to the southwest. This is reflected in the gently sloping land surface, and pronounced local relief can largely be attributed to recent fluvial processes and underground solution activity. GEOLOGIC TIME SCALE ERA PERIOD EPOCH RECENT QUATERNARY PLEISTOCENE PLIOCENE CENOZOIC MIOCENE TERTIARY OLIGOCENE EOCENE PALEOCENE MESOZOIC PALEOZOIC Before Present APPROXIMATE RADIOMETRIC DATES 5000 YEARS B.P. 2 MILLION YEARS B.P 12 Ml LLION YEARS B.P. 25 MILLION YEARS B.P. 38 MILLION YEARS B.P 55 MILLION YEARS B.P 65 MILLION YEARS B P 225 MILLION YEARS B.P. 600 MILLION YEARS B.P. .. DUNES ARTIST'S RECONSTRUCTION OF HOW THE TAMPA AREA MAY HAVE APPEARED DURING TERTIARY TIME 37

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GENERAL GEOLOGY The thick carbonate rock sequence underlying the Tampa area has been divided into lithologically similar, mappable units or formations. These formations are generally bounded above and below by ancient erosion surfaces. Formations can be mapped on the basis of rock exposures at land surface (outcrops), and from samples retrieved during the drilling of water wells or core-test holes. An examination of the surface geology in the Tampa area reveals that rocks of Tampa age outcrop in several locations along the banks of the Hillsborough River and can be seen in other stream channels, sinkholes, roadcuts, etc. Ballast Point was considered a classic locality for studying Tampa 38 sediments during the late 1800's and early 1900's, but now the exposures are limited and inaccessible at high tide. The Hawthorn Formation, which occurs east of Tampa, can also be studied in a number of exposures. Much of the Tampa area is covered by a veneer of Pleistocene and Recent sandy deposits. In the map, these deposits have been stripped away to reveal what lies directly beneath them. Because each formation has distinct physical attributes, mapping and <:ross-sections of these units provide some key to the depth and extent of economically valuable deposits, highly producti;e water bearing zones, and zones susceptib l e to subsurface solution which could manifest on the land surface as sinkholes. Florida Bureau of Geology drilling rig ) OLD TAMPA BAY GEOLOGIC MAP OF THE TAMPA AR%A: lj(fl /\ I J \ KEY MACDILL A I R FDRCE BASE Hawthorn Formation T A M P A Phosphatic Sand and Clay Unit J ---------&... Hawthorn Formation Limestone Unit Tampa Limestone Suwannee Limestone 0 1 2 3 MILES (Modified from Carr and Alverson, 1959) BAY MANGO VA RICO

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Crystal' River Formation (Eocene) The Crystal River Formation is a granular, white to tan limestone which, in part, is largely made up of fossil fragments cemented by a calcareous matrix, giving it the appearance of coquina rock. Due to its porosity, some portions have been washed out and filled with clay. Masses of chert also occur within the formation. The limestone was studied and named in a quarry in Citrus County. Here, and in adjacent counties where it lies near the surface, the formation's overall purity and uniform texture make it economical to mine. In the Tampa area, the Crystal River is generally deeply buried and of no economic importance at present. Suwannee Limestone (Oligocene) In general, the Suwannee Limestone is a pure, very fossiliferous limestone Qf variable hardness. It contains a minor amount of fine quartz sand cemented among the abundant fossil fragments and imprints. The formation was named for exposures that occur along the Suwannee River. Much of the Suwannee Limestone has been altered by ground water since its deposition. This accounts for some of the differences in texture, hardness and porosity within the formation. The base of the Suwannee Limestone in the Tampa area is marked locally by clay lenses. Some core samples from Tampa reveal the presence of peat in varying amounts in the lower portion of the formation. The Suwannee, like the Crystal River Formation, is mined for crushed stone in counties north of the Tampa area where it occurs near the surface. In the Tampa area, the Suwannee is a principal source of water to many supply wells. Tampa Stage (Miocene) In the Tampa area, rocks of Tampa age are soft, white, impure limestones averaging between about 40 and 160 feet io thickness. It can be seen from both the map and cross-section that the Tampa limestone is absent in the northeast portion of the study area. In some localities, the upper portion of the deposit is composed of calcareous sands and clays grading downward into unconsolidated or loosely cemented lime mud. Chert layers and silicified fossils are also common to the upper portion of the deposit. In a few locations, phosphate nodules or pebbles occur within the Tampa limestone. The base of this unit is frequently marked by beds of clay and clayey sand. Although the sediments are generally not as fossiliferous as the underlying Suwannee Limestone, there are zones within the Tampa that are consequently highly porous. This is because the fossil fragments are generally coarse grained and irregularly shaped and thus do not pack together as tightly as the finer calcium carbonate grains. Most of the Tampa limestone is very sandy and crumbly. Due to the sand content of the rock and the occurrence of renses of clay and sand within the limestone, the formation is not quarried for crushed stone. The Tampa limestone is valuable, however, as a source of water and yields large quantities to many wells in the Tampa area. The loose cementation and high porosity of portions of the Tampa limestone make it susceptible to weathering and dissolution by ground and surface waters. Many solution cavities, sinkholes and collapse structures occur in the formation, especially where it lies near the surface. Hawthcrn Formation (Miocene) This formation exhibits a great variation in composition and physical properties. In general, the formation in the Tampa area consists of an upper sand unit, a phosphatic clay unit, and a lower limestone unit. These layers occur in varying thicknesses and tend to interfinger. In most of the Tampa area, the formation is absent, and where it does occur, frequently only one or two of the units are present. Maximum thickness of the formation in Hillsborough County is about 250 feet. Fossils are rare in Hawthorn deposits. The formation thickens to the east and becomes a significant deposit in Polk County, where it is overlain by the Bone Valley Formation, which is thought to be residual material from the weathering of the upper parts of the Hawthorn Formation. It is this residuum that contains the rich concentrations of phosphate so extensively mined in Polk County. In the Tampa area, the clays of the Hawthorn Formation, along with clays in the upper part of the Tampa Limestone, make up the impermeable confining layers overlying the limestones of the Floridan aquifer. Undifferentiated Plio-Pleistocene and Recent Deposits These deposits cover most of the Tampa area and vary from a few inches to many feet thick. They are predominantly fine grained quartz sands which contain varying amounts of organic material. Some of these deposits are of economic value and are discussed further in the Mineral Resources section. I +IOO'A +50' -50' -100' -200' -300' -400' Hillsborough 2 Bay McKay Bay 4 0 2 Miles GEOLOGIC CROSS SECTION showing SOUTHWESTERLY DIP OF STRATA in the TAMPA AREA 39

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40 SINKHOLES Sinkholes exhibit varying characteristics in the Tampa area and are difficu lt to classify There are two basic sink hole types: 1. Collapse sinks produced by collapse of the limestone roof above an underground void. 2 Solution (funnel) sinks deve l oped slowly downward by disso l ution beneath a soi l mantle without rupture of the rock in whi ch they develop. Collapse sinks are normally steep sided, rocky and abruptly descending Formation of collapse sinks is unpredictable and often instantaneous, thus they constitute the greater threat to land development Solution sinks may be funne l-shaped depressions broadly open upward, or pan or bowl-shaped. They deve lop s l owly and are usually heralded by the formation of a radial fracture pattern in the soil or even in concrete or asphalt overlying them. Though their formation may not have the devastating effect of a collapse sink their occurrence can equally limit land use. Sinkholes in the Tampa area may be of either type, o r some variety and are commonly formed in an environment with the following physical characterist i cs: 1) occu"ence of permeable limestones in which a cavity system has been developed through dissolution by ground water 2) these limestones are generally overlain by a relatively thin layer of unconsolidated sediments 3) overlying sediments are usually well drained and permeable 4) a water table higher than the potentiometric surface of the artesian aquifer Overlying sediments may slowly ravel or wash downward, filling in the cavity system and resulting in a structural sag reflected at the sur f ace; or, the cavity system may continually enlarge until the cavern roofs are too thin to bear the weight of the overburden, resulting in catastrophic collapse Two act1v1t1es which tend to increase the likelihood of sinkhole occurrence are dewatering the aquifer and increas ing stresses on the land surface. When the potentiometric surface is lowered, dewatered cavities in the limestone prov i de less support to overbu r den layers. Similarly, the added weight of buildings or fill material may exceed the st r ength of underlying cavernous l imestones. G U I. IF ) lE 0 R of MEXffCO This large portion of the State represents the area where the piezometric surface is at or above land surface and/or the clastic overburden is in excess of 100 feet thick It appears to be the least probable area for sinkhole development This area is the portion of the State characterized by stable prehistoric sinkholes, usually flat bottomed, steep sided, both dry and containing water Modifications in geology and hydrology may activate process again. This portion of the State is characterized by limestones at or very near the surface. The density of sinkholes in this area is high, however, the intensity of surface collapse is moderate due to the lack of overburden. Exploration by drilling and geophysical methods for near-surface cavities can be realistically accomplished. This portion of the State has moderate overburden overlying cavernous limestones and appreciable water use. These areas have histories of steep-walled, wider sinkhole collapse but require more detailed study. A thick overburden or high water table present within these areas lessen the probability of sinks occurring. G A ATI.ANTffC r _r--l I I COLLIER

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Sinkholes in the Tampa area may or may not be filled with water. Sinkhole lakes are characteristically circular and deep. Unl ess sinkholes have been filled with impermeable material, they are directly connected to the Floridan aquifer and provide a rapid means of recharge. Such direct recharge is not conducive to the removal of contaminants from water by filtration or chemical reaction. It is therefore essential to safeguard the quality of water entering sinkholes. Sinkholes in the Tampa area generally occur in a wide northwest-southeast trending band. There is a concentration of them in the northwest area, but their apparent predominance here is partially due to more detailed mapping in this section (see map). Although ex1stmg sinkholes can be mapped, predicting specific areas of potential collapse is difficult. No part i cular pattern to the cavity system in limestones has been discovered. The most widely used method for detecting sub-surface cavities is drilling bore holes. This approach has the obvious disadvantage of producing little data for the amount of effort expended. Other new procedures have been used experimentally in an attempt to identify sub-surface cavities, but the results are not foolproof. One method utilizes airborne remote sensing devices. Computer processed imagery obtained from flights over a test area reveals thermal and apparent moisture-stressed vegetative patterns that may be associated with sub-surface cavities. Additional data collection and refinement of techniques are necessary before the effectiveness of this method can be evaluated. Another experimented method of identifying sub-surface cavities is gravity mappin9. A gravity meter records, on the land surface, local differences in gravity which, after correction factors have been applied, are directly related to differences in density of the underlying rocks. Areas underlain by cavern ous limestones produce lower gravity readings than ar e a s underlain by limestones containing fewer voids. Gravity surveying as a means of detecting subsurfac e voids has certain limitations. The smaller the cavity and the more deeply it is buried, the less detectable it is by gravity methods. A cavity with a diameter equ a l to or greater than its depth of burial is readily detectable because the gravity anomaly is great. Small gravity anomalies can be produced by a variety of subsurface conditions and theref o re may or may not be indicative of small and/or deeply buried subsurface cavities. Victor Stringfield (U.S.G.S.) examines sinkhole near Lake Magdale ne. (photo by J.W. Stewart) .J OLD I .......... H!LLSBOROUG/i BAY AREAS OF OCCURRENCE OF SINKHOLES AND SINKHOLE TYPE LAKES TAMPA BAY /"' DAT A OBTAINED F ROM T OPOGRAP HIC MAPS A NDJ.W. S TEW AR T, 1 970 MAP SERIES 39 DATA OBTAINED FRO M SOUTH WEST F LORIDA W ATER MAN AGE M ENT DIS T R I CT AERIAL P H OTOGRAPHS .1: 200 SCALE W I TH ONE FOOT CONTO U R I NTERVALS AND J.W.ST EWART, 1 970 ,MAP SERIES 39. ARE A S IN W HICH SUBSURFACE CAVITIES OR RELI CT KARST F EATURES HAVE B EEN E N C OUN TERED IN DR I LLING Data from OROFlNO and Co 0 4 MILES t::=======::=::::::l SCALE 60 41

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STRUCTURE The map presented on this page shows the top of the first consistent limestone. The data is referenced to mean sea level, therefore the contours reflect the actual topography of the bedrock surface. Knowledge of this bedrock surface is important in understanding surface features which are often genetically related to the underlying rock. The complexity of the contours is due, in part, to post-depositional alteration of the rock. This could i nclude s hifting and settling, differential compaction of the limestone strata at some time after deposition, erosion of the r ock sllrface between depositional cycles, and solution weathering of the limestone by ground water. The contours, however, do reveal something about ancient paleogeogtaphy. For example, the minus ten 42 foot contour line (shown as a bold line on the map). can be considered an approximation of
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GEOlOGY ANO URBAN PlANNING Two of the more severe problems associated with urbanization are proper waste disposal and adequate water supplies during periods of water shortage. Recent investigations indicate that in some areas there are possibilities for simultaneous alleviation of both problems by utilizing the technique of deep well injection. Successful application of this technique hinges on a good knowledge of subsurface strati graphy and hydrology. The method of deep well injection involves injecting treated wastewaters and/or storm runoff into subsurface permeable zones that do not other wise lend themselves to water supply or mineral production. Many factors, however, must be carefully evaluated before such a project can commence. Further, according to Garcia-Bengochea, et. al. ( 1973, p 5-6). Underground disposal of wastewater by wells . can be achieved successfully if five general requirements are fulfilled. These are: 1. There is a stratum or strata (aquifer) which can accept the waste. 2 The hydraulic and structural characteristics of the aquifer will not be changed significantly by the disposal of the waste. 3. The disposal of such waste will not impair the present or future use of the water in such aquifer. 4. The disposal of such waste will not impair the present or future use of the water in adjoining aquifer or surface-water supplies. 5 The installation is designed properly, with consideration of the physical, chemical, and biological characteristics of the waste and the hydrogeological characteristics of the receiving aquifer and confining strata." "Present hydrological knowledge indicates that the treated fresh water effluent should not readily mix ( with the saline waters of the aquifer but would create a large fresh water bubble in storage at the top of the aquifer which could be partially recovered at a later date for low quality uses (irrigation) or for further specific treatment and reuse." (Garcia-Bengochea, et. al. 1973, p. 4-5) Deep well injection is being carried on in several areas in Florida and additional sites are being evaluated. Several sites currently under investigation are within the geological realm of the Tampa area. These include a site to the east of the Tampa area in Mulberry and several sites in Pinellas County. According to Wilson, Rosenshein and Hunn (1973, p. 1, abstract). an injection well in Mulberry was completed in 1972 at a chemical plant which produces a liquid waste from phosphate processing that has a high chloride content and high acidity (pH generally less than 2). This effluent is injected into several permeable zones penetrated by the well between 4040 and 4984 feet deep. Tests performed at the Mulberry well provided not only information about the characteristics of the injection zones, but also suggested additional evaluative techniques that might be employed at other sites Mr. H J. Woodard, Geologist with the Department of Natural Resources, is supervising a pilot hole in St. Petersburg which is a cooperative effort by the Division of Interior Resources and the City of St. Petersburg. The project is to study the feasibility of injecting excess surface water into a saline aquifer and recovering it for subsequent use According to Garcia-Bengochea, et. al., 1973, p 27 the objectives of the project are to determine: 1. the characteristics of the deep underground formation at that site; 2. the quality of the deep ground water; 3 the injection rate capacity and associated increase in pressure; 4 ratio of the amount of fresh water that could be subsequently recovered to the amount injected; and 5 quality of the recovered water. According to H J Woodard, as of July, 1973, the pilot hole is completed to a depth of 3500 feet. One injection test was performed at a depth of about 850 feet, and two additional tests are slated for zones that appear promising. One shallower, less saline zone may be suitable for stormwater disposal and a second deeper zone (greater than 3000 feet deep) may be found satisfactory to receive secondarily treated sewage TYPICAL WEL L for DISPOSAL of TREATED WASTES PLU G F OR WAT E R LEVEL M EASUREME N T S A QU ICLUD E BING (STAINLESS STE E L OR PLASTIC) (from: R. 0. Vernon, 1970, p. 4) The deep well injection technique has the potential to provide some relief to the waste disposal and water shortage problems of urban centers such as the Tampa Bay area At present, the need to continue basic geologic and hydrologic data collection cannot be over-emphasized. If deep, permeable zones could be identified and mapped, and their geohydrologic properties and stratigraphic relationships studied, determination of the feasibility of subsurface storage of waste in this area could be greatly facilitated. Deep well injection studies serve to further illustrate the integral role that geology plays in many phases of urban planning. 43

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MINERAl RESOURCES

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46 INTRODUCTION During 1970 mineral resources valued at slightly more than 20 million dollars were produced from Hillsborough County, giving it a rank of third among all Florida counties, as shown in Table 1. The figures, however, do not give insight into the impact on Tampa of massive phosphate operations and the mining of construction sands in adjacent Polk County, nor of the quarrying of limestone i n Sumter and Hernando counties and the extraction of clay in Citrus County. Practically every aspect of our modern way of life depends in some way on mineral resources. Mineral resources are necessary for building homes, constructing and maintaining roads and highways, manufacturing automobiles and planes, and for producing food crops to feed the people of the world. No one can question that our society depends upon mineral resources. Furthermore no one can question that mineral resources are finite; they are exhaustible. If they are not mined where they occur, they are lost to society In recent years it has become evident that mining, especially of mineral resources near the land surface, can result in extensive environmental damage. Air may be polluted. Stream life may be partially or totally destroyed. Land may be left in a state no longer useful. However, it also has been shown that with planning and controls, mining can take place with minimal environmental damage The necessity of mining and the necess ity to r11inimize environmental damage and reclaim mined-out land has led some investigators to emphasize the need for leadership in undertaking minera l evaluation studies on large land areas prior to development. Then, when social l y necessary mining operations have been completed, leadership is again appropriate for reclaiming the land m i ned. The need for planning i s most pressing in areas of rapid population growth. Mineral resources in t h e general v icinity of Tampa include phosphate, sand, clay, limestone, cement, oyster she lls and peat. T hese products wi II be considered separate l y PHOSPHATE ) TABLE 1 ;-1''"'--'.r-.,_"""-GEORGIA i --,------\ N ASSAU ,) .. 7----r----,1 1 { MAO I SON H A M ILTON \ ':.r"'\."""',....,_ ) '\ _____ ,, // -J I SAKER ,/ DUVAL L y--t SUWANNEE I COLUMBIA I j TAYLOI I .,_ i l l)NION / I I LAFAYETTE "\ ? l. _/ i cLAY '.v-"\ j 1-----y! '---............... \. <-----( I ALACHUA ___ .., Value of Mineral Producti on in Florida for Leading Counties 1 -J DIXIE ) ----1 r P UTNAM )-'---1 . i -, -----1. ATLANTI C Year County Value Minerals Produced in (Thousands) Orde r of Value Polk $140,598 Phosphate rock, sand and gravel, peat Dade 35,184 Cement, limestone, sand and gravel 1970 Hillsborough 20,041 Cement, phosphate rock, sand and gravel, oyster shell, peat Broward 11,930 Limestone, sand and gravel Sumter Withheld Marion 2,562 Limestone, fuller's earth, sand and gravel, phosph ate rock Polk 137,696 Phosphate rock, sand and gravel peat Dade 33,953 Cement, limestone sand and gravel 1969 Hillsborough 22,555 Cement, phosphate rock, oyster shell, sand and gravel Broward 11, 187 Limestone, sand and gravel Sumter 3,741 Limestone, lime, peat GULF of / '-T-'4.J \ ,( l l EVY j ... -.J i i MAR ION ...... ..... \ i CITR U S ', j L ______ ("--.. .... _.r \ r,.J I MEXICO ---,_ __ { S U TEl i HERNANDO -....... I l j OltANGE ; _____ .. I I PAS C 0 rJ L.\. .,------j-1 \ i i \ .. --1 0 S C E 0 LA POLK I ' j or. \ R IVE R ___ E X PLANATION H AIDEE l (;OKEECHOBE E : -----; H IGHLAND;\ j ST. LUCIE C REST OF OCALA U P LIFT L i __ \.. S ARAsOTA! DE SOTO 1 f D A REAS T HAT I N C LUDE PEBBLE I j ["" ..J PHOSPHATE DEPOSIT S -----------i-----'"'-...i G LADES I _,,/ MART IN ! ,/ 1 Data from Bureau of Mines Minera l s Year Books, 1969 and 1970. PHOSPHATE Although phosphate is used in the manufacture of a wide variety of products, including well-known detergents, wate r softeners and metal polishes, most phosphate is used in the manufacture of fertilizers. The importance of fertilizers in feeding the people of the world would be difficult to exaggerate, and Flo r ida has long been a world leader in supplying phosphate. It is evident therefore, that the needs of the world, not Florida alone, must measure the impact of Florida's phosphate. FIGURE L PEBB L E PHOSPHAT E DEPOSITS OF FLORIDA : T H E CRES T INDICATED BY A HEA V Y DARK LINE MODIFIED FROM PIRKLE ET A L.(\967 F I G I P 238) Location and Reg i onal Significance of Pebble Phosphate Deposits By far the greatest production of phosphate rock in Florida is of the type called "pebble phosphate The deposits consist of phosphate particles mixed with varying amounts of quartz sand and clay. The phosphate particles usually range from colloidal size to pebbles an i nch or more in diameter Figure 1 shows locations of known pebble phosphate deposits on the Florida peninsula. An examination of the figure reveals that the deposits occur along the flanks or fringes of the Ocala Uplift, an upwarped area cresting in eastern Citrus and Levy counties along the western side of the peninsula Knowledge of this relationship has been useful in exploration programs.

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Some phosphate rock is produced from Hamilton County in the northern part of the peninsula (Fig. 1 l, but most of Florida's phosphate rock is mined east of Tampa from the large area known as the "Bone Valley District." During 1970 phosphatic sediments produced from the Bone Valley District had a value of approximately 150 million dollars and accounted for almost three-fourths of our domestic needs and one-third of the world's needs. Most of the rock in one form or another is shipped through the port of Tampa. In fact, phosphate is responsible for nearly 50 per cent of the tonnage entering and leaving this important port. Obviously the mining of phosphate rock has an enormous influence on the economy of the Tampa area and the State of Florida (Table 2). The Bone Valley phosphate field of central Florida is shown on Figure 2. The northern part of the region contains the highest grade phosphate rock and has been m1ned most extensively. If mining continues it must spread into the southern part of the area. TABLE 2 Nature of Sediments in the Bone Valley District Three types of sediments are encountered in the phosphate mines (Fig. 3). From the land surface downward these materials are: ( 1) loose quartz sands and clayey sands (top soil and sand overburden), (2) phosphate beds of the Bone Valley Formation (leached zone and ore zone or matrix), and (3) bed rock (limestone) or bedclay of the Hawthorn Forma tion. The mixture of phosphate particles, sand and clay of the Bone Valley Formation is the material mined for its phosphate content. Data illustrating various characteristics of the overburden sediments, the phosphate beds, and the underlying bedrock or bedclay are given in Table 3. These data are of samples collected from a test hole drilled on the Lakeland Ridge between the towns of Bartow and Mulberry. FLORIDA PHOSPHATE INDUSTRY* Item 1971 1970 1969 1968 1967 Employees 6,662 7,563 7,464 9,060 10400 Payroll $ 59,000,000 $ 59,061 ,293 $ 59,093,035 $ 68,848,000 $ 69,000,000 Production of marketable rock (short tons) 30,500,000* 29,300,000* 29,900,000* 33,000,000* 31 ,900,000* (*Includes N.C. production-U.S. Bureau of Mines) State ad valorem taxes paid $ 5,215,968 $ 5,996,090 $ 5,882,553 $ 5,856,154 $ 6,326,018 Polk County ad valorem taxes paid $ 3,619,312 $ 4,635,566 $ 4,577,014 $ 4,627,404 $ 4,583,587 State sales taxes $ 3,135,273 $ 3,129,152 $ 2,836,648 $ 2,385,727 $ 2,112,112 New construction expenditures $ 30,000,000 $ 22,189,867 $ 18,227,300 $ 35,420,585 $ 56,827,650 Expenditures for raw materials, equipment, supplies $174,764,731 $161,192,084 $181,658,064 $175,487,087 $175,086,157 *Data furnished by the Florida Phosphate Council. Five-year comparison Surface Sands: The overburden of top soil and loose to slightly hardened quartz sand and clayey sand (Fig. 3) ranges in thickness from a few feet to more than 50 feet A through H, Table 3), and typically from 5 to 25 feet. Some investigators believe these surface sands Figure 3. Typical section in central Florida Phosphate district. Modified from Fountain and Zellers, Fig. 2, 1972 ___ 1 __ _____ [': i HILLSBORO GH! P L ANT snl LA5fLAN0 I p 0 L K i W i i i -j----------, i JOLFO SPR NGS i V> 'o M A N A T E E i H A R 0 E E lz ______ _j I ., I I"' I t ,_ ;______ OAB.CAOIA j:x: Seo l e SARASOTA i DESOTO i i EXPLANATION NOITHfiN ,AIT-,lOVEN GlADATIONAL ZONE SOUTHfiN ,AIT-lNDICAHD FIG. 2 BONE VALLEY PHOSPHATE DISTRICT OF FLORIDA. THE DISTRICT IS DIVIDED INTO A HIGH-GRADE NORTHERN PART AND A LOW-GRADE SOUTHERN PART. (Mop furnished by Mr. Joe Weaver of Wayne Thomas, Inc.) were deposited under marine conditions as seas encroached and retreated from the area during Pleistocene time. Other workers consider the quartz sand blanket to represent a simple insoluble residue accumulated on-site from the weathering of underly ing sediments. 47

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TABLE 3* Channel Samples from Grace Drill Hole SW %, Section 4, T.30S., R.24 E., Polk County, Florida Approximately 4 Miles West of Bartow Surface Sands and Phosphatic Sediments of the Bone Valley District Insoluble Residue Depth Quartz Clay Total P20s Total Spl. in feet Sand (-325 mesh) Soluble Heavies in% in% in% in% in% Overburden Sands and Clayey Sands A 0-10 97.01 1.70 .20 .18 1.14 B 10-15 95.52 2.39 .20 .16 1.07 c 15-20 86.47 9.49 2.50 .22 1.17 0 20-30 78.95 19.68 .70 .70 .77 E 30-33 79.86 18.41 .60 1.26 1.06 F 33-40 91.33 7.50 .50 1.10 1.12 G 40-47 83.96 13.33 1.20 .68 .71 H 47-51 96.00 3.40 .1 0 .22 .77 Matrix (Commercial Zone) I 51-60 35.62 11.08 52.72 15.88 .26 J 60-69 27.68 12.50 59.22 15.66 .1 0 Bedrock K 69-80 26.23 10.24 63.19 6.68 .05 L 80-87 17.44 7.99 74.50 3.64 .08 *Modified from Pirkle et al. (1967, Table 11, p. 253) 48 Phosphate Beds of the Bone Valley Formation : Phosphate beds (Fig 3) beneath the surface sands consist of varying mixtures of phosphate particles, quartz sand and clay (Spls. I and J, Table 3). The phosphate particles, often referred to as phosphorite, range in color from white or cream to dark gray or black and assay from less than 65 per cent to as much as 80 per cent bone phosphate of lime (BPL) or tricalcium phosphate, Ca3 (P04 ) 2 The unweathered phosphate mineral is apatite, more specifically car bonate-fluorapatite. I n the upper parts of the phosphate beds, where the sediments are more subject to weathering processes, much of this apatite changes to various aluminum phosphate minerals, partly through reactions with surrounding sediments. This upper zone containing the aluminum phosphate minerals is called the aluminum phosphate zone or, locally, the leached zone (Fig 3). It s thickness usually is between 5 and 10 feet. During mining this upper zone normally is stripped off and discarded as overburden. The "matrix" or commercial zone of the phos phate beds (Fig. 3) occurs beneath the upper weathered aluminum phosphate zone. Its average district-wide composition according to Altschuler et al. (1964, p. 25) has the following range: Apatite (carbonate-fluorapatite) . 35-40 per cent Clay (montmorillonite) ....... 20-25 per cent Quartz sand and some chert ..... 25-40 per cent This lower zone may be more than 50 feet in thickness, but commonly is between 10 and 20 feet, with an average for the district of approximately 15 feet. w z w ) Hawthorn Bedrock or Bedclay: The commercial phosphate beds or matrix rests either on bedclay or on bedrock (Fig. 3). The bedclay is a phosphatic, impure clay, sandy clay or clayey sand and the bedrock is a pale yellow, impure, phosphatic limestone (Spls. K and L, Table 3). Neither bedclay nor bedrock carries sufficient phos phate content to be commercial. Characteristics of the overburden sands, the phosphate beds and the underlying bedclay or bedrock are summarized on Figure 4. DESCRIPTION Terrace sands Nearly pure quartz sand Upper unlf Quartz sand and aluminum phosphate (some cloy but no apot1te nodules. May be ves1culorl Lower un1t LOCAL APPROXIMATE MINERAL OCCURRENCE NAMES Alum mum phosphate (wovelllte and psebowovell1le) J Overburden sand Leached zone Quartz sond,cloy,ond c;' opollte nodules (Lower port generally h1gh 1n cloy.) f--+.1 Bed cloy Quartz sond,cloy,opotile w nodules, and calcium ( : t-carbonate (upper part soft) Bed rock FIGA STRATIGRAPHIC RELATIONS, LOCAL TERMINOLOGY AND MINERAL COMPOSITION OF THE OVERBURDEN SANDS, THE LEACHED ZONE AND MATRIX OF THE PHOSPHATE BEDS, AND THE UNDERLYING BEDCLAY AND BEDROCK. MODIFIED FROM CATHCART et at. (1953, Fig.3, p.82).

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History of Mining Pebble phosphate was originally discovered in the Bone Valley District along the Peace River in 1881 by Captain J. Francis LeBaron of the Army Engineers (Davidson, 1892), and mining of the river-pebble deposits began in 1888. In 1891 production from land-pebble deposits was initiated as mining activities began to shift from the irregularly distributed deposits of river beds and flood plains to the more continuous ores beneath the surface sands of the region. Since this early beginning, approximately 97,000 acres of phosphate land have been mined. It is estimated that today an average of 6,500 tons of marketable product are produced from each acre of phosphate land mined. I n the early days, however, a large volume of the smaller phosphate particles that are removed today could not be extracted from the sediments. In fact, in recent years some of the waste from these earlier operations has been remined to recove r the small phosphate particles. Mining and Land Reclamation Difficult environmental problems result from any mini n g operation in which the top layers of the earth are removed to reach a valuable mineral product, or in which the top layers of the earth are stripped off as the valuable mineral p roduct. This type of mining, called strip mining, is practiced in the Bone Valley Dist r ict. Overburden sands and clayey sands are removed by giant, electric-powered draglines to uncover the valuable phosphate beds (Fig. 5). The phosphate beds in turn are removed by dragl i nes, one of which can pick up as much as 49 cubic yards of sediments at a time The phosphatic sediments are dumped by the draglines into sumps where the ore is mixed with water and then pumped to recovery plants. During the ear l y days of mining, no thought was given to r estoring the mined-out land to useful purposes. An area, after mining, was left turned upside-down with man-made ridges and hills com posed mostly of sand and clayey sand interspersed with low areas and filled sludge ponds or settling ponds which take many yea r s to dry sufficiently to permit any type of beneficial lJSe. With changing times it has become evident that such valuable land cannot be left in an unreclaimed, unuseable state. In 1961 the mining companies agreed among themselves to restore to useful condi tions as much of the mined-out land as they could afford. Since that agreement the Florida phosphate industry has reclaimed an average of approximately 1 ,500 to 2,000 acres of mined ,out land each year. Additional incent i ves to reclaim land stem from the mineral severance tax law passed by the Florida L egislature in 1971 Furthermore, Polk, Mana t ee and Sarasota counties have zoning ordinances requiring a certain amount of phosphate land r eclamation Nearly all of the phosphate companies have reclaimed signif icant land areas. Some of the projects are t abulated on Table 4. Current pro j ects include Lakeland Skyview Mobile Home area and golf course, Sanlan Ranch Campgrounds and simultaneous min ing and reclamation on Lake Parker in Lakeland. However, major reclamation problems exist These problems are complex and to the present are largely unsolved A clay water slurry (slime) is produced in the processing of the phosphate rock. This slurry d ries very slow l y and after s t anding for many years still has a volume nearly 6 times greater than the original clay volume In fact the volume is about twice as g r eat as the original volume of the matrix mined. S l ightly more than two-thirds of the land m i ned must be used as settling areas for these slimes. T herefore a substantial amount of the mined-out land is not readily available for reclamation. Much study has been d i rected toward this problem o f the slimes with encouraging results (Timberlake, 1969). Undoubtedly such studi es will con t inue to demand a high priority un t i l the slime problem is solved TABLE 4 Examples of land Reclamat ion Activities of Various Phosphate Compan i es* Example Company Description of Project 1 IMC Southwest Bartow-100 acres-A t r act adjoining IMC's Bartow offices. Mined 1965-66. Residentia l sites 2 3 4 5 6 7 8 9 IMC IMC IMC IMC (Armour) (Armour) U S 17 strip-135 acres-South of Bartow. Right-of-way for anticipated fourlane road Good for commercial West Mulberry-31 acres-2,500 ft. frontage on Fla. 60. Sold to outof-state industrial firm. Noralyn recovery plant site-20 acres -office, lab, on reclaimed land Mulberry area-1 ,000 acres-North, south and south east of Mulberry; all acreage fronting on a highway. One part recreational another agricultural, rest of reclaimed area for residential or commercial uses. West Bartow Elementary School-Dedicated in May 1966; Deeded to city in 1960. Clark Property-170 acres-Swampland prior to mining. A real estate subdivision after reclamation. (Cyanamid) Saddle Creek Park -740 acres-Originally a swamp; land has been donated to people of Polk County for recreational area Swimming, fishing, picnicing, and other activities. East of Lakeland (Cyanamid) Orange Park, north of Lakeland-2,224 acres reclaimed-mining and simultaneous reclamation Reclamation completed within a month after mining. 10 (Cyanamid) 315 acres-east of Lakeland-donated to Florida Audubon Society as a wildlife sanctuary Largest 11 12 13 14 reserve owned by society in state (Mobil) Peace River Park-donated to city of Bartow (east of city limits) as recreational area (Mobil) Christina Park-1 ,100 acres-large area south of lakeland. Sold to private interests for housing development. (Cyanamid) Pleasant Grove Fish Management area, east of Tampa-1,160 acres-Under supervision of Fla. Game and Fresh Water Fish Commission (IMC) Bartow Civic Center-10 acres-1966, land was donated to city for civic center 15 (Cyanamid) Sydney-1,613 acres reclaimed-15 miles east of Tampa. Sold portion of reclaimed land for 18-hole golf course 16 (W.R Grace) Sylvester Shores-Fashi onable residential subdivision built on reclaimed land in southeast Lakeland Mined in 1955. Reclaimed in 1960. 17 (W.R. Grace) North Mulberry area-367 acres fronting on SR 37 and Carter Road. Potential commercial and residential property. 2,600 ft. reclaimed on SR 37. 18 (W R Grace) East Mulberry area-155 acres with 4,400 ft. on SR 60. Potential commercial property. Data furnished by the Florida Phosphate Council and phosphate companies. Figure 5. Mining with giant dragline. 49

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50 Pollution Control and Water Conservation The phosphate producers also have been con cerned with problems of air and water pollution. During the past 10 years more than 40 million dollars have been spent by the phosphate companies to install equipment to reduce emissions to the air of fluorides, sulfur dioxide, and dust. Furthermore, an amount in excess of 30 million dollars has been spent during the same period of time for water quality control, with phosphorus and nitrogen discharges receiving much attention. In addition, millions of dollars have been spent to install and operate water conservation systems. The magnitude of the efforts expended toward the control of air and water pollution and for the conservation of water is suggested by the vast expenditures directed toward these ends. Expenditures. for the past 5 years are summarized on Table 5. Substantial progress has been realized. The recircu lation of water is much above the national industry average. Airborne fluoride emissions were reduced about 90 per cent during the period from 1959 to 1966. Likewise discharges of phosphorus and nitro gen into local streams have been reduced almost 90 per cent during recent years. Interesting Elements and Minerals At one time or another, interest has been expressed in the presence of various materials in the phosphatic sediments of the Bone Valley District or in the tailings left after the processing of phosphate rock. For example, more than one-third of the phosphate values mined can not be extracted profit ably and must be discarded with waste materials. Therefore the waste contains a relatively high per cent of unclaimed phosphate. Also, the phosphatic sediments of the district contain minor amounts of uranium. With such tremendous volumes of phos phate rock being mined, the minute amount of uranium in individual phosphatic particles adds up to an impressive quantity of urani.um handled in the mining operations. During World War II, studies were made on extracting the uranium from the phosphatic sediments and several plants were constructed in which small amounts of uranium were recovered on a pilot scale. Furthermore, the Bone Valley sediments contain traces of heavy minerals such as ilmenite, rutile, zircon and monazite. Rutile and ilmenite are import ant source materials for titanium which has many uses such as a whitener in paper and cloth, a white paint pigment, and a source for titanium metal. Zircon is used in molds in making castings and as a source of zirconium metal. Monazite is a source of Item ) rare elements. Also the phosphate rock contains 3 to 4 per cent fluorine, and the district has interest as a possible source of vast quantities of this element. Partly as a result of pressure from air pollution laws and as a result of a shortage of the principal mineral source of fluorine, plants to recover fluorine from phosphate rock have been planned for the Bone Valley District, and some have become realities. Investigations indicate that phosphate rock may eventually become a significant source of aluminum fluoride, according to some estimates by the mid1970's. TABLE 5 EXPENDITURES FOR AIR AND WATER POLLUTION CONTROLS AND FOR WATER CONSERVATION PRACTICES* 1971 1970 1969 Expenditures to install air pollution controls $5,532,090 $2,850,370 $1,925,330 Expenditures to install water pollution controls $3,353,867 $2,1'36,658 $2,544,587 Expenditures to install water conservation systems $2,528,070 $ 892.400 $1,276,970 Expenditures to operate air pollution controls $4,591,511 $4,111,540 $4,365,305 Expenditures to operate water pollution controls $3,354,340 $3,000,902 $5,592,750 Expenditures to operate water conservation systems $2,623,739 $2,035,770 $2.417.492 *Data furnished by the Florida Phosphate Council. 1968 1967 $5,173,066 $9,079.869 $2,832,692 $4,822,825 $ 729,575 $3,530,218 $3,981,000 $4,040,120 $4,830,500 $5,569,370 $2,530,900 $1,848,020

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SANO Construction Sands The costs of homes, buildings, roads and highways reflect the availability and quality of such common construction sands as concrete sand, plaster sand and mortar sand All commercially useful sands contain grains of various sizes (diameters). Concrete sand is a clean, relatively coarse sand graded to contain grain sizes within specific ranges (Table 6). Plaster and mortar sands are finer than concrete sand, but like concrete sand, must be clean and graded to specifica tions (Table 7). Because much of the surface of Florida is covered with a blanket of quartz sand it might seem that concrete sand could be produced at almost any site. Nothing could be farther from the truth. The median diameters of surface sands collected along east-west traverses crossing the Florida peninsula are given on Figure 6 From this figure it can be seen that the coarsest surface sands in peninsular Florida occur near the center of the peninsula, trend in a nearly north-south direction, and coincide with the general area of Trail Ridge and the Lake Wales Ridge. A comparison of the median diameter (Md) of the surface sands (Fig. 6) with the median diameters (Md) of concrete sand (Table 6) shows that most surface sands collected along the traverses are too fine to serve as a source for quality concrete sand. In order to obtain large quantities of concrete sand in the peninsula it has been found necessary to extract coarse sands from sediments occurring beneath the surface sands. These underlying coarse sands are present only in the area of the Lake Wales Ridge (Fig. 7). There sand is mined from the Citronelle Formation which locally contains con centrations of very coarse sand grains, quartz gran ules, and small quartzite pebbles. These localized concentrations of coarse sediments are the materials from which construction sands are produced. At some localities the surface sands must be removed as overburden before mining the deeper, coarser sands; in other areas, however, surface sands can be mined with the underlying Citronelle sedi ments. In either case open pit mining methods are used, utilizing dragliries in those pits which are dry, and dredges with barge-mounted pumps in pits which are partly water-filled. Sand removed from the ( Sieve Size 4 8 16 30 50 100 FM* Md.** pits is washed and sized by screens to meet required specifications of concrete and plaster sands and then shipped by truck or rail to the market area. Because transportation is a major cost factor in the sand and gravel industry, various population centers in the peninsula receive their construction sand from pits in that part of the Lake Wales Ridge area closest by road or rail. For example, Jacksonville receives its quality construction sands from mines in Clay and Putnam counties in the northern part of the ridge area Orlando receives its coarse construction sands from mines in Lake and Polk counties. The Tampa area receives a major part of its quality construction sand from the Lake Wales Ridge area in Polk County. However some production for the Tampa market has come from other localities, such as sites on the Lakeland Ridge southwest of Bartow (Fig. 7). TABLE 6 Screen Analyses by Weight of Finished Concrete Sands Collected at Major Producing Mines within the Area of the Florida Lake Wales Ridge State Road Site Site Site Specifications A B c % Cumulative Putnam County Lake County Polk County 05 0.00 0.00 0 0 015 3.2 1.2 1 0 3 -35 12. 6 10.8 13 2 3075 39. 3 39.7 50. 4 65-95 69.9 81.1 73.0 95-100 94. 5 99.5 93.6 221 232 231 .47 .52 .60 *Sum of cumulative values for samples. Expression of coarseness. **Median diameter (mm). Site D Polk County 0.0 0.3 6.3 30. 0 64.5 97.5 199 .39 G E 0 R G 0 ... 0 materials of quality construct ion sands in the Flor ida peninsu la. These sedi ments also contain kaolin clay. TABLE 7 Grading of Sands for Masonary and Mortar Uses* Sieve Size 4 8 16 30 50 100 Percentage Passing each screen by weight 100 95 to 100 60 to 100 35 to 15 to 70 35 0 to 15 *Recommendations of the American Society for Testing Materials -51

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U1 "-l ,. ,. @ r \ DISTAL oo ATOLLS ., ,\ II \ \ \H 5 0 5 10 15 C'MI.E "="' FIGURE 6 SITES AT WHICH SURFACE SAND SAMPLES WERE COLLECTED ALONG EAST-WEST TRAVERSES CROSSING THE FLORIDA PENINSULA. THE VALUE GIVEN AT EACH SITE IS THE MEDIAN DIAMETER IN MILLIMETERS OF THE QUARTZ SAND COLLECTED AT THAT LOCALITY.

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A Specialty Sand Glass sand, an important specialty sand, is pro duced in both Polk and Hillsborough counties. The glass sand from Polk County is mined in the Lake Wales Ridge area near Davenport where the sands are separated from the same sediments from which concrete and plaster sands are produced. Special processing, including flotation to remove heavy minerals and other impurities, is required to obtain a high quality product. The glass sand from Hillsborough County is presently produced from surface sands in the Plant City area. Parts of this deposit contain a very high-grade glass sand which in its natural state meets high quality requirements, both texturally and chem ically. There are very few natural deposits of glass sand anywhere that meet the quality of these Plant City sands for manufacturing glass. Prior to 1970 flotation was not used in processing the sand. Since that date, however, flotation has been used to remove heavy minerals and other impurities to ensure a reliable product. Glass sands must be of very high purity; even a fraction of a percentage of some impurities, such as iron, will color the glass produced. Table 8 illustrates the allowable percentages of certain of the more common impurities found in sand deposits. Further more glass sand must have a uniform grade-size distribution of sand particles with most of the grains having diameters falling within a range of approxi mately 0.840 to 0.149 mm ( -20 mesh to + 100 mesh). Glass manufacturers differ somewhat in the details of their specifications for glass sands. Requirements quoted by one major manufacturer for a high-grade glass sand are given below. 1. Chemical Composition -The glass sand shall be composed of the following oxides in the following percentages by weight as determined by analysis based on ignited samples. Oxide Si02 Al203 Fe203 CaO, MgO Percent not less than 98.500 not more than 0.500 not more than 0.035 not more than 0.200 ( 2. Grain Size -The glass sand shall conform to the following requirements with respect to grain size: percent remaining on 16 mesh screen percent remaining on 30 mesh screen percent remaining on 60 mesh screen percent remaining on 120 mesh screen percent passing through 120 mesh screen none 0-20 40-80 15-30 0-10 Some of the glass sands in Hillsborough County and similar deposits in Manatee County in their natural state regularly approach these specifications for high purity glass sand. Analyses of a sample of Plant City sand as taken from the ground are given on Table 9. The value of the deposits near Plant City as a glass sand was recognized in 1961 (Pirkle et al., 1963, p. TABLE 8* Specifications for Chemical Composition of Glass Sands Percentage composition based on ignited samples Si02 Al2 03 Fe 2 03 CaO+MgO Qualities Minimum Maximum, Maximum Maximum First quality, optical glass 99.8 0.1 0.02 0.1 Second quality, flint-glass 0.035 0.2 containers and tableware 98.5 0.5 Third quality, flint-glass 95.0 4.0 0.035 0 5 Fourth quality, sheet glass rolled and polished plate 98.5 0.5 0.06 0.5 Fifth quality, sheet glass, rolled and polished plate 95.0 4 0 0.06 0.5 Sixth quality, green glass containers and window glass 98.0 0.5 0.3 0.5 Seventh quality, green glass 95.0 4.0 0.3 0.5 Eighth quality, amber glass containers 98.0 0.5 1.0 0.5 Ninth quality, amber 95.0 4 0 1.0 0.5 *Taken from Fettke (1926, p, 400). TABLE 9 Plant City Glass Sand Accumulative percent retained on mesh Heavy Site 12 16 20 30 50 60 1 00 140 Minerals Fe2 03 in% in% Plant City 0.0 Tr. 0.4 3.6 41.3 58.3 87.0 93.9 0.154 0.016 128). Since that time studies have been undertaken to locate additional deposits. During one study the following procedure for locating deposits of the Plant City type was followed by the authors. At the outset, all areas of St. Luci sands were plotted from soil maps onto topographic maps of Hillsborough and Manatee counties. Field checks of these areas were then made to determine which of the regions of St. Luci sands support a true scrub vegetation. Holes were drilled in the sands supporting a true scrub growth, and the sands taken from the holes were analyzed for texture (sand size), heavy mineral content and iron content. From the analyses it was found that the sand in many of the regions is too fine for glass purposes. However, sands from some areas were found to be of the same quality as the Plant City deposits. The final result of the study was the location of new resources of glass sand of the Plant City type. It must be added, however, that this procedure for locating glass sands will not work in other parts of Florida. Different methods of explora tion must be devised for other areas. Sand mine at Plant City. 53

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ClAY Among the most interesting Florida clays from the commercial viewpoint are kaolinitic clays for ceramic purposes, fuller's earth clays for their adsorbent properties, and bloating clays for their use in making lighweight aggregate. None of these clays is currently mined in Hillsborough County. However all are mined in the Florida peninsula and are a part of the mineral environment of Tampa. Kaolinitic Clays of the Citronelle Formation The north-south trending L ake Wales Ridge area which divides the Florida peninsula into an eastern and western part (Fig. 7) is underlain by Citronelle sands that contain varying amounts of kaolinitic clay. These, usually assigned a late Miocene or Pliocene age, are the materials previously discussed as the source sediments for quality construction sands of the peninsula. The kaolinitic clay occurs disseminated throughout the sands, usually constituting from 2 or 3 per cent to as much as 25 per cent of the beds. The kaolinite of the Citronelle Formation is a high quality ceramic clay. It has been mined at one time or another in Clay, Lake and Putnam counties, the production from Putnam County being continuous since 1892. In addition to its value as a ceramic clay, the kaolinite of the Citronelle Formation may have potential as a future source of aluminum. Citronelle clays are not present in Hillsborough County, but they do occur in the eastern, central and northern parts of adjacent Polk County. Fuller's Earth Clays of the Hawthorn Formation The Hawthorn Formation conta ins fuller's earth clays, utilized for their adsorbent properties. The dominant clay minerals are montmorillonite and attapulgite. Extensive mining of the clays is carried out in Gadsden County northwest of Tallahassee and in southwestern Georgia. The production of the adsorbent clays closest to the Tampa area is at Lowell in Marion County. Clay from that site is shipped to the Tampa market for use as an adsorbent cat litter, as a pesticide carrier, and as an intercaking agent for fertilizers. Although Hawthorne sediments are present in the subsurface of Hillsborough County, no extensive occurrences of fuller's earth type clays suitable for mining have been reported. 54 Bloating Clays Some clays will expand o r bloat when heated, often taking on the appearance of a burned, porous or cellular cinder rock. The expanded or bloated material is relatively light and if sufficientl y strong is ideal as a lightweight aggregate for use in the production of concrete and concrete products. Clays Along the St. Johns River : The only site from which bloating clays currently are mined in Florida is near Russell just west of the St. Johns River in Clay County. However, there are other occurrences of s i milar clays known to be present along the St. Johns These clay bodies apparently are confined to the genera l vicinity of the river valley. Deposits of Clayey Sediments in West-Central Peninsular Florida : Within the past few years massive bodies of clayey sediments possibly useful as a bloating clay have been found in northern Pinellas County (west and south west of Lake Tarpon) and in the vicinity of Telegraph Swamp in Charlotte County. These clays have been drilled and studied by members of the Florida Bureau of Geology, the Geology Department of the Un iversi ty of Florida, and the United States Bureau of Mines Laboratories (Wahl and Timmons, 1972). Figure 8 is a fence diagram showing the stratigraphic positi9n of the clay body near Lake Tarpon Wahl and Timmons ( 1972, p 1 09) report that the large clay deposit probably is Miocene in age, consists of montmorillo nite type clays, has an average thickness of 25 to 35 feet, and is overlain by unconsolidated Pleistocene sands. The clays have good bloating characteristics across an acceptable temperature range and develop a good cellular structure with a fairly thick and apparently tough wall structure However the deposit is in an area of rapid population growth and mining may not be feasible. In regard to this problem Wahl and Timmons (1972, p 112) state: "It is possible that development of the Pinellas County deposit to its maximum potential m ight already be prohibited by urbanization, for the P i nellas-H i llsborough County area is one of the fastest growing regions in the state at the present time. It is, indeed, imperative that other similar deposits throughout the state be located and their potential for development be realized so that land-use planning and resource develooment can be coordinated." In light or these comments by Wahl and Timmons it is of interest to note that extensive deposits of clayey sediments that may have potential as a base material for the manufacture of lightweight aggregate are present in a number of other counties in west-central peninsular Florida, including Pasco, Polk and Hillsborough In evaluating these clayey sedi ments a number of economic factors must be KEY SAND C L AYEY SAND CLAY SANDY CLAY EliB SANDY LIMESTON E DOLOMI T E SILTY LIMESTONE considered Obviously the overburden covering the clay deposits should be as thin as possible so that the cost involved i n its removal is not substantial. Also, the moisture content of the clay should be low. Every bit of moisture present is significant in that it increases processing costs. It is desirable that the clay be a natural bloating clay; however, coal or fuel oil can be used to make the clay bloat if the melting range of the clay is over a sufficient temperature span. In addition to these factors, transportation costs and problems related to the environment and to the restoration of mined-out land must be given serious consideration. MEXICO FIGURE a : FENCE DIAGRAM CONSTRUCTED FROM FIVE DRILL HOLES IN PINE L LAS COUNTY WIT H INSERT MAP S HOWING LOCA T ION OF DRILLED AREA MODIFIED FROM WAHL AND TI MMONS (1972, FIG.!5)

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There are different methods that could be used in attempti ng to locate and p inpoint deposits of these clays To illustrate, Figure 9 shows a section through Pasco, Sumter and Lake counties. From this section it is clearly seen that the Ocala Arch crests beneath Sumter County (holes 3 4 and 5). The near-surface sediments on the flanks of the arch are shown to be sandy clay (yellow color with dashes and dots). These sandy clays flanking the crest area of the Ocala Arch grade away from the arch into sediments containing less clay (yellow color). Clearly the sediments closest to the crest area are the highest in clay content and should be considered as broad targets for possible clay deposits. EXPLANATION Depth to top of the Floridan Aquifer, m feet below land surface D o-1o D 7 5 -loo D 1o-25 100-2oo 0 25-50 1!!!1 G reoterthon200 050-75 Figure 10 is a map of the same general area showing the depth to the top of the Floridan aquifer (usual ly limestone). By combining information from this figure with information from Figure 9 the target areas for the clays flanking the Ocala Uplift can be further localized. That area colored dark yellow on F igure 10 marks the crest area of the uplift. Limestone is within 10 feet of the land surface and a thick deposit of clay would not likely be present over the limestone. Beneath the area colored l ight yellow the limestone is at a depth of 10 to 25 feet. Again the closeness of the limestone to the land surface would tend to preclude the presence of a mass i ve deposit of thick, clayey materials between the land surface and the limestone, although the occurrence of a potential clay b ody could not definitely be ruled out. Throughout the area colored yellow-green the limestone is from 25 to 50 feet below the land surface. This depth t o the Figure 10 Green Swamp and surrounding areas showing thickness of sediments over the Floridan aquifer. (Reproduced from R Pride et al. 1966, Fig 3) -18 0 1 7 0 EX PLANATION -160 D Surfi c i ot s ond D Howlhorn formal ion(phosphori te unil) -15 0 Loose massive quartz sand. Porfly Recent wind deposit, partly r esidval. F.l"'l Gray 1 0 b ro w n, cloylly,fine-grained quartz sand; inttuslitiol secondary p hospha tes. Gray Ia brow n, claye y quartz sand and phosphorite ; l in e-grained quartz s an d ; phosphorite nodu l es ore as Iorge os pebbles Tampa limestone{cl oyunit) limes ton e lohosphorite unit) S u w ann ee J j m es too e Sl/ghlly sandy limestone. -l30 Greenish-gray to brown,sondy fine W h i l e lo cloy-sized grained) cloy. and clay E -120 o Ocala l imestone -g -JJO A lmost l imes/o ne DADE CITY AREA t> 1oo L _ ---:: ___________ -!3!!'.'2!.!...!!!!!!'..!'!!!'-'!!!f!c_ ______ .2' -90 ] e o -70 -60 '0 -40 55 H a r d-rod p ho sphate m ine 3 H ard-rod phosphol e mine 4 ', Ocala l im e stone Suwannee l ime s t o n e rubb l e '......_ Ocal a li m e s t o n e "Figurell. SECTION FROM BROOKSVILL E SOUTHEASTWARD T HROUGH THf BROOKSVIL L E RIDGE. NOTE CLAY UNIT OF TAMPA FORMATION IS CLOSE TO THE LAND SURFACE ALONG THE FLANKS OF THE BROOKSVILLE RIDGE (HOLES 5 AND 9). Modified f rom Ketner and McGreevy (1959 Plat e s 3 and 4 ) 2 3 4 MILES SCA L E Location Sources of Data limestone should be sufficient for c lay o c curre nces and for clay mining. Thus on the basis o f the work of Pride, Meyer and Cherry ( 1966) the yell ow-green area on F igure 10 of this report should be considere d as are as in which clays of interest for t hei r b loating qualities may be present. Additional information of significance in speculat ing on the possible occurrences of bloating clays is given in the work of Ketner and McGreevy (1959 Plates 3 and 4). Information from their plates has been selected and reproduced here as Figure 11. This figure shows subsurface sed iments along a line from Brooksville southeastward through Dad e C ity into Polk County. In this section the materials marked by d a shes are designated by Ketner and McGreevy as the clay unit of the Tampa Formation. In Pasco County this clay unit is shown to be near the land surface along the flanks of the Brooksvi lie Ridge as indicated by holes 5 and 9 on Figure 11. Therefore another broad target area for possible clay deposits would be alcng the flanks of the Brooksville Ridge where clayey sed iments are not covered by thick overburden sands. Obviously these published reports by the Florida Bureau of Geology and the United States Geological Survey can be used as starting points in planning for exploration programs directe d toward the recognition of potential clay resour ces in the gener al area of Tampa. 200 100 SEA LEVEL -100 -200 A \_ '...__.---, HERNANDO co. I I II ------,SUMTER! LAKE co. 'I ORANGE CO. PASCO co. II co. I I I 6 7 8 2 I .....,.A josc-EOLA c-o. I POLK CO. L_ ____ Ske t ch Ma p Showing Location of C rossS e c t i on Figu re 9 SECTION THROUGH PARTS OF PASCO, SUMTER AND LAKE COUNTIES. THE CREST OF THE OCAL A ARCH IS IN T H E VICINITY OF SUMTER C OU N TY N E AR CORE HOLE N0.4 NOTE THE CLAY CONTE N T O F SEDIMENTS I S HIGHEST AROU N D THE FLA NKS O F T HI S ARC H (YELLOW COLOR WITH D ASHES)_ MODIFIED FROM P RIDE E T AL. (1966, F I G 8). EX PLANATION Undifferentiated clastic deposits ( cloyey sand on left side graded into sandy cloy on right side) Undifferentiated cloy .. Suwannee Limestone D Crystal Rivet Formation D Williston Formation CJ Inglis Formation Avon Pork Limestone Fault; arrows indicate direction of movement

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56 Centers of Limestone Production During 1970 slightly more than 40 million tons of crushed limestone valued at 55.2 million dollars were produced in Florida from 90 quarries in 23 counties {Table 10). The producing areas can be grouped into two major centers of limestone production, one north of Tampa in the area of the Ocala Uplift {Fig. 12), and the other in the southeastern part of the peninsula in Dade and Broward counties. All of the Florida peninsula can be supplied with limestone products from these two centers. Of most direct interest to Tampa is the center in the Ocala Uplift area. There lime stones arched upward from depth are now exposed or covered by only a thin veneer of overburden sediments. They are accessible for mining by open pit methods and may be removed with draglines, power shovels, front end loaders and bulldozers. TABLE 10* Florida: Crushed limestone sold or used by producers, by counties (Thousand short tons and thousand dollars) County 1970 Number Quantity of Value quarries Alachua 4 1,744 $ 1,335 Broward 16 6,924 11,303 Collier 6 1,679 2,502 Dade 14 11 '134 13,356 Hernando 6 7,719 13,023 Levy 2 249 155 Marion 10 924 2,121 Monroe 2 917 615 Palm Beach 2 w w Sumter 3 2,604 2,456 25 6,316 8,310 Tota12 90 40,210 55,176 W Witheld to avoid disclosing individual company confidential data; included with "undistributed. 2 Includes Charlotte, Citrus, Lee, St. Lucie, Suwannee, Taylor, and Palm Beach counties. Data may not add to totals shown because of independent rounding. *Bureau of Mines Minerals Yearbook, 1970. LIMESTONE D MINE SITES POLK Figure 12. Center of limestone production north of Tampa. The crest of the Ocala Uplift is indicated by a heavy black line. Areas in which active limestone quarries are present are shown in color. Note their correlation with the area of uplift. Uses of Li mstone Limestone mined in Florida is used principally as a roadbase, as concrete aggregate, and in the manu facture of cement and lime {Table 11 ). The loose, granular "Ocala Lime Rock," mined extensively within the Ocala Uplift area in many counties including Alachua, Marion, Levy and Sumter, is used as a roadbase material and in the manufacture of lime. A crystalline limestone called "Brooksville stone," mined 'primarily in Hernando County, is marketed as a concrete aggregate, although some is used for railroad ballast and for agricultural purposes. During the past, much of the limestone used in making cement for the Tampa market came from mines in Citrus and Hernando counties. Now, however, limestone sediments are being imported from the Bahamas for the Tampa cement market. Some carbonate rocks have a relatively high content of magnesium. These rocks, often called dolomites or dolomitic limestones, are used mainly as fertilizer filler and for soil improvement. They are mined north of Tampa in some parts of the up I itt area and south of Tampa in Manatee and Sarasota counties. TABLE 11* Florida: Crushed l imestone sold or used by producers, by uses (Thousand short tons and thousand dollars) 1970 Use Quantity Value Con crete aggregate . . . . . . . 9,824 $16,302 15,232 20,398 2,820 4,214 Dense graded m'l.dbase stone ...... Other madstone .............. 2,866 2,788 375 1,353 Unspecified aggregate and madstone .. Agricultural purposes 2 ........... Fill ......... ............. . 3,373 2,651 120 165 5,600 7,306 Railroad ................ Other uses ......... ......... Tota1 4 ........... ....... 40,210 55,176 10ther roadstone includes bituminous aggregate, macadam aggregate, and surface-treatment aggregate. 2 include stone used in poultry grit. 3 1ncludes asphalt filler, cement, chemical stone, other filler, lime, stone sand. 4 Data may not add to totals shown because of independent rounding. *Bureau of Mines Minerals Yearbook, 1970.

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Limestone Reserves Like many other low unit-value mineral resources, limestone deposits must have natural purity and be easily accessible for mining in order to be economic ally important. Although the Tampa area is underlain by vast quantities of limestone, the thickness of overburden coupled with the impure nature of the limestone renders the sediment throughout most of the area insignificant as economic deposits However, about 10 miles northwest of Lakeland there is a large region in which limestone is close to the land surface (Fig. 10, yellow-green color). That area, partly in Hillsborough County, has potential as a source region. Florida's reserves of limestone are monumental. Reves (1962, p. 7) states that in the northern half of the peninsula alone, the amount of limestone which has less than 15 feet of overburden, if mined to a depth of 40 feet, would approach 4 2 trillion tons. A vast amount is a very high calcium limestone, ranging from a minimum of 95 per cent calcium carbonate to as much as 99.8 per cent calcium carbonate. Furthermore there is a great deal of dolomitic limestone. For example, Vernon (1951, p 218) reports more than 100 square miles underlain by dolomitic limestone in Citrus and Levy counties alone. Other occurrences of dolomitic limestone are known in Florida, including deposits along the Gulf Coast in Dixie, Taylor, Jefferson and Wakulla counties (Reves, 1962, p. 12) and in Pasco, Hernan do, Suwannee, Manatee and Sarasota counties (Max well, 1970, p 26). Potential Deposits of Crystalline Limestone Recently Yon and Hendry ( 1972) investigated the occurrences of crystalline limestone in Hernando and Pasco counties Limestone products from these counties, just north of Tampa, would have a marked impact on the Tampa market Yon and Hendry determined that crystalline limestone suitable for concrete aggregate is associated with an elongated subsurface h igh extending from Pasco County north westward into Hernando County (Figs. 13 and 14). They interpreted the buried "ridge" of limestone as a possible carbonate bank built during Oligocene time in a warm shallow sea. The highs and lows of the upper surface of this buried limestone "ridge" conform in general with the highs and lows of the land surface. To prospect in that area for limestone suitable for aggregate, one may superimpose contour maps of land surfaces onto Yon and Hendry's contour map of the upper surface of the limestone high (Fig 13) The crystalline limestone should be close to the land surface at those sites where the two sets of contour lines show nearly the same elevations (Yon and Hendry, 1972, p. 40) These correlations brought out by Yon and Hendry constitute a vivid illustration of the significance of basic geological studies in pointing to occurrences of accessible mineral resources. Limestone mine i n Sumter County. EXPLANATION + OUTCROP o WELL or CORE HOLE QUARRY IT:TI CRYSTAL RIVER 12Z::J FORMAT I ON FAULT LINE in REF to SEA LEVE CONTOUR INTERVAL 25 FEET, EXCEPT in INSET, CONTOUR INTERVAL is 50 FEE Figure 13. CONTOURS DRAWN on the TOP of the SUWANNEE LIMESTONE in HERNANDO and PASCO COUNTIES._ A HIGH, ELONGATED AREA JUST WEST of DADE CITY is CLEARLY SHOWN. ITS TREND is NORTHWEST-SOUTHEAST. (FROM YON and HENDRY,1 972, Fig.5,p.m Figure 1.4. AREA of POTENTIAL LIMESTONE AGGREGATE in HERNANDO and PASCO COUNTIES is SHOWN in COLOR. THIS AREA CORRESPONDS to the HIGH on FIGURE 13. (FROM YON and HENDRY, 1972, Fig.16,p.39 ) 57

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58 CEMENT,OYSTER SHEll,& PEAT Cement Cement itself is not a mineral but normally is considered a mineral resource. The raw materials needed in its production are lime or limestone and minor amounts of silica, alumina, and iron oxides. In manufacturing portland cement the raw materials are crushed, then proportioned under strict chemical controls, ground to a powder or slurry and fed .into an inclined rotary kiln. The powdered material moves under gravity from the upper toward the lower end of the rotating kil n where intense heat is produced. The heat fuses the powdered charge to a glassy clinker composed o f calcium silicates and aluminates. The clinker is then mixed w it h a small amount of gypsum, whi ch later helps regulate setti ng time, and the mass is gro u nd to a f in e powder. T h i s powder is portlan d cement. The limestone used in produci ng portland cement must not contain m ore t han 3 per cent magnesia T his is a st ringent requirement that eliminates many potential l imestone sources. Part of the small amount s of silica, iron oxides, and alumina needed may be present in the limestone as impurities. Additional amounts usually are added by introducing clays or other materials containing these substances. Staurolite from the heavy mineral operations near Starke has been used to some extent in Florida as a source of iron and aluminum. Factors important in establishing a cement plant include the availability and quality of deposits of limestone and the other raw materials. In addition, a satisfactory source of fuel for the rotary kilns must be considered. Most important, however, is the location of the market area The plant should be established as close as possible to major population centers to reduce costs of transportation. At present there are four plants producting cement in Florida. Three are in the Dade County or Miami area and one is in the Hillsborough County or Tampa area. The Tampa plant, with an annual capacity of 6 million barrels of cement, is by far the largest in the state. Nevertheless, a cement shortage exists in the Tampa region and cement is being imported into the area. One of the new sources is Honduras in Central America. Approximately 87 per cent of the cement produced in Florida during 1970 went to building material dealers, concrete products manufacturers, and ready-mix concrete manufacturers (Minerals Yearbook, 1 970). Much of the remainder was used by highway contractors and government agencies. Limestone for the cement plant in the Tampa area was mined for years at sites in Citrus and Hernando counties. Now limestone sediment (aragonite) is being dredged near Bimini in the Bahamas and shipped to the Tampa plant. The clay needed to furni sh small amoun ts of iron oxi des a n d alumina is mined in Citrus County. Soon, however, clay for the Tampa operation wil l be mined from a new pit to be opened in Hernand o County. The quantity of raw materi als consumed in the production of cement at the Tampa site is enormous. Dust from the clinker burning process makes for a significant problem which currently i s of a crisis nature at the Tampa plant. A new cement plant is in the planning stage for Manatee County just south of Hillsborough County. T his will reportedly be a pollution-free plant, but resistance to its construction is already substantial. If a population center is to thrive it must have cement and other construction materials, and it must be able to obtain them at a reasonable cost. Raw materials necessary for the production of cement are available to the Tampa region. However, as illustrated by the Tampa plant, cement manufacturing can be plagued by pollution problems. The need for cement, when considered with problems associated with its production, serves as a striking illustration of the need for informed leadership in planning for the economical and popularly acceptable manufacture of a product necessary for a thriving and expanding population center. ) Scenes at cement p lant in T a m p a

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Oyster Shells For years oyster shells have been dredged from Tampa and Hillsborough Bays, with an estimated tonnage of slightly more than one-half million cubic yards now being produced annually_ The sites of current dredging operations are shown on Figure 15. Most of the oyster shells are used for road base materials, the city of Tampa being among the largest of the consumers. According to Mr. E. Medard of Bay Dredging and Construction Company (personal communication), the shell layer being mined in the bay ranges in thickness from 2 to 20 feet, approximately, and is overlain by 4 to 15 feet of overburden. The amount of reserves is unknown. Mountain of oyster shells at Bay Dredging and Construction Co. ( I ) TAMPA FIGURE 15 GENERALIZED AREAS IN TAMPA and HILLSBOROUGH BAYS FROM WHICH OYSTER SHELLS CURRENTLY ARE 8 A Y BEING DREDGED. /\> c;:,; 0._ / ;?_ ( D a tofr o m B a y Ored girHJOOd Con s Co. ) Dredgin g of these shells in the bay area has been the subject of much concern during recent months. The problems include possible destruction of marine life and biological resources and possible adverse effects on local water quality. Again there is insufficient data to evaluate all aspects of these concerns intelligently and effectively, and clear-cut recommendations or decisions cannot be drawn with comfort and conviction. To illustrate the dilemma, late last year when the Florida Cabinet considered requests for renewal of permits to continue dredging operations for oyster shells in Tampa and Hillsborough Bays, it was faced with different opinions from different individuals, institutions, and state agencies The consensus was that further study was needed. Peat During 1970 peat was produced in Florida from 8 plants in 6 different counties including Hillsborough Total production from the entire state amounted to approximately 46,000 tons valued at slightly more than 300,000 dollars (Minerals Yearbook, 1970). Most of the peat is used for improving the physical character of soil. The production i.n Hillsborough County is largely for local needs and comes from sites near Mango. Davis ( 1946) has made a thorough study of Florida's peat deposits. That work can be consulted for discussions of the various kinds of peat and mucks, their distribution, origins and characteristics CONCLUDING REMARKS This brief discussion of mineral resources of the Tampa area touches upon interesting and crucial environmental and land-use problems. Some of the problems can not be evaded and will become more and more pressing with time. They are both philosophical and practical. It is evident that among the most significant needs for understanding any of the problems are reliable, basic data. These data can not be accumulated in a few days or i n a few months; their accumulation takes years. A strong case can be built that one of our most severe deficiencies in preparing fo r the land-use and environmental problems that face us today has been our lack of support for those studi es and for the wor k of those agencies which supply basic data. Whe r e and when p lans and decisions can be based by competent leadership upon reliable data, socially beneficial solutions to these challenging problems will be more easily obtainable. 59

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ENGINEERING GEOlOGY

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62 Introduction Engineering geology may be defined as: "The application of the geological .sciences to engineering practice for the purpose of assuring that the geologic factors affecting the location, design, construction, operation, and maintenance of engineering works are recognized and adequately provided for"1 As such, engineering geology is concerned with the physical characteristics of earth materials and deals with quantitative data obtained from testing the suitability of those materials for specific uses or roles In the Tampa area, construction planning perhaps most frequently demonstrates the simultaneous use of engineering and geological eoncepts. Likewise, soils studies incorporate engineering and geological prin ciples. This phase of the report will deal with the use of engineering geology techniques applied to con struction planning and the study of soils. In planning the construction of any building, of primary consideration is the character of the earth materials upon which the building will rest. Various physical properties of these materials determine how much weight they can bear and, in turn, how a given building must be supported. Three factors are involved in the selection of an appropriate foundation design: FOUNOATI ONS 1. The nature and competency (strength and compressibility) of the subsurface materials. lncompentent (weak and/or compressible) subsur face materials may necessitate special site preparation prior to construction and/or a complex foundation system. 2. The size and type of building. The size of the building is important in that small, I ight buildings such as residences obviously require less support than heavy multi-story structures; and likewise low-rise structures, such as shopping malls, generally require less support than heavy high-rise buildings. The type of building con struction, such as steel, concrete, masonry or wood, determines the building's adaptability and tolerance to settlement and its effects. 3 Economics. The cost of constructing a feasible foundation system should be in balanced proportion to the cost or value of the structure itself. All three factors must be weighed in determining the suitability of a site for construction. It may also be pointed out that the same three factors listed above also determine the scope and extent of the subsurface investigation and study which is required for a building site. The thickness and character of surficial soil deposits and the depth to rock often are of prime importance in the selection of a building site and development of construction plans. Probably the most accurate statement that can be made about the surficial soil deposits and the depth to the rock surface in the Tampa area is that they are character ized by their inconsistency. The thickness and extent of the cohesionless and cohesive soils-that is, the sands and clays-can vary greatly, even among the borings made at one site. In addition, soils intermediate in nature between the noncohesive sands and the cohesive clays, such as sandy clays and clayey sands are quite common. In some instances, sands grade slowly downward into clayey sands and then sandy clays and then relatively pure clays. In other instances, clayey lenses are found within the sands; and sand lenses within the clays. Consequently, accurate mapping of the thickness of the cohesive and non-cohesive soils in the Tampa area is very difficult. ) In addition to the areal extent and thickness of the cohesionless sands and cohesive clayey soils; the strength and compressibility of these soils is a vital parameter. Standard penetration tests provide so me indication of both the relative strength and relative compressibility of soil deposits. The specific pro cedures for performing this test and obtaining soils samples is comprehensively presented in American Society for Testing and Materials specification 0 1586. In general, this procedure involves driving a 2 inch split spoon sampler 18 inches into the soil by means of the energy imparted by a 140 pound drop hammer falling 30 inches The number of blows required to drive the sampler the last foot into the soil is the standard penetration resistance, commonly called the 'blow count'. Other supplemental invest igative procedures, such as the auger borings or cone penetrometer borings are sometimes used to obtain additional information regarding the nature of the surficial soil deposits; but the standard penetration test is the most widely used method of determining and evaluating the nature of the subsurface condi tions. However, it should be noted that the data obtained from this procedure is rather limited and more qualitative than quantitative in nature. More specific and quantitative information regarding shear strength and compressibility of soi Is is generally obtained by laboratory testi n g of undisturbed soil samples. Sometimes f ield lo a d tests are necessitated because of the nature and geology of the soil deposits. .,

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Subsurface conditions which limit the suitability of a site for construction can generally be overcome by the use of certain site preparation techniques or special foundation design, or both. Before subsurface problems and their solutions can be discussed, some pertinent terms need defining: Shallow Foundation Systems This type of foundation bears at a very shallow depth and imparts the foundation loads to the shallow subsoils. There are a number of types of shallow foundations, all of which are used to spread the superimposed loads over a sufficient area so that the safe bearing capacity of the foundation soils are not exceeded. The type that is best suited for a particular site depends upon the subsurface condi tions. The following are the three major types of shallow foundation systems listed in the order of least costly to most costly. SHALLOW FOUNDAT ION SHALLOW FOUNDATION Individual spread footing ( I ndividual or Continuous Foundations-Individual spread footings are utilized to support columns; whereas continuous spread footings are used to support load carrying walls. These are normally the least costly type of foundation systems and are utilized where good subsurface conditions exist. Strap Foundations-This type of foundation is utilized to support a row of two or more columns. The foundation strap is structurally designed with sufficient stiffness and rigidity to function as a single unit. This type of foundation system is used where somewhat poor subsurface conditions exist and when it is desirable to reduce subsurface stresses and minimize potential settlement between columns. Mat Foundations-A mat or raft foundation, com monly called the floating foundation, encompasses the entire base of the structure and spreads the building load over the entire building area. The main functions of such a foundation system are to reduce subsurface stresses in compressible soils, bridge weak zones or possible subsurface cavities, and reduce total and differential settlement. This is generally the most costly of the various types of shallow foundation systems. STRAP FOUNDATION Deep Foundation Systems Piles or caissons are the most common type of deep foundations. Their purpose is to transfer a load which cannot be supported at a shallow depth to a greater depth where adequate support is available. Caissons are rarely used in the Tampa area because of installation difficult ies imposed by the general geo logy of the area; whereas timber, steel and/or concrete piling are commonly used. Because of the variable and unreliable nature of the clayey subsoils, the pi I ing are usually end-bearing on the I i mestone bedrock. The cost of piling can vary widely, depending upon their length and capacity. Subsurface Grouting This generally refers to the pumping of sandcement mixtures or chemical grouts into weak porous permeable zones and/or underground cavities or networks of cavities in order to strengthen and stabilize the subsurface strata. This procedure, al though not commonly used, is frequently necessitated in certain areas within the Tampa area because of the geological conditions. The cost of this type of site preparation work is extremely variable and can be quite expensive. MAT FOUNDATION DEEP FOUNDATION Piles or Caissons 63

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SANDS Foundation problems common to the Tampa area can be dealt with in a variety of ways depending on the severity of the problem and the nature of the structure. Four fundamentally undesirable site condi tions include: loose sands, compressible clay, organic materials, and sinkholes. LOOSE SANDS Structures built on loose sands may settle and crack if the sands density or compress Densification can result from the imposed load, changes in ground water levels, or from vibration of the ground due to traffic, sonic booms, machinery, etc. In order to prevent settlement, three alternatives are possible: 1) loose sands can be removed and replaced, 2) pilings can be utilized for support, or 3) the sands can be densified. Even for high rise buildings, excavation of loose sands for foundations rarely exceeds depths of ten feet. With deeper excavat i ons, costs a r e higher, and the water table becomes a problem. If the entire ground floor area of a building must be excavated, every foot of material removed results in a significant increase in cost. Following removal of loose sands, the site is back filled and properly compacted. In-place densification of loose sand is usually the least expensive means of adequately preparing the site for buildings. The older method of densifying loose cohesionless soils was to excavate it, replace it in thin layers and compact it_ However, modern compaction 64 equipment and techniques now make possible the densification or appreciable thicknesses of sand without excavation If surface deposits of loose cohesionless soils are only moderately thick, the use of large heavy vibratory compaction equipment usually will adequately density the soils; whereas if the loose sands are either very thick or buried, a process called "Vibroflotation"1 can be utilized. This latter system utilizes water and vibration to compact the sand. All methods of in-place densification are reasonable in cost. In the Tampa area, pure quartz sands and sands with minor amounts of silt, clay, and organic material generally range from a few inches to more than 30 feet thick. The sands tend to thih toward the Bay. The meandering contour lines on the map partially reflect the effects of stream channel development and the erosion of sands by streams. The reaches of the river channels exhibit thinner sand than adjacent areas. 1 Trademark '---....._TAMPA ..........__ \ \ \ \ I \ SAND THICKNESS (In feet) ) Hillsborough Bay TAMPA BAY 2 3 4MILES Lake Thonotosassa ----.1

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SANO SUITABiliTY AS A FOUNDATION MATERIAl T he map p r esented here i ncorporates both thick n ess and compress i bil ity of the relatively pure surface sands and outlines the areas or problem sands and sat i sfacto r y sands It must be borne in mind that the map has been compiled from data currently availab l e and is thus generalized. Close spac ing of "good" and "poor sands bears wit n ess to the l ocal variability of sand c h aracterist ics. I t can be seen from the map that thick loose sands are especia l ly prevalen t in the Temple T errace U nive rs ity of Sou t h Florida area and around B r an don. F irm sands are fairly well scattered but appear t o be concentrat ed in the downtown and inte r bay areas With regard to s ite suitabi lity for construction, this map illustrates one of the many aspects which must be considered, and it wil l be utilized as an overlay in the L and Use section of the report. Good: Firm sands five feet or greater in thickness have been encountered in these areas T hese sands are capable of supporting many types of structures with no pre -construction site preparation. Variable: These areas have been found to contain varying thicknesses of sand that exhibits eradic compressibility. Because of their unpredictable nature pre construction treatment for the sands may be required Moderate: This includes areas i n which sands are predom i nantly firm but contain compressible lenses and areas in which less than five feet of loose sand lies at the surface and is underlain by more than five feet of firm sand Depending upon the type of con struction proposed, very little treatment may be necessary to render these sands suitable to provide adequate foundation support. Poor: Included are areas in which sands are 10 feet or greater in thickness and are predominantly loose, but contain lenses of firm sand Also, included are totally loose sands five to ten feet thick These two conditions have been grouped as "poor" because some preconstruction site preparation would proba bly be required but may not be as extensive as in the areas labeled "very poor". Very Poor: This includes areas in which loose sands ten feet or greater in thickness have been encountered, areas in which f i rm sands less than five feet thick are underlai11 by loose sand greater than five feet thick, and areas in which sands containing organic deposits have been found. All of these conditions would likely necessitate treatment prior to construction. I t should be noted that sands l ess than five feet thick have been omitted from consideration in this map When very thin sands are encountered, the mater ial underlying them i s generally of equal or greater importance in foundation planning. These areas will be brought to light in the discussion of clays. ( SAND SUITABI LITY for FOUNDATIONS 00 Hillsborough Bay TAMPA BAY A EXPLANATION OvERY POOR DPOOR DvARIABLE D MODERATE '"""'"' : --=---JI G 00 D 65

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ClAYS The presence of clays at or near the surface presents a problem to many types of construction. This is due to the low shear strength of many days as well as thei r compressibility T o compound the problem, compressibility and shear strength of the clays in the Tampa area are very variable and inconsistent. Furthermore, clays or cohesive soils cannot normally be mechanically improved One method of treatment is to remove the weak, compressible, cohesive soils and replace them w ith properly compacted competent materials. Unfortun ately, this i s only feasible when they lie at or near the surface; which in the Tampa area they rarely do Where they are deeply buried, the soils overlying them may be sufficiently thick and competent to adequately support a structure. However, when the weak clays are shallow, they generally necessitate some spec ial attention in foundation design. If the underlying l i mestone is also shallow, piling can be used to transfer the foundation loads through the weaker compressible clays to bedrock. However, since piling is an expensive means of supporting small structures, shal low weak clays can be a bigge r stumbling b lock to small construction projects than to large ones The map on this page shows the areas i n wh i ch firm clays have been found underlying surface sands, and areas in which soft clays or clays cbntain ing soft lenses have been encountered beneath the sands I n addition, areas are shown in which clay occurs only as thin lenses within the sand or mixed with sand as a minor constituent. Like the map illustrating sand conditions this map is generalized on the basis of the network of known values The thickness and com pressibility of clay and cohes i ve soils varies as much as if not more than the sands. It is virtually impossible to predict the conditions that will occur at a specific site without performing a subsurface investigation at the site. On the map, soft clays have been shown according to thickness ranges (less than five feet, five feet to ten feet, and greater than ten feet). If the soft clays are of significance to a particular construction project then the greate r their thickness, the more of a problem they become No attempt has been made however, to categorize the clays according to the severity of the problem they may cause Whether or not the clays ,l, will be a problem at all, largely depends on their depth and thickness, and thickness and competency of the overlying soils, the magnitude of the bu i lding loads to be imparted and the structure tolerance to settlement. This map will be used in the Land Use section in combination with other maps to indicate land suitability for construction CLAY CONDIT I ONS \ \ \ \ Areas in wh i c h soft clays greater than ten feet thick are found to occur. This includes soft clays with interspersed lenses, clays containing peat layers and karst areas with greater than ten feet of clay Areas in which five to ten feet of soft clay have been encountered. CLAY CONDITIONS -66 Areas in which soft clays less than f i ve feet thick occur. Areas in which clays occur only as thin lenses within the sand or as a minor faction mixed with sands Areas ih which firm clays contain ing no soft lenses occur. T hese clays are of varying thickness. (Data from J F Orofino and Co. ) 0 Hillsborough Bay TAMPA

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ORGANICS ORGAN I C MATERIALS Deposits of organic soils, including peat and muck are undesirable for almost all construction. Like clays, they cannot be mechan i cally improved and in most cases, must be removed and replaced with suitable fill. Since areas where organic deposits occur are generally swampy or lowlying, such sites have other disadvantages imposed by the high ground water table Many swampy areas, however, have been excavated, fi lied and compacted to provide accept able building sites. The map shows areas which are designated as marshes or swamps on the topographic maps of the Tampa area. In many instances, these swamps we r e filled after the topographic maps were compiled but all of the areas des i gnated on the map can be expected t o contain organic deposits While these areas need not be eliminated from consideration as potential building s i tes, it should be realized that their surfic ial deposits may l i mit land use or impose additional expense for pre-construction site prepara t i on. OLD p A 1--1lMILE TAMPA ---------------_____ j BAY DISTRIBUTION OF WETLANDS IN THE TAMPA AREA D MARSH MANGROVE WOODED MARSH #' -. I - 4 .. VALRICO . ;.,..-, .... : 67

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OLD H illsborough Bay TAMPA BAY 68 / / / / POTENTIAL COLLAPSE Areas underlain by cavernous limestones present special foundation problems especially for heavier buildings. Stronger foundations for high rise structures are a necessity in such areas and inexpensive spread foundations are usually not adequate. 1-f the problem is not severe, strap foundation (which is the next least expensive) may be adequate, but in many cases more costly mat foundations must be used A pile foundation is not generally a satisfactory alternative; since when sinks develop, slumping of sediments creates lateral pressure which may cause standard piling to fail. Other steps which may be taken in order to minimize the potential risk of loss of foundation support include proper.site drainage and design of the structure to minimize the net increase in stress on the subsurface deposits. Stress increases can be minimized by placing a basement beneath a structure and in this way the total weight of the building may not be substantially greater than the weight of the soils excavated for the basement. A last resort in dealing with the problem of collapse is subsurface grouting. However, this is very expensive and the amount of grouting required is unpredictable When grouting is undertaken, the final cost and success of the effort is unknown. An alternative action, though not necessarily a solution to the problem is to move the location of the building to a different position on the site where cavities in the limestone have not been encountered in the subsurface investigation. I t is difficult to assess the risk involved in constructing in an area of potential collapse Al though imminent risk of collapse can be minimized by site treatment and careful foundation design, there is still a potential risk of loss of foundation support due to cavities which may not have been revealed by the subsurface investigation. DEPTH TO ROCK (in feet) BELOW LAND SURFACE (Thickness of overburden) "The final decision as to the type of foundation system to utilize will be dependent upon the owner's willingness to incur certain costs and assume certain risks: These must be balanced against one another in view of the type structure, intended use and consequence of problems which might develop if the risk becomes a reality "1 Areas in which collap ses h ave occurred in the past are shown on a map in the Geology section of the report with the discussion of sinkholes. DEPTH TO ROCK A map showing the position of the rock surface relative to mean sea level is presented in the Geology section Whereas that map is prerequisite to under standing subsurface relationships, the matter of concern in construction planning is the depth to rock measured from land surface as illustrated on this page The contour lines reflect not only variations in the bedrock surface, but also variations in local topography. This map can also be considered a map of the thickness of surficial deposits and is a useful tool in construction planning. When the surficial deposits are incompetent as a support material, it is vital to know how deeply buried the rock surface is so that a decision can be made as to whether it would be more economical to improve the surficial deposits or to utilize piling for support. This map is an important component of land suitability for construction as presented in the Land Use section of the report. 1 James F. Orofino, Orofino and Company, (Personal Communication).

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SOl LS Soils are an integral aspect of both geology and land u s e planning. The mantle of sand deposited in Hillsborough County during Pleistocene time is the parent material for many of the soils which developed in the area. Drainage, climate, vegetation, and topography have also played roles in the formation of local soil types. The Soil Conservation Service (S.C S ) has identi fied and mapped the soils of Hillsborough County on the basis of their characteristics as determined in the field and lab. These include color, texture, structure, consistence, depth of soil over bedrock or compact layers, steepness of slope, degree of erosion nature of underlyi ng parent material acidity or alkalinity of the soil, etc. The so i l layer studied and described by the S.C.S ranges from 40 inches to 72 inches thick. On the basis of observed analytically determined characteristics, so ils are classified into phases, types and series "The soil type is the basic classification unit. A soil type may consist of several phases. Types that resemble each other in most of thei r characteris tics are g rouped into soil series."1 Detailed maps of soil phases in the Tampa area are presented i n the Hillsborough County Soil Survey. In addition, a County map showing soil associations is included and a revised map is presented in the Supplement to the Soil Survey. Part of this map is reproduced here and the major characteristics of each association are given Soils that occu r together in a regular pattern in the landscape have been grouped into soil associations. The i ndividual soils within each association may or may not have similar properties and interpretati ons. POMELLO-ST LUCIE ASSOCIATION : Areas dominated by nearly level to gently sloping, nearly white, excessively to somewhat poorly drained, strongly acid, deep sands. The native vegetation consists of scrub oak, slash pine, saw palmetto and sand pine Soils in thi s association are low in organic matter and fertility and are very droughty, hence they are poorly suited to cultivated crops and citrus. LAKELAND-ARREDONDO ASSOCIATION : Areas dominated by nearly level to gently sloping, well to somewhat excessively drained, slightly to very strong ly acid deep, brownish colored phosphatic and non phosphati c sands The native vegetat ion consists primarily of turkey oak, pine, shrubs, grasses, and a few palmettos. The soils in this association are low in organic matter content and fertility and have a low available water capacity BLANTON LEON ASSOCIATION : Areas dominated by nearly level to gently slopi ng, moderately well d r ained, deep sands. Native vegetation includes pine, oaks, grasses and palmettos. The soi Is have low o r ganic matter content, low natural fertil ity, and low available water capacity. D D D LEON-PLUMMER ASSOCIATION : Areas dominated by nearly level, very str ongly aci d, deep, somewhat poor ly drai ned sands with an organic stained sub surface layer. The native vegetation i ncludes slash pine, saw palmetto, runner oak, gallberry woody shrubs and various grasses The soi Is are low in organic matter content, natural fertility and available water capacity. DNA-SCRANTON-LEON ASSOCIATION : Areas dominated by nearly level to gently sloping, somewhat poorly drained, strongly ac i d, deep sands on broad, low flatland. The natural vegetat ion consists of p i ne, turkey oak, live oak, saw palmetto, woody shrubs and grasses Most soils in this associat ion have moderatel y high to high organic matter content, and are moderately low in natural ferti l ity. RUSKINSUNNILAND-BRADENTON ASSOCIATION: Areas dominated by nearly level, somewhat poorly drained, sandy soil with loamy to clayey subsoils The native vegetation is pine, cabbage pa lmetto trees, saw palmetto, runner oak, woody shrubs, and grasses. T he soils have low organic matter content, and low to moderate natural fertil ity and ava i lable water capac ity. RUTLEDGEFRESH WATER SWAMP-PLUMMER ASSOCIATION: Areas dominated by nearly level, very poorly drained, deep, strongly acid to medium acid sands in low wetland. Native vegetat ion is mainly water-tolerant grasses and sedges pickerelweed and St. Johnswort, with cypress bay, gum and occasional pine t r ee s in swampy areas. Soils have low to high organic matter content and low fertility Wetness is an outstanding limitat ion for many uses of these soils. BRIGHTON -TERRA CEIA ASSOCIATION : Areas dominated by nearly level very poor ly drained, shallow to moderately deep, acid to neutral organic soils in marshes and swamps. Native vegetation consi sts of sawgrass and various othe r sedges and grasses. Organic soils in this association are high in nitrogen but low in all other plant nutr ients Excess ive wetness i s cha r acteristic FRESH WATER SWAMP : Areas dominated by nearly level, very poorly drained mineral a p d organic soils in stream bottoms and swamps. Native vegetat ion consists of hardwoods, cypress, bay, cabbage, palmet to, pines, shrubs, vines, ferns and grasses SALT WATER SWAMPS AND MARSHES : Areas dominated by nearly level very poorly d r a ined, saline soils lying adjacent to and affected by salt water tidal ac t ion Native vegetation includes salt -tolerant grasses and mangrove trees MINE PITS AND DUMPS : Areas dominated by open pebble phosphate mines and adjacent spoil mounds. 1 Soil survey, Hillsborough County, Florida, 1958, p 58 D D D 0 D D \ \ \ I I I I I I I I HILLSBOROUGH BAY TAMPA BAY 69

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70 SOIL RELATIONSHIPS Soil data can be utilized in a variety of projects which are of concern to local and regional planners. In addition, the S.C.S. can provide technical assistance on water management, soil erosion and stabili zation, agronomy, biology, etc. "One of the most talked about concepts in recent years is the idea of spreading the effluent fr.om municipal sewage treatment plants on the land to eliminate the discharge of the effluent into surface waters in the state.''1 Soil properties and plant relationships play a vital role in land renovation of waste water. The cation exchange capacity of the soils (especially clayey soils) is a most important soil property. This soil property along with plant nutri ent removal and denitrifying bacteria can very effec tively remove certain constituents of waste water. "Any design of a system for land spreading of waste materials must consider the soil system and its relation to the local landscape, which includes the stratigraphy, geomorphology, and hydrology of the area under consideration.''2 The local Soil and Water Conservation District has expended a good deal of effort toward solving drainage problems in the Tampa area. Although much of this effort has involved agricultural lands, the drainage principles have been applied to urban lands as well. For example, shortly after the completion of Tampa Stadium, it was found that the parking area became flooded and unusable after rains. the standard soil survey in conjunction with field investigations, the S.C.S., working through the Hills borough Soil and Water Conservation District, de signed a subsurface drainage system for the parking areas, and the flooding problem was eliminated. Soils data can and should be used along with geologic and hydrologic data as an input source for environmental planning. 1 Livingston, J. B., Land Renovation of Waste Water, p. 1 from : Workshop Proceedings-Use and Interpretations of Soil Surveys and Engineering Principles of Water Management, 1972, Soil Conservation Service. 2 Daniels, R. B., Water Movement in Soils, p, 7, from Workshop Proceedings-Use and Interpretations of Soil Surveys and Engineering Principles of Water Management, 1972, Soil Conservation Service. 1n URBAN PlANNING Shallow excavation showing a soil profile. Soil Conservation Service control structure in northwest Hillsborough County. Tampa Stadium parking area after installation of the subsurface drainage system

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Many land uses are essentially "surface" uses and consequently, soil characteristics are the most import ant geohydrologic consideration in planning. The land use most vitally linked with soils is agriculture or agronomy Land areas in which the soils are particularly productive warrant consideration for designation as agricultural lands. The S.C.S. has compiled detailed information on the productivity of various soils with regard to assorted crops. Other land uses in which surficial materials (soils) are of primary concern include recreational areas, highway and airport sites cemeteries, golf courses, single story buildings, etc Shown on this page is Table 5 from the Supplement to the Soil Survey: Hillsborough County, Florida. This lists the degree of limitations, restric tions and hazards for various land uses by soil associations. Two factors should be borne in mind when this table is examined: 1) This generalized table is derived from more detailed S.C.S. tables and maps. Final evaluation of a specific site for a proposed use must be supported by detailed on-site investigations 2) The limitations listed in the table are based on the characteristics of only the top 4().72 inches of material. The Rating System None to slight: Soils have properties favorable for a particular use. Limitations are so minor that they can be overcome easily. Good performance and low maintenance can be expected from these soils. Moderate : Soils have properties moderately favorable for a particular use Limitations can be overcome or modified with planning, design, or special maintenance. Severe : Soils have one or more properties unfavorable for a particular use. Limitations are difficult and costly to modify or overcome, requiring major soil reclamation, special design, or intense maintenance Very severe : Soils have one or more properties so unfavorable for a particular use that overcoming their limitations is very difficult and costly Reclamation is extreme, re quiring the soil material to be removed, replaced or completely. modified The rating provided for each association is for the predominant soil in the association Other soils in the association may have different ratings. These ratings are actually measures of "degree" or "intensity" of soil limitations, restrictions, or hazards for a certain use. Most soils are suitable for all uses if provisions can be made to overcome or eliminate the problems. DEGREES OF LIMITATIONS, RESTRICTIONS AND HAZARDS FOR SELECTED USES BY SOIL ASSOC IATIONS, HILLSBOROUGH COUNTY, FLORIDA (MODIFIED FROM SOIL CONSERVATION SERVICE, 1969, TABLE 5) NAME OF ASSOCIATION FOUNDATIONS HIGHWAYS, DIRT ROADS CAMP SITES GOLF COURSES FALLOUT CEMETERIES WITH COMPONENT SOILS AND PERCENT OF EACH FOR LOW AIRPORTS, UNPAVED STREETS PICNIC AREAS SHELTERS BUILDINGS STREETS, PAVED AND PARKING AND AND ROADS AND AREAS PLAYGROUNDS BASEMENTS POMELLO-ST. LUCIE POMELLO 31 ST LUCIE 24 OTHERS 45 LAKELAND-ARREDONDO LAKELAND 41 ARREDONDO 23 OTHERS 36 BLANTON-LEON BLANTON 24 LEON 23 OTHERS 53 LEON-PLUMMER LEON 61 PLUMMER 9 OTHERS 30 MODERATE WT SLIGHT MODERATE WT SEVERE WT, FL PAVED PARKING AREAS SLIGHT SLIGHT MODERATE WT, FL MODERATE WT, FL SEVERE TRAF MODERATE TRAF MODERATE TRAF, WT, FL, SL MODERATE TRAF, WT, FL DNA-SCRANTON-LEON SEVERE SEVERE WT, FL SEVERE TRAF, WT, FL ONA 30 WT, FL SCRANTON 21 LEON 16 OTHERS 33 RUSKIN-SUNNILAND-BRADENTON SEVERE MODERATE WT,SH-SW MODERATE WT, TRAF RUSKIN 40 WT SUNNILAND 30 BRADENTON 15 OTHERS 15 RUTLEGE-FRESH WATER SWAMPPLUMMER RUTLEGE 25 FRESH WATER SWAMP 24 PLUMMER 10 OTHERS 41 BRIGHTONTERRA CEIA BRIGHTON 34 TERRA CEIA 30 OTHERS 36 FRESH WATER SWAMP SALT WATER SWAMPS & MARSHES MINES, PITS AND DUMPS SEVERE FL,WT SEVERE WT, FL SEVERE WT, FL VERY SEVERE VERY SEVERE VERY SEVERE WT, FL, PBV TSC, WT, FL TRAF, WT, FL VERY SEVERE VERY SEVERE VERY SEVERE FL, WT WT, FL FL, WT VERY SEVERE VERY SEVERE VERY SEVERE WT. FL, PBV FL, WT, TSC FL, WT, TSC (VARIABLE) (VARIABLE) (VARIABLE) SEVERE TRAF, PROD SEVERE TRAF MODERATE WT, FL, TRAF, SL MODERATE WT, TRAF, FL MODERATE WT, TRAF MODERATE WT, TRAF SEVERE WT, FL SEVERE PROD, AWC MODERATE PROD,AWC MODERATE WT, AWC MODERATE WT,FL MODERATE WT MODERATE WT SEVERE WT, FL MODERATE WT SLIGHT MODERATE WT ,FL SEVERE WT, FL SEVERE WT,FL SEVERE WT,FL SEVERE WT, FL MODERATE WT, PROD, AWC SLIGHT MODERATE WT FL, PROD SEVERE WT, FL SEVERE WT, FL SEVERE WT, FL SEVERE WT, FL VERY SEVERE VERY SEVERE VERY SEVERE VERY SEVERE TRAF, WT, FL TRAF, WT, FL WT, FL WT, FL VERY SEVERE VERY SEVERE VERY SEVERE VERY SEVERE FL, WT FL, WT FL, WT FL, WT VERY SEVERE VERY SEVERE VERY SEVERE VERY SEVERE FL, WT, TRAF WT FL, TRAF, WT FL WT, FL SALINITY, PROD (VARIABLE) (VARIABLE) (VARIABLE) (VARIABLE) ABBREVIATIONS: WT-WATER TABLE, TRAF-TRAFFICABILITY, FL-FLOOD HAZARD, AWC-AVAILABLE WATER CAPACITY, PROD-PRODUCTIVITY, PBV-PRESUMPTIVE BEARING VALUE, SL-SLOPE, TSC-TRAFFIC SUPPORTING CAPACITY, PERM-PERMEABILITY, ORG-ORGANIC 7 1

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ENERGY RESOURCES ' ' < . .. .

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PRIMARY ENERGY SOURCES For purposes of this ene r gy discussion, the Tampa Bay Area will be assumed to include Hillsborough, Pinellas, Pasco, Polk and Manatee Counties Adequate suppl i es of primary energy sources, at reasonable costs, are essential to modern livi ng. Without such supplies every facet of our way of life is handicapped. Growth of industry and of population is dependent upon the relative cost of such suppl i es Histor i ca lly and right up to the end of 1972, the area is 100% deficit in i nternal primary energy supplies. All primary energy used in the area, both directly and through conversion to secondary energy (electricity), is imported. Most is "domestic", imported from other parts of the United States, some is foreign, imported from other countries. This complete dependence upon imports may change in the future. It i s now suspected that there may be petroleum deposits in the area. I t is known that uranium (the fuel source of nuclear power plants) exists in connection with the phosphate deposits in the eastern portion of the area Develop ment of this resource may become economically feasible in the future. More detailed discussion of these possible future energy sources will be found in other sections of this report. Primary energy is imported to the area in the forms of l iquid petroleum products, natural gas and coal. Table "A" lists the various primary energy sources brought into the area during 1971 and ill ustrates the growth for 1 2 months ending October 3 1 1972. For ease in comparing utilization value, tons of coal and MCF (million cubic feet) of gas have been converted to "equivalent barrels" of o il. Some indeterminate portion of the liquid products brought into the area is exported to other parts of Florida by truck, rail and pipeline There appear to be no available stati stics covering these movements but a guess is that they may amount to 15-20% of the quantities shown in the table 7 4 33 AUTOMO TIVE 1111 1111111 G ASOLINE' I 14.8 RESIDUAL FUEL! 15.21 PETROLEUM LIQUIDS TOTAL 63 Million Bbls. 1971 OAL (Equiv. Bbls.) A 1971 In addition to the quantities shown i n the table, 7,957,000 barrels of residual oil were b rought into Port Manatee in 1972, all of which was barged up the coast to F lori da Power Co rporation's plant at Crystal River All of this residual was of foreign origin L iquid petroleum products are with very minor exceptions, brought in by water through the Port of Tampa (includ ing Weedon I sland in St. Petersburg) and Port Manatee All of the crude oil, most of the residual fuel and minor amounts of the jet fuel and diesel oil are used as power plant fuel in the generation of electricity. The balance of the residual is used in i ndustrial heat i ng and for fueling sh ips in the port, while the uses of the other products are obv i ous. Most of the residua l i s of foreign origin, mostly from Venezuela and the Dutch West Indies (Starting i n 1973 there will be substantial imports of residual from the Virgin Islands) All of the crude oil is imported from Libya The balance of the liquid petroleum products is of domestic origin, principally from the refineries along the Texas and L ouisiana coasts of the Gulf of Mexico. As an approximation, the cost of transportation of petroleum products and of coal, i n large quanti ties by ocean vessel, i s about 1 /30 of the cost of moving the same quantity overland by t r uck. Spec i fically, at this wr i ting, a barrel of residua l oil moves 2,000 m iles from the r efinery in Venezuela to t he Port of Tampa for about 30 cents. It costs over 50 cents mor e to then move the same barrel 100 miles by truck from Tampa. There are no more than three other ports in Peninsu l ar Florida which can handle ships as large as can be handled in Tampa Bay And none of these have as extensive oil handling and ter minal facil i t i es as does the Port of Tampa ( i ncluding Port Manatee) The net result is that the Tampa Area can offer fuel using industries all grades of petroleum products, from more suppliers, and at lower costs than ca n almost any other area in Florida or for that matter, in the entire southeast. TABLE A Prim ary Ene r gy Sources R e ceiv e d in Tampa Bay Area ( B arrels of 42 U.S. G allons) Aviation Gasoline Automotive Gasoline Jet F uel & Kerosene D iesel F uel (No 21 Residua l (No .6) Propane Crude O i l Total liquid Coal (tons) Coal (equiv bbls) Total Water Deli veries Gas (MCFI Gas (equ i v bbls) Tota l Primary Energy Fo r eign Origin Year 1971 1,168,000 32,994,000 7 ,253, 000 5,944,000 14,825,000 822 ,000 63,006,000 2,845,000 10 ,353,000 7 3,359,000 21,827,000 3,520,000 7 6,8 79,000 1 1,701,000 1 2 M onths End i ng 9/30/72 1,597,000 36,849,000 6,103,000 6,820,000 12,846,000 838 ,000 556 ,000 65,609,000 3,9 19,000 1 2,343,000 77,952,000 11,396,000 (Assume 3.639 bbls/tonl (Equiva lent bbls ) (Assume 6 32 MC F/bbl.) (Equivale n t b bls. ) (Almost exc l usively No 6 and crude) Note: Basic data from reports issued by the T ampa Port Authority.

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Natural gas i s brought into the area by the pipeline system of the Florida Gas Transmission Company which extends from southern Texas around the Gulf into Florida Most of the gas handled by the pipeline originates in Texas and Louisiana. Relatively small amounts are now being picked up from the new oil fields in northwest Florida Approximately 45% of the gas the pipeline brings into the area is used in genexation of electricity. Another 30% is sold directly to large industrial users, with the balance being sold to 8 retail gas distributor systems for resale for residential, commercial and small industrial use. The pipeline facilities of the Florida Gas Trans mission Company and of the retail distribution systems suppl ied by it have expanded and kept pace with the demand for gas in the area. In spite of the nationwide shortage of natural gas, there has been very little curtailment, or interruption, of gas supply to industrial users, and none at all to commercial and residential users. Ho'wever, at least until the nation wide gas supply picture improves, Florida Gas is accepting no new large industrial customers but to date there has been no restriction placed on serving new residential, commercial and small industrial customers. All of the coal brought into the area is used by Tampa Electric Company for generation of electri city. This coal originates in strip mines in Western Kentucky and Southern Illinois and is moved in river barges down the Ohio and Mississippi Rivers to a transship facility below New Orleans. At this point it is reloaded into ocean going barges, holding over 20,000 tons each, for the Gulf of Mexico crossing to the Tampa Electric docks where it is unloaded by fast, automatic machines The barges return loaded with phosphate rock, an operation which substantial ly reduces the transportation cost of the coal. --------\ ,, : ,_) .JACKSONVILLE FLORIDA GAS TRANSMISSION LINES 75

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76 ELECTRIC ENERGY The entire State of Florida is blanketed by a network of high voltage transmission lines which i ntercor1nect the load areas with 35 power plants of four investor owned power systems, four major municipally owned systems several smaller municipal systems and. one small federally owned plant Additi onally, the t r ansmission network is intercon nected at severa l points to the north and west with the country's overall network. Various portions of the Florida network are owned by the individual power supplying systems. However, it is completely interconnected and operated substantially as though i t were all under one ownership. This results in a high degree of service reliab i lity, with every electrical load (lrea be ing served by multiple sources. With rare exceptions, power plant and transmission failures do not cause inter ruption of electrical service anywhere in the state. The accompanyi ng map shows the portion of this transmission network within the Tampa Bay Area as of January 1, 1972, with most of the circuits operating below 115,000 volts omitted for clarity Also not shown are some 50 of the small substations where power is stepped down to lower vo l tages fo r distribution to ultimate users and many of the industrial substations where power is del i vered to l arge users at transmission voltages. The Tampa Bay Area is served by three investor owned and one municipally owned e lectric utility systems Hillsborough County, the eastern portion of Polk County, and mino r portions of Pinellas and Pasco Counties are served by Tampa Electric Com pany. Florida Power Corporation serves, with minor exceptions, Pinellas, Pasco and the west portion of Polk County. Manatee County is served by Florida Power and L ight Company. The City of Lakeland and some adjacent territory is served by the Lakeland Department of Elect r ic and Water Utilities Electric power distribution in some portions of the area is by mun i c i pally owned d istribution systems and Rural Electr i c Coope r atives, all of whom purchase their power wholesale from one or another of the suppliers:_, .........__ _l _______ "' MAR I 0 N I "', ......., \-----,-----j, /nvern. ess \ I r \ CITRUS '; ( '"'-_r------. 1------; Sanford ) ,II i (' SEMINOLE Br.oksviit'e'.....___ a!shne/1, [ H ERNAND_o __ I --j ORANGE _ _!_ _ _ I I I Dad. City J J--''----t-------------p A s c o _jv-' L Kissimmee r \. 1---"J ..___?OSCEOLA PRIN('IPL [ TRANSMISSION T <. OLK \ I e aarto w \ ---1 \ 1 i / 1 1 Sebring \ [ HARDEE j I \. I I -....,, ------, / HIGHLANDS i : --------,, '/;\ L / ttrcadia ----j DESOTO i r-----\\ SARASOTA 1 -------+----_j MANATEE radenton \. GLADES M oore Havene ---------fTLa Belle-----I NTERCONNECTED POWER FACILITIES HENDRY 0 5 10 2 0 30Mi l e s

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Plant N a m e There are power plants at eight locati ons within the area as detailed in Table 1 w ith a total capability of 2975 MW. The interconnected t r ansmission net work enables any part of the area to be served iri case of need from any of the 35 power p lants in the state which have a total capability of over 14000 MW. That the elect r ic utilities servi n g the a r ea are keeping abre ast of ne e ds i s shown by the fact that generating capability w ithin the a r ea has doubled since 1965 and that addi tional capabi lity now under constr .uction or defin itely planned, w ill, in the next four years, more than double the present capability. Dependi ng on the type of generating unit and the economics of a particular situation, these power plants burn a variety of fuels-all brought into the area through the Port of Tampa (except natural gas, which is pipelined in). Table II shows the total amount of each fuel used and the percentage this represents of the total brought into the area. In summary 29% of the total pr imary energy sources, coal oil and gas, brought into the Tampa Bay A r ea are converted by the utiliti es into e lectric P.nP rn" TAB LE I T ampa B a y Area Pow e r P l ants (1/1/73 ) Cap ability ( MW) N o G e nerating Units Type Fu e l FLORIDA POWER C ORP. Bartow 478 3 S T HO G Baybo ro 5 7 3 ST H O H iggin s 140 3 ST H O-G Bartow 200 4 G T c o Higgins 164 4 GT L O-G TAMpA ELECTRIC CO. Hooker s P oint 201 5 ST HO Gannon 1,082 6 s c Big Bend 352 ST c Gannon 18 GT L O Big B end 18 GT LO CITY OF LAKELAND Larsen 127 4 ST HO/G Plant No. 3 103 1 ST HO-G Larsen 39 3 GT LO Plant No.3 6 2 D LO TOTAL CAPABILITY 2975 MW Plant Types Fue l Types 1 972 N e t Output (Millio n s o f KWH ) 3 058 22 9 780 2 0 7 115 1,079 5,136 1,977 10 444 456 Included in S.T. 13,491 ST ... .............. Steam T urbines HO ..... ......... Resid ual (No.6) O il GT ................... Gas Turbines CO .................. ... Cr ude Oil D ......................... Diesel LO .............. Li ght O i l ( distillate ) G ...................... Natural G a s C ............................ C oal N ote: Data supplied by t h e utilities Greek owned tanker "Demosthenes V" discharging 140,000 barrels of Venezuelan re s idual oil at F l orida Power C o rp, Weedon Island, St. Petersburg. (photo courtesy of Flori d a Power Corp ) T y p e Resi dual Oil Gas Coal Light Oils C r ude Oil Total Equiv. Bbls. TABL E II T ampa B ay A rea Power Plant Fu e l Use ( Y ear 1972) Qu a ntity Used 9 ,527,632 bbl 8.451 ,0 1 3 MCF (1 ,337 ,Hi5 equ i v. bbl.) 3,349,724 tons ( 1 2 ,189,646 equiv bbl. ) 73,101 bbls 465,075 bbls. 23,592,639 Note: Data suppl ied by the utilities, %of T ota l Shi p p e d into Area 74 % 39 % 100% negligible 100% 29% 77

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78 Preliminary figures indicate that during 1972 the electric utilities supplieo over 15 billion KWH of electric energy, broken down as follows: Millions of KWH % of Total Residential 6,007 39 Commercial 3,183 21 Industrial' 4,470 29 Other2 1,598 11 Total 15,258 100 1 Approximately 50% of industrial use was in the phosphate mining and processing industries. 21ncludes street lighting and other municipal uses, sales for resale, company's own use, etc. Rates for electric service in the Tampa Bay Area are generally closely in line with National and Florida average rates, and far below the highest rates in the "lower 48" states. These highest rates are generally found in the New England and New York City areas. Rates lower than charged in the Tampa Bay Area are generally found in areas abundantly supplied with hydro-energy, with its zero fuel costs, or in areas within coal or gas fields where there is little or no transportation component in the utilities fuel costs. Table Ill I ists rates in effect on January 1, 1971 As the direct result of spiralling fuel costs, general inflation and the high costs of meeting environmental demands, most of the country's electric utilities have been forced to increase rates during the intervening two years. Therefore the actual rate figures given in the table are no longer applicable. However, there would be no important change in the relative positions of the various areas listed. TABLE Ill Typical Electric Bills January 1, 1971 Highest in 48 States (cities of 50,000 -.; ;::; c E .. -Ol.t: c: ;:: -->< -.;0 ELO VJN or more) 12.78 National Average 7.84 Florida Average 7.39 Tampa Bay Area Avge. 8.03 Tampa Bay Area Highest 8.13 Tampa Bay Area Lowest 6.93 -.; ;::; c ., -oo ;;; E ., __ C:.t:. E ;:: :::o-"'-0 27.66 19.24 19.51 19.50 19.73 19.27 -.; c:; 0 E... O.t: o;:: -->< -.;0 ELO VJI' 43.07 28.45 30.65 32.68 36.18 29.19 Sources : Federal Power Commission Publication "Typical Electric Bills", December, 1971. 392.80 $2,333 252.43 1,269 253.28 1,157 245.16 1,129 275.65 1,256 214.68 1,002 RESIDENTIAL 39% (6007 MKWH*) OTHER 2 11% 1598MKWH* 1 Approximately 50% of industrial use was in the phosphate mining and processing industries. 2lncludes street lighting and other municipal uses, sales for resale, company's own use, etc. INDUSTRIAL I 29% (4470 MKWH*) USE OF ELECTRICITY *MILLION KILOWATT HOURS

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ENERGY OF THE FUTURE Modern man needs sources of energy to support his way of life. Such sources are needed to provide light, heat and cooling of his buildings; to move his automobiles, airplanes, trains, trucks, ships; to power his shops, factories and mines and for countless other uses. Without adequate supplies of energy, civilization and life would end. For the United States, 97% of the energy used comes from the three fossil fuels, coal, oil and gas. Hydro-electric and nuclear energy supply the remain ing 3%. About 26% of the fossil fuels are converted into electricity, the balance is used directly. The figures for the rest of the world are not greatly different, except that in some areas wood and other organic materials contribute to the energy supply in a small way. The fossil fuels represent a finite resource-once used they can not be replaced. Therefore there must inevitably come a day when there are no more fossi I fuels to support a civilization. Opinions vary as to when this day will come but the best estimates indicate that by the end of this century supplies of natural gas will be substantially exhausted, liquid petroleum supplies may last through the middle of the next century, coal will probably last 300 to 500 years. In the intervening years we can expect constantly increasing costs, coupled with spasmodic but in creasingly severe shortages. The local shortages of natural gas and heating oil during the winter of 1972-73 were an insignificant illustration of what will become commonplace if substitute sources of energy are not developed. To date there appear to be two such substitutes which have reasonable hopes of being developed into practical sources of energy-nuclear power and solar power. Nuclear power is furthest along, having been developed to the point where it is (early 1973) contributing 2% or 3% of the nation's total energy needs, all of this in the form of electric energy. Present! indications are that by 1985, nuclear will be contributing between 11% and 15% of the country's energy needs. Florida's two largest utilities have been among the leaders in the nuclear field. In January 1973 they had one large nuclear generating unit operating, three in various stages of construction and one more in the advanced planning stage. All of Florida's utilities are studying the need for, and feasibility of additional nuclear units. None of the nuclear units now definitely planned for Florida will be in the Tampa Bay Area. However, the area will probably see such units in the future since there are locations in the area which meet the rather stringent siting requirements for such generat ing units. The current commercial types of nuclear generat ing units consume uranium as a fuel, much as a fossil unit consumes coal, oil or gas. Uranium, like the fossil fuels, is a finite resource. As available supplies are used up, the price increases. It is known that there are fairly large amounts of uranium ore in connection with the phosphate deposits in the eastern portion of the Tampa Bay Area. It is currently estimated that this ore is recoverable at costs of around $15 per pound of refined U3 08 The current market price of U3 08 is less than $8 per pound and industry sources estimate that it wi II be the late 1900's before market conditions will make recovery of Florida's uranium ore economically feasible. (See W. R Oglesby's article on this subject, Page 48, Tallahassee Area study published by the Bureau of Geology in 1972.) PRESENT U. S. ENERGY SOURCE U.S. ENERGY SOURCE PROJECTED TO 1985 Hydro 97% FOSSIL FUELS Coal Oil Gas 85% FOSSIL FUELS Coal Oil Gas There are four major processing steps involved in converting the U3 08 to actual nuclear plant fuel. Special requirements make it most unlikely that Florida would ever be an attractive location for plants involved in the first two of these steps, conversion of the powder U308 into the gaseous UF6, and enrichment of this gas by increasing its contained percentage of the isotope Uz 3 s However, the remaining steps, conversion of the gaseous, enriched UF6 to the powder U02 pelletiz ing this powder, and assembling the pellets into reactor fuel assemblies are exactly the type of industries which Florida likes and which like Florida. They are light, clean, high precision industries, requiring good supplies of highly skilled labor and abundant resources of engineering and scientific manpower. Given an adequate local market for their output, which should exist by the early 1980's, it should be possible to attract this industry to Florida. Going back now to the statement that uranium is a finite resource, it is evident that, like the fossil fuels, there must come a day when it is exhausted. Before that day comes, perhaps early in the next century, another type of energy source must have been brought to commercial practicality. Uranium oxide could be produced from 'wet process' phosphate plants. Photo courtesy of the Florida Phosphate Council 79

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The "breeder reactor" which actually can produce more fuel than it consumes, has been proven in the laboratory stage. Funded jointly by the electric utility industry and the Federal Government, the first "demonstration" plant, using the breeder process, is now in the engineering stage. Because of the problems involved in converting a laboratory process to a practical commercial power plant, many in areas of new and unknown technology, it is expected that it will be the mid 1980's before the first commercial breeder plant will be operational, at a total develop mental cost of well over one billion dollars. But, if the "breeder" or some equivalent process is not available by early in the next century, civilization as we know it must come to an end! Solar energy research has been sadly neglected, perhaps because it does not have the glamor of nuclear and other advanced scientific development. The work which has been done in this field, largely at the University of Florida leads us to believe that if a small fraction of the money and scientific man hours which are going into nuclear development were put into solar development, then we would have the means to capture enough of the limitless solar energy to supply all of the energy needs of the world as long as it exists. And F.lorida, because of its unique climate, should be the center of such research. 80 MT. CARMEL FIELD G I ./ EASTERN MARGIN OF MISSISSIPPI SALT BASIN FLORIDA Scale In Miles OIL ANO GAS ..... LEHIGH ACRES W. SUNOCO-FELDA LAKE TRAFFORD FIELD SUNNILAND FIELD SOUTH FLORIDA BASIN There. is no oi I or gas production within the Tampa Area, and no immediate prospects for such production. Hillsborough County, and the six counties surrounding it within a 50-mile radius, have had 41 oil tests drilled therein between 1900 and 1973. However, only 12 of these tests have been drilled within the past 30 years, since the discovery of Sunniland Field, in Collier County. Sunniland marked the entry of Florida into the ranks of oil producing states, and we now rank 12th out of 32 states which have petroleum production. Many of the earlier wells in the Tampa area were not adequate to test the potential pay zones. In short, these seven counties remain in the Twilight Zone, as far as their petroleum prospects are concerned; they are possible but not probable areas from which oi I or gas may be, recovered some day. The preceding statement is made in light of the following considera tions: 1. The known producing trend in south Florida extends along the northeastern portion of the Shelf associated with the South Florida Basin 2. The known producing trend in northwest Florida extends along the eastern margin of the Mississippi Interior Salt Basin. 3. The Tampa Area is not located in a basin but rather on the central Florida platform, a structurally positive area. There is no particular reason to believe adequate petroleum source beds exist on or in conjunction with this central platform.

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The lack of oil production in the vicin ity of Tampa does not signify that the availability of gasoline or fuel oil is less here than in other metropolitan areas. Austin, the capital of Texas, experienced a dozen critical periods of petroleum shortage during 1972. The City of San Antonio, Texas, was threatened by a blackout when the municipal electric power system could not obtain natural gas to operate in the spr ing of 1973. No power shortages due to lack of fuel were reported in the Tampa area. Tampa, like the rest of Florida, but unlike Texas and most of the United States has no liquid petroleum products pipe lines; and hence has complete flexibility of its sources of supply. Tampa is one of four deep sea ports in the Gulf Coast of the U.S. and is open to the fuel markets of the world. On the other hand, most of the inland cities of the Un i ted States are served by product pipe lines which are inflexible. If the input supply of such pipe lines is curtailed, the output at the d istribution point is likewise curtailed Although there is no pipe line supply of petroleum to Tampa, the city is served by the natural gas line of Florida Gas Transmission Company Natural gas for domestic use is no real problem; the supply of natural gas for generating electricity is, unfortunately, in here as in other cities. This is not due to lack of capacity of the pipe line. Its carrying capacity could be i ncreased by the simple expedient of increased compressor capacity along the line There is a real shortage of natural gas at the sources of supply. Company officials of Florida Gas recently have announced an intention to convert one of the parallel lines in their gas transmission system to a products pipe line If this is done, Tampa as well as other areas of Florida served by the Florida Gas Company will enjoy lower transmission costs of fuel ove r land and reduced trucking on the highways However, users of this fuel may find they have traded a flexi ble seaborne supply open to world markets for a rigid source controlled by the supply available at the input points to the pipeline SEA LEVEL 5000 10000 JURASSIC, SEA LEVEL TER IAR JURASSIC LINE of SECTION (J 1 Crude oil produced in Florida is from two w idely separated basins which are: The Mississippi Interior Salt Basin and the South Florida Basin, shown on P age 80. Production occurs below 11 ,000 feet in the South Florida Basin and below 15,000 feet in the Florida portion of the Mississippi Salt Basi n The production from Jurassic age strata i n Jay, Blackjack C r eek and Mt. Carmel Field s occurs i n the Norphlet Sand, which immed i ately overlies the Louann Salt, and in the Smackover Limestone wh ich ove r l ies the Norphlet Sand. These three fields will p r oduce about 100,000 barrels of o il and 100,000,000 cubic feet of gas per day, when fully deve l oped, about 20% more than their current producti on rate The Sunniland Li mestone of lower Cretaceous age supplies the balance of crude oil production from six fie lds center i ng around Immokalee, Collier County, Flor ida The combined daily p roduction from these fields is about 13,000 barrels of crude oi I. No comme r cial amount of gas is der ived from these undersaturated r eservoirs 8 1

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82 Florida produces about 30,000,000 barrels of crude oil annually and uses about 7 times this amount of refined petroleum products. All of the crude produced in Florida is exported to refineries in other states and all its petroleum products are imported by sea. Therefore, oil production in the state has no more direct effect on Florida's petroleum products supply than it has on other areas in the United States. However in the case of gas, Jay Field produces about a tenth of the supply carried for distribution by Florida Gas Transmission pipe line to the Tampa area and around the State. Gas is a desirable, clean, and currently, low cost fuel. If enough of it is discovered in the state, we could solve the environmental problems connected with electric power generating plants while the supply lasted. CAPACITY 150 MILLION GAGE BBLS IN MILLIONS 100 CAPACITY 100 M ILLION BARRELS FILL-UP TIME GAGE BBLS BARRELS FILL-UP IN MILLIONS TIME 30 YEARS TO ONE-HALF FULL 1.75 YEARS(Est.) 3.25 YEARS 5YEARS 22 YEARS I rmmTITT1"T"n..,------nTTTm'llllDEC. 1979 5 YEARS TO FILL UP( Est.) DEC.I978 DEC.I977 -DEC.I976 DEC.I975 NATURAL GAS

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THE U.S. ENERGY GAP 1970-1990 [=:J IMPORTS [==:J HYDRO-NUCLEAR c:::::J COAL [==:J GAS [==:J OIL I = = .o.nnnn. = = I C? 7 1970 1975 1980 1985 1990 *cRUDE OIL EQUIVALENT Source: SHELL OIL CO. EFFECT ON BALANCE OF PAYMENTS EFFECT ON POLITICAL, ECONOMIC POLICIES NEED FOR NEW FACILITIES-TANKERS, SUPER PORTS, REFINERIES, PIPELINES INCREASED IMPORTANCE OF CONSERVATION MEASURES Ultimately, Florida, like the rest of the country, will be forced to shift to an energy base other than petroleum and natural gas, as the domestic supply becomes exhausted. The international supply can augment our own petroleum resources; but for economic, security and political reasons it is nonsense to suppose we could exist as a wholly dependent fuel imports nation. This is illustrated by a chart entitled "The U.S. Energy Gap 1970-1990" from a publication by Shell Oil Company shown in reproduction. The graph shows total oil imports of about 2Y, million barrels per day (B/0) in 1970, rising to 6'/2 million B/0 in 1975, and to 23Y, million BID in 1990. If the true cost of foreign oil in 1970 is taken at $1.00 per barrel (considering that United States companies operating abroad must pay foreign royalties and taxes, and that shipping costs are paid to foreign nationals) our trade deficit on oil was about $900,000,000. By 1975, this cost may well double, as both oil prices, royalties, and transport costs increase. Hence the 1975 deficit estimated on oil imports is 4 billion dollars. These costs will probably redouble by 1990, so that the deficit on oil imports may attain 34 billion dollars. These projections do not allow for dollar inflation which the Organization of Petroleum Export Countries insists must be adjusted with more dollars The chart indicates we will produce 10 million barrels of oil per day in the U.S., and import 23Y, million barrels by 1990. If this occurred, the Nation would be dependent on foreign sources for the energy necessary to our military and industrial survival, for the two are interdependent. The obvious answer is that the charted projection will not occur and that we will not be using a total of 33Y, million barrels of petroleum in 1990. Either we shall have adapted to such alternate sources available by reduction of coal, oil shales, and tar sands to petroleum liquids, or perhaps shifted to a hydrogen energy base through electrolysis of water in a related nuclear reactor program furnishing electric power. A third course, to reduce our total use of energy, will take place as the cost of fuel increases relative to other items in the gross national product. 83

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LANO USE

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CURRENT LAND USE CURRENT LAND USE WATER D PUB LIC D TO URIST COM f\lERCI A L c:::::] RETA I L CQ1,1f,IERCIAL SINGLE FAI.11LY D RECREATION AND OPEN SPACE D 1\GRICULTURE AND IVIINING D ',10GILE HOMES D lhiDCJSTRIAL D TRANSPORTATION Af\lf11JTILITIES (so ... rc:!: T:imp
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FUTURE LAND USE Presented on this page is the Hillsborough County Planning Commission's Provisional Plan of Develop ment through 1990. At the time of thi s writing, the plan had not been finalized, .and the copy shown here is subject t'o rev i sion The plan is based on existing major land use categories Areas which are currently urbanized represented the starting point for the Plann i ng Commission Preferred future expansion areas include those areas into which urbanization anticipated by 1980 and by 1990 may best be channeled. It should be po inted out that in both categories, two to three times more land has been assigned for urbanization than trends for future land consumption indicate is needed. Th i s extra allotment is to compensate for portions of the designated land which may be found undevelopable, and to allow for additional urbaniza tion that could not be foreseen at this time. Around the fringes of the Tampa area land is slated to remain undeveloped or to be used as agricultural land. According to the Planning Com mission, much of thi s land is deve lopable, however, it i s not needed for current o r projected land use requirements. Substantial portions of land have been designated as interim or permanent open area Included in this category are preservation and conservation areas or those lands which should experience little or no development. Riverine and swamp environments fall into this category, and it is envisioned that recreation will be the primary land use he r e Also included a r e Southwest Florida Water Management Dist r ict's exist ing and proposed reservoir areas In preparing t h e Plan of Development the Plann ing Commission has utilized a sequential approach. I nitial l y, environmental factors were evaluated and a series of maps indicat i ng land use suitabilities were constructed l argely on the basis of geohydrologic considerati ons These maps were used i n conjunction with socio-economic projections i n order to establish a basic pattern for g rowth. I n delineating specific urbani zation patterns with i n suitable areas, seve ral planning concepts we r e uti lized T he concentric pattern of deve lopment (where growth takes place around the perimeter of the ex i sting urban center) was used in combination with the radiating plan (where urbanization expands along highway routes) and the satellite citi es concept (discussed on the fol l owing page) to establish what is hoped to be an equitable and environmental ly compatible plan of development. With regard to specific land uses, several noteworthy policies are employed by the P lanning Commission. Because of the need to de centralize traffi c flow and d i ffuse pollution, planning of concentrated industrial areas is avoided In general industr ial parks help achieve the goal of d i luting the problems often assoc iated with industry With l arge periphera l land areas and attractive plant ing, industri al parks can be a v i sually pleasing addition to the landscape Busch Gardens is a notable local example. Transportati on is another important considerat i on in planning for the growing Tampa area. The Planning Commission attempts to coordi nate all phases of transportation and to incorporate highway, port and airport t r affic into a s i ngle efficient network. An additional effort of the Planning Commission is to de-emphasize development in northwest Hills borough Co unty i n the area of the we l l fields The plan shown on this page r eflects the envi r on mental awareness of the Plann ing Commission As new data becomes available and growth trends change, the p l an of development will be revised and updated. A future land use plan, by nature, constantly evolves in response to changing regional needs and increas i ng cognizance of local potentials Both the H illsborough County Planning Commission and the Tampa Bay Regional P l anning Council are currently involved in updating future land use plans for the Tampa area. TBRPC prepared a preliminary plan for 1985 in 1968. A portion of that plan is presented on the fol l owing page. T-------------I I I I I I i f rom O uRBANIZED AREAs, 1980 DuRBANIZED AREAs, 1990 Bay MAJOR COMMERCIAL AREA DLIGHT INDUSTRY HEAVY INDUSTRY .MAJOR PUBLIC USE D INTERIM OPEN AREA PERMANENT OPEN AREA D UNDEVELOPED PROPOSED COMMUNITY CENTERS .---,EXPRESSWAY ;::: EXPRESSWAY 8 A Y THOROUGHFARE ===PROPOSED MAJOR THOROUGHFARE ,....._,__..__ ? t:===:=:=:=:::!f==:::Jf MILES SCALE 87

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,--------------------0 I .......... 1985 PRELIMINARY REGIONAL PLAN EXPLANATION RESIDENTIAL HIGH DENSITY D MEDIUM DENSITY LOW DENSITY II COMMERCIALL__j TOURISM UOPENSPACE INDUSTRY II POTENTIAL L__j MINING II AGRICULTUREL__j OPEN RANGE c:::JwATER REGIONAL TRANSPORTATION'' SYSTEM FREEWAYS ---ARTERIALS WATERWAYS and PORTS 88 From: Tampa Bay Regional Planning Council, 1985 Preliminary Regional Plan. According to the Council, "The preliminary plan provides for the alloca tion of the region's developable land resources into patterns of use which will be required to serve the future population." Among 'the objectives of the plan are the following: LAND DEVELOPMENT Encourage compatible land use arrangements through purposeful site plan ning to provide compatible, compact and diversified land development. WATER SUPPLY Provide a guaranteed water supply for the region through the investigation, development and preservation of all possible sources including watersheds, surface supplies, salt water conversion, and aquifers. WATER AND AIR POLLUTION -Stop water and air pollution through better public management and control of wastes, location planning for polluting industries, the formation of effective sanitary sewer districts, the establishrr,ant of on-site treatment of industrial wastes, and the investigation of a regional solid wastes disposal system. SHORELINE DEVELOPMENT Discourage shore line development in conflict with existing develop ment, natural tidal flows and irreplaceable marine resources. OPEN SPACE/RECREATION Adopt a multi-use open space program for the acquisition and develop ment of lands for recreation, conservation, cultural and scenic uses thereby protecting this economic resource which plays a major role in generating new resident and tourist growth. It is evident that the Council has a great concern for the physical environment. In many instances the Council relies heavily on available geohydrologic information for making land use decisions. During the planning process, many specific questions arise that can best be answered by the geologist or hydrologist. The answers to such questions are rarely readily available and must be based on careful evaluation of existing data. This illustrates the importance of continuing basic geologic and hydrologic data collec tion programs and expanding these programs in areas for which accelerated development is predicted. In the Tampa area growth projections indicate that areas peripheral to urban Tampa will experience the greatest increase in development between now and the year 2000. In conjunction with future develop ment, the Tampa Bay Regional Planning Council believes that two new concepts in urban planning might be applicable to the Tampa area These are the "new town" policy and the city" concept. The "new town" policy involves designing small self-sustaining cities outside the realm of existing metropolitan areas. The "satellite cities" concept entails encouraging development in existing suburbs so that they could essentially function independently but would in part be dependent on the urban center. A major objective of the two concepts is to deemphasize over development of urban areas. In formulating plans for "new towns" and "satellite cities", the Planning Council will be looking first at environmental considerations. Concern with environmental factors has also prompted state legislation. Recently, the Florida Land and Water Management Act was passed. The purpose of the Act is to permit development without destroying Florida's resources or environment and to provide for the designation of areas of critical state concern and development of regional impact. In designating areas of critical state concern, the state or the local government will set forth develop mental guidelines to insure preservat ion of historical and archaeological resources, and guidelines for water storage areas, significant marine resource areas and so on. Development of regional impact is defined as any development which, because of its character, mag nitude or location, would have a substantial effect upon the health, safety or welfare of citizens of more than one county. In evaluating regional impact generated by development, such things as the degree to which development would contribut'e to air, water and noise pollution, number of new residents, vehicular traffic and the likelihood of subsidiary development are to be regarded in establishing guidelines.

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Geology, engineering geology, and hydrology have long been of eminent importance to transportation planners. When new highway sites are designated, on-site soil surveys and subsurface explorations are carried out. The State Department of Transportation maintains an Office of Materials and Research which is charged with the responsibility of carrying out these investigations. TRANSPORTATION PlANNING & GEOlOGY emphasize areas of special land use such as gravel, sand and clay extractive industries, outdoor museums and monuments, etc., which require special considera tion during the planning phase. Property boundaries maps show the limits of indiv i dually owned land Drainage maps outline existing drainage patterns at the time of mapping. Soils maps provide an indication of the engineering so i l types within the corridor. These can be roughly correlated with the AASHO classification. A portion of one of the engineering soils maps, along with the soils classification is shown on this page The first phase of study is an office procedure that entails gathering all available information on the soils and geologic conditions in the project area. Aerial photographs, Soil Conservation Service publications, topographic maps and geologic maps and reports published by the United States Geological Survey and Florida Bureau of Geology are utilized as primary data sources. After the evaluation of general site conditions, a detailed field investigation follows which centers around a comprehensive test boring program. Borings are spaced according to site conditions and the requirements of the given project. Vital phases of the field exploration program are sample description and testing. Among the soil and rock properties logged in the field description are: color, principal and modify ing constituents, hardness, cementation, grading, relative density, consistency, moisture content, par ticle shape, etc. Field tests frequently include standard penetration tests, miniature vane shear tests, etc. In addition, laboratory tests quantify various properties of samples collected at the site. Some of the common tests include the following : CLASSIFICATION Soil T ests Moisture Content Speci fic Gravity Atterberg Limits & Indices Density Grain Size Distribution Compaction Test Permeability Test Consolidation Test Unconfined Compression Test Direct Shear Test Triaxial Shear Test Rock Tests Specific Gravity Density Porosity Absorption Los Angeles Abrasion Sodium Sulphate Test Unconfined Compression Test Triaxial Shear Test Qualitative & Quantitative Mineral Identification 1. discussions of the character and depth of soils and/or rock encountered onsite 2. the nature and severity of the problems which these materials might impose on the design or performance of the roadway 3 treatments which might be undertaken to alleviate the potential problems. 4 comments on slope erosion possibilities, occur rence of springs, swamps, seeps, and recommenda tions for borrow pit locations As with any engineering project, the transporta tion planning project that is most successful is the one which is based on the larger and more detailed c R p Silty or clayey sand @ Fine sand H .. I I ... 1000 Peat and muck Man-made land (filled areas) Sinkhol e 0 1000 3000 Feet R array of basic data. The more that is known about an area geologically (i. e the more avaifable basic data). the fewer the problems, less the expense, and greater the accu r acy in transportation planning within that area The recent creation of the Remote Sensing Section within the Topographic Office of the State Depart ment of Transportation is an excellent example of current environmentally oriented thinking in trans portation planning. The topic ot pilot study com pleted in 1970 by the Remote Sensing Section is the proposed Tampa Bypass Corridor The study area (about 40 miles long and 4 miles wide) is shown in the figure. The corridor study was based on aerial photographic interpretation with the goal of the project being to locate and identify physical and cultural features within the corridor ... to a degree of detail consistent with the information needs for preliminary location and design, and within a time frame ... more realistic than that required by ground mapping methods. "1 The study includes five separate photo-map series delineating the following: land use, key features, property boundaries, drainage, and engineering soils Except for the property boundaries series, mapping was based exclusively on air photo interpretation. The land use maps show 53 different land uses within 12 basic categories. The key feature maps -Sourc e : DEPARTMENT of TRANSPORTA TI O N ENGINEERING SOILS MAP The use of remote sens i ng can greatly facilitate transportation planni n g T he potential of multiple sensor techniques ( i ncluding black and white pan chromatic, black and white infrared, color, and color infrared photography; m u lti-band photography; and thermal and multi-spectral line scan imagery for indicating thermal properties, vegetative patterns, solution activity, permeability, physiography and potential borrow pits is being investigated. It is hoped that airborne data collection can be implemented to provide rapid, accurate, economical, and detailed information for use by transportation planners. 1 Remote Sensing Section, Topographic Office, State of Fla. D.O.T., July, 1970, Tampa By-Pass Corridor Study, p 1 i i i I i WINTER HAVEN -------------+--P_Q_i,..!$_ _____ ATEE COUNTY HARDEE ARASOIA-to.l I i I I I I I I N 0 10 2 0 M ILES b----+-= +======1 LOCATION o f the TAMPA BY-PASS CORRIDOR a a

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90 GEOlOGIC FACTORS & CONSTRUCTION In the Engineering Geology section of this study, a detailed discussion of construction planning was presented. Information from that section was combined with information from the Water Resources and Geology sections to produce this overview of land suitability for construction. The wetlands map was superimposed on the flood prone area map which was superimposed on the clay conditions map which was superimposed on the sinkholes and sinkhole-type lakes map which was superimposed on the sand suitability for foundations map which was superimposed on the depth to rock map ... .

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... to produce this map of suitability for construction which the planner can super i mpose on maps of ecolog i cal factors, economic factors, urban expansion projections, e t c., i n order to make the wisest dec i s i ons fo r construction plann i ng BAY ( I I I I I / I TAMPA J BAY LAND SUITABILITY FOR CONSTRUCTION One unfavorable conditi on: flood p rone and wetland areas 0 sand poor fo r foundations 0 clay poor for foundati ons O areas of sinkhole occurence Two unfavorab l e conditions: flvodprone and wetland areas+ poor sands f lood prone and wetland areas + poor clays flood prone and wetland areas + sinks 0 poor sands + poor clays Q poor sands+ sinks poor clays+ sinks Three unfavorable conditions : flood prone and wetland areas + poor sands + poor clays e flood prone and wetland areas+ poor sands+ sinks flood prone and wetland areas+ poor clays+ s i nks poor sands + poor clays + sinks e Four unfavorable conditions Areas where rock lies near land surface (suitable for seating piling for high rise structures) 9 1

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GEOLOGIC fACTORS & SANITARY LANDFILLS Solid waste disposal has become a topic of concern in the Tampa area where population growth has resulted in increasing production of waste and decreasing undeveloped land areas suitable for waste disposal. In the past, few controls were placed on solid waste disposal, and site selection was based largely on convenience. Gradually, damaging environmental effects resulting from indiscriminate waste disposal become apparent and the concept of the sanitary landfill was introduced. The American Society of Civ.il Engineers defines a sanitary landfill as: "A method of disposing of refuse on land without creating nuisances or hazards to public tlealth or safety, by utilizing the principles of engineering to confine the refuse to the smallest practical area, to reduce it to the smallest practical volume, and to cover it with a layer of earth at the conclusion of each day's operation, or at such more frequent intervals as may be necessary." Essentially, a sanitary landfill consists of a series of trenches which, in the Tampa area are excavated to dimensions on the order of 400 feet long, 80 feet wide and 1 0 feet deep. Trash and garbage emptied into the trenches are compacted, then covered daily with a thin layer of earth in order to minimize odor, fire hazard, insect and rodent problems, etc. Waterborne pollutants are also a significant poten tial problem of sanitary landfills. Rains infiltrate the refuse in a sanitary landfill and pick up dissolved solids. Under certain conditions this "leachate" may find its way to a local water supply. For this reason, certain geohydrologic factors must be thoroughly investigated prior to selection of a landfill site. Hillsborough County sanitary landfill trench (photo by J.W. Stewart) Among other things, sanitary landfill sites should be relatively "dry" in terms of both surface and ground water conditions, and surficial sediments should be clayey and relatively impermeable. Under these conditions, flow of the leachate may be retarded and potential pollutants filtered and ab sorbed. The map presented on this page is based on U.S.G.S -F B.G. Map Series 39 and on maps presented earlier in this publication. Rating criteria are as follows: 1. Type of unconsolidated material. Favorable: clay, silty clay, clayey silt, and silt. Unfavorable: sand. 2. Thickness of unconsolidated materials. Favor able: at least 25 feet. Unfavorable: less than 15 feet. 3. Site topography. Favorable: adequate drainage and not subject to flooding. Unfavorable: low swampy areas; areas subject to flooding; sinkholes and areas near sinkholes; along stream channels hydraulical ) y connected with Floridan aquifer. 4. Ground-water levels. Nonartesian aquifer: Favorable: greater than 15 feet below land surface. Unfavorable: less than 5 feet below land surface. Artesian aquifer: Favorable: potentiometric surface at least 5 feet above water table. Unfavorable: potentiometric surface near or below the water table. 5 Character of limestone aquifer. Favorable: dense, unfractured. Unfavorable: fractured and cavernous. 6 Relation to public water supply wells. Favor able: at least several miles downgradient from large pumping withdrawals. Unfavorable: adjacent to or within the immediate cone of influence of large-scale pumping. UNFAVORABLE FACTORS IN SELECTING SANITARY LANDFILL SITES 0 1 flood prone and wetland areas Q 2 high water table 0 3 rock surface at shallow depth 0 4 areas of sinkhole occurence 1 + 2 Q1 + 3 1 + 4 ()2+3 2+4 ()3+4 1 + 2 + 3 1 + 2 + 4 1+3+4 2+3+4 1+2+3+4 VALNCO BAY TAMPA ____________ j BAY 92

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REFERENCES INTRODUCTION Committee of 100 of the Greater Tampa Chamber of Commerce 1970 Tampa Facts. 1971 Tampa's decade of development, the fabulous growth of a city: (table). Florida Department of Natural Resources 1971 Outdoor recreation in Florida: Div. of Rec. and Parks, 349 p. Florida Department of Transportation 1971 Average daily intensity map. 1971 Map of existing and proposed recreational facilities in the Tampa area: Bur. of Planning Hillsborough County Planning Commission 1972 Hillsborough County, Florida population projections and environmental factors, 1960-1990: 42 p 1970 1970 Census tracts (map). Tampa Bay Regional Planning Council 1970 1970 Census of population and housing first count summary data. 1968 Parks and open spaces: Summary Rept. No.6, 73 p. The Greater Tampa Chamber of Commerce 1972 Highlights of Tampa history: (brochure) TOPOGRAPHY Menke, C. G 1961 (and Meridith, E. W., Wetterhall, W S.) Water resources of Hillsborough County, Florida: Fla. Geol. Survey Rept. of lnv. 25, 101 p. U.S. Geological Survey 1968 Index to topographic maps of Florida. 1971 Tools for planning: topographic maps (brochure). WATER RESOURCES Barraclough, J. T. 1962 (and Marsh, 0. T.) Aquifers and quality of ground water along the gulf coast of western Florida: Fla. Geol Survey Rept. of lnv. 29, 28 p. Beard, M. E 1969 The Florida District Water Quality Laboratory: U.S Geol. Survey, Water Resources Division Briley, Wild and Associates 1968 Comprehensive plan for water and sanitary sewer systems in the Tampa region of Florida, (for): The Tampa Bay Regional Planning Council, 148 p. Cherry, R.N. 1970 (and Stewart, J. W and Mann, J. A ) General hydrology of the middle gulf area, Florida: Fla. Bur. of Geol Rept. of lnv. 56, 96 p. Federal Water Pollution Control Administration 1969 Problems and management of water quality in Hillsborough Bay, Florida: 86 p. Ferguson, G. E. 1947 (and Lingham, C. W ., Love, S. K., Vernon, R. 0.) Springs of Florida: Fla Geol Survey Bull 31,196 p. Florida Board of Conservation 1969 Florida lakes, part Ill gazetteer: Div. of Water Res., 145 p. 1966 Florida land and water resources southwest Florida: Div. of Water Res., 181 p. Florida Bureau of Geology 1972 Environmental geology and hydrology Tallahassee area, Florida: Fla. Bur. of Geol. Spec. Pub. 16, 61 p. Florida State Board of Health 1965 Biological, physical chemical study of Lake Apopka, 1962-64. Hillsborough County Planning Commission 1972 Hillsborough County, Florida population projections and environmental factors, 1960-1990: 42 p. Hillsborough Soil and Water Conservation District 1961 Work plan for upper Tampa Bay watershed Hillsborough, Pasco and Pinellas Counties, Florida: 62 p 1971 Work plan for Pemberton Creek Watershed Hillsborough County, Florida: 54 p. Klein, H. 1971 Depth to base of potable water in the Floridan Aquifer, Florida: Bur. of Geol. Map Series No. 42. Peek, H. M 1959 Record of wells in the Ruskin area of Hillsborough County, Florida: Fla. Geol. Survey lnf. Circ. 22,85 p Menke, C. G. 1964 (and Meridith, E. W., Wetterhall, W. S.) Water resources records of Hillsborough County, Florida: Fla. Geol. Survey lnf. Circ. 44,95 p. Rickert, D A. 1971 (and Spieker, A.M.) Real-estate lakes: U.S Geol Survey Circ. 601-G, 19 p State Board of Conservation 1948 Observed rainfall in Florida, monthly totals from beginning of records to Dec. 31, 1947: Div. of Water Survey and Research, 427 p. Stewart, J. W. 1970 (and Hanan, R. V .) Hydrologic factors affecting the utilization of land for sanitary landfills in northern Hillsborough County, Florida: Dept. of Nat. Res., Bur. of Geol., Map Series No. 39. 1971 (and Mills, L. R., Knochenmus, D D., Faulkner, G. L.) Potentiometric surface and areas of artesian flow, May 1969, and change of potentiometric surface 1964 to 1969, Floridan Aquifer, Southwest Florida Water Management District, Florida: U.S. Geol. Survey Atlas HA-440. 1968 Hydrologic effects of pumping from the Floridan Aquifer in northwest Hillsborough, northeast Pinellas and southeast Pasco Counties, Florida: U.S. Geol. Survey Open File Rept., 226 p. Tampa Bay Regional Planning Council 1972 The iriterim comprehensive water quality and pollution abatement plan-Tampa Bay region: 188 p. Thornthwaite, C. W. 1957 (and Mather, J R.) Instructions and tables for computing potential evapotranspiration and the water balance : Drexel Institute of Technology, Vol. X, No.3. U.S Department of Agriculture 1965 Water and related land resources, Florida west coast tributaries: (Report). 1965 Water and related land resources, Florida west coast tributaries: (Appendix). U.S. Army Engineer District, Southeast 1961 Comprehensive report on Four River Basins, Florida: Serial No. 185, 66 p. 1961 Comprehensive report on Four River Basins, Florida: (Appendices), Serial No. 185. U.S. Department of Commerce Climatological Data: Environmental Science Service Administration, monthly records Jan.1970-Dec.1971; Vol. 74, No.1-Vol. 75, No.12. Climatological Data, Florida: Annual Summary 1949 (vol. Llll, no. 13) to 1971 (Vol. 75, no. 13). U.S. Geological Survey 1970 Water resources data for Florida: 303 p 1972 1970 Water resource data for Florida, Part I, surface water records, Vol. 1; Streams-'Northern and Central Florida: 303 p. 1972 1970 Water resources data for Florida, Part I surface water records; Vol. 3, Lakes: 167 p. 1970 1968 Water resources data for Florida, Part II Water quality records: 251 p. GEOLOGY American Geological Institute 1962 Dictionary of Geological Terms: Doubleday and Co Inc., 545 p. Carr, W. J. 1959 (and Alverson, D. C.) Stratigraphy of Middle Tertiary rocks in part of west-central Florida: U.S. Geol. Survey BulL 1092, 111 p. Cathcart, J. B. 1959 (and McGreevy) Results of geologic exploration by core drilling, 19531and-pebble phosphate district Florida: U.S. Geol. Survey Bull. 1046-K. Cooke, C. W. 1945 Geology of Florida: Fla Geol. Survey Bull. 29, 339 p, Dunbar, C. 0. 1969 (and Waage, K. M.) Historical Geology: John Wiley and Sons Inc. 556 p Florida Bureau of Geology 1972 Environmental geology and hydrology Tallahassee area, Florida: Bur. of Geol Spec. Pub. 16,61 p. Mac Neil, F. S. 1949 Pleistocene shore lines in Florida and Georgia: U.S. Geol. Survey Pro. Paper 221-F. Puri, H. S. 1964 (and Vernon, R. 0.) Summary of the geology of Florida and a guidebook to classic exposures: Fla Geol. Survey Spec Pub 5, 312 p. Shinn, E. 1963 Spur and groove formation of the Florida reef tract: Journal of Sed. Petrol. Vol. 33, No. 2, p. 295. 93

PAGE 92

94 Southwest Florida Water Management District 1971 Aerial Mapping Index (northwest Hillsborough Basin) Stewart, J. W. 1970 (and Hanan, R V.) Hydrologic factors affecting the utilization of land for sanitary landfills in northern Hillsborough County, Florida: Dept of Nat. Res., Bur. of Geol., Map Series No. 39 White, W A. 1970 The geomorphology of the Florida peninsula: Fla. Bur. of Geol Bull. 51, 164 p. MINERAL RESOURCES Altschuler, Z. S. 1960 (and E. J. Young) Residual origin of the "Pleistocene" sand mantle in central Florida uplands and its bearing on marine terraces and Cenozoic uplift: U.S Geological Survey Prof. Paper 400-B, pp. B 202-B 207. 1964 (and Cathcart, J B., Young, E. J ) Geology and geochemistry of the Bone Valley Formation and its phosphate deposits, West central Florida: Guidebook, Field Trip No.6, Geol. Soc. America Convention, Miami Beach, Fla., 68 p Bell, Olin G 1924 A preliminary report on the clays of Florida (exclusive of Fuller's earth): Florida Geol. Survey, 15th Annual Rept., p. 53-266. Calver, James L. 1957 Mining and mineral resources: Florida Geological Survey, Bull. 39, 132 p Cathcart, J. B. 1950 Notes on the land-pebble phosphate deposits of Florida, in Symposium on mineral resources of the southeastern United States: Un i versity of Tennessee Press, pp. 132-151. 1963 Economic geology of the Chicora quadrangle, Florida: U.S Geol. Survey Bull. 1162-A, 66 p. 1963 Economic geology of the Keysville quadrangle, Florida: U S Geol. Survey Bull. 1128,82 p, 1963 Economic geology of the Plant City quadrangle, Florida: U.S Geol. Survey Bull. 1142-D, 56 p 1964 Economic geology of the Lakeland quadrangle, Florida: U.S. Geol Survey Bull 1162-G, G1-G128. 1966 Economic geology of the Fort Meade quadrangle, Polk and Hardee counties, Florida: U.S. Geol. Survey Bul l. 1207,97 p. 1953 (and Blade, L. V., Davidson, D. F., Ketner, K B.) The geology of the Florida land-pebble phosphate deposits: 19th lnternat. Geol. Cong Algier, Comptes rendus, sec. 11, fasc. 11, pp. 77-91. Cooke C Wythe 1945 Geology of Florida: Florida Geol Survey Bull. 29. Davidson, W. B M 1892 Notes on the geological ongm of phosphate of lime in the United States and Canada: Am lnst. Mining Eng Trans., v 33, pp. 139-152. Davis, John H. 1946 The peat deposits of Florida: Florida Geological Survey, Bull 30, 247 p Fettke, C. R 1926 American glass sands, their properties and preparations: Amer. lnst. Min. and Met. Eng. Trans ., Vol. LXIII, pp. 398-423. Fountain, R. C. 1972 (and Zellers, M. E.) A program for ore control in the central Florida phosphate district, in Seventh forum on geology of industrial minerals: Florida Bur of Geology Special Pub. 17, pp. 187-193. Freas, D. H. 1968 (and Riggs, S. R.) Environments of phosphorite deposition in the central Florida phosphate district, in Fourth forum on geology of Industrial minerals: Bureau of Economic Geology, Univ. of Texas, pp. 117-128. Ketner, K B 1959 (and McGreevy, L. J.) Stratigraphy of the area between Hernando and Hardee counties, Florida: U.S. Geol. Survey Bull. 1074-C, pp. 49-124. Martens, James H. C. 1928 Sand and gravel deposits of Florida: Florida Geol. Survey 19th Ann. Rept., pp. 33-123. Maxwell, E. L. 1970 Mineral producers in Florida, 1968: Florida Bureau of Geology, I nf. Cir. 66, 40 p Pirkle, E. C 1960 Kaolinitic sediments in peninsular Florida and origin of the kaolin: Econom i c Geology, vol. 55, pp. 1382-1405. 1964 (and Yoho, W. H Allen, A. T.) Origin of the silica sand deposits of the Lake Wales Ridge area of Florida: Econ Geol., Vol. 59, pp.1107-1139. 1963 (and Yoho, W. H., Edgar, Allen C.) Citronelle sediments of peninsular Florida: Fla Acad. Sci. Vol. 26, pp. 105-149. 1967 (and Yoho, W. H., Webb, S. D ) Sediments of the Bone Valley Phosphate District of Florida: Econ. Geology, Vol. 62, pp. 237-261 Pride, R. W. 1966 (and Meyer, F. W ., Cher ry, R N .) Hydrology of Green Swamp area in central Florida: Florida Geol. Survey Rept. of lnv. 42, 137 p Reves, William D. 1962 Mineral resources adjacent to the proposed trans-Florida barge canal (revised): Florida Geological Survey, 44 p Riggs, S. R. 1965 (and Freas, D. H.) Stratigraphy and sedimentation of phosphorite in the central Florida phosphate district: Society of Mining Engineers, AIME, preprint 65H84, 17 p. Sellards, E. H. 1915 The pebble phosphates of Florida: Florida Geol. Survey 7th Ann. Rept., pp. 25-116. Timberlake, R. C. 1969 Building land with phosphate wastes : Min. Eng., v 21, No. 12, pp. 38-40. Vernon, Robert 0. 1951 Geology of Citrus and Levy counties : Florida Geological Survey, Bull. 33, 256 p. 1943 Florida mineral industry: Florida Geological Survey, Bull. 24, 207 p. Wahl, F. Michael 1972 (and Timmons, Bobby J.) Miocene clay deposits of peninsular Florida, in Seventh forum on geology of industrial minerals: Florida Bureau of Geology Spec Pub 17, pp, 109-116. Yon, J. William 1972 (and Hendry, C. W., Jr.) Suwannee Limestone in Hernando and Pasco counties, Florida: Florida Bureau of Geology, Bull 54, part 1, pp. 1 42. ENGINEERING GEOLOGY AND SOILS Anti I, J. M 1967 (and Ryan, P.W.S.) Civil engineering construction: Angus and Robertson, Std Sydney, 631 p. Hillsborough Soil and Water Conservation District 1972 Use and interpretations of sail surveys and engineering principles of water management: (work shop). Merritt, F. S. 1968 Standard Handbook for Civil Engineers: McGraw-Hill, Inc., ch. 7, 80 pp., and ch. 8, 94 pp. U.S. Department of Agriculture, Soil Conservation Service 1958 Soil Survey: Hillsborough County, Florida: U.S. Government Printing Office, Series 1950, No.3, 68 p., 96 plates. ENERGY RESOURCES Florida Petroleum Council 1972 The Sun Below: Garcia-Bengochea, J I. 1970 Recharge of carbonaceous saline aquifer of South Florida with treated sanitary wastewater: unpublished arti cle, Artificial G roundwater Recharge Conference, University of Reading, Berkshire . England (Sponsored by Water Research Assoc Buckinghamshire, England, Sept. 21-24, 1970.) National Petroleum Council 1972 U .S. Energy Outlook: A summary report, Dec 1972. Shell Oil Company 1973 The National Energy Outlook: March, 1973. The Oil and Gas Journal Weekly publication, Gulf Publishing Co. World Oil Monthly publication, Gulf Publishing Co. LAND USE American Society of Civil Engineers 1959 Sanitary landfill: Manuals of Engineering Practice no 39, New York, Am. Soc of Civil Eng Florida Department of Transportation 1970 Tampa by-pass corridor study: (Remote Sensing Section, Topographic Offi ce) p 1 1 971 Soils and foundations: Flori da Land and Water Management Act of 1972 1972 House Bill 629 Hillsborough County Planning Commission 1972 Hillsborough County, Florida papulation projections and environmental factors : 42 p, Leopold, L. B 1971 (and Clarke, F. E., Hanshaw, B B., Balsley, J R.) A procedure of evaluating environmental impact: U.S. Geol. Survey Circ. 645, 13 p. McHarg, I. L. 1969 Design With Nature: Garden City, New York, Natural History Press, 197 p.

PAGE 93

rLORIDA GEOLOGICAL SURVEV. 903 W. TENNESSEE STREET J .ALLAHASSEE, FLORIDA 32304

PAGE 94

'' 39380000146540 11111111111111111 FLORIDA GEOLOGICAL SURVEY


Environmental geology and hydrology, Tampa area, Florida
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 Material Information
Title: Environmental geology and hydrology, Tampa area, Florida
Physical Description: v, 94 p." ill (some col.); 27 x 43 cm
Language: English
Creator: Wright, Alexandra P.
Publisher: Tallahassee: State of Florida, Dept. of Natural Resources, Division of Interior Resources, Bureau of Geology
Publication Date: 1974
 Notes
General Note: Series: Florida Geological Survey. Special publication; no. 19
General Note: Subjects: Geology--Florida--Tampa Bay Region. Hydrology--Florida--Tampa Bay Region. Land use--Florida--Tampa Bay Region.
General Note: Series Added Entries: Special publication (Florida. Bureau of Geology) ;--no. 19
General Note: http://publicfiles.dep.state.fl.us/FGS/FGS%5FPublications/SP/SP19EnviroGlyHydrolTampa1974
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Holding Location: University of Florida
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Table of Contents
    Front Cover
        Page i
        Page ii
    Table of Contents
        Page iii
    Acknowledgements and production
        Page iv
    Preface
        Page v
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
    Topography
        Page 6-7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
    Water resources
        Page 14-15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
    Geology
        Page 34-35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
    Mineral resouces
        Page 44-45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
    Engineering geology
        Page 60-61
        Page 62
        Page 63
        Page 64
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
    Energy resources
        Page 72-73
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
        Page 83
    Land use
        Page 84-85
        Page 86
        Page 87
        Page 88
        Page 89
        Page 90
        Page 91
        Page 92
    References
        Page 93
        Page 94
    Back Cover
        Page 95
        Page 96
Full Text







ENVIRONMENTAL GEOLOGY AND HYDROLOGY


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STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Harmon Shields, Executive Director




DIVISION OF INTERIOR RESOURCES
Robert O. Vernon, Director


BUREAU OF GEOLOGY
C. W. Hendry, Jr., Chief




SPECIAL PUBLICATION NO. 19


o0 aa (eotloE~-ral Survey
S Library
903 West Tennessee Street
T Ialhas Ee Florida 32304


ENVIRONMENTAL GEOLOGY AND HYDROLOGY
TAMPA AREA, FLORIDA


by Alexandra P. Wright




Prepared by the
BUREAU OF GEOLOGY
DIVISION OF INTERIOR RESOURCES
FLORIDA DEPARTMENT OF NATURAL RESOURCES

TALLAHASSEE, FLORIDA
1974


















CONTENTS


ACKNOWLEDGEMENTS AND PRODUCTION


PREFACE,Charles W. Hendry, Jr. ...... ........................ v


INTRODUCTION
Population ...............
Recreation ...............
Transportation, Carleton J. Ryffel, A. P.

TOPOGRAPHY
Topographic Maps ...........
Topography of the Tampa Area . .
Physiography ..............
Topography and Land Use Planning ..

WATER RESOURCES
Water Cycle . . . . . . .
Rainfall and Evapotranspiration . .
Drainage . . . . . . . .
Water Quality . . . . . . .
Lakes . . . . . . . . .
Streams . . . . . . . .
Hillsborough River . . . . . .
Water Table and Swamps . . . .
Floridan Aquifer and Springs . . .
Water Use ...............
Flooding ................

GEOLOGY
Geologic History . . . . . .
General Geology . . . . . .
Sinkholes ................
Structure . .. .. ......... .


MINERAL RESOURCES, E. C.Pirkle, W. H. Yoho, Fredric L.Pirkle, A.P. Wright
Phosphate . . . . . . . . . . . . . . . . . .
Sand . . . . . . . . . . . . . . . . . . .
Clay .. . . . . . . . . . . . . . . . .... . .
Lim estone . . . . . . . . . . . . . . . . . .
Cerhent, Oyster Shells and Peat ........................
Concluding Remarks ..............................


Wright


ENGINEERING GEOLOGY
Foundations, A.. Wright, James F. Orofino ....
Sands ........... ..... .. ....
Sand Suitability as a Foundation Material . . .
Clays . . . . . . . . . . . .
Organics . . . . . . . . . . .
Potential Collapse . . . . . . . . .
Soil Associations . . . . . . . . .
Soil Relationships in Urban Planning . . . .

ENERGY RESOURCES
Primary Energy Sources, W. B. Simonds . . .
Electric Energy, W. B. Simonds ..........
Energy of the Future, W. B. Simonds . . . .
Oil and Gas, W. R. Oglesby . . . . . ...

LAND USE
Current Land Use .. ..............
Future Land Use ..................
Transportation Planning and Geology . . . .
Geologic Factors Affecting Construction . . .
Geologic Factors and Sanitary Landfills . . .

REFERENCES ....................


. . . . . . . . . . ...... 43


Geology and Urban Planning .






















ACKNOWLEDGEMENTS


Gratitude is expressed to Dr. Robert O. Vernon,
Director of the Division of Interior Resources, Mr.
Charles W. Hendry, Jr., Chief of the Bureau of
Geology and Mr. Steve R. Windham, Assistant
Bureau Chief, for making this publication possible.
Appreciation is expressed to the staff of the
Bureau of Geology for encouragement throughout
the project and assistance in reviewing the text.
Special thanks are due J. W. Yon, Jr. who gave
generously of his time to assist in the preparation of
this publication.
Sincere thanks are extended to Dr. Joseph S.
Rosenshein, Subdistrict Chief of the U.S. Geological
Survey's Tampa office and to his staff for generously
providing data and helpful suggestions for the Water
Resources chapter. Assistance from Mr. Gerald
Parker, Chief Hydrologist, and other staff members of
Southwest Florida Water Management District and
from staff members of the Tallahassee District U.S.
Geological Survey office is also gratefully acknow-
ledged. Mr. Samuel R. Lockwood, past Superin-
tendent of the City of Tampa Water Department also
provided invaluable data.
Special thanks is expressed to James F. Orofino,
Orofino and Company whose extensive assistance
made possible the Engineering Geology chapter of the
study.
Appreciation is also due William B. Forney, past
District Conservationist, Soil Conservation Service
who kindly gave of his time to assist with the soils
sections of the study.
Gratitude is expressed to the following people for
assisting in the preparation and review of the Mineral


Resources chapter: T. Walter Herbert, Bobby J.
Timmons, J. S. Weaver, Thomas J. Patterson, Bruce
Congleton, Allen C. Edgar, L. B. Carnes, James L.
Eades, Walter W. Rowe, and Edward Medard. The
Department of Physical Science and the Department
of Geology, University of Florida and the Florida
Phosphate Council are also acknowledged. Sincere
appreciation is expressed to Xiomara Ortiz for typing
and lay-out of materials.
Sincere appreciation is extended to Timothy
Varney, past Environmental Planner, Hillsborough
County Planning Commission. William Ockunzzi and
other staff members of the Tampa Bay Regional
Planning Council provided much useful information
with regard to land use. Thanks are expressed to both
planning agencies for extending encouragement and
sincere interest during the study.
Thanks are also due the following people for
providing vital information and assistance with
various parts of the study; Peter McPhee, Division of
Recreation and Parks, Thomas Griepentrog, Depart-
ment of Transportation, Dr. Daniel P. Spangler,
University of South Florida, H. J. Woodard, Bureau
of Water Resources, S. Melodie Oleson, Southwest
Florida Water Management District, Robert W.
Johnson and Bishop Beville, Soil Conservation Ser-
vice, and Philip Linn, Hillsborough County Planning
Commission.
Genuine thanks are extended to the many people
too numerous to mention who have taken an interest
in the project and cooperated throughout the
preparation and production of this publication.


PRODUCTION


Coordinator

Technical Assistant

Graphic Consultants


Photography


Drafting


Art-text

-chapter title pages

Typing and Type Setting


Printing


Alexandra P. Wright

Carleton J. Ryffel

Juanita D. Woodard
Donald F. Tucker

Simmie L. Murphy
Stephen J. Wharton

D. E. Beatty
Robert M. Grill
Dorothy P. Janson
Philip R. Shaw
Harry Whitehead

Dorothy P. Janson

Anne M. Prytyka

Gloria Monk
Xiomara Ortiz
Janis Roberts
Juanita Woodard

Stephen J. Wharton













PREFACE


"Environmental geology. The collection, analysis,
and application of geologic data and principles to
problems created by human occupancy and use of the
physical environment, including the maximization of
a rapidly shrinking living space and resource base to
the needs of man, the minimization of the deleterious
effects of man's interaction with the Earth, and the
accommodation of the exponentially increasing
human population to the finite resources and terrain
of the Earth. It involves studies of hydrogeology,
topography, engineering geology, and economic geo-
logy, and is concerned with Earth processes, Earth
resources, and engineering properties of Earth materi-
als. It involves problems concerned with construction
of buildings and transportation facilities, installation
of utility facilities, safe disposal of solid and liquid
waste products, development and management of
water resources, evaluation and mapping of rock and
mineral resources, and overall long-range physical
planning and development of the most efficient and
beneficial use of the land." So states the Glossary of
Geology, published by the American Geological
Institute, and to this end this publication is pre-
sented.
To accommodate the exponentially increasing
human population to the finite resources and terrain
of the earth has become the foremost responsibility
of government officials, planners and technical
researchers within the last two decades. In the not
too distant past, it seemed we had inexhaustible
supplies of clean air, potable water, energy and other
mineral resources, but such excesses are no longer
assured. We have entered the era of shortages and
recycling which has resulted in the reestablishment of
priorities and the sequential uses of our resources in
order to insure our survival.
This publication is presented not as the answer to
any of the monumental problems facing those with
the responsibility of planning for the future, but as a
tool to help those with such responsibilities.


Charles W. Hendry, Jr.

















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POPULATION


Although Tampa's first incorporation occurred in
1849 with a population of 185, Tampa officially
became a city after a second incorporation in 1855.
Since that time Tampa and its surrounding suburbs
have experienced a population explosion. To put
Tampa's growth into perspective, the following table
provides a summary of census facts:

%


U.S.
Florida
Hillsborough County
Tampa


1870 pop.
38,558,371
187,748
3,216
796


1970 pop.
203,184,772
6,789,443
490,265
277,767


increase
427
3,516
15,144
34,795


Population figures alone have little environmental
significance. The statistic that probably relates most
directly to the physical setting is population density,
or the number of people per acre of land. Based on
1970 census data, figure one shows population
densities within the Tampa area.

Obviously, the individual requires a certain
minimal space for life, work and leisure and it seems
reasonable to assume that creature discomfort and
environmental damage can result from overcrowding.
Establishing an optimum space requirement for the
individual is an interdisciplinary problem and no
reliable estimate can be given here.

Attention can be paid, however, to future growth
patterns and specific areas in which accelerated
population increases are anticipated. For this


purpose, the graphs below exhibit population
projections through the year 2000 for the fourteen
areas outlined on figure one. These graphs indicate
that the population of some areas will increase by
many times during the next 30 years. It is these areas
which are prime candidates for the environmental
damages that have historically accompanied
indiscriminant development.

Prudent planning must keep pace with
development in these areas and such planning must be
based on thorough knowledge of both physical and
biological environ. It is the job of scientific agencies
to provide planners with such information if
environmental crises are to be avoided as more and
more people populate the Tampa area.



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* I .AREA11 (2.5 x
0.
- 1970 '5 '80 '85 '90 '95 2000

POPULATION PROJECTIONS BY CENSUS AREA
(SOURCE: TAMPA BAY REGIONAL PLANNING COUNCIL)
(1.3X) Number of times by which the population will increase.


-n-350
z
I-
Z




z
0
I-
z -3oo


0




. -250-


1970 '75 80 '85 '90 '95 2O00~


--- -


1970 'i5


'80 '85 '9b '45 20000
















Recreational facilities are a significant asset to any
area in both the intangible enjoyment they provide
and the role they play in the local economy. Due to
the great influx of tourists to the area as well as the
accelerated resident population increases, Tampa's
recreational demands are especially high. In fact,
according to the Division of Recreation and Parks,
current and projected demands for recreational
facilities in the Tampa region1 are the highest in the
state.

Fortunately, the area is endowed with many
natural resources which are the crux of outdoor
recreation. Geologic features frequently provide the
focal point for recreational facilities in the Tampa
area. Springs, for example, are a main attraction of
many local parks. Another example of a unique
natural feature can be found in Hillsborough River
State Park where the occurrence of a rock outcrop in
the river provides a scenic stretch of rapids. A
primary natural asset of the Tampa Bay area is the
Bay itself. Although the Bay has not been as
significant a recreational resource as it might have
been, several proposed recreation sites are located on
the Bayfront.


1,500,1



S1.000,0


500,0





M


2000



000 2000 P

1975
)00-
1975
1970
100-




LAND ACREAGE NEEDED FOR
CAMPING, PRIMITIVE
CAMPING, BEACH, HIKING
TRAILS, NATURE STUDY,
PICNICING


O SALT AND FRESH WATER
SURFACE ACREAGE NEEDED
FOR BOATING, FISHING,
SWIMMING, WATER SKIING


The map shows existing and proposed recreational
facilities within the Tampa area. The status of
proposed facilities varies from the "drawing board
stage" to "development near completion". Tampa's
current and projected recreational demands are great,
and the proposed recreation areas will not meet all of
the needs. The task of the recreation planner,
however, is simplified by the fact that any site
distinguished by its natural or historical elements has
potential for recreational development. The
important point is that the creation of a list of
potential recreational lands and acquisition of those
lands should be done now. This is necessary for two
reasons: the rising costs of real estate, and the need to
preserve the lands' natural resource assets until such
time as the sites can be developed for recreation. The
fact that demands for water related recreation are
greatest further emphasizes the necessity of properly
managing the regional water resources.


includes Hillsborough, Pinellas, Pasco, Polk, Manatee,
Hardee, DeSoto, Sarasota and Highlands counties.


RECREATION


RECREATIONAL NEEDS OF THE TAMPA AREA CONTRASTED WITH THOSE OF
THE MIAMI AREA (DATA SOURCE; DIVISION OF RECREATION AND PARKS, 1971)


PASCO COUNTY OLK CO
-- -- -. -..------ .------ -- ----------- 7
-I / LOWER HILLSBOROUGH RIVER /
7 RESERVOIR PARK /

I K 'LAKEPARK BLACKWATER CREE
RESERVOIR PARK

-0

'oUi


P TEMPLELA

T M P TAP SAY-.7' RIVER92
,UPPERTK .r w PLANT CITY I



aOLD T A M P A


S TAMPA SEDDON
FANSPOERKAY TI

BAY j / PLEASANT GROVEON
\ !\) RESERVOIR PARK
Hillsborough


EXISTING and PROPOSED RECREATIONAL LTHASPRI*
FACILITIES in HILLSBOROUGH COUNTY ALLARIVER I- PARK-
TAMPABAYPARK -

E3 i0
a-

TAMPA 2




EXPLANATION
I LBAY






TREAMPA BAY REGIONAL PL NG COUNCIL
/ MAN"" NTEE COU N

r '~ ' '~ ~ MANATEE ~ - - COU'NTY - - - - --












TRANSPORTATION


Historically, transportation in the Tampa area has
been vitally linked with the expanding population of
the area. The existence of the natural estuary (ideally
suited for the development of a port), played an
important role in the location and subsequent growth
of the City of Tampa.

Tampa channel was initially dredged in the late
1800's, and has since been deepened several times to
accommodate larger ships and cargo. The port was first
used for shipping cattle to Cuba in the 1800's. Later,
with the discovery of phosphate in the area, a
prosperous future for the port was assured. Currently,
phosphate is the leading product shipped from Port
Tampa, and many area residents depend directly or
indirectly on the port for their livlihood.

Whereas the port is a key to the economy of the
Tampa area, the supporting role of the railroads for
carrying goods to the port cannot be ignored. Like
the shipping industry, the rail industry was initiated
in Tampa during the late 1800's. In 1883, the railroad
stretched eastward toward Plant City and by 1885 it
was linked with the north. With the expansion and
diversification of industry in the area, rail trade
continued to grow.

A benchmark in transportation history was the
completion of Gandy Bridge in 1924, then the
world's longest auto toll bridge. Today's impressive
network of highways reflects local and regional
growth patterns in the Tampa area. Tampa is served
by U. S., state and interstate highways.

The airline industry was born in 1914 in the
Tampa area when Tony Janus made the first regularly
scheduled flights from St. Petersburg to Tampa in an
airboat. Tampa's new International Airport is a
monument to the spectacular growth of air travel.

Tampa's transportation facilities are an important
asset to the area. They provide convenience to
residents, in addition to facilitating the flow of
tourists to the area. Many transportation planning
studies, now underway, incorporate environmental
considerations to insure that future development of
transportation facilities will have minimal
environmental repercussions.


< 5000 Vehicles
5000-15000 Vehicles
-- 15000-50000 Vehicles
>50000 Vehicles













WATER


In 1971, Port Tampa handled over thirty six
million tons of cargo. This is the largest tonnage
handled by any port in Florida. Further, the port
ranks eighth in the nation in total tonnage handled,
and fourth in export tonnage. With the proposed
deepening of the channel, the projected tonnage may
reach sixty million tons by 1985, and one hundred
million tons by the year 2000.

At the present time, the U. S. Geological Survey
and the Tampa Port Authority have undertaken an
estuarine hydrology and environmental study of
Tampa Bay, to insure the wisest environmental and
commercial management of the Bay. The present
status and the fate of Tampa Bay have long been
subjects of heated controversy. The comprehensive
Bay study will provide a plethora of data including:
--the quality of Bay waters and sediments
--the quality of inflow to the Bay
--flushing mechanisms
--circulation patterns
--characteristics of bottom and sub-bottom
deposits.


Among the most sophisticated estuarine
investigations ever undertaken, the Tampa Bay study
will entail development of a computer model which
will provide accurate predictions of changes in the
Bay environment so that improvements in the ship
channel can be planned and designed to minimize
environmental effects.

The deepening project is necessary to
accommodate the larger new ships which the
phosphate industry (the largest user of port facilities)
will be using. The dredging operation will increase the
channel depth to forty-seven feet. The actual desired
depth is forty-three feet, but two foot allowances
must be made for error and for slumping of the
sediment after dredging is completed. It is expected
that fifty million cubic yards of sediment will be
removed under the supervision of the Army Corps of
Engineers, which is the agency responsible for
maintenance of the channels. Some sediments
removed from the Bay will be used for construction
purposes. The remainder will be used in spoil areas.


... . .i, *. -.I . .


The new Tampa International Airport has been
designated an intercontinental facility and jet
terminal by the Federal Aviation Authority, and its
runways and terminal complex are designed to
accommodate all commercial aircraft including the
747 and SST. Currently, ten major scheduled airlines
operate from Tampa International. Completed in
1971, the airport features four levels: baggage claim,
ticketing, transfer (landside-airside shuttle), and
parking. The multi-level concept and radial design
minimize walking distance from automobile to
aircraft seat and maximize efficiency.

The remainder of the airports in the area (exclusive
of Macdill) are for private use. They offer flight
schools, aircraft sales, service and leasing, or some
combination of these.


SURFACE

Hillsborough County is served by interstate
highways 4 and 75. On completion, 1-75 will enable
driving from Tampa to Saulte Ste. Marie, Michigan on
the Canadian border. Interstate 4 provides easy access
to Florida's east coast, and in Daytona Beach it
connects with 1-95 which runs along the entire
eastern coast of the United States.

With regard to rail transportation, the Tampa area
is served by Seaboard Coastline, the eighth largest
railroad in the nation. Seaboard is primarily a carrier
of phosphate, and to a lesser degree, citrus products
and passengers. Seaboard is also a feeder line to
junctions where goods are transferred to other
railroads and carried to more distant destinations.


Photo by R.C. Reichenbaugh








TOPOGRAPHY


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TOPOGRAPHIC MAPS


Topography (or the shape of the land surface) is of
great significance to virtually every aspect of land use
planning. The relationship of relief to geography and
physiography, location and thickness of mineral
resources, drainage patterns, climatology, vegetative
patterns, occurrence of natural disasters, soil
development, physical aesthetics, etc. points up the
value of a familiarity with the topography of the
study area. The shape of the land, portrayed by
contour lines (lines of equal elevation), is the
distinctive feature exhibited on topographic maps,
however, a wealth of information about the area is
also shown on the maps.
The Tampa area encompasses all, or portions of
sixteen quadrangle maps, each showing an area of 7.5
minutes latitude by 7.5 minutes longitude. The scale
on these maps is 1:24,000 that is, one inch on the
map equals 24,000 inches or 2000 feet on the
ground. The contours are imaginary lines following
the land surface at a constant elevation above sea
level. The contour interval (given at the bottom of
each map) is the vertical difference in elevation
between adjacent contours on the map. In flat areas
such as Tampa, the contour interval is generally small
so that contour lines are not far apart.

Several characteristics of contour lines are
noteworthy:
1) Contour lines never cross or intersect one
another, nor do they split.
2) Every contour line closes on itself either within
or beyond the limits of the map.
3) The closer the spacing of contour lines, the
steeper the slope.
4) Contour lines curve upstream, but cross the
stream at right angles to its course.


Topographic maps are ideal for pinpointing exact
locations, as they are referenced to latitude-longitude,
and contain a sectional gridwork within each
township. Township is given on the sides of each
map, and range on the top and bottom. Each of the
36 sections within a township represents one square
mile, and each section number is shown in red on the
map.

Color coding and numerous map symbols indicate
a variety of physical and cultural features. Black is
used for man-made features (roads, buildings, etc.),
blue for water, brown for contour lines, mines, etc.,
green for vegetative cover, and red for urban areas,
section lines, etc. In addition, lavender is used on
photorevised maps to show new features.
Cross sections (as shown in the diagram) can easily
be constructed from topographic maps and are useful
in representing cross country relief or slope of the
land surface.

Topographic maps covering the Tampa area are
available through the U. S. Geological Survey in
Washington, D. C.


CROSS SECTION


50'
40'


VERTICAL EXAGGERATION X40


INTERIOR-GEOLOGICAL SURVEY W SHINGTON,D.C -1970-NS
0.3 MI. TO U.S.92 82922
TAMPA (CH.) 6.9 MI.
ROAD CLASSIFICATION
Heavy duty........... Light duty.........
Medium duty........ -- Unimproved dirt =...
0 Interstate Route U.S. Route 0 State Route
SULPHUR SPRINGS, FLA.
N2800-W8222.5/7.5
1956
PHOTOREVISED 1969
AMS 4540 IIISW-SERIES V847


SCALE 1:24000
1 2 0 1 MILE
1000" 0 1000 2000 3000 4000 5000 6000 7000 FEET
1 .5 0 1 KILOMETER


CONTOUR INTERVAL 5 FEET
DATUM IS MEAN SEA LEVEL









TOPOGRAPHY OF THE TAMPA AREA


The index map on this page shows the boundaries
of the sixteen 7.5 minute topographic quadrangles
which encompass the Tampa area. Seven of them
have been photorevised. Space does not permit
reproduction of each quadrangle, however, the
Tampa, Gandy Bridge, and Sulphur Springs quads are
discussed on subsequent pages.


The simplified contour map presented here
portrays the general topography of the Tampa area.
The interbay peninsula, and the coastal strip (which
ranges from about 1 to 3 miles wide) are
characterized by elevations rarely exceeding 20 feet
above sea level. Low relief extends inland for some
distance from the mouths of the river channels. The
area gradually slopes upward to the north and east.
Highest elevations are found within the Polk Upland
(see Physiography Section) in the eastern part of the
area.


GENERALIZED TOPOGRAPHY
of the
TAMPA AREA


2800'o


0 2 3 4
SCALE









UNITED STATES
DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY






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FLORI DA-HLLSBOROUH SCOC
7S MINUTE SERIES (TOPOGRAPHIC)


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SULPHUR SPRINGS, FLA
.... v 41 ...


Lake Magdalene


Sulphur Springs Quadrangle

The southern half of this quadrangle is highly
urbanized. Physically, two distinctive regions are
evident a lake region and a swamp region. The
western part of the map exhibits a preponderance of
lakes, whereas the eastern half contains almost none.
The elevations of most lakes are printed on the map
within the surface area of the lake.

The northeastern quarter of the map is covered by
wooded swamp, which accounts for the lack of
development in that area. With the continued growth
of the University of South Florida community, it is
conceivable that urbanization may push its way
toward the swamps as developers attempt to
overcome the limitations of this hitherto low-priority
land.

Another interesting feature of the map is the
cluster of sinkholes near 109th Street and Florida
Avenue. These appear as series of concentric circular
contour lines with hachure marks indicating a drop
rather than a rise in elevation. The blue symbol for
water appears in the center of the sinkholes on the
original map, but cannot be seen on this
reproduction.


26 ;


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UNITED STATES
DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY





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The Gandy Bridge quadrangle e.t.oh.
the western half of the ,nieit.'
peninsula. Much "made-land" anfi rmai
alterations of the coast are evidenced by
the artificial shape of the shoreline. in
the northwest corner of the map, the
mangrove symbol appears prominently
along the coast.


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GANDY BRIDGE QUADRANGLE
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TAMFA QUADRANGLE
FLORIDA-HILLSBOROUGH CO
75 MINUTE SERIES (TOPOGRAPHiC)


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TAMPA, FLA
Nioro IWsea :


3ANDY BRIDGE, FLA












MARIANNA LOWLANDS PHYSIOGRAPHY
The Tampa area lies within the major physiographic subdivision known as the
GEORGIA -Gulf Coastal Plain and in general exhibits little variation in physiography.
HbRLAN-D---- JACKSONVILLE
S AHAE "\ VL- The terrain is flat and low-lying, reflecting the relatively low relief of the
C NORTHERN ZONE bedrock. In the eastern part of the area, the land surface becomes gently rolling
S-k with smoothly rounded hills and shallow depressions.
onsof rom Purln r On the basis of local physiographic features, the area can be divided into
L4" regions. These regions have been discussed in detail by White (1970).

Q ISULA ZONE Notable physiographic features within the area are related to the marine origin
STAMPA 1 of the region. Traces of ancient stands of sea level are found in parts of the study
TAMPA LAKELAND
1 r area where the landscape has not been greatly altered by fluvial processes.

._, GULF COASTAL LOWLANDS

The western part of the Lowlands is very swampy and many lakes are present.
Sokeecobee Relict marine features, such as bars, barrier islands, etc., formed during ancient
stands of sea level are found in the Gulf Coastal Lowlands. The area is largely
SOUTHERN ZONE covered by somewhat poorly drained sands with an organic pan and is
MIAMI characterized by flat topography and swamps. Sinkholes are scattered in the
northwest area and will be discussed in greater detail later.

Each of the Pleistocene glacial stages was followed by an interglacial stage
during which the ice melted and the seas encroached on the land. Each encroachment reached successively lower
levels and consequently the remnants of interglacial shorelines can still be identified on land. These remnants provide
clues to paleogeography. The Pamlico shoreline represents an advance of the sea to an elevation of about 25 feet
above present sea level. From the configuration of the Pamlico shoreline in the Tampa area, it can be deduced that
this area was occupied by a large and more open estuary during late Pleistocene time. Several islands also existed,
primarily in the area of what is now Pinellas County. Relict sand dunes are found in the Temple Terrace area.

The extent of the Pamlico shoreline is shown on the map. This is the only Pleistocene shoreline that is well
preserved in the Tampa area.

THE CENTRAL HIGHLANDS

The Central Highlands comprise a number of upland areas within mid-peninsular Florida. Among these is the Polk
Uplands which is of considerably less elevation and local relief than many of the other Upland features. The general
Central Highlands also encompasses several lowlands including the Western Valley. These lowland and highland
features can be attributed to differential erosion which reduced unprotected soluble areas to lower elevations,
leaving residual remnants of former regional upland areas.

The Hillsborough River Valley: The Hillsborough River Valley trends northeast-southwest through the central
portion of the area and represents the southern end of the Western Valley which includes both the Hillsborough and
Withlacoochee Rivers. There is evidence that the Western Valley may have once held only one long stream.
Periodically, the Withlacoochee overflows into the Hillsborough River via a topographic saddle.

The Hillsborough River Valley has gently sloping to flat relief and is dissected by the Hillsborough River and its
numerous tributaries. The size of Hillsborough Bay into which the river flows, coupled with the fact that a
Pleistocene shoreline can be traced part way up the river valley suggests that the Hillsborough River has existed for
some time. The river's broad, swampy flood plain is also indicative of an older river. Although well drained, deep
sands cover much of the area, portions of the River Valley are swampy, and relatively few lakes are present.

The Polk Upland: The eastern part of the study area encompasses a small portion of the Polk Upland. This area is
topographically higher than the surrounding Coastal and River Valley lowlands and attains elevations of 100 to 130
feet. The terrain is gently rolling and bounded on the west by a scarp whose slope steepens toward the Hillsborough
River. The area is covered by well drained sands which are mixed with phosphatic material in places.


0 I 2 3 MILES
SCALE











TOPOGRAPHY AND LAND USE PLANNING


Because of the detail and accuracy of topographic
maps and the relevancy of topography to land use,
planners can utilize topographic maps for myriad
purposes. Some examples are given below:

Locating and Evaluating Mineral Resources

Valuable mineral deposits are often associated with
physiographic features (arches, relict beach dunes,
etc.) that are revealed on topographic maps. In
addition, if the elevation of the top of an economic
mineral deposit has been mapped, this map can be
superimposed on a topographic map of the area and
the land surface elevation minus the deposit elevation
is equal to -the thickness of overburden that will have
to be removed prior to mining.

Selecting Industrial and Residential Sites

Topographic maps provide information that is
useful in selecting industrial and residential sites.
Topographic maps can be used as base maps for
showing utility lines, access roads and waterways,
zoning boundaries, potential water supply and the
present industrial-residential pattern of the
community.

Planning Recreation Areas

Topographic maps are ideal for locating areas with
unique physical attributes that may be suitable as
recreation areas. Potential hiking and canoe trails can
be sketched on topographic maps, then evaluated in
the field. Lack of urbanization is often a primary
criteria for recreation areas, and undeveloped land
can be spotted at a glance on topographic maps.

Defining and Evaluating Water Resources

Topographic maps serve as a tool for planning
watersheds, recharge areas, well fields, surface water
supply sources, flood control structures, reservoirs,
etc. Indeed their applications to hydrology are almost
limitless. The map illustrates how surface drainage
patterns and drainage basin boundaries can be
delineated on a topographic map. Such flow nets are
used in planning flood control and drainage projects
and in correlating climatological conditions with
surface water flow.


Incorporating Physical Aesthetics in the Regional Plan

In many areas there is an aesthetic quality to the
"lay of the land". Creative planners can sometimes
capitalize on inherent physical appearances by
emphasizing the natural landscape in the land use
plan. Topographic maps can be a starting point from
which a land use design that is harmonious with
natural features can be developed.


.4-




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LOCATION

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WATER CYCLE


One of the consequences of urbanization is an
increasing demand upon available water resources for
public supply, recreation, industry and other
purposes.
As the competition for water intensifies, hydrology
becomes a more prominent aspect of planning, and
sound and equitable water management becomes a
necessity. The hydrologic cycle is a fundamental
concept in understanding, planning for and managing
water resources.
Fresh water on land is derived from ocean water
evaporated by the sun's heat. Evaporated water in
vapor form is transported by convective air currents
through the atmosphere to inland areas, where part of
the vapor condenses and precipitates.
Rain that reaches the land returns either to the
ocean by gravity flow or to the atmosphere by
evaporation from land, water and plant surfaces.
Before the basic cycle is completed, however, much
interchange of water may take place between lakes,
swamps, streams and the ground. Time required for a
'water particle to complete the cycle may vary from
an instant to many years, depending on the path it
takes.
Once rain reaches the land surface its path depends
on the terrain. Two important characteristics are the
slope of the land surface and the permeability of the
surficial and underlying materials.
Steep slopes and low permeabilities promote the
runoff of rainfall to streams or to lakes, swamps, and
sinkholes which may or may not connect to streams
leading to the ocean.
Gentle slopes and high permeabilities promote the
infiltration of rainfall into the ground. Much of the
water that infiltrates is stored in a soil zone, serving
to supply water for vegetation, but part of it moves
down to the water table, ultimately to emerge at
some lower level, usually in areas that contain or
adjoin streams, lakes and swamps.
In Hillsborough County water may also move
downward into the Floridan aquifer, which underlies
the water table aquifer and is generally separated
from it by a layer of relatively impermeable material
called a confining bed. Sinks in the bottoms of some


streams and lakes may connect directly with the
Floridan aquifer. Water in the Floridan aquifer
eventually emerges as springflow in streams, lakes,
swamps, or the ocean.
Recharge to and discharge from the Floridan
aquifer are dependent on the relative position of the
waters involved and the fact that water always moves
from higher to lower elevations. Because water in the
Floridan aquifer is confined, its potential elevation is
represented by an imaginary surface, called the
potentiometric surface, which is determined by the
level at which water freely stands in tightly cased
wells that penetrate the aquifer. Given the necessary
openings in the confining bed, water can move into
the Floridan aquifer from water bodies which stand


above the potentiometric surface; conversely, the
Floridan aquifer can discharge water into water
bodies whose levels stand below the potentiometric
surface.
It is evident that all components of the hydrologic
system are interrelated to form a delicate balance,
and when one component of the system fluctuates,
other components fluctuate similarly. This can be
illustrated by the relationship between streamflow,
lake and well levels. These levels respond to both
natural and artificial alterations in the quantity of
water within the system. Projects involving water
withdrawal, addition, or diversion should be
evaluated in terms of possible effects on the entire
hydrologic system.


WINDS


SOLAR RADIATION


LAKE


EVAPORATION


GUF of
GULF of MEXICO








PRECIPITATION AND EVAPOTRANSPIRATION


1900 1910 1920 1930 L940
YEARS
YEARLY PRECIPITATION, IN INCHES,


AT TAMPA, FLORIDA


Replenishment of lakes, streams, and aquifers in
the Tampa area is largely dependent on precipitation.
Normal annual precipitation at Tampa is 51.57
inches, however, total yearly precipitation fluctuates
widely. The lowest yearly total recorded was 28.89
inches in 1956, and the highest recorded was 76.57
inches in 1959.
Monthly variations in precipitation are important
to farmers, construction companies, homeowners,
etc. Two wet seasons are defined by the graph of
monthly precipitation in Tampa: a pronounced one
during the summer, and lesser one early in spring.
Most rainfall occurs between June and September as a
result of thunder storms, tropical depressions or
hurricanes. During these months, outdoor activity is
often restricted by frequent showers, and local
flooding may occur.
Lack of precipitation in late spring may bring
about regional drought which causes the vegetation to
experience moisture stress. At this time, there are
critical demands on water resources for irrigation and
sprinkling, and restrictive measures are sometimes
imposed.
Whereas precipitation is the primary source of
replenishment of the water resources in the area, the
amount of water that actually enters the hydrologic
system is sharply reduced by evapotranspiration (ET).


Potential monthly ET can be calculated on the
basis of mean monthly temperatures and sunlight
duration. During months when precipitation exceeds
the potential ET value, all potential ET can take
place. If the precipitation is less than the potential
ET, actual ET consumes all precipitation plus some of
the moisture stored in the soil, and the actual ET is
less than the potential ET. This leaves a moisture
deficit.
During rainy months there may be a moisture
surplus. This is equal to the precipitation that remains
after all potential ET has taken place and the soil
moisture retention has been restored to full capacity
(about 4 inches per foot in the Tampa area). Each
month when there is a moisture surplus, about half of
the accumulated excess water leaves the area as
runoff.
It is easy to see that evapotranspiration takes a
heavy toll on precipitation, and the "leftovers" must
be carefully managed. Although drainage is essential
to optimum land use in many locations within the
Tampa area, the consequences of drought can be
lessened by retaining as much excess water in the area
as is feasible.


MONTHS
MAXIMUM, MINIMUM, AND MEAN MONTHLY PRECIPITATION, 1952- 1971


WATER BUDGET-TAMPA, FL., 1971
(methodology from Thornwaite & Mather, 1957)


PRECIPITATION
(INCHES)

POTENTIAL
EVAPOTRANSPIRATION
(INCHES)

ACTUAL EVAPOTRANSPIRATION
(INCHES)

MOISTURE DEFICIT
(INCHES)

MOISTURE SURPLUS
(INCHES)


J F M A M J J A S O N D TOTAL
.86 4.25 .54 1.80 4.09 2.54 7.74 7.46 10.16 4.70 1.40 .79 46.33


.99 1.44 1.41 2.63 4.47 6.02 6.45 6.18 5.07 4.28 1.97 2.21 43.12


.99 1.44


1.34 2.42 4.33 3.92 6.45 6.18 5.07 4.28 1.94 1.86 40.22


0 0 .07 .21 .14 2.10


0 2.68


0 0 0 0 .03 .35 2.90


0 0 0 0 0 1.28 5.09 .42 0 0 9.47


I- - I:. -I I I T I- i T I .


- '.l I F NFALL


EXCESS EVAPO-
TRANSPIRATION


1971 17















On one hand, the Tampa area is facing
ever-increasing demands for water, which are difficult
to meet with present supply sources...
A critical need exists to retain water on or
below the land surface.
On the other hand, many acres of valuable land are
flood prone and many additional acres are swampy
and unusable throughout most of the year...
A critical need exists to dispose of, or provide
facilities for the disposal of excess water.
The polarity of these problems provides the
greatest challenge to water management efforts.
Ideally, projects which deal with one problem can
be planned so as not to intensify the other; or water
management can be directed toward alleviating, in
part, both problems simultaneously.
Water management projects in the Tampa area are
currently underway by the U. S. Army Corps of
Engineers and the Soil Conservation Service.

UPPER TAMPA BAY WATERSHED
Soil Conservation Service

The watershed includes about 103 square miles in
which the two principal problems are flood damage
and drainage. The objectives of the SCS watershed
project are 1) to protect improved pasturelands,
citrus groves and other agricultural developments
from flood water damage (2) to provide drainage
outlets, and 3) to conserve water during the dry
season.


kINAGE MAP



..-----DIRECTION OF SURFACE FLOW
-----DIRECTION OF GROUND WATER FLOW


DRAINAGE







These objectives will be accomplished by land
treatment measures, channel construction and
improvement and installation of channel control
structures.
The average annual cost of the project ($160,000)
compared to the average annual benefits ($212,340)
places the benefit: cost ratio at 1.33 to 1.
The main objective 6f SCS is to improve
agricultural land, however, when lowlying areas are
drained, they become suitable for other land uses
which may have higher economic priority.
Consequently, as land values increase the ownership
and use of the land may gradually change.
Although SCS proposes to retain much of the
drainage and flood water, evapotranspiration losses
will be high, as all retention areas will be above
ground. If the excess water could be rapidly
recharged to the Floridan aquifer, more could be
conserved and the raised potentiometric surface
would reduce the threat of salt water encroachment.
(One of the SCS structures can be seen in the soil
portion of this study.)

FOUR RIVER BASINS PROJECT
U. S. Army Corps of Engineers

The objective of the total project is to deal with
the following items: flood control, major drainage,
navigation, recreational boating, water conservation,
pollution abatement, and salt water intrusion. Several
works of improvements are slated for the
Hillsborough River. Of special importance to the
Tampa area are the lower Hillsborough River
"Detention Area" (discussed previously) and the
Tampa Bypass Canal.
The Canal, when completed, will lead south from
the Lower Hillsborough Reservoir and pass east of
urban Tampa. During time of flood, it will divert
water from the Hillsborough River directly to the
bay. It is designed to give urban Tampa maximum
protection from floods including one so severe, its
likelihood of occurrence is once in about 200 years.
The benefit: cost ratio of the entire Four River
Basins project is estimated at about 1.5 to 1.


Sections of the Canal have been excavated below
the top of the Floridan aquifer and below the level of
the potentiometric surface. Here, newly made springs
are discharging into the canal and the potentiometric
surface is being lowered. It is hoped that an adequate
number of control structures will be installed to raise
the water levels in the Canal and thereby prevent a
large decline in the potentiometric surface, excessive
drainage from the aquifer, and salt water
encroachment. (A view of the Canal can be seen in
the Geology section of this study.)











WATER QUALITY


A variety of chemical and biological constituents
are present in water sources in varying amounts, and
the quality of any water sample reflects many factors,
including:
1) source of the sample
2) season during which the sample was taken
3) time of sampling
4) specific location and depth of the sample
5) nature of soils, rocks and vegetation that the
water has contacted
6) kind and amount of matter that has been
introduced to the water source by man.
Water quality standards have been established for
public water supply, shellfish harvesting, recreation,
agriculture, industry, navigation and utility. In
addition, quality standards have been set for specific
water uses such as production of carbonated
beverages, pulp, canned foods, etc. These standards
necessitate the following considerations in planning:
-- is the existing quality of the available water
source suitable for a given use, or will extensive
treatment be necessary?


Since all water "used" is actually "borrowed" and
will eventually be returned to the environment in
some form, a second consideration is important:
-- will the use add detrimental constituents to
the water in such quantity that treatment will
be necessary before the water can be returned
to the environment?
Discharge of noxious liquid effluents is only one
means of fowling a water body. Alteration of the land
surface or landscape may also have detrimental
effects on water quality. For example, removing
vegetation from a construction site may accelerate
erosion and increase turbidity in a nearby stream or
lake.
Detriment to the water resources may not be
readily evident after a project has been completed,
but it may be avoided if the possibility is considered
during the planning phase of the project.


SOURCE & SIGNIFICANCE OF CHEMICAL CONSTITUENTS IN WATER


Constituent or property


Bicarbonate (HCO3) and Car-
bonate (C03)

Calcium (Ca) and Magnesium (Mg)'


Chloride (CI)


Dissolved solids (TDS)


Fluoride (F)


Nitrate (N03)


Phosphate (P04)


Silica (SiO2)


Sodium (Na) & Potassium (k)


Specific conductance (Kx 106)


Sulfate (SOa)


Source or Cause


Produced by reaction of atmospheric CO2 with water.
Dissolved from carbonate rocks such as limestone and
dolomite.
Dissolved from most soils and rocks, especially limestone,
dolomite, and gypsum. Magnesium is present in large
quantities in seawater.
Dissolved from rocks and soils. Present in sewage and
abundant in ancient, and industrial brines and seawater.
Chief mineral constituents dissolved from rocks and soils.

Dissolved in small quantities from most rocks and soils.
Enters many water from fluoridation of municipal supplies.

Decaying organic matter, sewage, fertilizers, and nitrates in
soil.

Dissolved from many rocks and soils. Some from fertilizers,
detergents, domestic and industrial wastes.

Dissolved from most rocks and soils, usually in small amounts
from 1-30 mg/I.
Dissolved from most rocks and soils. Found in ancient brines,
seawater, industrial brines, and sewage.

Measure of the'ability of water to conduct electrical current.


Dissolved from rocks and soils containing gypsum, iron
sulfides, and other sulfur compounds. Usually present in
sewage, mine waters and some industrial waters.


Significance. Maximum tolerable concentration for public
water supply is shown in parentheses.


HCO3 and CO3 produce alkalinity. In combination with
calcium and magnesium, cause carbonate hardness.

Cause most of the hardness and scaleforming properties of
water; consumes soap.

About 300 mg/I in combination with sodium gives salty taste
to water. Increases the corrosiveness of water. (250 mg/I).
Water containing more than 1,000 mg/1 of dissolved solids are
unsuitable for many purposes (500 mg/1).

Fluoride in drinking water can reduce tooth decay but may
cause mottling of teeth depending on concentration and
other factors (1.4 to 1.6 mg/l depending on air temperature).
Concentrations much greater than the local average may
suggest pollution. Nitrate encourages growth of algae and
other organisms which produce undesirable tastes and odors.
Phosphates stimulate the growth of algae. Excessive amounts
may indicate pollution from phosphate mining or domestic
wastes.
Forms hard scale in pipes and boilers. Inhibits deterioration
of zeolite-type water softeners.
Large amounts, in combination with chloride, give a salty
taste. High sodium content may limit the use of water for
irrigation.
Specific conductance is directly proportional to dissolved
mineral content of water. Can also be related to individual
constituents in water.
Sulfate in water containing calcium forms hard scale in
steam boilers. In large amounts, sulfate in combination with
other ions gives bitter taste to water (250 mg/l).


= 250 mr9/

WATER QUALITY IN THE TAMPA AREA SHOWING
RELATIVE PROPORTIONS OF TOTAL DISSOLVED
SOLIDS AND CHEMICAL CONSTITUENTS OF
TOTAL DISSOLVED SOLIDS.
(Data from: U.S.G.S. Provisional records)


SILICA (SiO2)

SODIUM PLUS POTASSIUM (Na + K)

CHLORIDE, FLUORIDE & NITRATE
(CI, F and NO3)


Modified: M. E. Beard, 1969, The Florida District Water Quality Laboratory:













LAKES


The Tampa area is dotted with numerous lakes
which are especially abundant north of the city (see
map). Here, lakes are concentrated on a low sandy
ridge which is 20 to 40 feet higher than adjacent
poorly drained swamplands.
Some lakes occupy depressions that intersect the
shallow water table. Water levels in these lakes
respond to changes in water table elevation. Other
lakes occupy partly filled sinkholes or cavities
connected to the Floridan artesian aquifer, and
fluctuate with the potentiometric surface. A third
lake type is found in depressions lined with relatively
impermeable material perched above the water table.
Although water levels in all lakes are affected by
rainfall and evaporation, perched lakes depend almost


entirely on rainfall to maintain their levels. It is
doubtful that perched lakes in the Tampa area would
have any permanence, as such lakes in the Tampa
climate would soon be filled with vegetation.
Underground movement of water to or from a lake
depends on the relationship between lake level,
water-table level, potentiometric surface, and the
nature of the deposits underlying the lake. J. W.
Stewart (1968, p. 118) has found that the decline in
levels of some lakes near the well fields in northwest
Hillsborough County was in part due to the
cumulative effects of well pumpage. In order to
prevent large fluctuation in water level, control
structures have been installed at many lakes in the
Tampa area.


^Do
I









i

Ii

g

i


Gornto e
Ten Mie


LAKE LEVEL CONTROLLED BY:

-SOUTHWEST FLORIDA WATER C
I MANAGEMENT DISTRICT STRUCTURE

*HILLSBOROUGH COUNTY STRUCTU


0 I 2 3 4 MILES
SCALE L
DISTRIBUTION OF LAKES IN THE TAMPA AREA
(INFORMATION FROM S.W. FLA.WATER MANAGEMENT DISTRICT)


OM~agdoIeno

4EfIen %
; Frto P ----------------
White Trot j





--....---- ---- I


--------------I-


East
0


%Mango


*Weeks
iHooker

Long
o/arico


HYDROGRAPHS OF SELECTED LAKES IN THE TAMPA AREA


,J






PRECIPITATION


The chemical quality of lake water is an important
factor in the continued use of lakes in the area.
Although the quality of lake water is generally good,
the total dissolved solids in several of the larger, more
urbanized lakes in the area are increasing with time.
Conductance and turbidity of several local lakes are
shown in the graph.
A decrease in the quality of lake water may reflect
either the direct addition of contaminants to the lake
water such as by surface drainage or indirect addition
by seepage. Lands with high animal populations,
septic tank fields, or receiving high pesticide
applications may indirectly contribute contaminants
to a nearby lake.
Eutrophication is another factor which threatens
lakes. This is the enrichment of water with nutrients
that promote excessive plant and animal growth.
Eutrophication accompanies the natural aging process
of a lake, but may be greatly hastened by the
activities of man. Study is essential to determine
which lakes are under accelerated enrichment before
any corrective measures can be employed.
During the developments of subdivisions, dredging
of lake bottoms is sometimes undertaken to increase
the size or depth of a lake and provide fill material to
adjacent property. Such projects have the potential to
disturb the ecology of the lake basin, change the
drainage area, remove impermeable material from the
lake bottom with consequent altering of lake level
characteristics, and render the lake highly turbid.
Extremely fine particles suspended in lake water may
not settle for many years.


In some areas, new man-made lakes have been
created. It is clear that a thorough investigation of the
geology and hydrology of the area must precede such
a project. With careful planning, some borrow pits
may be reclaimed and converted to lakes bordered by
attractive landscaping.
Lakes in the Tampa area are utilized largely for
recreation and residential focal points. Property
values usually increase with proximity to a lake.
Continued recreational and residential benefits hinge
on maintaining adequate chemical quality, and
reasonable water level fluctuations. Some range of
fluctuation in lake level is conducive to the health of
the lake.
Some of the potential lake problems which should
be considered in developing and managing lakes and
adjoining property are:
1) lakefront flooding
2) abnormal recessions in lake levels
3) sedimentation caused by stripping nearby
terrain (a special threat during the
rainy season)
4) contamination from:
a) septic tanks
b) outboard motor oil
c) storm runoff from urban areas
d) runoff from agricultural or
farm-lands (pesticides,
nutrients).
A lake planning and management model is
presented on this page.


Cost of
Preventing Pollution
from Entering
the Lake


Influent Tributary Streams n I_
-- -- ;
Runoff-Overland Flow and
Interflow i I

Runoff--Storm Drainage System 0


L_


Discharge to Streams

.. ,---


Treatment Cost of
S system Water Quality
Improvement


Regulation


From: U.S.G.S.Circular 601-G, Real Estate Lakes,D.A.Rickert and A.M.Spieker


SCHEMATIC DIAGRAM OF A BASIC LAKE PLANNING AND MANAGEMENT MODEL.


Typical circular collapse structure.
(photograph by J.W. Stewart)




"To improve lake quality three major
things must be accomplished:
1. The nutrients must be reduced in the
lake and future sources of input reduced or
stopped.
2. A significant zone of rooted aquatic
vegetation must be maintained.
3. The lake must be allowed to fluctuate
in a manner similar to the historical natural
fluctuation of the lake."
Southwest Florida Water Management
District Hydroscope, Vol. 3, No. 11.


Shoreline of Lake Thonotosassa (photo by R.C. Reichenbaugh)


WATER QUALITY AT SELECTED LAKES, 1970 AND 1971


TURBIDITY SPECIFIC CONDUCTANCE


JACKSON TURBIDITY UNITS


(FROM USGS PROVISIONAL RECORDS)


MMHOS

















STREAMS


Excluding the Hillsborough River, which will be
treated separately, there are four major streams
within the Tampa area which discharge into Tampa
Bay. Streamflow is highly variable seasonally as well
as annually due to climatological conditions.
Water in the four streams is generally not of the
highest quality because of the addition of urban
wastes to streams within the Tampa area and
contamination from upstream sources which may be
outside the County. The ultimate recipient for all
streamflow from the area, Tampa Bay, receives
328,400 pounds of suspended solids per year from
sewage treatment plants alone. Some important
points, regarding streams, that should be land use
planning considerations include:
-- Any development which alters the
topography will likely alter the drainage
pattern in the area.
Any emplacement of contaminants in a
stream may endanger the downstream uses of
the water.
-- The lower the flow in a stream, the greater
the chances for salty bay water to move
upstream.
Two consequences of the movement of bay water
inland during low flow are: mineralization of the
stream itself, and seepage of brackish water into the
aquifer.
Competent and effective drainage basin
management is mandatory if the effects of drought,
flood and pollution are to be minimized and stream
channel aesthetics maintained.


Land use planning for riverfront areas must be,
prudent. An assessment should be made of present
riverfront land use, and existing physical, chemical,
and biological conditions of the stream. In addition,
an order of priorities (or a downstream order) for use
of the water and waterfront lands should be
established.
Stream channel segments may be designated as:
--sites for historic monuments or archaeological sites,
--sites for scenic or aesthetic natural areas,
--sites for water supply plants, dams, bridges, canals,
--recreational sites,
--low or high density residential sites;
--industrial sites


400

300-

200


' SWEETWATER CREEK

1961 62 63 64 65 66 67 68 69 70
MEAN STREAMFLOW AT GAGING STATIONS 1/61 9/70


ALAFIA RIVER
S R





SIXMILE CREEK



ROCKY
S\CREEK \
















Sweetwater Creek


STREAM CHARACTERISTICS


Stream
Alafia River

Sixmile Cr.
(Palm River)
Rocky Cr.

Sweetwater Cr.


Total Drainage
Basin Area
460 mi.2

40 mi.2

45 mi.2

25 mi.2


Average Discharge
at gageI
Period of Record
249 mgd
38 yrs.
39 mgd
13 yrs.
25.8 mgd
17 yrs.
4.9 mgd
19 yrs.


Estimated Average
Flow at Mouth2
369 mgd

56 mgd

33.3 mgd

16.5 mgd


Maximum -.. Minimum Flow
Date Date


29,651 mgd
9/7/33
833 mgd
9/11/60
1835 mgd
7/29/60
283 mgd
3/17/60


4.26 mgd
6/5,6/45
2.8 mgd
5/27/62
NO FLOW
4/7-5/5/67
NO FLOW
Often


CHEMICAL QUALITY3 (Samples taken at gage)


- ....... .,
(






F .. ..: W .'
,. -


.


..


Stream

Alafia River
Sixmile River
(Palm River



Rocky Cr.
Sweetwater Cr.


41


Total dissolved
solids mg/14
457


Chloride pH
mg/i units


PO45
mg/1


80 7.6 25 4/26/71
17 7.9 0.21 5/22/70




23 7.3 0.13 5/13/71
24 6.6 0.94 5/9/70


Gaging station locations shown on may on preceding page.
Discharge at gage times basin factor (ratio of total drainage area to area
above gage) plus any springflow downstream from gage
(Data from:


Pollution Loads discharged
To Tampa Bay (Ibs/day)


Date Sewage Plants
Sampled Discharging to Stream


Total Filterable
Residue
16,760
3570


NH4 + NO2
+ NO3
6870
170


Total
P04
43,470
100


Discharge from treatment plants (Ibs./days)
BOD SUSPENDED SOLIDS


4 385 580

3From U.S.G.S. provisional water quality data
4Residue at 180 C
5 Orthophosphates as PO4


Rocky Creek


4A4 p
ra ,r~r
..


.4. 4r


-4 -


. *


Alafia River


_ ~ ~ __I


4 4i, ...
.. . ..














The Hillsborough River rises in the Green Swamp
area south of the Withlacoochee River. Crystal
Springs, Sulphur Springs and numerous small springs
feed the river. The channel is about 54 miles long and
flows through Polk, Pasco and Hillsborough Counties.
Tampa has acquired the majority of its water
supply from the Hillsborough River since the mid
twenties. The water treatment plant, located at the
dam near twenty-second Street, has a capacity of 60
million gallons a day (mgd). The "firm flow" of the
river is estimated to be 50 mgd. During 1971,
pumpage averaged 49 mgd (see figure 1).


HILLSBOROUGH RIVER


In 1964, the Tampa water supply was augmented
by flow from Sulphur Springs. During periods of low
flow in the river, 20 mgd have been diverted from the
Spring to the Reservoir. Currently, the firm available
supply of the Hillsborough Reservoir does not meet
the water needs of the City, and plans for
development of well fields are being implemented.
The quality of water from the Hillsborough River
is not ideal. High values are obtained for turbidity,
settleable solids, color, odor, and taste. Treatment by
the city water plant includes flocculation,
sedimentation, filtration, chlorination, algae control,
coagulation, stabilization, clarification, pH control,
and taste and odor control.


A notable problem in water quality is the presence
of a disturbing number of coliform bacteria1 (figure
2). Only one of 13 samples taken from the swimming
area of the Hillsborough River State Park between
January 14 and July 27, 1971 by the Hillsborough
County Health Department was found to have less
than 1000 bacteria per 100 milliliters (ml) (the upper
limit for public water supply, according to state law).
2400 bacteria per 100 ml were found in water
samples collected from the stream from the dam
upstream to the Polk County line. The effluent of dt
least six sewage treatment plants finds its way to the
Hillsborough River--four of these plants are in Polk
County.


Another problem is the presence of water
hyacinths, which at times cover Tamps's entire water
supply reservoir. Hyacinths are treated with a
chemical herbicide (2-4 D) and sink to the bottom of
the Reservoir or are discharged downstream. The
hyacinths are a hindrance to recreational uses of the
river. Also when they are discharged to Tampa Bay
and decompose, each acre of hyacinths can
contribute 200 pounds of nitrogen and 26 pounds of
phosphate (Florida State Board of Health. 19fiB.

tSource-intestinal tract of warm blooded animals;
significance-general indicator of pollution.


Hillsborough River


Total drainage basin area
Average discharge at gage/period of record
Estimated average flow at mouth
Maximum flow/date
Minimum flow/date
CHEMICAL QUALITY

Total dissolved solids (mg/I)
Chloride (mg/lj
pH (units)
Nitrate (mg/I)
Sewage plants discharging to stream
POLLUTIONAL LOADS discharged TO BAY
Total filterable residue
NH4 + NO2 + N03
Total phosphate


690 square miles
*428 mgd/32 years
485 mgd
*9432 mgd/3-21-60
*none/ 11-30 to 12-2-45
SAMPLED 5/15/69.
(Data from U.S.G.S. water quality records)
195
16
8.5
1.7
6 (4 in Polk County)

11,470 Ibs./day
250 lbs./day
630 lbs./day


*these figures do not include water diverted for use by the City of Tampa


AVERAGE DAILY
PUMPAGE(MGD)


MEAN DAILY
DISCHARGE (MGD) I


FIG. I DISCHARGE OF HILLSBOROUGH RIVER E PUMPAGE FROM
RIVER BY CITY OF TAMPA WATER DEPARTMENT.


FIGURE 2. COLIFORM CONTENT AT PLANT INTAKE CITY WATER WORKS AT HILLSBOROUGH RIVER DAM












Much of the land adjacent to the Hillsborough
River is being acquired for construction of the Lower
Hillsborough River Flood Detention area in
Hillsborough County and the Upper Hillsborough
River Flood Detention area in Pasco and Polk
Counties. These areas will be set aside for temporarily
detaining flood waters during extreme high flow
conditions.
The multi-use concept will be employed in the
Lower Hillsborough River Detention area. Much of
the area is still in a wilderness state and lends itself to
recreation and conservation. Exclusive of the primary
purposes of the reservoir (prevention of flood damage
and improvement of ground water levels), land-use
plans for the reservoir area include:


1) development of a well field in the western
portion
2) establishment of a high intensity day use
recreation area to be leased to local agencies,
The University of South Florida, and
Tampa University
3) incorporation of a portion of the reservoir in
the existing program of Hillsborough River
State Park
4) leasing of lands to the Florida Game and
Fresh Water Fish Commission for
management purposes and limited hunting.


In addition, over seventeen miles of the river
channel in Hillsborough and Pasco Counties has bedn
proposed for designation as a scenic river and canoe
trail by the Florida Division of Recreation and Parks.
This means that the natural environment of this
segment of the river will be preserved for public
enjoyment.
The Hillsborough River is a tri-county resource.
Regional planning is obviously the basis for successful
maintenance and management of the river channel.


Z-r
sl
.
,.



N ,0

SMQA SM
PARKIS SUPENDD'TEM ORAI
PENDNG JINT EST Y TH


_-w 0NO ULCHATAN


DIVSIN O RCRETI(Ak,?PA


COUNTY
COUNTY


AMPA LOWER HILLSBOROUGH
RESERVOIR-WELL FIELD -


EXPLANATION
STATE OWNED PARKLANDS

HIGH INTENSITY DAY USE AREA
PROPERTY TO BE INCORPORATED IN
HILLSBOROUGH RIVER STATE PARK
I- WILDLIFE MANAGEMENT and
SLake I CONTROLLED HUNTING
Thonotosassa


LOWER HILLSBOROUGH RIVER RESERVOIR
RECREATION AREA.


Sou e S.W.Flordo ManagementDistrict


- -U:'"


SCENES AT HILLSBOROUGH RIVER STATE PARK


LIM^











WATER TABLE


The sandy surface deposits in Hillsborough County
generally contain water. The upper surface of the
saturated zone is the water table. Water table
contours generally follow topographic contours with
the water surface lying a few feet below land surface.
The level of the water table fluctuates primarily in
response to rainfall, which is the principal source of
recharge to the shallow aquifer.
Discharge of water from the aquifer is by seepage
into lakes and streams, drainage from canals and
ditches, evapotranspiration, pumpage from wells, and
natural drainage from springs.


In some places, the water-table aquifer is
hydraulically connected to the underlying artesian
aquifer. The primary uses of the shallow aquifer are:
1) as a source of recharge to the Floridan
aquifer
2) as a source of water for lawn irrigation.
Wells can be driven or drilled into the water table
aquifer easily and inexpensively, but because the
water produced is small in quantity and of poor
quality, it is not useful as a source of public supply.
Since the water table lies so close to land surface, the
shallow aquifer is suspectible to pollution.
Pollution of the shallow aquifer should be carefully
avoided in areas where it rapidly recharges the
Floridan aquifer, perhaps our most valuable water
resource.


--I 0-5' I


O 10' 5' TA 1MPA
BAY
DEPTH BELOW LAND SURFACE,
IN FEET,OF SHALLOW WATER TABLE
I


26
(Stewart and Hanan, Map Series 39,1970)


0 1 2 3 4MILES
SCALE


..-- -.......................'....



WAT -.-.-.. .."""- -- : ... ... ..- -:-:- --.":::""
-....... sA- ND :-. - REC H A RG E -
..-..LA-FL'O-RLDAN AQUIFER ----
... -- --_ ------_-- -- . . ... ." ".".". ." ." ." ".".".". . " "."."." " "."-;- -"-"".".


COUNTY












AND SWAMPS


The type and abundance of native vegetation
present in an area is in part dependent on the position
of the water table with respect to land surface.
Where the water table is above land surface, lakes
or swamps occur. Swamps, cypress domes or
bayheads represent a distinct ecosystem in which the
flora and fauna are specifically adapted to the
environment. Development in low-lying wetlands is
preceded by drainage, filling, or both.
Since the swampland biota is dependent on the
presence of excessive water, drainage or filling results
in a relatively barren landscape.


Another limitation of swamps for development is
the character of the subsurface material. Many
swamps are underlain by thick organic or peaty
deposits which form unstable foundation conditions
for many types of construction. In addition,
low-lying areas are generally flood prone.
Despite the limiting factors, many swamplands
have been successfully developed for a variety of land
uses. Prior to developing swamplands, the potential
destruction of a unique habitat should be considered.


WATER LEVEL IN WATER TABLE WELL NEAR
TAMPA, AND ACCUMULATED PRECIPITATION
MINUS ACCUMULATED EVAPOTRANSPIRATION
AT TAMPA


J FM A M J


J A S O ND
1971


~IW
'.r '. ,y
I.? 7* r

-' ~aIv'~ Li, Vd'4,.L --


Unique swampland biota (photo by J. W. Stewart)


A flourishing swamp (photo by J. W. Stewart)


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5^

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FLORIDAN AQUIFER


The Floridan aquifer is the principle source of
ground water in the state. It includes the Lake City,
Avon Park and Ocala Limestones (Eocene age),
Suwannee Limestone (Oligocene), Tampa limestone
and parts of the Hawthorn Formation (Miocene). It is
exposed at the surface in some areas and underlies
several hundred feet of sediments in others.
In the Tampa area, the top of the Tampa
limestone can be considered the top of the Floridan
aquifer. The aquifer is artesian, and in some places
wells that penetrate it flow. An aquifer is artesian
when it is confined by an impermeable layer and the
water in the aquifer is under sufficient hydrostatic
pressure to cause it to rise above the base of the
confining bed in wells.
The level to which water will rise in wells
penetrating the artesian aquifer is called the
potentiometric surface. When the potentiometric
surface is above land surface, the well is said to be
flowing.
Water in the Floridan aquifer moves into
Hillsborough County from adjacent counties and
most fresh water discharge from the aquifer occurs
inland of Tampa Bay. Currently, the Floridan aquifer
produces a large quantity of good quality water from
wells in the Tampa area, however, decline in water
quality and/or severe reduction of water stored in the
aquifer can result from improper land use or
sholt-sighted planning.
Recharge or "replenishment" of water to the
aquifer takes place where the confining layer is thin
or absent and rain water can infiltrate permeable
surficial deposits and percolate into the aquifer itself.
Recharge occurs also as leakage through the confining
layer wherever the altitude of the water table exceeds
the altitude of the potentiometric surface of the
Floridan aquifer. Recharge areas should be identified
and land maintained as "open space". In addition,
recharge in these areas can be accelerated by artificial
means. When development occurs in recharge areas,
the wastes associated with urbanization have ready
access to the aquifer and can damage water quality.
Likewise, pavement (the ever-present foundation of
urbanization) prevents water from infiltrating the soil
and greatly reduces the recharge potential of an area.


Recharge can also take place through sinkholes
that breach the confining layer. Great damage to the
quality of water in the aquifer can result when
sinkholes are used as dumps or waste basins.
Another threat to the aquifer in any coastal area is
salt-water encroachment. At depth saline water
underlies the fresh water in the aquifer. Theoretically,
the depth below sea level to the top of this salt water
is forty times the height of the potentiometric surface
above sea level. Or, for every foot that the
potentiometric surface is lowered, salt water moves
forty feet upward in the aquifer.
During the twenties, public supply wells for the
City of Tampa were abandoned due to ever increasing
salinity in the water. This is the result of drilling wells
too close to the coast, too deep, or overpumping
them.
Salt-water encroachment can also take place when
canals are dredged inland from the coast. If the
aquifer is exposed by the excavation, the
potentiometric surface would be lowered as fresh
water was drained to the ocean. During periods of
low water levels and high tides, salt water inl the
canals can move inland and contaminate the aquifer.
Construction of dams or water level control
structures near the coast can reduce potential salt
water encroachment in such canals by maintaining a
higher fresh water level.


OCEAN


SALT WA


SALTY
PUMPING WELL

LAND SURFACE -
.~POTENTIOMETRIC SURFACE-
-- MEANSEA LEVELn


L.. FRESH

TER PI,
,f C'


WATER


SALT WATER ENCROACHMENT


d










AND SPRINGS






Water table springs generally occur where the
permeable material in the water table is exposed or
crops out in a ditch or along the side of a steeply
sloping bank. Artesian springs are found where the
limestone aquifer lies at or near land surface and the
potentiometric surface is higher than land surface.
There are five large springs in the Tampa area and
these have been studied by the U. S. Geological
Survey. In addition, there are innumerable small
springs in the area that have been flowing for years.
Springs can be used to supplement water supply
and are a valuable asset to recreation areas. Continued
use of springs for these purposes is dependent on
maintenance of water quality through wise
management of recharge areas which supply the
springs.


SPRING DISCHARGE


Scenic Lithia Springs, a popular recreation area.


Wells and a storage tank in a northwest Hillsborough County well field. These wells pump
large amounts of potable water from the Floridan aquifer.


ESTIMATED DI














WATER USE


Water in Hillsborough County is mainly used for
irrigation, industry, and public supply. In 1970,
about 69 mgd was used for irrigation and 56 mgd for
industry. Most of this water was self-supplied. Twelve
of the major public supply systems are shown on
figure 1. Their combined pumpage for 1971 (or 1970,
as indicated on the map) was 33,933 million gallons
or 93 mgd. About a third of this water was removed
from Northwest Hillsborough County for use in
Pinellas County.
There is a vast quantity of fresh water within the
Tampa Bay region, however, only a portion of it can
be withdrawn from the hydrologic system without
creating serious environmental repercussions
(declining lake levels, parched vegetation, etc.)
G. G. Parker (1972) states that "If we can capture
for our consumptive use more than one-third of
runoff, we will be fortunate indeed." For the Tampa
Bay region (Hillsborough, Pinellas, Pasco, and
Manatee counties), Parker estimates one-third of the
runoff to be on the order of 254 billion gallons per
year or. 695.4 mgd. Projected water needs for the
Tampa Bay region are illustrated on this page. The


figures are based on population projections in
"Florida Land and Water Resources, Southwest
Florida, 1966", and the assumption that 300 and 500
gpcd represent reasonable minimum and maximum
figures for regional needs. Although the picture
apparently looks grim (interpolation indicates that
water demand will equal water supply in 1973 at the
500 gpcd rate of withdrawal or 1987 at the 300 gpcd
rate), two factors should be borne in mind as the
illustration is examined: 1) The figures are based on
the assumption that the water withdrawn is
permanently consumed. They do not take into
account the fact that much water that is withdrawn is
re-cycled or at some time returned to the hydrologic
cycle and therefore, much is not permanently
consumed. 2) As time goes by, greater sophistication
in water management will improve the outlook.
A water use projection for Hillsborough County is
also shown on this page. This graph applies Parker's
per capital water use rates (300 and 500 gallons/day)
to the population projections for Hillsborough
County published by the Hillsborough County
Planning Commission in April, 1972.


IIh




-*j Ci r^ i
W.-.*
..,.r
00


* I '..


Water stage recorder at Hillsborough River dam. (photo by W. M. Woodham)


400-


--_



ri i i
CIf^,:.::'H


From GG Parker,SWFWMD


300-


200 245


147


268



161


177


328 I


217


1970 1975 1980 1985 1990

FIGURE 3. WATER USE PROJECTIONS -
HILLSBOROUGH COUNTY

O AT 300 GALLONS PER CAPITAL PER DAY (GPCD)
O- AT 500 GPCD


~a I
r













The water problems of Hillsborough County have
been widely publicized. Much of the problem can be
attributed to the inadequacy of the facilities rather
than the sources.
Governmental agencies and private consulting firms
have submitted innumerable recommendations for
remedial actions to alleviate the City's and County's
water problems. Some of the measures suggested
include:
1) establish flood retention reservoirs
2) develop the Lower Hillsborough River
Reservoir well field immediately
3) establish control structures on dams and
streams to reduce salt-water encroachment
4) supplement the water supply by pumping
water from sinkholes
5) investigate the possibility of acquiring
springs in neighboring counties
6) create recharge facilities for rapid replen-
ishment of water to the aquifer
7) reduce waste of water by plugging
abandoned flowing wells, and encouraging
re-use of water by industry and agriculture
8) treat and re-cycle waste waters


Many of these plans are now being implemented.
The seriousness of the water situation and the
suggested courses of action highlight the role that
hydrology must play in land use planning.


Hillsborough River dam. (photo by W. M. Woodham)




WATER USE FACTS

Number of industries in Hillsborough
County1 650
Number of electrical power plants' 3
Population served by public supply2 370,000
Population served by ground water2 65,000
Population served by surface water2 305,000
Number of acres irrigated2 47,000
Saline water (self-supplied)2
Used by industry 86
Used for thermoelectric power 1899
Cost of water1
From Hillsborough River $92.74/million gallons
From Lower Hillsborough
Reservoir Well Field $31.71/million gallons


.4 mgd
mgd


'1971 Data
21970 Data


)


SI .) IN HI

















FLOODING



"Those of us who work in the water management
field know that some of the multimillion dollar
public works projects that we are now constructing
could have been prevented if the citizens had simply
not been allowed to construct their houses, businesses
and developments on land that is often flooded by
the stream, creek, river or lake that it abuts. Yet, day
after day, we see more and more marginal and
submarginal land being developed and sold -- often
times to unwary buyers -- who after the first normal
rainy season or two, come to us and demand flood
control. We believe that much of their anquish and
heartache -- and lots of public works money -- could
be saved if the construction process included a
requirement for full knowledge of the historic or
predictable water conditions at that site so the
proposed construction could be accommodated to
the conditions, or be prevented altogether."
Dale Twachtmann
Ex-Executive Director
Southwest Florida WaterManagement District
Everyone is aware of the loss of life and property
often associated with floods, but unfortunately, not
everyone is aware of the flooding potential of the
area in which they reside.
Many flood prone areas have already been
developed, and others are in the path of urban
expansion. Now is the time to strengthen controls on
flood prone land and provide 1) a zoning
classification which would prevent development in
these areas, and/or 2) guidelines for construction in
flood prone areas where development is allowed.
Additional drainage projects could provide even
more widespread flood protection, but such projects
are costly and may tend to diminish regional water
resources.





Results of Hurricane Agnes, June, 1972. (photo by Bill Wood)


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.-..., -,- -
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-' -.

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1000 0 1000 2000 3000 4000 5000 6000 7000 FEET





The large map presented here was constructed by compiling and reducing all
the 1:24000 scale flood prone quadrangle maps of the Tampa area which were
completed by the U.S. Geological Survey. The detail above shows a small area at
the actual scale of the 1:24000 maps. The following explanation appears at the
base of each quadrangle map of flood-prone areas, and is quoted verbatim:



The purpose of the flood-prone area maps is to show to administrators, planners, and
engineers concerned with future land developments those areas that are occasionally
flooded. The U.S. Geological Survey was requested by the 89th Congress to prepare these
maps as expressed in House Document 465. The flood-prone areas have been delineated
by the Geological Survey on the basis of readily available information.
Flood-prone area maps were delineated for those areas that meet the following criteria:
(1) Urban areas where the upstream drainage area exceeds 25 square miles, (2) rural areas
in humid regions where the upstream drainage area exceeds 100 square miles, and (3) rural
areas in semiarid regions where the upstream drainage area exceeds 250 square miles.
This map indicates only areas that may be occasionally flooded, and provides no infor-
mation on the frequency, depth, duration, and other details of flooding. Larger areas than
those shown on the map may be inundated by less frequent floods.
Flood-hazard reports provide the detailed flood information that is needed for economic
studies, for formulating zoning regulations, and for setting design criteria to minimize
future flood losses. When detailed information, such as that contained in the flood-hazard
reports, is required, contact the U.S. Army, Corps of Engineers; the U.S. Geological Survey;
or the Tennessee Valley Authority in the areas of their jurisdiction.




















GEOLOGY


. . .


-

-
-
- -


- -
- - -
-

- -
-
-
______________ ..-, - -.
----..--- -


- -
-


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--

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.




'













GEOLOGIC HISTORY


Depending on the depth, temperature, and
circulation of the water, varying assemblages of
organisms flourished and their skeletal remains make
up much of the sedimentary sequence. The physical
characteristics of the rocks and the fossils they
contain enable the geologist to reconstruct a picture
of the ancient geography and environment.

During Paleocene and Eocene time, the Tampa area
was covered by open ocean in which layers of
limestone were deposited. Intermittently, the seas
regressed and the limestone was subjected to
weathering. As sea level fluctuated, the local
environment changed and limestones with slightly
different physical characteristics and dissimilar fossils
were deposited in succession. At the close of Eocene
time, the seas retreated from the Tampa area and did
not return until later in Oligocene time.

The nature of local late Oligocene sediments
indicates that they were laid down in a warm, quiet,
shallow sea in which mollusks and micro-organisms
flourished. The limestones are relatively pure and of
economic value in those parts of the state where they
are available to surface mining.


The geology of Florida is reflected in the
topography of the state, the nature and occurrence of
water resources, the character of soils, and the type
and extent of valuable minerals. As all of these are
important factors in land use planning, the planner
should be knowledgeable about what lies blow the
land surface.

Beneath the Tampa area, there are several thousand
feet of carbonate rocks (chiefly limestones) which
were deposited during Cenozoic time. These rocks
overlie sandstones, shales and igneous rocks of
Mesozoic and Paleozoic age.

The thick carbonate sediments were deposited in
the warm, shallow seas that covered all of peninsular
Florida at one time or another during the Cenozoic
era. Accumulation of these sediments was
accompanied by subsidence of the land surface with
numerous transgressions and regressions of the sea.
When sea level was low the emerged land areas were
exposed to erosion; consequently, the rock record is
not complete.


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2~lll-r -



r n1L


Photo by R.C. Reichenbaugh


From: Bulletin 29, Florida Geological Survey


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4;~h~















Throughout Miocene time, more and more rocks
eroding from the highlands north of Florida were
washed southward and deposited in the Tampa area.
Due to the great distance of transport, these minerals
were abraded and broken into sand and clay size
particles. Considerable quartz sand is found in the last
consistent limestone deposit of the area. The Miocene
and Oligocene limestones of the Tampa area are
generally permeable and yield substantial quantities
of water to wells.

During late Miocene time, sand and limy,
phosphatic clays were deposited in the very shallow,
sometimes stagnant seas, estuaries and swamps of the
Tampa area. As the shoreline migrated, islands,
lagoons and lakes developed in various, locations.
Marine, fresh water and land fossils have been found
in Miocene deposits around Tampa.

Pliocene sediments similar to late Miocene
sediments, are scanty and difficult to differentiate
from late Miocene sediment in the vicinity of Tampa.
In eastern Hillsborough County, sands and clays
containing abundant phosphate nodules are presumed
to be Pliocene in age and may have been weathered
from older deposits. In Polk County, these
phosphate-bearing sediments are mined extensively.


Throughout Pleistocene time, the alternate
formation and melting of glaciers caused sea level to
move back and forth over the Tampa area and seas
washed quartz sand over Tampa and much of the
state several times. These fluctuations left behind
terraces which are still evident today and record
ancient sea level stands. The mantle of quartz sand
covering the area served as parent material of many of
the soils which later developed. In areas where the
sands are thick and pure, they are of economic value.

Well developed stream channels in Tampa, and
relict dunes on the campus of the University of South
Florida reflect the effect that wind and water had on
the sandy deposits. Gradually, a landscape with
abundant vegetation developed.

Throughout the Cenozoic history of Tampa,
deposits accumulated essentially as horizontal
blankets of sediment which dip slightly to the
southwest. This is reflected in the gently sloping land
surface, and pronounced local relief can largely be
attributed to recent fluvial processes and
underground solution activity.


GEOLOGIC TIME SCALE


ERA PERIOD EPOCH APPROXIMATE
RADIOMETRIC DATES


CENOZOIC


RECENT


QUATERNARY
PLEISTOCENE

PLIOCENE


TERTIARY


MIOCENE

OLIGOCENE

EOCENE


PALEOCENE


MESOZOIC

PALEOZOIC


5000 YEARS B.P. *


2 MILLION YEARS B.P.

.12 MILLION YEARS B.P.

25 MILLION YEARS B.P.

38 MILLION YEARS B.P.

.55 MILLION YEARS B.P.

65 MILLION YEARS B.P.

225 MILLION YEARS B.P.

600 MILLION YEARS B.P.


* Before Present


Tampa By-pass Canal


ARTIST'S RECONSTRUCTION OF HOW THE TAMPA
AREA MAY HAVE APPEARED DURING TERTIARY TIME













GENERAL GEOLOGY


The thick carbonate rock sequence underlying the
Tampa area has been divided into lithologically
similar, mappable units or formations. These
formations are generally bounded above and below
by ancient erosion surfaces.

Formations can be mapped on the basis of rock
exposures at land surface (outcrops), and from
samples retrieved during the drilling of water wells or
core-test holes.

An examination of the surface geology in the
Tampa area reveals that rocks of Tampa age outcrop
in several locations along the banks of the
Hillsborough River and can be seen in other stream
channels, sinkholes, roadcuts, etc. Ballast Point was
considered a classic locality for studying Tampa
































38


sediments during the late 1800's and early 1900's,
but now the exposures are limited and inaccessible at
high tide.

The Hawthorn Formation, which occurs east of
Tampa, can also be studied in a number of exposures.
Much of the Tampa area is covered by a veneer of
Pleistocene and Recent sandy deposits. In the map,
these deposits have been stripped away to reveal what
lies directly beneath them.

Because each formation has distinct physical
attributes, mapping and cross-sections of these units
provide some key to the depth and extent of
economically valuable deposits, highly productive
water bearing zones, and zones susceptible to
subsurface solution which could manifest on the land
surface as sinkholes.


(Modified from Carr and Alverson, 1959)


Florida Bureau of Geology drilling rig






Crystal River Formation (Eocene)


The Crystal River Formation is a granular, white to
tan limestone which, in part, is largely made up of
fossil fragments cemented by a calcareous matrix,
giving it the appearance of coquina rock. Due to its
porosity, some portions have been washed out and
filled with clay. Masses of chert also occur within the
formation.

The limestone was studied and named in a quarry
in Citrus County. Here, and in adjacent counties
where it lies near the surface, the formation's overall
purity and uniform texture make it economical to
mine. In the Tampa area, the Crystal River is
generally deeply buried and of no economic
importance at present.

Suwannee Limestone (Oligocene)

In general, the Suwannee Limestone is a pure, very
fossiliferous limestone of variable hardness. It
contains a minor amount of fine quartz sand
cemented among the abundant fossil fragments and
imprints. The formation was named for exposures
that occur along the Suwannee River. Much of the
Suwannee Limestone has been altered by ground
water since its deposition. This accounts for some of
the differences in texture, hardness and porosity
within the formation.

The base of the Suwannee Limestone in the Tampa
area is marked locally by clay lenses. Some core
samples from Tampa reveal the presence of peat in
varying amounts in the lower portion of the
formation.

The Suwannee, like the Crystal River Formation, is
mined for crushed stone in counties north of the
Tampa area where it occurs near the surface. In the
Tampa area, the Suwannee is a principal source of
water to many supply wells.

Tampa Stage (Miocene)

In the Tampa area, rocks of Tampa age are soft,
white, impure limestones averaging between about 40
and 160 feet in thickness. It can be seen from both
the map and cross-section that the Tampa limestone
is absent in the northeast portion of the study area.
In some localities, the upper portion of the deposit is
composed of calcareous sands and clays grading
downward into unconsolidated or loosely cemented
lime mud. Chert layers and silicified fossils are also
common to the upper portion of the deposit. In a few
locations, phosphate nodules or pebbles occur within
the Tampa limestone. The base of this unit is


frequently marked by beds of clay and clayey sand.
Although the sediments are generally not as
fossiliferous as the underlying Suwannee Limestone,
there are zones within the Tampa that are
consequently highly porous. This is because the fossil
fragments are generally coarse grained and irregularly
shaped and thus do not pack together as tightly as the
finer calcium carbonate grains. Most of the Tampa
limestone is very sandy and crumbly. Due to the sand
content of the rock and the occurrence of lenses of
clay and sand within the limestone, the formation is
not quarried for crushed stone. The Tampa limestone
is valuable, however, as a source of water and yields
large quantities to many wells in the Tampa area. The
loose cementation and high porosity of portions of
the Tampa limestone make it susceptible to
weathering and dissolution by ground and surface
waters. Many solution cavities, sinkholes and collapse
structures occur in the formation, especially where it
lies near the surface.

Hawthorn Formation (Miocene)

This formation exhibits a great variation in
composition and physical properties. In general, the
formation in the Tampa area consists of an upper
sand unit, a phosphatic clay unit, and a lower
limestone unit. These layers occur in varying
thicknesses and tend to interfinger. In most of the
Tampa area, the formation is absent, and where it
does occur, frequently only one or two of the units
are present. Maximum thickness of the formation in
Hillsborough County is about 250 feet. Fossils are
rare in Hawthorn deposits. The formation thickens to
the east and becomes a significant deposit in Polk
County, where it is overlain by the Bone Valley
Formation, which is thought to be residual material
from the weathering of the upper parts of the
Hawthorn Formation. It is this residuum that
contains the rich concentrations of phosphate so
extensively mined in Polk County.
In the Tampa area, the clays of the Hawthorn
Formation, along with clays in the upper part of the
Tampa Limestone, make up the impermeable
confining layers overlying the limestones of the
Floridan aquifer.

Undifferentiated Plio-Pleistocene and Recent Deposits

These deposits cover most of the Tampa area and
vary from a few inches to many feet thick. They are
predominantly fine grained quartz sands which
contain varying amounts of organic material. Some of
these deposits are of economic value and are
discussed further in the Mineral Resources section.


+100'


-400'


A A'
S 7


GEOLOGIC CROSS SECTION showing SOUTHWESTERLY DIP

OF STRATA in the TAMPA AREA
















SINKHOLES


G E 0 R G I A


Sinkholes exhibit varying characteristics in the
Tampa area and are difficult to classify. There are
two basic sink hole types: 1. Collapse sinks produced
by collapse of the limestone roof above an
underground void. 2. Solution (funnel) sinks
developed slowly downward by dissolution beneath a
soil mantle without rupture of the rock in which they
develop.

Collapse sinks are normally steep sided, rocky and
abruptly descending. Formation of collapse sinks is
unpredictable and often instantaneous, thus they
constitute the greater threat to land development.
Solution sinks may be funnel-shaped depressions
broadly open upward, or pan or bowl-shaped. They
develop slowly and are usually heralded by the
formation of a radial fracture pattern in the soil or
even in concrete or asphalt overlying them. Though
their formation may not have the devastating effect
of a collapse sink, their occurrence can equally limit
land use.

Sinkholes in the Tampa area may be of either type,
or some variety and are commonly formed in an
environment with the following physical
characteristics:


1) occurrence of permeable limestones in
which a cavity system has been developed
through dissolution by ground water
2) these limestones are generally overlain by a
relatively thin layer of unconsolidated
sediments
3) overlying sediments are usually well drained
and permeable
4) a water table higher than the potentiometric
surface of the artesian aquifer

Overlying sediments may slowly ravel or wash
downward, filling in the cavity system and resulting
in a structural sag reflected at the surface; or, the
cavity system may continually enlarge until the
cavern roofs are too thin to bear the weight of the
overburden, resulting in catastrophic collapse.

Two activities which tend to increase the
likelihood of sinkhole occurrence are dewatering the
aquifer and increasing stresses on the land surface.
When the potentiometric surface is lowered,
dewatered cavities in the limestone provide less
support to overburden layers. Similarly, the added
weight of buildings or fill material may exceed the
strength of underlying cavernous limestones.


G U L F

\\ IAfYE

of



M E X I C 0



This large portion of the State represents the area
where the piezometric surface is at or above land
surface and/or the plastic overburden is in excess of
100 feet thick. It appears to be the least probable
area for sinkhole development.


This area is the portion of the State characterized by
stable prehistoric sinkholes, usually flat bottomed,
steep sided, both dry and containing water.
Modifications in geology and hydrology may activate
process again.


I This portion of the State is characterized by
limestones at or very near the surface. The density of
sinkholes in this area is high, however, the intensity
of surface collapse is moderate due to the lack of
overburden. Exploration by drilling and geophysical
methods for near-surface cavities can be realistically
accomplished.


This portion of the State has moderate overburden
overlying cavernous limestones and appreciable water
use. These areas have histories of steep-walled, wider
sinkhole collapse but require more detailed study. A
thick overburden or high water table present within
these areas lessen the probability of sinks occurring.


A TLANTIC


C E A


PALM BEACH


COLLI-ER
COLLIER I


~-- ."i


ROWARD


HENRY


D A D E












Sinkholes in the Tampa area may or may not be
filled with water. Sinkhole lakes are characteristically
circular and deep. Unless sinkholes have been filled
with impermeable material, they are directly
connected to the Floridan aquifer and provide a rapid
means of recharge. Such direct recharge is not
conducive to the removal of contaminants from water
by filtration or chemical reaction. It is therefore
essential to safeguard the quality of water entering
sinkholes.

Sinkholes in the Tampa area generally occur in a
wide northwest-southeast trending band. There is a
concentration of them in the northwest area, but
their apparent predominance here is partially due to
more detailed mapping in this section (see map).

Although existing sinkholes can be mapped,
predicting specific areas of potential collapse is
difficult. No particular pattern to the cavity system in
limestones has been discovered.

The most widely used method for detecting
sub-surface cavities is drilling bore holes. This
approach has the obvious disadvantage of producing
little data for the amount of effort expended. Other
new procedures have been used experimentally in an
attempt to identify sub-surface cavities, but the
results are not foolproof.


One method utilizes airborne remote sensing
devices. Computer processed imagery obtained from
flights over a test area reveals thermal and apparent
moisture-stressed vegetative patterns that may be
associated with sub-surface cavities.

Additional data collection and refinement of
techniques are necessary before the effectiveness of
this method can be evaluated.

Another experimental method of identifying
sub-surface cavities is gravity mapping. A gravity
meter records, on the land surface, local differences
in gravity which, after correction factors have been
applied, are directly related to differences in density
of the underlying rocks. Areas underlain by cavernous
limestones produce lower gravity readings than areas
underlain by limestones containing fewer voids.
Gravity surveying as a means of detecting subsurface
voids has certain limitations. The smaller the cavity
and the more deeply it is buried, the less detectable it
is by gravity methods. A cavity with a diameter equal
to or greater than its depth of burial is readily
detectable because the gravity anomaly is great. Small
gravity anomalies can be produced by a variety of
subsurface conditions and therefore may or may not
be indicative of small and/or deeply buried subsurface
cavities.


DATA OBTAINED FROM TOPOGRAPHIC MAPS AND J.W. STEWART, 1970, MAP SERIES 39.
DATA OBTAINED FROM SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT AERIAL
PHOTOGRAPHS.1:200 SCALE WITH ONE FOOT CONTOUR INTERVALS AND J.W.STEWART,1970.MAP SERIES 39.
AREAS IN WHICH SUBSURFACE CAVITIES OR RELICT KARST FEATURES HAVE BEEN /
ENCOUNTERED IN DRILLING. Data from OROF4NO and Co. /


Victor Stringfield (U.S.G.S.) examines sinkhole
near Lake Magdalene. (photo by J.W. Stewart)


0 1 2 3 4 MILES
I 1 1 c LE
SCALE









COUNTY


STRUCTURE


The map presented on this page shows the top of
the first consistent limestone. The data is referenced
to mean sea level, therefore the contours reflect the
actual topography of the bedrock surface. Knowledge
of this bedrock surface is important in understanding
surface features which are often genetically related to
the underlying rock.

The complexity of the contours is due, in part, to
post-depositional alteration of the rock. This could
include shifting and settling, differential compaction
of the limestone strata at some time after deposition,
erosion of the rock surface between depositional
cycles, and solution weathering of the limestone by
ground water.

The contours, however, do reveal something about
ancient paleogeography. For example, the minus ten


foot contour line (shown as a bold line on the map),
can be considered an approximation of an ancient
shoreline that occurred here some million years ago
when sea level was ten feet lower than it is now, and
before surficial sands and clays were deposited. At
this time, the Tampa area had a broader estuary, a
smaller interbay peninsula and Old Tampa Bay
extended further inland. In a broad sense, the
topography of the present land surface in the Tampa
area reflects bedrock topography.

The bedrock underlying the area generally strikes
or trends in a northwest-southeast direction. The rock
surface dips gently downward toward the bay in a
southwesterly direction with a slope on the order of
0.1% or about 5 feet per mile. The dip of the beds is
perhaps better illustrated on the cross section (found
on another page in this section).


0 1 2 3 4MILES
SCALE

















Two of the more severe problems associated with
urbanization are proper waste disposal and adequate
water supplies during periods of water shortage.
Recent investigations indicate that in some areas
there are possibilities for simultaneous alleviation of
both problems by utilizing the technique of deep well
injection. Successful application of this technique
hinges on a good knowledge of subsurface strati-
graphy and hydrology.
The method of deep well injection involves
injecting treated wastewaters and/or storm runoff
into subsurface permeable zones that do not other-
wise lend themselves to water supply or mineral
production. Many factors, however, must be carefully
evaluated before such a project can commence.
Further, according to Garcia-Bengochea, et. al.(1973,
p. 5-6), Underground disposal of wastewater by wells
" . can be achieved successfully if five general
requirements are fulfilled. These are:


1. There is a stratum or strata (aquifer) which can
accept the waste.
2. The hydraulic and structural characteristics of
the aquifer will not be changed significantly by
the disposal of the waste.
3. The disposal of such waste will not impair the
present or future use of the water in such
aquifer.
4. The disposal of such waste will not impair the
present or future use of the water in adjoining
aquifer or surface-water supplies.
5. The installation is designed properly, with
consideration of the physical, chemical, and
biological characteristics of the waste and the
hydrogeological characteristics of the receiving
aquifer and confining strata."
"Present hydrological knowledge indicates that the
treated fresh water effluent should not readily mix


with the saline waters of the aquifer but would create
a large fresh water bubble in storage at the top of the
aquifer which could be partially recovered at a later
date for low quality uses (irrigation) or for further
specific treatment and reuse." (Garcia-Bengochea, et.
al., 1973, p. 4-5)
Deep well injection is being carried on in several
areas in Florida and additional sites are being
evaluated. Several sites currently under investigation
are within the geological realm of the Tampa area.
These include a site to the east of the Tampa area in
Mulberry and several sites in Pinellas County.
According to Wilson, Rosenshein and Hunn (1973,
p. 1, abstract), an injection well in Mulberry was
completed in 1972 at a chemical plant which
produces a liquid waste from phosphate processing
that has a high chloride content and high acidity (pH
generally less than 2). This effluent is injected into
several permeable zones penetrated by the well
between 4040 and 4984 feet deep. Tests performed
at the Mulberry well provided not only information
about the characteristics of the injection zones, but
also suggested additional evaluative techniques that
might be employed at other sites.
Mr. H. J. Woodard, Geologist with the Department
of Natural Resources, is supervising a pilot hole in St.
Petersburg which is a cooperative effort by the
Division of Interior Resources and the City of St.
Petersburg. The project is to study the feasibility of
injecting excess surface water into a saline aquifer and
recovering it for subsequent use.
According to Garcia-Bengochea, et. al., 1973, p.
27, the objectives of the project are to determine:
1. the characteristics of the deep underground
formation at that site;
2. the quality of the deep ground water;
3. the injection rate capacity and associated
increase in pressure;
4. ratio of the amount of fresh water that could
be subsequently recovered to the amount
injected; and
5. quality of the recovered water.
According to H. J. Woodard, as of July, 1973, the
pilot hole is completed to a depth of 3500 feet. One
injection test was performed at a depth of about 850
feet, and two additional tests are slated for zones that
appear promising. One shallower, less saline zone may
be suitable for stormwater disposal, and a second
deeper zone (greater than 3000 feet deep) may be
found satisfactory to receive secondarily treated
sewage.


GEOLOGY AND URBAN PLANNING


:TE iL O'R PLASTIC)


(from: R. O. Vernon, 1970, p. 4)


The deep well injection technique has the poten-
tial to provide some relief to the waste disposal and
water shortage problems of urban centers such as the
Tampa Bay area. At present, the need to continue
basic geologic and hydrologic data collection cannot
be over-emphasized. If deep, permeable zones could
be identified and mapped, and their geohydrologic
properties and stratigraphic relationships studied,
determination of the feasibility of subsurface storage
of waste in this area could be greatly facilitated.
Deep well injection studies serve to further
illustrate the integral role that geology plays in many
phases of urban planning.


TYPICAL WELL
for
DISPOSAL of TREATED WASTES
PLUG FOR WATER LEVEL MEASUREMENTS
WASTE ----- VALVE
GAUGE
S PLATE
. .. .:::. :::::::::









,4YM j4


MINERAL RESOURCES


''
'

















PHOSPHATE


INTRODUCTION


During 1970 mineral resources valued at slightly
more than 20 million dollars were produced from
Hillsborough County, giving it a rank of third among
all Florida counties, as shown in Table 1. The figures,
however, do not give insight into the impact on
Tampa of massive phosphate operations and the
mining of construction sands in adjacent Polk
County, nor of the quarrying of limestone in Sumter
and Hernando counties and the extraction of clay in
Citrus County. Practically every aspect of our modern
way of life depends in some way on mineral
resources. Mineral resources are necessary for building
homes, constructing and maintaining roads and
highways, manufacturing automobiles and planes, and
for producing food crops to feed the people of the
world. No one can question that our society depends
upon mineral resources. Furthermore no one can
question that mineral resources are finite; they are
exhaustible. If they are not mined where they occur,
they are lost to society.
In recent years it has become evident that mining,
especially of mineral resources near the land surface,
can result in extensive environmental damage. Air
may be polluted. Stream life may be partially or
totally destroyed. Land may be left in a state no
longer useful. However, it also has been shown that
with planning and controls, mining can take place
with minimal environmental damage. The necessity of
mining and the necessity to minimize environmental
damage and reclaim mined-out land has led some
investigators to emphasize the need for leadership in
undertaking mineral evaluation studies on large land
areas prior to development. Then, when socially
necessary mining operations have been completed,
leadership is again appropriate for reclaiming the land
mined. The need for planning is most pressing in areas
of rapid population growth.
Mineral resources in the general vicinity of Tampa
include phosphate, sand, clay, limestone, cement,
oyster shells and peat. These products will be
considered separately.


TABLE 1

Value of Mineral Production in Florida for Leading Counties


Year County


Value Minerals Produced in
(Thousands) Order of Value


G EO R G I A
---- --- NASSA

MADISON /
I HAMLTON --i '- / F'
----- / 2 iBAKER D..V. AL
-. SUWANNEE COLUMBIA

TAYLO I UNION/ I
LAFAYETTE '- CLA

O GILCHRIST ALACHUA
DIXIE ~ PUTNAM

A .I--


GULF


Polk $140,598 Phosphate rock, sand and
gravel, peat
Dade 35,184 Cement, limestbne, sand and
gravel
1970 Hillsborough 20,041 Cement, phosphate rock, sand
and gravel, oyster shell,
peat
Broward 11,930 Limestone, sand and gravel
Sumter Withheld
Marion 2,562 Limestone, fuller's earth,
sand and gravel, phosphate
rock

Polk 137,696 Phosphate rock, sand and
gravel, peat
Dade 33,953 Cement, limestone, sand and
gravel
1969 Hillsborough 22,555 Cement, phosphate rock,
oyster shell, sand and
gravel
Broward 11,187 Limestone, sand and gravel
Sumter 3,741 Limestone, lime, peat

'Data from Bureau of Mines Minerals Year Books, 1969 and 1970.


A TL ANTIC


MARION


, VOLUSIA


of 7\ '--. ---
CITRUS i L A K E

MEXICO ---- SUMTER
HERNANDO \
----- I L


'-- F .. .. .. ..._ .. -1







PLANATION -"..
CREST OF OCALA UPLIFT 11
SSARAASOTA DE SOTO
AREAS THAT INCLUDE PEBBLE |
PHOSPHATE DEPOSITS _L .. .. .
S F ..F -HA-I OTTE
PHOSPHATE DEPOSITS


EX
C
c
A


PHOSPHATE

Although phosphate is used in the manufacture of
a wide variety of products, including well-known
detergents, water softeners and metal polishes, most
phosphate is used in the manufacture of fertilizers.
The importance of fertilizers in feeding the people of
the world would be difficult to exaggerate, and
Florida has long been a world leader in supplying
phosphate. It is evident, therefore, that the needs of
the world, not Florida alone, must measure the
impact of Florida's phosphate.


---i 'U
i SEMINOLE

ORANGE


OCEAN


lINDIAN RIVER


OK EECHOBEE
HIGHLANDS S LC-
-\ i ..----.
FGLADES MARTIN


FIGURE 1. PEBBLE PHOSPHATE DEPOSITS OF FLORIDA. THE CREST OFTHEOCACALARCH-fS-
INDICATED BY A HEAVY DARK LINE. MODIFIED FROM PIRKLE ET AL.(1967, FIG. I, 238).


Location and Regional Significance of
Pebble Phosphate Deposits

By far the greatest production of phosphate rock
in Florida is of the type called "pebble phosphate."
The deposits consist of phosphate particles mixed
with varying amounts of quartz sand and clay. The
phosphate particles usually range from colloidal size
to pebbles an inch or more in diameter. Figure 1
shows locations of known pebble phosphate deposits
on the Florida peninsula. An examination of the
figure reveals that the deposits occur along the flanks
or fringes of the Ocala Uplift, an upwarped area
cresting in eastern Citrus and Levy counties along the
western side of the peninsula. Knowledge of this
relationship has been useful in exploration programs.











Some phosphate rock is produced from Hamilton
County in the northern part of the peninsula (Fig. 1),
but most of Florida's phosphate rock is mined east of
Tampa from the large area known as the "Bone
Valley District." During 1970 phosphatic sediments
produced from the Bone Valley District had a value
of approximately 150 million dollars and accounted
for almost three-fourths of our domestic needs and
one-third of the world's needs. Most of the rock in
one form or another is shipped through the port of
Tampa. In fact, phosphate is responsible for nearly 50
per cent of the tonnage entering and leaving this
important port. Obviously the mining of phosphate
rock has an enormous influence on the economy of
the Tampa area and the State of Florida (Table 2).
The Bone Valley phosphate field of central Florida
is shown on Figure 2. The northern part of the region
contains the highest grade phosphate rock and has
been mined most extensively. If mining continues it
must spread into the southern part of the area.


1970


Employees


6,662


Payroll


Production of marketable
rock (short tons)

State ad valorem taxes
paid

Polk County ad valorem
taxes paid

State sales taxes

New construction
expenditures

Expenditures for raw
materials, equipment,
supplies


7,563


7,464


Nature of Sediments in the Bone Valley District

Three types of sediments are encountered in the
phosphate mines (Fig. 3). From the land surface
downward these materials are: (1) loose quartz sands
and clayey sands (top soil and sand overburden),
(2) phosphate beds of the Bone Valley Formation
(leached zone and ore zone or matrix), and (3) bed-
rock (limestone) or bedclay of the Hawthorn Forma-
tion. The mixture of phosphate particles, sand and
clay of the Bone Valley Formation is the material
mined for its phosphate content. Data illustrating
various characteristics of the overburden sediments,
the phosphate beds, and the underlying bedrock or
bedclay are given in Table 3. These data are of
samples collected from a test hole drilled on the
Lakeland Ridge between the towns of Bartow and
Mulberry.


1968


9,060


1967


10400


$ 59,000,000 $ 59,061,293 $ 59,093,035 $ 68,848,000 $ 69,000,000


30,500,000* 29,300,000* 29,900,000* 33,000,000* 31,900,000*
(*Includes N.C. production-U.S. Bureau of Mines)

$ 5,215,968 $ 5996,090 $ 5,882,553 $ 5,856,154 $ 6,326,018


$ 3,619,312 $ 4,635,566 $ 4,577,014 $ 4,627,404 $ 4,583,587

$ 3,135,273 $ 3,129,152 $ 2,836,648 $ 2,385,727 $ 2,112,112


$ 30,000,000 $ 22,189,867 $ 18,227,300 $ 35,420,585 $ 56,827,650



$174,764,731 $161,192,084 $181,658,064 $175,487,087 $175,086,157


Surface Sands:
The overburden of top soil and loose to slightly
hardened quartz sand and clayey sand (Fig. 3) ranges
in thickness from a few feet to more than 50 feet
JSpls. A through H, Table 3), and typically from 5 to
25 feet. Some investigators believe these surface sands


___ P A S C 0_ t _1
H I LLS B 00 R




I MP A
i ti
/*


BRADENTON OLFOSPRINGS
MANATEE HADEE
s. sor. ._.MYAK.ACIT

ARCADIA
Si r ,I\ L _ i e R "
S 5 S A R A S A 0 TA D E S 0 T 0
NICEE

r-.----------
Sr C'H AR LOTT E
EXPLANATION --
NORTHERN PART-PROVEN
GRADATIONAL ZONE
SOUTHERN PART-INDICATED
FIG.2 BONE VALLEY PHOSPHATE DISTRICT OF FLORIDA. THE
DISTRICT IS DIVIDED INTO A HIGH-GRADE NORTHERN
PART AND A LOW-GRADE SOUTHERN PART.
(Mop furnished by Mr Joe Weaver of Wayne Thomas, Inc.)














were deposited under marine conditions as seas
encroached and retreated from the area during
Pleistocene time. Other workers consider the quartz
sand blanket to represent a simple insoluble residue
accumulated on-site from the weathering of underly-
ing sediments.


*Data furnished by the Florida Phosphate Council. Five-year comparison.


Figure 3. Typical section in central Florida Phosphate
district. Modified from Fountain and Zellers,
Fig. 2, 1972.


TABLE 2

FLORIDA PHOSPHATE INDUSTRY*






















TABLE".
Channel T-i., .. '..n:o Grace G" 'i' Hole
SW '.-.ri, 4. 4, T '.'.' R ..' E., i il- County, Florida
'.. ;,..* : -. ... 4 Miles West of Bartow
. face Sands and .i'. ..i ::. T l- ,; of the T.:-r,- .1,' ., District


Insoluble
-.. ,;- Quartz
in .'.
in %


0-10
10-15
15-.",
20-30

33-40
S, '"- 7
-: ..'-51


Residue
C-' Total
(- -'. mesh) Soluble
in % in %


P205 Total
Heavies
in % in %


..:. ,-, - -. and Clayey .'"


1.70
2.39
9.49
19 ?3,
18.41
7.
1. :
3.40


- Commercial
11 ..
1 .


.20
.20
2 5'0'
.70
.60
.50
1 .
.10


52.72
59.22


.18
.16
.22
.70
1.26
1.10
.68
.22


1.14
1.07
1.17
.77
1.06
1.12
.71
.77


15.88
15.66


Phosphate Beds of the Bone Valley Formation:
Phosphate beds (Fig. 3) beneath the surface sands
consist of varying mixtures of phosphate particles,
quartz sand and clay (Spls. I and J, Table 3). The
phosphate particles, often referred to as phosphorite,
range in color from white or cream to dark gray or
black and assay from less than 65 per cent to as much
as 80 per cent bone phosphate of lime (BPL) or
tricalcium phosphate, Ca3 (P04)2. The unweathered
phosphate mineral is apatite, more specifically car-
bonate-fluorapatite. In the upper parts of the
phosphate beds, where the sediments are more
subject to weathering processes, much of this apatite
changes to various aluminum phosphate minerals,
partly through reactions with surrounding sediments.
This upper zone containing the aluminum phosphate
minerals is called the aluminum phosphate zone or,
locally, the leached zone (Fig. 3). Its thickness
usually is between 5 and 10 feet. During mining this
upper zone normally is stripped off and discarded as
overburden.

The "matrix" or commercial zone of the phos-
phate beds (Fig. 3) occurs beneath the upper
weathered aluminum phosphate zone. Its average
district-wide composition according to Altschuler et
al. (1964, p. 25) has the following range:
Apatite (carbonate-fluorapatite) . 35-40 per cent
Clay (montmorillonite) ........ 20-25 per cent
Quartz sand and some chert ..... 25-40 per cent
This lower zone may be more than 50 feet in
thickness, but commonly is between 10 and 20 feet,
with an average for the district of approximately 15
feet.


Hawthorn Bedrock or Bedclay:
The commercial phosphate beds or matrix rests
either on bedclay or on bedrock (Fig. 3). The bedclay
is a phosphatic, impure clay, sandy clay or clayey
sand and the bedrock is a pale yellow, impure,
phosphatic limestone (Spls. K and L, Table 3).
Neither bedclay nor bedrock carries sufficient phos-
phate content to be commercial. Characteristics of
the overburden sands, the phosphate beds and the
underlying bedclay or bedrock are summarized on
Figure 4.


DESCRIPTION


Terrace sands -
Nearly pure quortz sand
( ,o b ie
phosphate .. .. -"| ii ,
some cloy but no opite
z nodule- a' F.* -
----- ---.;i
Lower unit
S sond,cly,and
Snodules
(Lower part generally
highin clay)
: i
-, ", , ,-


APPROXIMATE MI E


uor!z


CA


Apatile




=:1


LOCAL
NAMES


Overburden
sand


Leoched
zo re


Bedrock
K : ... 10.24 63.19 6
L 17. 7.:.'- 74..- 3.64 .08

i... ,. from et al. ( !' Table 11, p. 253)


Matrix



Bed cloa


FIG 4 STRATIGRAPHIC RELATIONS, LOCAL TERMINOLOGY AND MINERAL COMPOSITION
OF THE OVERBURDEN SANDS, THE LEACHED ZONE AND MATRIX OF THE
PHOSPHATE BEDS, AND THE UNDERLYING BEDCLAY AND BEDROCK.
MODIFIED FROM CATHCART et ol (1953, Fig., p.82).


97 (C

86.47
*
7 1.
; .033

96.00


68i
.68


UC%.K ri uN ArKV IM~tMItK L --UItl,








History of Mining

Pebble phosphate was originally discovered in the
Bone Valley District along the Peace River in 1881 by
Captain J. Francis LeBaron of the Army Engineers
(Davidson, 1892), and mining of the river-pebble
deposits began in 1888. In 1891 production from
land-pebble deposits was initiated as mining activities
began to shift from the irregularly distributed
deposits of river beds and flood plains to the more
continuous ores beneath the surface sands of the
region. Since this early beginning, approximately
97,000 acres of phosphate land have been mined. It is
estimated that today an average of 6,500 tons of
marketable product are produced from each acre of
phosphate land mined. In the early days, however, a
large volume of the smaller phosphate particles that
are removed today could not be extracted from the
sediments. In fact, in recent years some of the waste
from these earlier operations has been remained to
recover the small phosphate particles.

Mining and Land Reclamation

Difficult environmental problems result from any
mining operation in which the top layers of the earth
are removed to reach a valuable mineral product, or
in which the top layers of the earth are stripped off as
the valuable mineral product. This type of mining,
called strip mining, is practiced in the Bone Valley
District. Overburden sands and clayey sands are
removed by giant, electric-powered draglines to
uncover the valuable phosphate beds (Fig. 5). The
phosphate beds in turn are removed by draglines, one
of which can pick up as much as 49 cubic yards of
sediments at a time. The phosphatic sediments are
dumped by the draglines into sumps where the ore is
mixed with water and then pumped to recovery
plants.
During the early days of mining, no thought was
given to restoring the mined-out land to useful
purposes. An area, after mining, was left turned
up-side-down with man-made ridges and hills com-
posed mostly of sand and clayey sand interspersed
with low areas and filled sludge ponds or settling
ponds which take many years to dry sufficiently to
permit any type of beneficial use. With changing
times it has become evident that such valuable land
cannot be left in an unreclaimed, unuseable state. In
1961 the mining companies agreed among themselves
to restore to useful conditions as much of the
mined-out land as they could afford. Since that
agreement the Florida phosphate industry has re-
claimed an average of approximately 1,500 to 2,000
acres of mined-out land each year. Additional


incentives to reclaim land stem from the mineral
severance tax law passed by the Florida Legislature in
1971. Furthermore, Polk, Manatee and Sarasota
counties have zoning ordinances requiring a certain
amount of phosphate land reclamation.
Nearly all of the phosphate companies have
reclaimed significant land areas. Some of the projects
are tabulated on Table 4. Current projects include
Lakeland Skyview Mobile Home area and golf course,
Sanlan Ranch Campgrounds, and simultaneous min-
ing and reclamation on Lake Parker in Lakeland.
However, major reclamation problems exist. These
problems are complex and to the present are largely
unsolved. A clay-water slurry (slime) is produced in
the processing of the phosphate rock. This slurry
dries very slowly and after standing for many years
still has a volume nearly 6 times greater than the
original clay volume. In fact the volume is about
twice as great as the original volume of the matrix
mined. Slightly more than two-thirds of the land
mined must be used as settling areas for these slimes.
Therefore a substantial amount of the mined-out land
is not readily available for reclamation. Much study
has been directed toward this problem of the slimes
with encouraging results (Timberlake, 1969). Un-
doubtedly such studies will continue to demand a
high priority until the slime problem is solved.


TABLE 4
Examples of Land Reclamation Activities
of Various Phosphate Companies*

Example Company Description of Project
1 IMC Southwest Bartow-100 acres-A tract adjoining IMC's Bartow offices. Mined 1965-66. Residential
sites.

2 IMC U.S. 17 strip-135 acres-South of Bartow. Right-of-way for anticipated four-lane road. Good for
commercial.

3 IMC West Mulberry-31 acres-2,500 ft. frontage on Fla. 60. Sold to out-of-state industrial firm.

4 IMC Noralyn recovery plant site-20 acres-office, lab, on reclaimed land.

5 IMC Mulberry area-1,000 acres-North, south and south east of Mulberry; all acreage fronting on a
highway. One part recreational, another agricultural, rest of reclaimed area for residential or
commercial uses.

6 (Armour) West Bartow Elementary School-Dedicated in May, 1966; Deeded to city in 1960.

7 (Armour) Clark Property--170 acres-Swampland prior to mining. A real estate subdivision after reclamation.

8 (Cyanamid) Saddle Creek Park-740 acres-Originally a swamp; land has been donated to people of Polk County
for recreational area. Swimming, fishing, picnicing, and other activities. East of Lakeland.

9 (Cyanamid) Orange Park, north of Lakeland-2,224 acres reclaimed-mining and simultaneous reclamation.
Reclamation completed within a month after mining.

10 (Cyanamid) 315 acres-east of Lakeland-donated to Florida Audubon Society as a wildlife sanctuary. Largest
reserve owned by society in state.


(Mobil) Peace River Park-donated to city of Bartow (east of city limits) as recreational area.


12 (Mobil) Christina Park-1,100 acres-Large area south of Lakeland. Sold to private interests for housing
development.

13 (Cyanamid) Pleasant Grove Fish Management area, east of Tampa-1,160 acres-Under supervision of Fla. Game
and Fresh Water Fish Commission.

14 (IMC) Bartow Civic Center-10 acres-1966, land was donated to city for civic center.

15 (Cyanamid) Sydney-1,613 acres reclaimed-15 miles east of Tampa. Sold portion of reclaimed land for 18-hole
golf course.

16 (W.R. Grace) Sylvester Shores-Fashionable residential subdivision built on reclaimed land in southeast Lakeland.
Mined in 1955. Reclaimed in 1960.

17 (W.R. Grace) North Mulberry area-367 acres fronting on SR 37 and Carter Road. Potential commercial and
residential property. 2,600 ft. reclaimed on SR 37.

18 (W.R. Grace) East Mulberry area-1 55 acres with 4,400 ft. on SR 60. Potential commercial property.

*Data furnished by the Florida Phosphate Council and phosphate companies.


Figure 5. Mining with giant dragline.

















Pollution Control and Water Conservation


The phosphate producers also have been con-
cerned with problems of air and water pollution.
During the past 10 years more than 40 million dollars
have been spent by the phosphate companies to
install equipment to reduce emissions to the air of
fluorides, sulfur dioxide, and dust. Furthermore, an
amount in excess of 30 million dollars has been spent
during the same period of time for water quality
control, with phosphorus and nitrogen discharges
receiving much attention. In addition, millions of
dollars have been spent to install and operate water
conservation systems. The magnitude of the efforts
expended toward the control of air and water
pollution and for the conservation of water is
suggested by the vast expenditures directed toward
these ends. Expenditures. for the past 5 years are
summarized on Table 5.

Substantial progress has been realized. The recircu-
lation of water is much above the national industry
average. Airborne fluoride emissions were reduced
about 90 per cent during the period from 1959 to
1966. Likewise discharges of phosphorus and nitro-
gen into local streams have been reduced almost 90
per cent during recent years.


At one time or another, interest has been
expressed in the presence of various materials in the
phosphatic sediments of the Bone Valley District or
in the tailings left after the processing of phosphate
rock. For example, more than one-third of the
phosphate values mined can not be extracted profit-
ably and must be discarded with waste materials.
Therefore the waste contains a relatively high per
cent of unclaimed phosphate. Also, the phosphatic
sediments of the district contain minor amounts of
uranium. With such tremendous volumes of phos-
phate rock being mined, the minute amount of
uranium in individual phosphatic particles adds up to
an impressive quantity of uranium handled in the
mining operations. During World War II, studies were
made on extracting the uranium from the phosphatic
sediments and several plants were constructed in
which small amounts of uranium were recovered on a
pilot scale.
Furthermore, the Bone Valley sediments contain
traces of heavy minerals such as ilmenite, rutile,
zircon and monazite. Rutile and ilmenite are import-
ant source materials for titanium which has many
uses such as a whitener in paper and cloth, a white
paint pigment, and a source for titanium metal.
Zircon is used in molds in making castings and as a
source of zirconium metal. Monazite is a source of


rare elements. Also the phosphate rock contains 3 to
4 per cent fluorine, and the district has interest as a
possible source of vast quantities of this element.
Partly as a result of pressure from air pollution laws
and as a result of a shortage of the principal mineral
source of fluorine, plants to recover fluorine from
phosphate rock have been planned for the Bone
Valley District, and some have become realities.
Investigations indicate that phosphate rock may
eventually become a significant source of aluminum
fluoride, according to some estimates by the mid-
1970's.


TABLE 5


EXPENDITURES FOR AIR AND WATER POLLUTION CONTROLS
AND FOR WATER CONSERVATION PRACTICES*

Item 1971 1970 1969 1968 1967


Expenditures to install air pollution controls
Expenditures to install water pollution controls
Expenditures to install water conservation
systems

Expenditures to operate air pollution
controls

Expenditures to operate water pollution
controls

Expenditures to operate water conservation
systems


*Data furnished by the Florida Phosphate Council.


$5,532,090 $2,850,370 $1,925,330 $5,173,066 $9,079869
$3,353,867 $2,136,658 $2,544,587 $2,832,692 $4,822,825

$2,528,070 $ 892,400 $1,276,970 $ 729,575 $3,530,218


$4,591,511 $4,111,540 $4,365,305 $3,981,000 $4,040,120


$3,354,340 $3,000,902 $5,592,750 $4,830,500 $5,569,370


$2,623,739 $2,035,770 $2,417,492 $2,530,900


$1,848,020


,
,


Interesting Elements and Minerals











SAND


Construction Sands

The costs of homes, buildings, roads and highways
reflect the availability and quality of such common
construction sands as concrete sand, plaster sand and
mortar sand. All commercially useful sands contain
grains of various sizes (diameters). Concrete sand is a
clean, relatively coarse sand graded to contain grain
sizes within specific ranges (Table 6). Plaster and
mortar sands are finer than concrete sand, but like
concrete sand, must be clean and graded to specifica-
tions (Table 7).
Because much of the surface of Florida is covered
with a blanket of quartz sand it might seem that
concrete sand could be produced at almost any site.
Nothing could be farther from the truth. The median
diameters of surface sands collected along east-west
traverses crossing the Florida peninsula are given on
Figure 6. From this figure it can be seen that the
coarsest surface sands in peninsular Florida occur
near the center of the peninsula, trend in a nearly
north-south direction, and coincide with the general
area of Trail Ridge and the Lake Wales Ridge. A
comparison of the median diameter (Md) of the
surface sands (Fig. 6) with the median diameters (Md)
of concrete sand (Table 6) shows that most surface
sands collected along the traverses are too fine to
serve as a source for quality concrete sand.
In order to obtain large quantities of concrete sand
in the peninsula it has been found necessary to
extract coarse sands from sediments occurring
beneath the surface sands. These underlying coarse
sands are present only in the area of the Lake Wales
Ridge (Fig. 7). There sand is mined from the
Citronelle Formation which locally contains con-
centrations of very coarse sand grains, quartz gran-
ules, and small quartzite pebbles. These localized
concentrations of coarse sediments are the materials
from which construction sands are produced.
At some localities the surface sands must be
removed as overburden before mining the deeper,
coarser sands; in other areas, however, surface sands
can be mined with the underlying Citronelle sedi-
ments. In either case open pit mining methods are
used, utilizing dragliries in those pits which are dry,
and dredges with barge-mounted pumps in those pits
which are partly water-filled. Sand removed from the


pits is washed and sized by screens to meet required
specifications of concrete and plaster sands and then
shipped by truck or rail to the market area.
Because transportation is a major cost factor in the
sand and gravel industry, various population centers
in the peninsula receive their construction sand from
pits in that part of the Lake Wales Ridge area closest
by road or rail. For example, Jacksonville receives its
quality construction sands from mines in Clay and
Putnam counties in the northern part of the ridge
area. Orlando receives its coarse construction sands
from mines in Lake and Polk counties. The Tampa
area receives a major part of its quality construction
sand from the Lake Wales Ridge area in Polk County.
However, some production for the Tampa market has
come from other localities, such as sites on the
Lakeland Ridge southwest of Bartow (Fig. 7).


GLADES
A. S o.... ..... .
Figure 7. Areaof Citronelle sediments as mapped byCooke(1945). The Citronelle sediments are the major source
materials of quality construction sands in the Florida peninsula. These sediments also contain kaolin clay.


TABLE 6


Screen Analyses by Weight of Finished Concrete Sands Collected
at Major Producing Mines within the Area of the
Lake Wales Ridge
Florida
State Road Site Site Site
Sieve Specifications A B C
Size % Cumulative Putnam County Lake County Polk County
4 0- 5 0.00 0.00 0.0
8 0- 15 3.2 1.2 1.0
16 3- 35 12.6 10.8 13.2
30 30- 75 39.3 39.7 50.4
50 65- 95 69.9 81.1 73.0
100 95-100 94.5 99.5 93.6


TABLE 7


Grading of Sands for Masonary and Mortar Uses*


Sieve Size


Site
D
Polk County


FM* 221 232 231 199
Md.** .47 .52 .60 .39

*Sum of cumulative values for samples. Expression of coarseness.

*Median diameter (mm).


Percentage Passing
each screen by weight


4 100
8 95 to 100
16 60 to 100
30 35 to 70
50 15 to 35
100 0to 15



*Recommendations of the American Society for
Testing Materials



















""' -? )













-. r- h





*; '" ) "' 1 "' , ,'- .,



A.. . ... T) ;) '













s'' ' 'i ' ' ,



@ 1 @.12 &@ C232 -
@)





(' 0' 7 0-












/ i


V 091









'' I/ .










METERS OF THE QUARTZ SAND COLLECTED AT THAT LOCALITY.











2. Grain Size The glass sand shall conform to the
following requirements with respect to grain size:


A Specialty Sand
Glass sand, an important specialty sand, is pro-
duced in both Polk and Hillsborough counties. The
glass sand from Polk County is mined in the Lake
Wales Ridge area near Davenport where the sands are
separated from the same sediments from which
concrete and plaster sands are produced. Special
processing, including flotation to remove heavy
minerals and other impurities, is required to obtain a
high quality product.
The glass sand from Hillsborough County is
presently produced from surface sands in the Plant
City area. Parts of this deposit contain a very
high-grade glass sand which in its natural state meets
high quality requirements, both texturally and chem-
ically. There are very few natural deposits of glass
sand anywhere that meet the quality of these Plant
City sands for manufacturing glass. Prior to 1970
flotation was not used in processing the sand. Since
that date, however, flotation has been used to remove
heavy minerals and other impurities to ensure a
reliable product.
Glass sands must be of very high purity; even a
fraction of a percentage of some impurities, such as
iron, will color the glass produced. Table 8 illustrates
the allowable percentages of certain of the more
common impurities found in sand deposits. Further-
more glass sand must have a uniform grade-size
distribution of sand particles with most of the grains
having diameters falling within a range of approxi-
mately 0.840 to 0.149 mm (-20 mesh to + 100 mesh).
Glass manufacturers differ somewhat in the details
of their specifications for glass sands. Requirements
quoted by one major manufacturer for a high-grade
glass sand are given below.
1. Chemical Composition The glass sand shall be
composed of the following oxides in the following
percentages by weight as determined by analysis
based on ignited samples.


Percent
not less than 98.500
not more than 0.500
not more than 0.035
not more than 0.200


percent remaining on 16 mesh screen
percent remaining on 30 mesh screen
percent remaining on 60 mesh screen
percent remaining on 120 mesh screen
percent passing through 120 mesh screen


Qualities


none
0-20
40-80
15-30
0-10


Some of the glass sands in Hillsborough County
and similar deposits in Manatee County in their
natural state regularly approach these specifications
for high purity glass sand. Analyses of a sample of
Plant City sand as taken from the ground are given on
Table 9.
The value of the deposits near Plant City as a glass
sand was recognized in 1961 (Pirkle et al., 1963, p.


TABLE 8*

Specifications for Chemical Composition of Glass Sands
Percentage composition based on ignited samples
SiOZ A1203 Fe203
Minimum Maximum Maximum


First quality, optical glass

Second quality, flint-glass
containers and tableware

Third quality, flint-glass

Fourth quality, sheet glass
rolled and polished plate

Fifth quality, sheet glass,
rolled and polished plate

Sixth quality, green glass
containers and window
glass

Seventh quality, green
glass
Eighth quality, amber
glass containers

Ninth quality, amber


128). Since that time studies have been undertaken to
locate additional deposits. During one study the
following procedure for locating deposits of the
Plant City type was followed by the authors. At the
outset, all areas of St. Luci sands were plotted from
soil maps onto topographic maps of Hillsborough and
Manatee counties. Field checks of these areas were
then made to determine which of the regions of St.
Luci sands support a true scrub vegetation. Holes
were drilled in the sands supporting a true scrub
growth, and the sands taken from the holes were
analyzed for texture (sand size), heavy mineral
content and iron content. From the analyses it was
found that the sand in many of the regions is too fine
for glass purposes. However, sands from some areas
were found to be of the same quality as the Plant
City deposits. The final result of the study was the
location of new resources of glass sand of the Plant
City type. It must be added, however, that this
procedure for locating glass sands will not work in
other parts of Florida. Different methods of explora-
tion must be devised for other areas.


CaO+MgO
Maximum


99.8 0.1 0.02 0.1


98.5 0.5 0.035 0.2

95.0 4.0 0.035 0.5


98.5 0.5 0.06 0.5


95.0 4.0 0.06 0.5


98.0 0.5 0.3 0.5


95.0 4.0 0.3 0.5

98.0 0.5 1.0 0.5

95.0 4.0 1.0 0.5


*Taken from Fettke (1926, p. 400).


TABLE 9


Plant City Glass Sand

Accumulative percent retained on mesh Heavy
Site 12 16 20 30 50 60 100 140 Minerals Fe203
in % in %
Plant City 0.0 Tr. 0.4 3.6 41.3 58.3 87.0 93.9 0.154 0.016


Sand mine at Plant City.


Oxide
SiO2
Al2 03
Fe2 03
CaO, MgO














CLAY


Among the most interesting Florida clays from the
commercial viewpoint are kaolinitic clays for ceramic
purposes, fuller's earth clays for their adsorbent
properties, and bloating clays for their use in making
lighweight aggregate. None of these clays is currently
mined in Hillsborough County. However all are mined
in the Florida peninsula and are a part of the mineral
environment of Tampa.

Kaolinitic Clays of the Citronelle Formation

The north-south trending Lake Wales Ridge area
which divides the Florida peninsula into an eastern
and western part (Fig. 7) is underlain by Citronelle
sands that contain varying amounts of kaolinitic clay.
These, usually assigned a late Miocene or Pliocene
age, are the materials previously discussed as the
source sediments for quality construction sands of
the peninsula. The kaolinitic clay occurs disseminated
throughout the sands, usually constituting from 2 or
3 per cent to as much as 25 per cent of the beds.
The kaolinite of the Citronelle Formation is a high
quality ceramic clay. It has been mined at one time or
another in Clay, Lake and Putnam counties, the
production from Putnam County being continuous
since 1892. In addition to its value as a ceramic clay,
the kaolinite of the Citronelle Formation may have
potential as a future source of aluminum. Citronelle
clays are not present in Hillsborough County, but
they do occur in the eastern, central and northern
parts of adjacent Polk County.

Fuller's Earth Clays of the Hawthorn Formation

The Hawthorn Formation contains fuller's earth
clays, utilized for their adsorbent properties. The
dominant clay minerals are montmorillonite and
attapulgite. Extensive mining of the clays is carried
out in Gadsden County northwest of Tallahassee and
in southwestern Georgia. The production of the
adsorbent clays closest to the Tampa area is at Lowell
in Marion County. Clay from that site is shipped to
the Tampa market for use as an adsorbent cat litter,
as a pesticide carrier, and as an inter-caking agent for
fertilizers. Although Hawthorne sediments are present
in the subsurface of Hillsborough County, no
extensive occurrences of fuller's earth type clays
suitable for mining have been reported.


Bloating Clays

Some clays will expand or bloat when heated,
often taking on the appearance of a burned, porous
or cellular cinder rock. The expanded or bloated
material is relatively light and if sufficiently strong is
ideal as a lightweight aggregate for use in the
production of concrete and concrete products.

Clays Along the St. Johns River:

The only site from which bloating clays currently
are mined in Florida is near Russell just west of the
St. Johns River in Clay County. However, there are
other occurrences of similar clays known to be
present along the St. Johns. These clay bodies
apparently are confined to the general vicinity of the
river valley.

Deposits of Clayey Sediments in West-Central
Peninsular Florida:

Within the past few years massive bodies of clayey
sediments possibly useful as a bloating clay have been
found in northern Pinellas County (west and south-
west of Lake Tarpon) and in the vicinity of Telegraph
Swamp in Charlotte County. These clays have been
drilled and studied by members of the Florida Bureau
of Geology, the Geology Department of the Universi-
ty of Florida, and the United States Bureau of Mines
Laboratories (Wahl and Timmons, 1972). Figure 8 is
a fence diagram showing the stratigraphic position of
the clay body near Lake Tarpon. Wahl and Timmons
(1972, p. 109) report that the large clay deposit
probably is Miocene in age, consists of montmorillo-
nite type clays, has an average thickness of 25 to 35
feet, and is overlain by unconsolidated Pleistocene
sands. The clays have good bloating characteristics
across an acceptable temperature range and develop a
good cellular structure with a fairly thick and
apparently tough wall structure. However the deposit
is in an area of rapid population growth and mining
may not be feasible. In regard to this problem Wahl
and Timmons (1972, p. 112) state:
"It is possible that development of the Pinellas
County deposit to its maximum potential might
already be prohibited by urbanization, for the
Pinellas-Hillsborough County area is one of the fastest


growing regions in the state at the present time. It is,
indeed, imperative that other similar deposits
throughout the state be located and their potential
for development be realized so that land-use planning
and resource development can be coordinated."
In light ot these comments by Wahl and Timmons
it is of interest to note that extensive deposits of
clayey sediments that may have potential as a base
material for the manufacture of lightweight aggregate
are present in a number of other counties in
west-central peninsular Florida, including Pasco, Polk
and Hillsborough. In evaluating these clayey sedi-
ments a number of economic factors must be


KEY

SAND
CLAYEY
SAND
CLAY
SANDY
CLAY


considered. Obviously the overburden covering the
clay deposits should be as thin as possible so that the
cost involved in its removal is not substantial. Also,
the moisture content of the clay should be low. Every
bit of moisture present is significant in that it
increases processing costs. It is desirable that the clay
be a natural bloating clay; however, coal or fuel oil
can be used to make the clay bloat if the melting
range of the clay is over a sufficient temperature
span. In addition to these factors, transportation
costs and problems related to the environment and to
the restoration of mined-out land must be given
serious consideration.


FIGURE 8: FENCE DIAGRAM CONSTRUCTED FROM FIVE DRILL HOLES IN
PINELLAS COUNTY WITH INSERT MAP SHOWING LOCATION
OF DRILLED AREA. MODIFIED FROM WAHL AND TIMMONS
(1972, FIG. 5).


TAMPA
BAY








There are different methods that could be used in
attempting to locate and pinpoint deposits of these
clays. To illustrate, Figure 9 shows a section through
Pasco, Sumter and Lake counties. From this section it
is clearly seen that the Ocala Arch crests beneath
Sumter County (holes 3, 4 and 5). The near-surface
sediments on the flanks of the arch are shown to be
sandy clay (yellow color with dashes and dots). These
sandy clays flanking the crest area of the Ocala Arch
grade away from the arch into sediments containing
less clay (yellow color). Clearly the sediments closest
to the crest area are the highest in clay content and
should be considered as broad targets for possible
clay deposits.
Figure 10 is a map of the same general area showing
the depth to the top of the Floridan aquifer (usually
limestone). By combining information from this
figure with information from Figure 9 the target areas
for the clays flanking the Ocala Uplift can be further
localized. That area colored dark yellow on Figure 10
marks the crest area of the uplift. Limestone is within
10 feet of the land surface and a thick deposit of clay
would not likely be present over the limestone.
Beneath the area colored light yellow the limestone is
at a depth of 10 to 25 feet. Again the closeness of the
limestone to the land surface would tend to preclude
the presence of a massive deposit of thick, clayey
materials between the land surface and the limestone,
although the occurrence of a potential clay body
could not definitely be ruled out. Throughout the
area colored yellow-green the limestone is from 25 to
50 feet below the land surface. This depth to the


EXPLANATION
I Surfiial sand Ha.w.horn formto .n(sand uni) ..othorn forml.an(phosphor.te unit)
Loose, mossive quart sound Prtly Gray to brown, clyey, fine-groined quartz Gray brown, cayey quor sond ond
Recent wind deposit, portly resdual sand intersltioal secondary phosphlot phosphrte, /, ne-grtned quartz send;
phosphorte nodules are as large as pebi
T 2 Tampa limston (clay unt) Tampa limestone (phosphorite unit) Suwannae I mestone
Greenish-gray o brown, sandy (very fine White to brown, oncretonary, cloy-sized Slightly sandy hmestone
grained) cloy. opotte and clay

a Ocoa limestone lo"
Almosture hmslone DADE CITY AREA tro'


Hard-rock phosphate mine
S Hard-rock phosphale mine


EXPLANATION
Depth ,
D 0-10 [] 75-100
S10-25 1 100-200
[ r25-50 Greaterthan 200
F- 50-75


Figure 10. Green Swamp and surrounding areas showing
thickness of sediments over the Floridan aquifer.
(Reproduced from R. Pride et al. 1966, Fig. 3)


limestone should be sufficient for clay occurrences
and for clay mining. Thus on the basis of the work of
Pride, Meyer and Cherry (1966) the yellow-green area
on Figure 10 of this report should be considered as
areas in which clays of interest for their bloating
qualities may be present.
Additional information of significance in speculat-
ing on the possible occurrences of bloating clays is
given in the work of Ketner and McGreevy (1959,
Plates 3 and 4). Information from their plates has
been selected and reproduced here as Figure 11. This
figure shows subsurface sediments along a line from
Brooksville southeastward through Dade City into
Polk County. In this section the materials marked by





A
200-



1OC 3 4 5
I 2


SEA
LEVEL


-100
-200 -



-20C -


dashes are designated by Ketner and McGreevy as the
clay unit of the Tampa Formation. In Pasco County
this clay unit is shown to be near the land surface
along the flanks of the Brooksville Ridge as indicated
by holes 5 and 9 on Figure 11. Therefore another
broad target area for possible clay deposits would be
along the flanks of the Brooksville Ridge where
clayey sediments are not covered by thick overburden
sands. Obviously these published reports by the
Florida Bureau of Geology and the United States
Geological Survey can be used as starting points in
planning for exploration programs directed toward
the recognition of potential clay resources in the
general area of Tampa.





A'


I 3 It\ mL C3
SCALE





ORANGE CO,
LAKE CO.


Fossc


PASCO CO.


Ocola limestone


Figurell. SECTION FROM BROOKSVILLE SOUTHEASTWARD THROUGH THE
BROOKSVILLE RIDGE. NOTE CLAY UNIT OF TAMPA FORMATION
IS CLOSE TO THE LAND SURFACE ALONG THE FLANKS OF THE
BROOKSVILLE RIDGE (HOLES 5 AND 9).
Modified from Ketner and McGreevy (1959, Plates 3 and 4).


I 0 ,5 4 MILES
SCeAL


of Data


POLK CO. L....
Sketch Map Showing Location of Cross-Section

Figure 9. SECTION THROUGH PARTS OF PASCO, SUMTER AND
LAKE COUNTIES. THE CREST OF THE OCALA ARCH
IS IN THE VICINITY OF SUMTER COUNTY NEAR
CORE HOLE NO.4. NOTE THE CLAY CONTENT OF SEDI-
MENTS IS HIGHEST AROUND THE FLANKS OF THIS
ARCH (YELLOW COLOR WITH DASHES). MODIFIED
FROM PRIDE ET AL. (1966, FIG.8).


EXPLANATION
Undifferentiated clostic
deposits(clayey sand on
left side graded into sandy
cloy on right side)

SUndifferentiated clay

Suwannee Limestone


S| Crystal Rivet Formation

SWilliston Formation


W-- Inglis Formation

Avon Park Limestone

SFault, arrows indicate
61 direction of movement

















LIMESTONE Uses of Limstone


Centers of Limestone Production


During 1970 slightly more than 40 million tons of
crushed limestone valued at 55.2 million dollars were
produced in Florida from 90 quarries in 23 counties
(Table 10). The producing areas can be grouped into
two major centers of limestone production, one north
of Tampa in the area of the Ocala Uplift (Fig. 12),
and the other in the southeastern part of the
peninsula in Dade and Broward counties. All of the
Florida peninsula can be supplied with limestone
products from these two centers.
Of most direct interest to Tampa is the center in
the Ocala Uplift area. There limestones arched
upward from depth are now exposed or covered by
only a thin veneer of overburden sediments. They are
accessible for mining by open pit methods and may
be removed with draglines, power shovels, front end
loaders and bulldozers.






TABLE 10*

Florida: Crushed limestone sold or used by producers, by counties
(Thousand short tons and thousand dollars)


1970
Number Quantity


County


Value


quarries


Alachua ...............
Broward ..............
Collier . ...... .......
Dade .................
Hernando ..............
Levy .................
M arion ...............
M onroe ...............
Palm Beach ............
Sum ter ...............
Undistributed1 ....
Total2 .....
W Witheld to avoid
data; included wil


1,744 $ 1,335


11,303
2,502
13,356
13,023
155
2,121
615
W
2,456
8,310
55,176


6,924
1,679
11,134
7,719
249
924
917
W
2,604
6,316
40,210


O MINE SITES


disclosing individual company confidential
th "undistributed."


SIncludes Charlotte, Citrus, Lee, St. Lucie, Suwannee, Taylor,
and Palm Beach counties.

2 Data may not add to totals shown because of independent
rounding.

*Bureau of Mines Minerals Yearbook, 1970.


Figure 12. Center of limestone production north of Tampa.
The crest of the Ocala Uplift is indicated by a
heavy black line. Areas in which active limestone
quarries are present are shown in color. Note
their correlation with the area of uplift.


Limestone mined in Florida is used principally as a
roadbase, as concrete aggregate, and in the manu-
facture of cement and lime (Table 11). The loose,
granular "Ocala Lime Rock," mined extensively
within the Ocala Uplift area in many counties
including Alachua, Marion, Levy and Sumter, is used
as a roadbase material and in the manufacture of
lime. A crystalline limestone called "Brooksville
stone," mined primarily in Hernando County, is
marketed as a concrete aggregate, although some is
used for railroad ballast and for agricultural purposes.
During the past, much of the limestone used in
making cement for the Tampa market came from
mines in Citrus and Hernando counties. Now,
however, limestone sediments are being imported
from the Bahamas for the Tampa cement market.
Some carbonate rocks have a relatively high
content of magnesium. These rocks, often called
dolomites or dolomitic limestones, are used mainly as
fertilizer filler and for soil improvement. They are
mined north of Tampa in some parts of the uplift
area and south of Tampa in Manatee and Sarasota
counties.





TABLE 11*

Florida: Crushed limestone sold or used by producers, by uses
(Thousand short tons and thousand dollars)

1970
Use Quantity Value

Concrete aggregate ............ . 9,824 $16,302
Dense graded roadbase stone . ...... 15,232 20,398
Other roadstone .............. 2,820 4,214
Unspecified aggregate and roadstone . 2,866 2,788
Agricultural purposes ........... 375 1,353
Fill ................. ..... ... 3,373 2,651
Railroad ballast ... ........... .. 120 165
Other uses3 .................. 5,600 7,306
Total4 .................... 40,210 55,176

Other roadstone includes bituminous aggregate, macadam
aggregate, and surface-treatment aggregate.
2Data include stone used in poultry grit.
Includes asphalt filler, cement, chemical stone, other filler,
lime, stone sand.
4Data may not add to totals shown because of independent
rounding.


*Bureau of Mines Minerals Yearbook, 1970.




















Limestone Reserves

Like many other low unit-value mineral resources,
limestone deposits must have natural purity and be
easily accessible for mining in order to be economic-
ally important. Although the Tampa area is underlain
by vast quantities of limestone, the thickness of
overburden coupled with the impure nature of the
limestone renders the sediment throughout most of
the area insignificant as economic deposits. However,
about 10 miles northwest of Lakeland there is a large
region in which limestone is close to the land surface
(Fig. 10, yellow-green color). That area, partly
in Hillsborough County, has potential as a source
region.
Florida's reserves of limestone are monumental.
Reves (1962, p. 7) states that in the northern half of
the peninsula alone, the amount of limestone which
has less than 15 feet of overburden, if mined to a
depth of 40 feet, would approach 4.2 trillion tons. A
vast amount is a very high calcium limestone, ranging
from a minimum of 95 per cent calcium carbonate to
as much as 99.8 per cent calcium carbonate.
Furthermore there is a great deal of dolomitic
limestone. For example, Vernon (1951, p. 218)
reports more than 100 square miles underlain by
dolomitic limestone in Citrus and Levy counties
alone. Other occurrences of dolomitic limestone are
known in Florida, including deposits along the Gulf
Coast in Dixie, Taylor, Jefferson and Wakulla
counties (Reves, 1962, p. 12) and in Pasco, Hernan-
do, Suwannee, Manatee and Sarasota counties (Max-
well, 1970, p. 26).


Potential Deposits of Crystalline Limestone

Recently Yon and Hendry (1972) investigated the
occurrences of crystalline limestone in Hernando and
Pasco counties. Limestone products from these
counties, just north of Tampa, would have a marked
impact on the Tampa market. Yon and Hendry
determined that crystalline limestone suitable for
concrete aggregate is associated with an elongated
subsurface high extending from Pasco County north-
westward into Hernando County (Figs. 13 and 14).
They interpreted the buried "ridge" of limestone as a
possible carbonate bank built during Oligocene time
in a warm shallow sea.
The highs and lows of the upper surface of this
buried limestone "ridge" conform in general with the
highs and lows of the land surface. To prospect in
that area for limestone suitable for aggregate, one
may superimpose contour maps of land surfaces onto
Yon and Hendry's contour map of the upper surface
of the limestone high (Fig. 13). The crystalline
limestone should be close to the land surface at those
sites where the two sets of contour lines show nearly
the same elevations (Yon and Hendry, 1972, p. 40).
These correlations brought out by Yon and Hendry
constitute a vivid illustration of the significance of
basic geological studies in pointing to occurrences of
accessible mineral resources.


I *


:L ..J oe -

^-^ A ,. ^-^ ^ ^ss^...~4-


Figure 13. CONTOURS DRAWN on the TOP of the SUWANNEE LIMESTONE in
HERNANDO and PASCO COUNTIES. A HIGH, ELONGATED AREA
JUST WEST of DADE CITY is CLEARLY SHOWN. ITS TREND is
NORTHWEST-SOUTHEAST. (FROM YON and HENDRY,1972, Fig.5,p.12)


Figure 14. AREA of POTENTIAL LIMESTONE AGGREGATE in
HERNANDO and PASCO COUNTIES is SHOWN in
COLOR. THIS AREA CORRESPONDS to the HIGH on
FIGURE 13. (FROM YON and HENDRY, 1972, Fig.16,p.39.)


Limestone mine in Sumter County.














CEMENT,OYSTER SHELL,& PEAT






Cement


Cement itself is not a mineral but normally is
considered a mineral resource. The raw materials
needed in its production are lime or limestone and
minor amounts of silica, alumina, and iron oxides. In
manufacturing portland cement the raw materials are
crushed, then proportioned under strict chemical
controls, ground to a powder or slurry and fed.into
an inclined rotary kiln. The powdered material moves
under gravity from the upper toward the lower end of
the rotating kiln where intense heat is produced. The
heat fuses the powdered charge to a glassy clinker
composed of calcium silicates and aluminates. The
clinker is then mixed with a small amount of gypsum,
which later helps regulate setting time, and the mass
is ground to a fine powder. This powder is portland
cement.
The limestone used in producing portland cement
must not contain more than 3 per cent magnesia. This
is a stringent requirement that eliminates many
potential limestone sources. Part of the small
amounts of silica, iron oxides, and alumina needed
may be present in the limestone as impurities.
Additional amounts usually are added by introducing
clays or other materials containing these substances.
Staurolite from the heavy mineral operations near
Starke has been used to some extent in Florida as a
source of iron and aluminum.
Factors important in establishing a cement plant
include the availability and quality of deposits of
limestone and the other raw materials. In addition, a
satisfactory source of fuel for the rotary kilns must
be considered. Most important, however, is the
location of the market area. The plant should be
established as close as possible to major population
centers to reduce costs of transportation.
At present there are four plants producing cement
in Florida. Three are in the Dade County or Miami
area and one is in the Hillsborough County or Tampa
area. The Tampa plant, with an annual capacity of 6
million barrels of cement, is by far the largest in the
state. Nevertheless, a cement shortage exists in the
Tampa region and cement is being imported into the
area. One of the new sources is Honduras in Central
America.


Approximately 87 per cent of the cement pro-
duced in Florida during 1970 went to building
material dealers, concrete products manufacturers,
and ready-mix concrete manufacturers (Minerals
Yearbook, 1970). Much of the remainder was used by
highway contractors and government agencies.
Limestone for the cement plant in the Tampa area
was mined for years at sites in Citrus and Hernando
counties. Now limestone sediment aragonitee) is being
dredged near Bimini in the Bahamas and shipped to
the Tampa plant. The clay needed to furnish small
amounts of iron oxides and alumina is mined in
Citrus County. Soon, however, clay for the Tampa
operation will be mined from a new pit to be opened
in Hernando County.
The quantity of raw materials consumed in the
production of cement at the Tampa site is enormous.
Dust from the clinker burning process makes for a
significant problem which currently is of a crisis
nature at the Tampa plant. A new cement plant is in
the planning stage for Manatee County just south of
Hillsborough County. This will reportedly be a
pollution-free plant, but resistance to its construction
is already substantial.
If a population center is to thrive it must have
cement and other construction materials, and it must
be able to obtain them at a reasonable cost. Raw
materials necessary for the production of cement are
available to the Tampa region. However, as illustrated
by the Tampa plant, cement manufacturing can be
plagued by pollution problems. The need for cement,
when considered with problems associated with its
production, serves as a striking illustration of the
need for informed leadership in planning for the
economical and popularly acceptable manufacture of
a product necessary for a thriving and expanding
population center.


V. .



I*1


Scenes at cement plant in Tampa


- MEMO"PssC~~?'~'A~~~~














Oyster Shells


For years oyster shells have been dredged from
Tampa and Hillsborough Bays, with an estimated
tonnage of slightly more than one-half million cubic
yards now being produced annually. The sites of
current dredging operations are shown on Figure 15.
Most of the oyster shells are used for road base
materials, the city of Tampa being among the largest
of the consumers. According to Mr. E. Medard of Bay
Dredging and Construction Company (personal com-
munication), the shell layer being mined in the bay
ranges in thickness from 2 to 20 feet, approximately,
and is overlain by 4 to 15 feet of overburden. The
amount of reserves is unknown.


Dredging of these shells in the bay area has been
the subject of much concern during recent months.
The problems include possible destruction of marine
life and biological resources and possible adverse
effects on local water quality. Again there is
insufficient data to evaluate all aspects of these
concerns intelligently and effectively, and clear-cut
recommendations or decisions cannot be drawn with
comfort and conviction. To illustrate the dilemma,
late last year when the Florida Cabinet considered
requests for renewal of permits to continue dredging
operations for oyster shells in Tampa and Hills-
borough Bays, it was faced with different opinions
from different individuals, institutions, and state
agencies. The consensus was that further study was
needed.


Peat

During 1970 peat was produced in Florida from 8
plants in 6 different counties including Hillsborough.
Total production from the entire state amounted to
approximately 46,000 tons valued at slightly more
than 300,000 dollars (Minerals Yearbook, 1970).
Most of the peat is used for improving the physical
character of soil. The production in Hillsborough
County is largely for local needs and comes from sites
near Mango. Davis (1946) has made a thorough study
of Florida's peat deposits. That work can be
consulted for discussions of the various kinds of peat
and mucks, their distribution, origins and character-
istics.

CONCLUDING REMARKS

This brief discussion of mineral resources of the
Tampa area touches upon interesting and crucial
environmental and land-use problems. Some of the
problems can not be evaded and will become more
and more pressing with time. They are both
philosophical and practical. It is evident that among
the most significant needs for understanding any of
the problems are reliable, basic data. These data can
not be accumulated in a few days or in a few months;
their accumulation takes years. A strong case can be
built that one of our most severe deficiencies in
preparing for the land-use and environmental
problems that face us today has been our lack of
support for those studies and for the work of those
agencies which supply basic data. Where and when
plans and decisions can be based by competent
leadership upon reliable data, socially beneficial
solutions to these challenging problems will be more
easily obtainable.


Mountain of oyster shells at Bay Dredging and Construction Co.






ENGINEERING


GEOLOGY


x


--aog cI -












FOUNDATIONS


Introduction


Engineering geology may be defined as: "The
application of the geological sciences to engineering
practice for the purpose of assuring that the geologic
factors affecting the location, design, construction,
operation, and maintenance of engineering works are
recognized and adequately provided for"'. As such,
engineering geology is concerned with the physical
characteristics of earth materials and deals with
quantitative data obtained from testing the suitability
of those materials for specific uses or roles.
In the Tampa area, construction planning perhaps
most frequently demonstrates the simultaneous use
of engineering and geological concepts. Likewise, soils
studies incorporate engineering and geological prin-
ciples. This phase of the report will deal with the use
of engineering geology techniques applied to con-
struction planning and the study of soils.
In planning the construction of any building, of
primary consideration is the character of the earth
materials upon which the building will rest. Various
physical properties of these materials determine how
much weight they can bear and, in turn, how a given
building must be supported.
Three factors are involved in the selection of an
appropriate foundation design:


1. The nature and competency (strength and com-
pressibility) of the subsurface materials.

Incompentent (weak and/or compressible) subsur-
face materials may necessitate special site prepara-
tion prior to construction and/or a complex
foundation system.

2. The size and type of building.

The size of the building is important in that small,
light buildings such as residences obviously require
less support than heavy multi-story structures; and
likewise low-rise structures, such as shopping
malls, generally require less support than heavy
high-rise buildings. The type of building con-
struction, such as steel, concrete, masonry or
wood, determines the building's adaptability and
tolerance to settlement and its effects.

3. Economics.

The cost of constructing a feasible foundation
system should be in balanced proportion to the
cost or value of the structure itself.


All three factors must be weighed in determining
the suitability of a site for construction. It may also
be pointed out that the same three factors listed
above also determine the scope and extent of the
subsurface investigation and study which is required
for a building site.
The thickness and character of surficial soil
deposits and the depth to rock often are of prime
importance in the selection of a building site and
development of construction plans. Probably the
most accurate statement that can be made about the
surficial soil deposits and the depth to the rock
surface in the Tampa area is that they are character-
ized by their inconsistency. The thickness and extent
of the cohesionless and cohesive soils-that is, the
sands and clays-can vary greatly, even among the
borings made at one site. In addition, soils intermedi-
ate in nature between the noncohesive sands and the
cohesive clays, such as sandy clays and clayey sands
are quite common. In some instances, sands grade
slowly downward into clayey sands and then sandy
clays and then relatively pure clays. In other
instances, clayey lenses are found within the sands;
and sand lenses within the clays. Consequently,
accurate mapping of the thickness of the cohesive and
non-cohesive soils in the Tampa area is very difficult.


- I




'V~


In addition to the areal extent and thickness of the
cohesionless sands and cohesive clayey soils; the
strength and compressibility of these soils is a vital
parameter. Standard penetration tests provide some
indication of both the relative strength and relative
compressibility of soil deposits. The specific pro-
cedures for performing this test and obtaining soils
samples is comprehensively presented in American
Society for Testing and Materials specification D
1586. In general, this procedure involves driving a 2
inch split spoon sampler 18 inches into the soil by
means of the energy imparted by a 140 pound drop
hammer falling 30 inches. The number of blows
required to drive the sampler the last foot into the
soil is the standard penetration resistance, commonly
called the 'blow count'. Other supplemental invest-
igative procedures, such as the auger borings or cone
penetrometer borings are sometimes used to obtain
additional information regarding the nature of the
surficial soil deposits; but the standard penetration
test is the most widely used method of determining
and evaluating the nature of the subsurface condi-
tions. However, it should be noted that the data
obtained from this procedure is rather limited and
more qualitative than quantitative in nature. More
specific and quantitative information regarding shear
strength and compressibility of soils is generally
obtained by laboratory testing of undisturbed soil
samples. Sometimes field load tests are necessitated
because of the nature and geology of the soil
deposits.












.1










Subsurface conditions which limit the suitability
of a site for construction can generally be overcome
by the use of certain site preparation techniques or
special foundation design, or both. Before subsurface
problems and their solutions can be discussed, some
pertinent terms need defining:

Shallow Foundation Systems

This type of foundation bears at a very shallow
depth and imparts the foundation loads to the
shallow subsoils. There are a number of types of
shallow foundations, all of which are used to spread
the superimposed loads over a sufficient area so that
the safe bearing capacity of the foundation soils are
not exceeded. The type that is best suited for a
particular site depends upon the subsurface condi-
tions. The following are the three major types of
shallow foundation systems listed in the order of least
costly to most costly.


Individual or Continuous Foundations-Individual
spread footings are utilized to support columns;
whereas continuous spread footings are used to
support load carrying walls. These are normally the
least costly type of foundation systems and are
utilized where good subsurface conditions exist.

Strap Foundations-This type of foundation is
utilized to support a row of two or more columns.
The foundation strap is structurally designed with
sufficient stiffness and rigidity to function as a single
unit. This type of foundation system is used where
somewhat poor subsurface conditions exist and when
it is desirable to reduce subsurface stresses and
minimize potential settlement between columns.

Mat Foundations-A mat or raft foundation, com-
monly called the floating foundation, encompasses
the entire base of the structure and spreads the
building load over the entire building area. The main
functions of such a foundation system are to reduce
subsurface stresses in compressible soils, bridge weak
zones or possible subsurface cavities, and reduce total
and differential settlement. This is generally the most
costly of the various types of shallow foundation
systems.


Deep Foundation Systems

Piles or caissons are the most common type of
deep foundations. Their purpose is to transfer a load
which cannot be supported at a shallow depth to a
greater depth where adequate support is available.
Caissons are rarely used in the Tampa area because of
installation difficulties imposed by the general geo-
logy of the area; whereas timber, steel and/or
concrete piling are commonly used. Because of the
variable and unreliable nature of the clayey subsoils,
the piling are usually end-bearing on the limestone
bedrock. The cost of piling can vary widely,
depending upon their length and capacity.

Subsurface Grouting

This generally refers to the pumping of sand-
cement mixtures or chemical grouts into weak porous
permeable zones and/or underground cavities or
networks of cavities in order to strengthen and
stabilize the subsurface strata. This procedure, al-
though not commonly used, is frequently necessi-
tated in certain areas within the Tampa area because
of the geological conditions. The cost of this type of
site preparation work is extremely variable and can be
quite expensive.


STRAP FOUNDATION


MAT FOUNDATION


SHALLOW FOUNDATION
Individual spread footing


DEEP FOUNDATION
Piles or Caissons


,I\

i


\i


"

~




















SANDS





Foundation problems common to the Tampa area
can be dealt with in a variety of ways depending on
the severity of the problem and the nature of the
structure. Four fundamentally undesirable site condi-
tions include: loose sands, compressible clay, organic
materials, and sinkholes.







LOOSE SANDS


Structures built on loose sands may settle and
crack if the sands densify or compress. Densification
can result from the imposed load, changes in ground
water levels, or from vibration of the ground due to
traffic, sonic booms, machinery, etc.
In order to prevent settlement, three alternatives
are possible: 1) loose sands can be removed and
replaced, 2) pilings can be utilized for support, or
3) the sands can be densified.
Even for high rise buildings, excavation of loose
sands for foundations rarely exceeds depths of ten
feet. With deeper excavations, costs are higher, and
the water table becomes a problem. If the entire
ground floor area of a building must be excavated,
every foot of material removed results in a significant
increase in cost. Following removal of loose sands,
the site is back filled and properly compacted.
In-place densification of loose sand is usually the
least expensive means of adequately preparing the site
for buildings. The older method of densifying loose
cohesionless soils was to excavate it, replace it in thin
layers and compact it. However, modern compaction


equipment and techniques now make possible the
densification or appreciable thicknesses of sand
without excavation. If surface deposits of loose
cohesionless soils are only moderately thick, the use
of large heavy vibratory compaction equipment
usually will adequately densify the soils; whereas if
the loose sands are either very thick or buried, a
process called "Vibroflotation"1 can be utilized. This
latter system utilizes water and vibration to compact
the sand. All methods of in-place densification are
reasonable in cost.
In the Tampa area, pure quartz sands and sands
with minor amounts of silt, clay, and organic material
generally range from a few inches to more than 30
feet thick. The sands tend to thin toward the Bay.
The meandering contour lines on the map partially
reflect the effects of stream channel development and
the erosion of sands by streams. The reaches of the
river channels exhibit thinner sand than adjacent
areas.

1Trademark








SAND SUITABILITY AS A





FOUNDATION MATERIAL


The map presented here incorporates both thick-
ness and compressibility of the relatively pure surface
sands and outlines the areas or problem sands and
satisfactory sands. It must be borne in mind that the
map has been compiled from data currently available
and is thus generalized. Close spacing of "good" and
"poor" sands bears witness to the local variability of
sand characteristics.
It can be seen from the map that thick loose sands
are especially prevalent in the Temple Terrace-
University of South Florida area and around Bran-
don. Firm sands are fairly well scattered but appear
to be concentrated in the downtown and interbay
areas.
With regard to site suitability for construction, this
map illustrates one of the many aspects which must
be considered, and it will be utilized as an overlay in
the Land Use section of the report.


Good: Firm sands five feet or greater in thickness
have been encountered in these areas. These sands are
capable of supporting many types of structures with
no pre-construction site preparation.
Variable: These areas have been found to contain
varying thicknesses of sand that exhibits eradic
compressibility. Because of their unpredictable nature
pre-construction treatment for the sands may be
required.
Moderate: This includes areas in which sands are
predominantly firm but contain compressible lenses
and areas in which less than five feet of loose sand lies
at the surface and is underlain by more than five feet
of firm sand. Depending upon the type of con-
struction proposed, very little treatment may be
necessary to render these sands suitable to provide
adequate foundation support.
Poor: Included are areas in which sands are 10 feet
or greater in thickness and are predominantly loose,
but contain lenses of firm sand. Also, included are
totally loose sands five to ten feet thick. These two
conditions have been grouped as "poor" because
some preconstruction site preparation would proba-
bly be required but may not be as extensive as in the
areas labeled "very poor".
Very Poor: This includes areas in which loose
sands ten feet or greater in thickness have been
encountered, areas in which firm sands less than five
feet thick are underlain by loose sand greater than
five feet thick, and areas in which sands containing
organic deposits have been found. All of these
conditions would likely necessitate treatment prior to
construction.


EXPLANATION
VERY POOR

POOR

JZ VARIABLE

MODERATE

GOOD


It should be noted that sands less than five feet
thick have been omitted from consideration in this
map. When very thin sands are encountered, the
material underlying them is generally of equal or
greater importance in foundation planning. These
areas will be brought to light in the discussion of
clays.


I 2 3 4 5 MILES
S I I

















CLAYS


The presence of clays at or near the surface
presents a problem to many types of construction.
This is due to the low shear strength of many clays as
well as their compressibility. To compound the
problem, compressibility and shear strength of the
clays in the Tampa area are very variable and
inconsistent. Furthermore, clays or cohesive soils
cannot normally be mechanically improved.
One method of treatment is to remove the weak,
compressible, cohesive soils and replace them with
properly compacted competent materials. Unfortun-
ately, this is only feasible when they lie at or near the
surface; which in the Tampa area they rarely do.
Where they are deeply buried, the soils overlying
them may be sufficiently thick and competent to
adequately support a structure. However, when the
weak clays are shallow, they generally necessitate
some special attention in foundation design. If the
underlying limestone is also shallow, piling can be
used to transfer the foundation loads through the
weaker compressible clays to bedrock. However, since
piling is an expensive means of supporting small
structures, shallow weak clays can be a bigger
stumbling block to small construction projects than
to large ones.
The map on this page shows the areas in which
firm clays have been found underlying surface sands,
and areas in which soft clays or clays containing soft


lenses have been encountered beneath the sands. In
addition, areas are shown in which clay occurs only as
thin lenses within the sand or mixed with sand as a
minor constituent. Like the map illustrating sand
conditions this map is generalized on the basis of the
network of known values. The thickness and com-
pressibility of clay and cohesive soils varies as much
as if not more than the sands. It is virtually
impossible to predict the conditions that will occur at
a specific site without performing a subsurface
investigation at the site.
On the map, soft clays have been shown according
to thickness ranges (less than five feet, five feet to ten
feet, and greater than ten feet). If the soft clays are of
significance to a particular construction project, then
the greater their thickness, the more of a problem
they become. No attempt has been made however, to
categorize the clays according to the severity of the
problem they may cause. Whether or not the clays
will be a problem at all, largely depends on their
depth and thickness, and thickness and competency
of the overlying soils, the magnitude of the building
loads to be imparted and the structure tolerance to
settlement.

This map will be used in the Land Use section in
combination with other maps to indicate land
suitability for construction.


CLAY CONDITIONS

Areas in which soft clays greater than ten feet
thick are found to occur. This includes soft clays with
interspersed lenses, clays containing peat layers and
karst areas with greater than ten feet of clay.
Areas in which five to ten feet of soft clay have
been encountered.
Areas in which soft clays less than five feet thick
occur.
Areas in which clays occur only as thin lenses
within the sand, or as a minor faction mixed with
sands.
Areas in which firm clays containing no soft lenses
occur. These clays are of varying thickness.







ORGANIC



ORGANIC MATERIALS

Deposits of organic soils, including peat and muck
are undesirable for almost all construction. Like
clays, they cannot be mechanically improved and in
most cases, must be removed and replaced with
suitable fill.
Since areas where organic deposits occur are
generally swampy or lowlying, such sites have other
disadvantages imposed by the high ground water
table. Many swampy areas, however, have been
excavated, filled and compacted to provide accept-
able building sites.
The map shows areas which are designated as
marshes or swamps on the topographic maps of the
Tampa area. In many instances, these swamps were
filled after the topographic maps were compiled but
all of the areas designated on the map can be
expected to contain organic deposits. While these
areas need not be eliminated from consideration as
potential building sites, it should be realized that
their surficial deposits may limit land use or impose
additional expense for pre-construction site prepara-
tion.


%e
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-.


('? LS' "l ...... "" ^/ (jwir









OLD ii T A M P A /
INTERNATIONAL do
7`A M PA 4 *y^L *v ''*



BAY PETER 0
KNIGHT AIR,
HILLSBOROUH






MACDILL AIRFORCE

TA MPA \ ,v



DISTRIBUTION OF WETLANDS IN THE TAMPA AREA

r-- MARSH

MANGROVE '

S WOODED MARSH













POTENTIAL COLLAPSE


Areas underlain by cavernous limestones present
special foundation problems especially for heavier
buildings. Stronger foundations for high rise
structures are a necessity in such areas and inexpen-
sive spread foundations are usually not adequate. If
the problem is not severe, strap foundation (which is
the next least expensive) may be adequate, but in
many cases more costly mat foundations must be
used. A pile foundation is not generally a satisfactory
alternative; since when sinks develop, slumping of
sediments creates lateral pressure which may cause
standard piling to fail.
Other steps which may be taken in order to
minimize the potential risk of loss of foundation
support include proper site drainage and design of the
structure to minimize the net increase in stress on the
subsurface deposits. Stress increases can be minimized
by placing a basement beneath a structure and in this
way the total weight of the building may not be
substantially greater than the weight of the soils
excavated for the basement.
A last resort in dealing with the problem of
collapse is subsurface grouting. However, this is very
expensive and the amount of grouting required is
unpredictable. When grouting is undertaken, the final
cost and success of the effort is unknown.
An alternative action, though not necessarily a
solution to the problem is to move the location of the
building to a different position on the site where
cavities in the limestone have not been encountered
in the subsurface investigation.
It is difficult to assess the risk involved in
constructing in an area of potential collapse. Al-
though imminent risk of collapse can be minimized
by site treatment and careful foundation design, there
is still a potential risk of loss of foundation support
due to cavities which may not have been revealed by
the subsurface investigation.


"The final decision as to the type of foundation
system to utilize will be dependent upon the owner's
willingness to incur certain costs and assume certain
risks. These must be balanced against one another in
view of the type structure, intended use and
consequence of problems which might develop if the
risk becomes a reality."1
Areas in which collapses have occurred in the past
are shown on a map in the Geology section of the
report with the discussion of sinkholes.


DEPTH TO ROCK

A map showing the position of the rock surface
relative to mean sea level is presented in the Geology
section. Whereas that map is prerequisite to under-
standing subsurface relationships, the matter of
concern in construction planning is the depth to rock
measured from land surface as illustrated on this
page. The contour lines reflect not only variations in
the bedrock surface, but also variations in local
topography. This map can also be considered a map
of the thickness of surficial deposits and is a useful
tool in construction planning. When the surficial
deposits are incompetent as a support material, it is
vital to know how deeply buried the rock surface is
so that a decision can be made as to whether it would
be more economical to improve the surficial deposits
or to utilize piling for support.
This map is an important component of land
suitability for construction as presented in the Land
Use section of the report.



SJames F. Orofino, Orofino and Company, (Personal
Communication).


4 S MILES


i
'c~s/
9A~ ig



r
a


i
/ii,


SCALE
SCALE










SOILS

Soils are an integral aspect of both geology and
land use planning. The mantle of sand deposited in
Hillsborough County during Pleistocene time is the
parent material for many of the soils which developed
in the area. Drainage, climate, vegetation, and
topography have also played roles in the formation of
local soil types.
The Soil Conservation Service (S.C.S.) has identi-
fied and mapped the soils of Hillsborough County on
the basis of their characteristics as determined in the
field and lab. These include color, texture, structure,
consistence, depth of soil over bedrock or compact
layers, steepness of slope, degree of erosion, nature of
underlying parent material, acidity or alkalinity of
the soil, etc. The soil layer studied and described by
the S.C.S. ranges from 40 inches to 72 inches thick.
On the basis of observed analytically determined
characteristics, soils are classified into phases, types
and series. "The soil type is the basic classification
unit. A soil type may consist of several phases. Types
that resemble each other in most of their characteris-
tics are grouped into soil series."'
Detailed maps of soil phases in the Tampa area are
presented in the Hillsborough County Soil Survey. In
addition, a County map showing soil associations is
included and a revised map is presented in the
Supplement to the Soil Survey. Part of this map is
reproduced here and the major characteristics of each
association are given.

Soils that occur together in a regular pattern in the
landscape have been grouped into soil associations.
The individual soils within each association may or
may not have similar properties and interpretations.

POMELLO-ST. LUCIE ASSOCIATION: Areas
dominated by nearly level to gently sloping, nearly
white, excessively to somewhat poorly drained,
strongly acid, deep sands. The native vegetation
consists of scrub oak, slash pine, saw palmetto and
sand pine. Soils in this association are low in organic
matter and fertility and are very drought, hence
they're poorly suited to cultivated crops and citrus.

LAKELAND-ARREDONDO ASSOCIATION: Areas
dominated by nearly level to gently sloping, well to r
somewhat excessively drained, slightly to very strong-
ly acid, deep, brownish colored phosphatic and non
phosphatic sands. The native vegetation consists
primarily of turkey oak, pine, shrubs, grasses, and a
few palmettos. The soils in this association are low in
organic matter content and fertility and have a low
available water capacity.

BLANTON-LEON ASSOCIATION: Areas dominated
by nearly level to gently sloping, moderately well
drained, deep sands. Native vegetation includes pine,
oaks, grasses and palmettos. The soils have low
organic matter content, low natural fertility, and low
available water capacity.


LEON-PLUMMER ASSOCIATION: Areas dominated
by nearly level, very strongly acid, deep, somewhat
poorly drained sands with an organic stained sub-
surface layer. The native vegetation includes slash
pine, saw palmetto, runner oak, gallberry, woody
shrubs, and various grasses. The soils are low in
organic matter content, natural fertility and available
water capacity.

ONA-SCRANTON-LEON ASSOCIATION: Areas
dominated by nearly level to gently sloping, some-
what poorly drained, strongly acid, deep sands on
broad, low flatland. The natural vegetation consists
of pine, turkey oak, live oak, saw palmetto, woody
shrubs, and grasses. Most soils in this association have
moderately high to high organic matter content, and
are moderately low in natural fertility.

RUSKIN-SUNNILAND-BRADENTON ASSOCIA-
TION: Areas dominated by nearly level, somewhat
poorly drained, sandy soil with loamy to clayey
subsoils. The native vegetation is pine, cabbage
palmetto trees, saw palmetto, runner oak, woody
shrubs, and grasses. The soils have low organic matter
content, and low to moderate natural fertility and
available water capacity.

RUTLEDGE-FRESH WATER SWAMP-PLUMMER
ASSOCIATION: Areas dominated by nearly level,
very poorly drained, deep, strongly acid to medium
acid sands in low wetland. Native vegetation is mainly
water-tolerant grasses and sedges, pickerelweed and
St. Johnswort, with cypress, bay, gum and occasional
pine trees in swampy areas. Soils have low to high
organic matter content and low fertility. Wetness is
an outstanding limitation for many uses of these soils.

BRIGHTON-TERRA CEIA ASSOCIATION: Areas
dominated by nearly level, very poorly drained,
shallow to moderately deep, acid to neutral organic
soils in marshes and swamps. Native vegetation
consists of sawgrass and various other sedges and
grasses. Organic soils in this association are high in
nitrogen but low in all other plant nutrients.
Excessive wetness is characteristic.

FRESH WATER SWAMP: Areas dominated by nearly
level, very poorly drained mineral and organic soils in
stream bottoms and swamps. Native vegetation
consists of hardwoods, cypress, bay, cabbage, palmet-
to, pines, shrubs, vines, ferns, and grasses.

SALT WATER SWAMPS AND MARSHES: Areas
dominated by nearly level, very poorly drained, saline
soils lying adjacent to and affected by salt water tidal
action. Native vegetation includes salt-tolerant grasses
and mangrove trees.

MINE PITS AND DUMPS: Areas dominated by larg,
open pebble phosphate mines and adjacent spoil
mounds.

ISoil survey, Hillsborough County, Florida, 1958, p. 58.


D



































-






*


0 I 2 3 MILES
i I ,1I I













SOIL RELATIONSHIPS


Soil data can be utilized in a variety of projects
which are of concern to local and regional planners.
In addition, the S.C.S. can provide technical assist-
ance on water management, soil erosion and stabili-
zation, agronomy, biology, etc.
"One of the most talked about concepts in recent
years is the idea of spreading the effluent from
municipal sewage treatment plants on the land to
eliminate the discharge of the effluent into surface
waters in the state."' Soil properties and plant
relationships play a vital role in land renovation of
waste water. The cation exchange capacity of the
soils (especially clayey soils) is a most important soil
property. This soil property along with plant nutri-
ent removal and denitrifying bacteria can very effec-
tively remove certain constituents of waste water.
"Any design of a system for land spreading of waste
materials must consider the soil system and its
relation to the local landscape, which includes the
stratigraphy, geomorphology, and hydrology of the
area under consideration."2
The local Soil and Water Conservation District has
expended a good deal of effort toward solving
drainage problems in the Tampa area. Although much
of this effort has involved agricultural lands, the
drainage principles have been applied to urban lands
as well. For example, shortly after the completion of
Tampa Stadium, it was found that the parking area
became flooded and unusable after rains. Using the
standard soil survey in conjunction with field
investigations, the S.C.S., working through the Hills-
borough Soil and Water Conservation District, de-
signed a subsurface drainage system for the parking
areas, and the flooding problem was eliminated.
Soils data can and should be used along with
geologic and hydrologic data as an input source for
environmental planning.



1 Livingston, J. B., Land Renovation of Waste Water, p. 1
from: Workshop Proceedings-Use and Interpretations of Soil
Surveys and Engineering Principles of Water Management,
1972, Soil Conservation Service.
SDaniels, R. B., Water Movement in Soils, p. 7, from
Workshop Proceedings-Use and Interpretations of Soil
Surveys and Engineering Principles of Water Management,
1972, Soil Conservation Service.


n URBAN PLANNING


Soil Conservation Service control structure in northwest
Hillsborough County.






Tampa Stadium parking area after installation of the
subsurface drainage system.




-


Shallow excavation showing a soil profile.


1i














Many land uses are essentially "surface" uses and
consequently, soil characteristics are the most import-
ant geohydrologic consideration in planning. The land
use most vitally linked with soils is agriculture or
agronomy. Land areas in which the soils are
particularly productive warrant consideration for
designation as agricultural lands. The S.C.S. has
compiled detailed information on the productivity of
various soils with regard to assorted crops.
Other land uses in which surficial materials (soils)
are of primary concern include recreational areas,
highway and airport sites, cemeteries, golf courses,
single story buildings, etc.
Shown on this page is Table 5 from the
Supplement to the Soil Survey: Hillsborough County,
Florida. This lists the degree of limitations, restric-
tions and hazards for various land uses by soil
associations.
Two factors should be borne in mind when this
table is examined:
1) This generalized table is derived from more
detailed S.C.S. tables and maps. Final evaluation of a
specific site for a proposed use must be supported by
detailed on-site investigations.
2) The limitations listed in the table are based on
the characteristics of only the top 40-72 inches of
material.





The Rating System

None to slight: Soils have properties favorable for a particular
use. Limitations are so minor that they can be overcome
easily. Good performance and low maintenance can be
expected from these soils.
Moderate: Soils have properties moderately favorable for a
particular use. Limitations can be overcome or modified
with planning, design, or special maintenance.
Severe: Soils have one or more properties unfavorable for a
particular use. Limitations are difficult and costly to
modify or overcome, requiring major soil reclamation,
special design, or intense maintenance.
Very severe: Soils have one or more properties so unfavorable
for a particular use that overcoming their limitations is
very difficult and costly. Reclamation is extreme, re-
quiring the soil material to be removed, replaced or
completely modified.
The rating provided for each association is for the
predominant soil in the association. Other soils in the
association may have different ratings. These ratings are
actually measures of "degree" or "intensity" of soil
limitations, restrictions, or hazards for a certain use. Most
soils are suitable for all uses if provisions can be made to
overcome or eliminate the problems.


NAME OF ASSOCIATION
WITH COMPONENT SOILS AND
PERCENT OF EACH


POMELLO-ST. LUCIE
POMELLO 31
ST. LUCIE 24
OTHERS 45

LAKELAND-ARREDONDO
LAKELAND 41
ARREDONDO 23
OTHERS 36


BLANTON-LEON
BLANTON
LEON
OTHERS

LEON-PLUMMER
LEON
PLUMMER
OTHERS


ONA-SCRANTON-LEON
ONA 30
SCRANTON 21
LEON 16
OTHERS 33

RUSKIN-SUNNILAND-BRADENTON
RUSKIN 40
SUNNILAND 30
BRADENTON 15
OTHERS 15

RUTLEGE-FRESH WATER SWAMP-
PLUMMER
RUTLEGE 25
FRESH WATER SWAMP 24
PLUMMER 10
OTHERS 41

BRIGHTON-TERRA CEIA
BRIGHTON 34
TERRA CEIA 30
OTHERS 36

FRESH WATER SWAMP


SALT WATER SWAMPS & MARSHES



MINES, PITS AND DUMPS


FOUNDATIONS
FOR LOW
BUILDINGS


MODERATE
WT



SLIGHT


HIGHWAYS, DIRT ROADS
AIRPORTS, UNPAVED STREETS
STREETS, PAVED AND PARKING
ROADS AND AREAS
PAVED PARKING
AREAS


SLIGHT




SLIGHT


SEVERE
TRAF



MODERATE
TRAF


MODERATE MODERATE MODERATE
WT WT, FL TRAF, WT, FL,
SL


SEVERE
WT, FL


SEVERE
WT, FL




SEVERE
WT




SEVERE
FL, WT






VERY SEVERE
WT, FL, PBV



VERY SEVERE
FL, WT

VERY SEVERE
WT. FL, PBV


CAMP SITES,
PICNIC AREAS
AND
PLAYGROUNDS


GOLF COURSES


FALLOUT
SHELTERS
AND
BASEMENTS


CEMETERIES


SEVERE SEVERE MODERATE MODERATE
TRAF, PROD PROD, AWC WT WT, PROD, AWC


SEVERE
TRAF



MODERATE
WT, FL,
TRAF, SL


MODERATE
PROD, AWC


SLIGHT


SLIGHT


MODERATE MODERATE MODERATE
WT, AWC WT, FL WT, FL,
PROD


MODERATE MODERATE MODERATE MODERATE SEVERE
WT, FL TRAF, WT, FL WT, TRAF, FL WT, FL WT, FL


SEVERE
WT, FL


SEVERE MODERATE MODERATE SEVERE
TRAF, WT, FL WT, TRAF WT WT, FL


MODERATE MODERATE
WT, SH-SW WT, TRAF


SEVERE
WT, FL






VERY SEVERE
TSC, WT, FL



VERY SEVERE
WT, FL

VERY SEVERE
FL, WT, TSC


SEVERE
WT, FL






VERY SEVERE
TRAF, WT, FL



VERY SEVERE
FL,WT

VERY SEVERE
FL, WT, TSC


(VARIABLE) (VARIABLE) (VARIABLE)


MODERATE MODERATE SEVERE
WT,TRAF WT WT, FL


SEVERE
WT, FL






VERY SEVERE
TRAF, WT, FL



VERY SEVERE
FL, WT

VERY SEVERE
FL, WT, TRAF


SEVERE
WT, FL






VERY SEVERE
TRAF, WT, FL



VERY SEVERE
FL, WT

VERY SEVERE
WT, FL, TRAF,
SALINITY, PROD


SEVERE
WT, FL






VERY SEVERE
WT, FL



VERY SEVERE
FL, WT

VERY SEVERE
WT, FL


SEVERE
WT, FL


SEVERE
WT, FL




SEVERE
WT, FL




SEVERE
WT, FL






VERY SEVERE
WT, FL



VERY SEVERE
FL, WT

VERY SEVERE
WT, FL


(VARIABLE) (VARIABLE) (VARIABLE) (VARIABLE)


ABBREVIATIONS: WT-WATER TABLE, TRAF-TRAFFICABILITY, FL-FLOOD HAZARD, AWC-AVAILABLE WATER CAPACITY, PROD-PRODUCTIVITY, PBV-PRESUMPTIVE
BEARING VALUE, SL-SLOPE, TSC-TRAFFIC SUPPORTING CAPACITY, PERM-PERMEABILITY, ORG-ORGANIC


DEGREES OF LIMITATIONS, RESTRICTIONS AND HAZARDS FOR SELECTED USES BY SOIL ASSOCIATIONS, HILLSBOROUGH COUNTY, FLORIDA
(MODIFIED FROM SOIL CONSERVATION SERVICE, 1969, TABLE 5)




ENERGY


RESOURCES


mILm


-.07












PRIMARY ENERGY SOURCES


For purposes of this energy discussion, the Tampa
Bay Area will be assumed to include Hillsborough,
Pinellas, Pasco, Polk and Manatee Counties.
Adequate supplies of primary energy sources, at
reasonable costs, are essential to modern living.
Without such supplies every facet of our way of life is
handicapped. Growth of industry and of population
is dependent upon the relative cost of such supplies.
Historically and right up to the end of 1972, the
area is 100% deficit in internal primary energy
supplies. All primary energy used in the area, both
directly and through conversion to secondary energy
(electricity), is imported. Most is "domestic",
imported from other parts of the United States, some
is foreign, imported from other countries.
This complete dependence upon imports may
change in the future. It is now suspected that there
may be petroleum deposits in the area. It is known
that uranium (the fuel source of nuclear power
plants) exists in connection with the phosphate
deposits in the eastern portion of the area. Develop-
ment of this resource may become economically
feasible in the future. More detailed discussion of
these possible future energy sources will be found in
other sections of this report.
Primary energy is imported to the area in the
forms of liquid petroleum products, natural gas and
coal.
Table "A" lists the various primary energy sources
brought into the area during 1971 and illustrates the
growth for 12 months ending October 31, 1972. For
ease in comparing utilization value, tons of coal and
MCF (million cubic feet) of gas have been converted
to "equivalent barrels" of oil.
Some indeterminate portion of the liquid products
brought into the area is exported to other parts of
Florida by truck, rail and pipeline. There appear to be
no available statistics covering these movements but a
guess is that they may amount to 15-20% of the
quantities shown in the table.


PETROLEUM
LIQUIDS

TOTAL
63 Million Bbls.


1971







COAL
(Equiv. Bbls.)


In addition to the quantities shown in the table,
7,957,000 barrels of residual oil were brought into
Port Manatee in 1972, all of which was barged up the
coast to Florida Power Corporation's plant at Crystal
River. All of this residual was of foreign origin.
Liquid petroleum products are, with very minor
exceptions, brought in by water through the Port of
Tampa (including Weedon Island in St. Petersburg)
and Port Manatee. All of the crude oil, most of the
residual fuel and minor amounts of the jet fuel and
diesel oil are used as power plant fuel in the
generation of electricity. The balance of the residual
is used in industrial heating and for fueling ships in
the port, while the uses of the other products are
obvious.
Most of the residual is of foreign origin, mostly
from Venezuela and the Dutch West Indies. (Starting
in 1973 there will be substantial imports of residual
from the Virgin Islands). All of the crude oil is
imported from Libya. The balance of the liquid
petroleum products is of domestic origin, principally
from the refineries along the Texas and Louisiana
coasts of the Gulf of Mexico.


Aviation Gasoline
Automotive Gasoline
Jet Fuel & Kerosene
Diesel Fuel (No. 2)
Residual (No. 6)
Propane
Crude Oil
Total liquid
Coal (tons)
Coal (equiv. bbls)
Total Water
Deliveries
Gas (MCF)
Gas (equiv. bbls)
Total Primary
Energy
Foreign Origin


(Equiv. Bbls.)


1,168,000
32,994,000
7,253,000
5,944,000
14,825,000
822,000
63,006,000
2,845,000
10,353,000
73,359,000
21,827,000
3,520,000

76,879,000
11,701,000


As an approximation, the cost of transportation of
petroleum products and of coal, in large quantities by
ocean vessel, is about 1/30 of the cost of moving the
same quantity overland by truck. Specifically, at this
writing, a barrel of residual oil moves 2,000 miles
from the refinery in Venezuela to the Port of Tampa
for about 30 cents. It costs over 50 cents more to
then move the same barrel 100 miles by truck from
Tampa. There are no more than three other ports in
Peninsular Florida which can handle ships as large as
can be handled in Tampa Bay. And none of these
have as extensive oil handling and terminal facilities
as does the Port of Tampa (including Port Manatee).
The net result is that the Tampa Bay Area can offer
fuel using industries all grades of petroleum products,
from more suppliers, and at lower costs than can
almost any other area in Florida or for that matter, in
the entire southeast.


1,597,000
36,849,000
6,103,000
6,820,000
12,846,000
838,000
556,000
65,609,000
3,919,000
12,343,000


(Assume 3.639 bbls/ton)


77,952,000 (Equivalent bbls.)

(Assume 6.32 MCF/bbl.)
(Equivalent bbls.)
11,396,000 (Almost exclusively No. 6 and crude)


Note: Basic data from reports issued by the Tampa Port Authority.


TABLE A

Primary Energy Sources Received in Tampa Bay Area
(Barrels of 42 U.S. Gallons)


12 Months Ending
9/30/72















Natural gas is brought into the area by the pipeline
system of the Florida Gas Transmission Company
which extends from southern Texas around the Gulf
into Florida. Most of the gas handled by the pipeline
originates in Texas and Louisiana. Relatively small
amounts are now being picked up from the new oil
fields in northwest Florida.
Approximately 45% of the gas the pipeline brings
into the area is used in generation of electricity.
Another 30% is sold directly to large industrial users,
with the balance being sold to 8 retail gas distributor
systems for resale for residential, commercial and
small industrial use.
The pipeline facilities of the Florida Gas Trans-
mission Company and of the retail distribution
systems supplied by it have expanded and kept pace
with the demand for gas in the area. In spite of the
nationwide shortage of natural gas, there has been
very little curtailment, or interruption, of gas supply
to industrial users, and none at all to commercial and
residential users. However, at least until the nation-
wide gas supply picture improves, Florida Gas is
accepting no new large industrial customers but to
date there has been no restriction placed on serving
new residential, commercial and small industrial
customers.
All of the coal brought into the area is used by
Tampa Electric Company for generation of electrici-
ty. This coal originates in strip mines in Western
Kentucky and Southern Illinois and is moved in river
barges down the Ohio and Mississippi Rivers to a
transship facility below New Orleans. At this point it
is reloaded into ocean going barges, holding over
20,000 tons each, for the Gulf of Mexico crossing to
the Tampa Electric docks where it is unloaded by
fast, automatic machines. The barges return loaded
with phosphate rock, an operation which substantial-
ly reduces the transportation cost of the coal.


TALL-H-'; ,E








FLORIDA GAS TRANSMISSION LINES


* *


ORLANDO
*ORLANDO


TAMPA *


Q



















ELECTRIC ENERGY




The entire State of Florida is blanketed by a
network of high voltage transmission lines which
interconnect the load areas with 35 power plants of
four investor owned power systems, four major
municipally owned systems, several smaller municipal
systems and. one small federally owned plant.
Additionally, the transmission network is intercon-
nected at several points to the north and west with
the country's overall network.
Various portions of the Florida network are
owned by the individual power supplying systems.
However, it is completely interconnected and
operated substantially as though it were all under one
ownership. This results in a high degree of service
reliability, with every electrical load area being served
by multiple sources. With rare exceptions, power
plant and transmission failures do not cause inter-
ruption of electrical service anywhere in the state.
The accompanying map shows the portion of this
transmission network within the Tampa Bay Area as
of January 1, 1972, with most of the circuits
operating below 115,000 volts omitted for clarity.
Also not shown are some 50 of the small substations
where power is stepped down to lower voltages for
distribution to ultimate users and many of the
industrial substations where power is delivered to
large users at transmission voltages.
The Tampa Bay Area is served by three investor
owned and one municipally owned electric utility
systems. Hillsborough County, the eastern portion of
Polk County, and minor portions of Pinellas and
Pasco Counties are served by Tampa Electric Com-
pany. Florida Power Corporation serves, with minor
exceptions, Pinellas, Pasco and the west portion of
Polk County. Manatee County is served by Florida
Power and Light Company. The City of Lakeland and
some adjacent territory is served by the Lakeland
Department of Electric and Water Utilities. Electric
power distribution in some portions of the area is by
municipally owned distribution systems and Rural
Electric Cooperatives, all of whom purchase their
power wholesale from one or another of the
suppliers. ,






There are power plants at eight locations within
the area, as detailed in Table 1, with a total capability
of 2975 MW. The interconnected transmission net-
work enables any part of the area to be served irn case
of need from any of the 35 power plants in the state
which have a total capability of over 14000 MW.
That the electric utilities serving the area are
keeping abreast of needs is shown by the fact that
generating capability within the area has doubled
since 1965 and that additional capability now under
construction or definitely planned, will, in the next
four years, more than double the present capability.
Depending on the type of generating unit and the
economics of a particular situation, these power
plants burn a variety of fuels-all brought into the
area through the Port of Tampa (except natural gas,
which is pipelined in). Table II shows the total
amount of each fuel used and the percentage this
represents of the total brought into the area. In
summary 29% of the total primary energy sources,
coal, oil and gas, brought into the Tampa Bay Area
are converted by the utilities into electric inprrn,


TABLE I


Type
Residual Oil
Gas

Coal

Light Oils
Crude Oil
Total Equiv. Bbls.


TABLE II

Tampa Bay Area
Power Plant Fuel Use

(Year 1972)

Quantity Used
9,527,632 bbl.
8,451,013 MCF
(1,337,185 equiv. bbl.)
3,349,724 tons
(12,189,646 equiv. bbl.)
73,101 bbls.
465,075 bbls.
23,592,639


% of Total Shipped into Area
74%
39%

100%

negligible
100%
29%


Note: Data supplied by the utilities.


Tampa Bay Area Power Plants (1/1/73)


Capability (MW)


No. Generating Units


1972 Net Output
Type Fuel (Millions of KWH)


FLORIDA POWER CORP.
Bartow
Bayboro
Higgins
Bartow
Higgins
TAMPA ELECTRIC CO.
Hookers Point
Gannon
Big Bend
Gannon
Big Bend
CITY OF LAKELAND
Larsen
Plant No. 3
Larsen
Plant No. 3
TOTAL CAPABILITY


ST ......
GT ........
D ..... ....


Plant Types
.......... Steam Turbines
........... Gas Turbines
.. ............. Diesel


Fuel T


HO
CO ..
LO
G ...
C ....


ypes
. .Residual (No. 6) Oil
......... Crude Oil
.. Light Oil distillatee)
....... Natural Gas
.............Coal


Note: Data supplied by the utilities





Greek owned tanker "Demosthenes V" discharging 140,000 barrels of Venezuelan residual oil at
Florida Power Corp, Weedon Island, St. Petersburg. (photo courtesy of Florida Power Corp.)


Plant Name


201
1,082
352
18
18


HO-G
HO
HO-G
CO
LO-G


HO
C
C
LO
LO


HO/G
HO-G
LO
LO


3,058
229
780
207
115


1,079
5,136
1,977
10



444
456
Included
in S.T.
13,491


127
103
39
6
2975 MW















Preliminary figures indicate that during 1972 the
electric utilities supplies over 15 billion KWH of
electric energy, broken down as follows:


Millions of KWH


6,007

3,183

4,470

1,598

15,258


% of Total

39

21

29


TABLE III


Typical Electric Bills
January 1, 1971


'Approximately 50% of industrial use was in the
phosphate mining and processing industries.
2Includes street lighting and other municipal uses,
sales for resale, company's own use, etc.


CD
0 E z
E 0 E
C = E E2

ES So E BO
(fl N 2 ,r ^ 1


Rates for electric service in the Tampa Bay Area
are generally closely in line with National and Florida
average rates, and far below the highest rates in the
"lower 48" states. These highest rates are generally
found in the New England and New York City areas.
Rates lower than charged in the Tampa Bay Area are
generally found in areas abundantly supplied with
hydro-energy, with its zero fuel costs, or in areas
within coal or gas fields where there is little or no
transportation component in the utilities fuel costs.
Table III lists rates in effect on January 1, 1971.
As the direct result of spiralling fuel costs, general
inflation and the high costs of meeting environmental
demands, most of the country's electric utilities have
been forced to increase rates during the intervening
two years.
Therefore the actual rate figures given in the table
are no longer applicable. However, there would be no
important change in the relative positions of the
various areas listed.


Highest in 48 States
(cities of 50,000
or more) 12.78 27.66 43.07
National Average 7.84 19.24 28.45
Florida Average 7.39 19.51 30.65
Tampa Bay Area Avge. 8.03 19.50 32.68
Tampa Bay Area
Highest 8.13 19.73 36.18
Tampa Bay Area
Lowest 6.93 19.27 29.19
Sources: Federal Power Commission Publication
"Typical Electric Bills", December, 1971.


392.80
252.43
253.28
245.16


275.65

214.68


$2,333
1,269
1,157
1,129

1,256

1,002


1Approximately 50% of industrial use
was in the phosphate mining and
processing industries.
2Includes street lighting and other
municipal uses, sales for resale,
company's own use, etc.


USE OF ELECTRICITY


*MILLION KILOWATT HOURS


Residential

Commercial

Industrial'

Other2

Total


E

.-_









ENERGY OF THE FUTURE



Modern man needs sources of energy to support
his way of life. Such sources are needed to provide
light, heat and cooling of his buildings; to move his
automobiles, airplanes, trains, trucks, ships; to power
his shops, factories and mines and for countless other
uses. Without adequate supplies of energy, civilization
and life would end.
For the United States, 97% of the energy used
comes from the three fossil fuels, coal, oil and gas.
Hydro-electric and nuclear energy supply the remain-
ing 3%. About 26% of the fossil fuels are converted
into electricity, the balance is used directly. The
figures for the rest of the world are not greatly
different, except that in some areas wood and other
organic materials contribute to the energy supply in a
small way.
The fossil fuels represent a finite resource-once
used they can not be replaced. Therefore there must
inevitably come a day when there are no more fossil
fuels to support a civilization. Opinions vary as to
when this day will come but the best estimates
indicate that by the end of this century supplies of
natural gas will be substantially exhausted, liquid
petroleum supplies may last through the middle of
the next century, coal will probably last 300 to 500
years.
In the intervening years we can expect constantly
increasing costs, coupled with spasmodic but in-
creasingly severe shortages. The local shortages of
natural gas and heating oil during the winter of
1972-73 were an insignificant illustration of what will
become commonplace if substitute sources of energy
are not developed.
To date there appear to be two such substitutes
which have reasonable hopes of being developed into
practical sources of energy-nuclear power and solar
power.
Nuclear power is furthest along, having been
developed to the point where it is (early 1973)
contributing 2% or 3% of the nation's total energy
needs, all of this in the form of electric energy.
Present indications are that by 1985, nuclear will be
contributing between 11% and 15% of the country's
energy needs.
Florida's two largest utilities have been among the
leaders in the nuclear field. In January 1973 they had
one large nuclear generating unit operating, three in
various stages of construction and one more in the
advanced planning stage. All of Florida's utilities are
studying the need for, and feasibility of additional
nuclear units.


None of the nuclear units now definitely planned
for Florida will be in the Tampa Bay Area. However,
the area will probably see such units in the future
since there are locations in the area which meet the
rather stringent siting requirements for such generat-
ing units.
The current commercial types of nuclear generat-
ing units consume uranium as a fuel, much as a fossil
unit consumes coal, oil or gas. Uranium, like the fossil
fuels, is a finite resource. As available supplies are
used up, the price increases.
It is known that there are fairly large amounts of
uranium ore in connection with the phosphate
deposits in the eastern portion of the Tampa Bay
Area. It is currently estimated that this ore is
recoverable at costs of around $15 per pound of
refined U30s. The current market price of U308 is
less than $8 per pound and industry sources estimate
that it will be the late 1900's before market
conditions will make recovery of Florida's uranium
ore economically feasible. (See W. R. Oglesby's article
on this subject, Page 48, Tallahassee Area study
published by the Bureau of Geology in 1972.)


PRESENT


U.S. ENERGY


SOURCE


U.S. ENERGY SOURCE

PROJECTED TO 1985


There are four major processing steps involved in
converting the U308 to actual nuclear plant fuel.
Special requirements make it most unlikely that
Florida would ever be an attractive location for plants
involved in the first two of these steps, conversion of
the powder U308 into the gaseous UF6, and
enrichment of this gas by increasing its contained
percentage of the isotope U235 .
However, the remaining steps, conversion of the
gaseous, enriched UF6 to the powder UO2, pelletiz-
ing this powder, and assembling the pellets into
reactor fuel assemblies are exactly the type of
industries which Florida likes and which like Florida.
They are light, clean, high precision industries,
requiring good supplies of highly skilled labor and
abundant resources of engineering and scientific
manpower. Given an adequate local market for their
output, which should exist by the early 1980's, it
should be possible to attract this industry to Florida.
Going back now to the statement that uranium is a
finite resource, it is evident that, like the fossil fuels,
there must come a day when it is exhausted. Before
that day comes, perhaps early in the next century,
another type of energy source must have been
brought to commercial practicality.


Uranium oxide could be produced from 'wet process' phosphate plants.
Photo courtesy of the Florida Phosphate Council 79












01 AND GAS


The "breeder reactor" which actually can produce
more fuel than it consumes, has been proven in the
laboratory stage. Funded jointly by the electric
utility industry and the Federal Government, the first
"demonstration" plant, using the breeder process, is
now in the engineering stage. Because of the problems
involved in converting a laboratory process to a
practical commercial power plant, many in areas of
new and unknown technology, it is expected that it
will be the mid 1980's before the first commercial
breeder plant will be operational, at a total develop-
mental cost of well over one billion dollars.
But, if the "breeder" or some equivalent process is
not available by early in the next century, civilization
as we know it must come to an end!
Solar energy research has been sadly neglected,
perhaps because it does not have the glamor of
nuclear and other advanced scientific development.
The work which has been done in this field, largely at
the University of Florida leads us to believe that if a
small fraction of the money and scientific man hours
which are going into nuclear development were put
into solar development, then we would have the
means to capture enough of the limitless solar energy
to supply all of the energy needs of the world as long
as it exists. And Florida, because of its unique
climate, should be the center of such research.


_y ALABAMA

SrANTA OSA OKALOO5A WALTON JACKSON G E O R G I A
ASHINGTON_ GTD -DN -- -.
GADSDEN M/ HAMILTON
v CALHOUN / MADISON

fl \u --~ TAYLOR I FYTT
GULF --- -A.N \ LAFAYETTE
FRANKUN


EASTERN MARGIN OF F ilxE

MISSISSIPPI SALT BASIN o E




^ I,























FLORIDA SOUTI
S l
Scale In Miles
/t
o J


There.is no oil or gas production within the Tampa
Area, and no immediate prospects for such produc-
tion. Hillsborough County, and the six counties
surrounding it within a 50-mile radius, have had 41
oil tests drilled therein between 1900 and 1973.
However, only 12 of these tests have been drilled
within the past 30 years, since the discovery of
Sunniland Field, in Collier County. Sunniland marked
the entry of Florida into the ranks of oil producing
states, and we now rank 12th out of 32 states which
have petroleum production.
Many of the earlier wells in the Tampa area were
not adequate to test the potential pay zones. In short,
these seven counties remain in the Twilight Zone, as
far as their petroleum prospects are concerned; they
are possible but not probable areas from which oil or
gas may be recovered some day. The preceding
statement is made in light of the following considera-
tions:
1. The known producing trend in south Florida
extends along the northeastern portion of the
Shelf associated with the South Florida Basin.
2. The known producing trend in northwest
Florida extends along the eastern margin of the
Mississippi Interior Salt Basin.
3. The Tampa Area is not located in a basin but
rather on the central Florida platform, a
structurally positive area. There is no particular
reason to believe adequate petroleum source
beds exist on or in conjunction with this central
platform.


H FLORIDA
BASIN
.90O












SEA LEVEL


The lack of oil production in the vicinity of
Tampa does not signify that the availability of
gasoline or fuel oil is less here than in other
metropolitan areas. Austin, the capital of Texas,
experienced a dozen critical periods of petroleum
shortage during 1972. The City of San Antonio,
Texas, was threatened by a blackout when the
municipal electric power system could not obtain
natural gas to operate in the spring of 1973. No
power shortages due to lack of fuel were reported in
the Tampa area. Tampa, like the rest of Florida, but
unlike Texas and most of the United States has no
liquid petroleum products pipe lines; and hence has
complete flexibility of its sources of supply. Tampa is
one of four deep sea ports in the Gulf Coast of the
U.S. and is open to the fuel markets of the world. On
the other hand, most of the inland cities of the
United States are served' by product pipe lines which
are inflexible. If the input supply of such pipe lines is
curtailed, the output at the distribution point is
likewise curtailed.
Although there is no pipe line supply of petroleum
to Tampa, the city is served by the natural gas line of
Florida Gas Transmission Company. Natural gas for
domestic use is no real problem; the supply of natural
gas for generating electricity is, unfortunately, in-
adequate here as in other cities. This is not due to
lack of capacity of the pipe line. Its carrying capacity
could be increased by the simple expedient of
increased compressor capacity along the line. There is
a real shortage of natural gas at the sources of supply.
Company officials of Florida Gas recently have
announced an intention to convert one of the parallel
lines in their gas transmission system to a products
pipe line. If this is done, Tampa as well as other areas
of Florida served by the Florida Gas Company will
enjoy lower transmission costs of fuel overland and
reduced trucking on the highways. However, users of
this fuel may find they have traded a flexible
seaborne supply open to world markets for a rigid
source controlled by the supply available at the input
points to the pipeline.


5000










10000


LINE of SECTION


Crude oil produced in Florida is from two widely
separated basins which are: The Mississippi Interior
Salt Basin and the South Florida Basin, shown on
Page 80. Production occurs below 11,000 feet in the
South Florida Basin and below 15,000 feet in the
Florida portion of the Mississippi Salt Basin.
The production from Jurassic age strata in Jay,
Blackjack Creek and Mt. Carmel Fields occurs in the
Norphlet Sand, which immediately overlies the
Louann Salt, and in the Smackover Limestone which
overlies the Norphlet Sand. These three fields will


produce about 100,000 barrels of oil and
100,000,000 cubic feet of gas per day, when fully
developed, about 20% more than their current
production rate.
The Sunniland Limestone of lower Cretaceous age
supplies the balance of crude oil production from six
fields centering around Immokalee, Collier County,
Florida. The combined daily production from these
fields is about 13,000 barrels of crude oil. No
commercial amount of gas is derived from these
undersaturated reservoirs.













Florida produces about 30,000,000 barrels of
crude oil annually and uses about 7 times this amount
of refined petroleum products. All of the crude
produced in Florida is exported to refineries in other
states and all its petroleum products are imported by
sea. Therefore, oil production in the state has no
more direct effect on Florida's petroleum products
supply than it has on other areas in the United States.
However in the case of gas, Jay Field produces about
a tenth of the supply carried for distribution by
Florida Gas Transmission pipe line to the Tampa area
and around the State. Gas is a desirable, clean, and
currently, low cost fuel. If enough of it is discovered
in the state, we could solve the environmental
problems connected with electric power generating
plants while the supply lasted.


NATURAL GAS


1.635

BCFG


CAPACITY
100 MILLION
BARRELS


FILL-UP
TIME


GAGE BBLS
IN MILLIONS


1.75 YEARS(Est.)


YEARS


30 YEARS TO
ONE-HALF FULL


CAPACITY
150 MILLION
BARRELS


5 YEARS TO
FILL UP(Est.)


GAGE BBLS
IN MILLIONS
100-.


FILL-UP
TIME
- DEC.1979























EFFECT ON
BALANCE OF
PAYMENTS





EFFECT ON
POLITICAL, ECONOMIC
POLICIES


THE U.S. ENERGY GAP 1970-1990


NEED FOR NEW
FACILITIES-TANKERS,
SUPERPORTS,
REFINERIES,
PIPELINES


INCREASED
IMPORTANCE
OF CONSERVATION
MEASURES


Source: SHELL OIL CO.


Ultimately, Florida, like the rest of the country,
will be forced to shift to an energy base other than
petroleum and natural gas, as the domestic supply
becomes exhausted. The international supply can
augment our own petroleum resources; but for
economic, security and political reasons it is nonsense
to suppose we could exist as a wholly dependent fuel
imports nation.
This is illustrated by a chart entitled "The U.S.
Energy Gap 1970-1990" from a publication by Shell
Oil Company shown in reproduction. The graph
shows total oil imports of about 2% million barrels
per day (B/D) in 1970, rising to 5% million B/D in
1975, and to 23% million B/D in 1990. If the true
cost of foreign oil in 1970 is taken at $1.00 per barrel
(considering that United States companies operating
abroad must pay foreign royalties and taxes, and that
shipping costs are paid to foreign nationals) our trade
deficit on oil was about $900,000,000. By 1975, this
cost may well double, as both oil prices, royalties,
and transport costs increase. Hence the 1975 deficit
estimated on oil imports is 4 billion dollars. These
costs will probably redouble by 1990, so that the
deficit on oil imports may attain 34 billion dollars.
These projections do not allow for dollar inflation
which the Organization of Petroleum Export
Countries insists must be adjusted with more dollars.
The chart indicates we will produce 10 million
barrels of oil per day in the U.S., and import 23%
million barrels by 1990. If this occurred, the Nation
would be dependent on foreign sources for the energy
necessary to our military and industrial survival, for
the two are interdependent. The obvious answer is
that the charted projection will not occur and that we
will not be using a total of 33% million barrels of
petroleum in 1990. Either we shall have adapted to
such alternate sources available by reduction of coal,
oil shales, and tar sands to petroleum liquids, or
perhaps shifted to a hydrogen energy base through
electrolysis of water in a related nuclear reactor
program furnishing electric power. A third course, to
reduce our total use of energy, will take place as the
cost of fuel increases relative to other items in the
gross national product.


A


1975


1980


*CRUDE OIL EQUIVALENT


4GED
6f84






LAND USE


1


7


el


i .&:


'lim*
^"^^ f^^ ^













CURRENT LAND USE


Although 86.5% of the land within the urban
limits of the City of Tampa is developed, only 15.1%
of the land within the Tampa area (as delineated by
the map) is developed. The following table shows the
percentage of land in the Tampa area that falls within
each land use category:


single family residences
multi-family residences
mobile homes
retail and services
tourist commercial
industrial
transportation and utilities
public and semi-public
recreation and open space
agriculture
vacant and open range
inland water






















1
N


1012
SCALE
(MILES)


8.0%
0.3%
0.6%
0.9%
0.1%
1.2%
0.9%
1.6%
1.6%
39.8%
43.4%
1.6%


Present land use largely reflects the "preference
development" practices of the past which were
essentially based on the location of certain natural
and cultural features and on economic considerations.
Certainly many examples of unwise land use within
the Tampa area could be identified, however, it is not
the purpose of this report to criticize the existing
conditions that cannot be significantly altered. It
should be pointed out that current land use patterns
do have a marked influence on the direction that
future development will take. As increasing know-
ledge about the area becomes available appropriate
legislation and zoning designations can serve to
channel development into patterns compatible with
environmental considerations.


(so-rcj. T-mp1a Da Regional Pla-:iing Co ,nil)


0 I 2 3 MILES
SCALE


PROJECTION OF THE PERCENT INCREASE IN DEVELOPED LAND
BETWEEN 1972 AND 2000.









FUTURE LAND USE


Presented on this page is the Hillsborough County
Planning Commission's Provisional Plan of Develop-
ment through 1990. At the time of this writing, the
plan had not been finalized, and the copy shown here
is subject to revision. The plan is based on existing
major land use categories. Areas which are currently
urbanized represented the starting point for the
Planning Commission.
Preferred future expansion areas include those
areas into which urbanization anticipated by 1980
and by 1990 may best be channeled. It should be
pointed out that in both categories, two to three
times more land has been assigned for urbanization
than trends for future land consumption indicate is
needed. This extra allotment is to compensate for
portions of the designated land which may be found
undevelopable, and to allow for additional urbaniza-
tion that could not be foreseen at this time.
Around the fringes of the Tampa area, land is
slated to remain undeveloped or to be used as
agricultural land. According to the Planning Com-
mission, much of this land is developable, however, it
is not needed for current or projected land use
requirements.
Substantial portions of land have been designated
as interim or permanent open area. Included in this
category are preservation and conservation areas or
those lands which should experience little or no
development. Riverine and swamp environments fall
into this category, and it is envisioned that recreation
will be the primary land use here. Also included are
Southwest Florida Water Management District's exist-
ing and proposed reservoir areas.
In preparing the Plan of Development the Planning
Commission has utilized a sequential approach.
Initially, environmental factors were evaluated and a
series of maps indicating land use suitabilities were
constructed largely on the basis of geohydrologic
considerations. These maps were used in conjunction
with socio-economic projections in order to establish
a basic pattern for growth.


In delineating specific urbanization patterns within
suitable areas, several planning concepts were utilized.
The concentric pattern of development (where
growth takes place around the perimeter of the
existing urban center) was used in combination with
the radiating plan (where urbanization expands along
highway routes) and the satellite cities concept
(discussed on the following page) to establish what is
hoped to be an equitable and environmentally
compatible plan of development.
With regard to specific land uses, several note-
worthy policies are employed by the Planning
Commission. Because of the need to de-centralize
traffic flow and diffuse pollution, planning of
concentrated industrial areas is avoided. In general
industrial parks help achieve the goal of diluting the
problems often associated with industry. With large
peripheral land areas and attractive planting, industri-
al parks can be a visually pleasing addition to the
landscape. Busch Gardens is a notable local example.
Transportation is another important consideration
in planning for the growing Tampa area. The Planning
Commission attempts to coordinate all phases of
transportation and to incorporate highway, port and
airport traffic into a single efficient network.
An additional effort of the Planning Commission is
to de-emphasize development in northwest Hills-
borough County in the area of the well fields.
The plan shown on this page reflects the environ-
mental awareness of the Planning Commission. As
new data becomes available and growth trends
change, the plan of development will be revised and
updated.
A future land use plan, by nature, constantly
evolves in response to changing regional needs and
increasing cognizance of local potentials. Both the
Hillsborough County Planning Commission and the
Tampa Bay Regional Planning Council are currently
involved in updating future land use plans for the
Tampa area. TBRPC prepared a preliminary plan for
1985 in 1968. A portion of that plan is presented on
the following page.



















According to the Council,
"The preliminary plan provides for the alloca-
tion of the region's developable land resources
into patterns of use which will be required to
serve the future population."

Among the objectives of the plan are the following:

LAND DEVELOPMENT Encourage compatible
land use arrangements through purposeful site plan-
ning to provide compatible, compact and diversified
land development.

WATER SUPPLY Provide a guaranteed water
supply for the region through the investigation,
development and preservation of all possible sources
including watersheds, surface supplies, salt water
conversion, and aquifers.

WATER AND AIR POLLUTION Stop water and
air pollution through better public management and
control of wastes, location planning for polluting
industries, the formation of effective sanitary sewer
districts, the establishrant of on-site treatment of
industrial wastes, and the investigation of a regional
solid wastes disposal system.

SHORELINE DEVELOPMENT Discourage shore-
line development in conflict with existing develop-
ment, natural tidal flows and irreplaceable marine
resources.

OPEN SPACE/RECREATION Adopt a multi-use
open space program for the acquisition and develop-
ment of lands for recreation, conservation, cultural
and scenic uses thereby protecting this economic
resource which plays a major role in generating new
resident and tourist growth.

It is evident that the Council has a great concern
for the physical environment. In many instances the
Council relies heavily on available geohydrologic
information for making land use decisions. During the
planning process, many specific questions arise that
can best be answered by the geologist or hydrologist.
The answers to such questions are rarely readily
available and must be based on careful evaluation of
existing data. This illustrates the importance of


continuing basic geologic and hydrologic data collec-
tion programs and expanding these programs in areas
for which accelerated development is predicted.
In the Tampa area growth projections indicate that
areas peripheral to urban Tampa will experience the
greatest increase in development between now and
the year 2000. In conjunction with future develop-
ment, the Tampa Bay Regional Planning Council
believes that two new concepts in urban planning
might be applicable to the Tampa area. These are the
"new town" policy and the "satellite city" concept.
The "new town" policy involves designing small
self-sustaining cities outside the realm of existing
metropolitan areas. The "satellite cities" concept
entails encouraging development in existing suburbs
so that they could essentially function independently
but would in part be dependent on the urban center.
A major objective of the two concepts is to
deemphasize over development of urban areas. In
formulating plans for "new towns" and "satellite
cities", the Planning Council will be looking first at
environmental considerations.
Concern with environmental factors has also
prompted state legislation. Recently, the Florida
Land and Water Management Act was passed. The
purpose of the Act is to permit development without
destroying Florida's resources or environment and to
provide for the designation of areas of critical state
concern and development of regional impact.
In designating areas of critical state concern, the
state or the local government will set forth develop-
mental guidelines to insure preservation of historical
and archaeological resources, and guidelines for water
storage areas, significant marine resource areas and so
on.
Development of regional impact is defined as any
development which, because of its character, mag-
nitude or location, would have a substantial effect
upon the health, safety or welfare of citizens of more
than one county. In evaluating regional impact
generated by development, such things as the degree
to which development would contribute to air, water
and noise pollution, number of new residents,
vehicular traffic and the likelihood of subsidiary
development are to be regarded in establishing
guidelines.


From: Tampa Bay Regional Planning Council,
1985 Preliminary Regional Plan.








Geology, engineering geology, and hydrology have
long been of eminent importance to transportation
planners. When new highway sites are designated,
on-site soil surveys and subsurface explorations are
carried out. The State Department of Transportation
maintains an Office of Materials and Research which
is charged with the responsibility of carrying out
these investigations.
The first phase of study is an office procedure that
entails gathering all available information on the soils
and geologic conditions in the project area. Aerial
photographs, Soil Conservation Service publications,
topographic maps and geologic maps and reports
published by the United States Geological Survey and
Florida Bureau of Geology are utilized as primary
data sources.
After the evaluation of general site conditions, a
detailed field investigation follows which centers
around a comprehensive test boring program. Borings
are spaced according to site conditions and the
requirements of the given project. Vital phases of the
field exploration program are sample description and
testing. Among the soil and rock properties logged in
the field description are: color, principal and modify-
ing constituents, hardness, cementation, grading,
relative density, consistency, moisture content, par-
ticle shape, etc. Field tests frequently include
standard penetration tests, miniature vane shear tests,
etc. In addition, laboratory tests quantify various
properties of samples collected at the site. Some of
the common tests include the following:



CLASSIFICATION


C Silty or clayey sand

R Fine sand

P Peatand muck

H Man-made land

(filled areas)

Sinkhole


TRANSPORTATION PLANNING & GEOLOGY


Soil Tests


Moisture Content
Specific Gravity
Atterberg Limits & Indices
Density
Grain Size Distribution
Compaction Test
Permeability Test
Consolidation Test
Unconfined Compression Test
Direct Shear Test
Triaxial Shear Test


Rock Tests


Specific Gravity
Density
Porosity
Absorption
Los Angeles Abrasion
Sodium Sulphate Test
Unconfined Compression Test
Triaxial Shear Test
Qualitative & Quantitative
Mineral Identification


1. discussions of the character and depth of soils
and/or rock encountered on-site
2. the nature and severity of the problems which
these materials might impose on the design or
performance of the roadway
3. treatments which might be undertaken to alleviate
the potential problems.
4. comments on slope erosion possibilities, occur-
rence of springs, swamps, seeps, and recommenda-
tions for borrow pit locations.
As with any engineering project, the transporta-
tion planning project that is most successful is the
one which is based on the larger and more detailed


array of basic data. The more that is known about an
area geologically (i.e., the more available basic data),
the fewer the problems, less the expense, and greater
the accuracy in transportation planning within that
area.
The recent creation of the Remote Sensing Section
within the Topographic Office of the State Depart-
ment of Transportation is an excellent example of
current environmentally oriented thinking in trans-
portation planning. The topic of pilot study com-
pleted in 1970 by the Remote Sensing Section is the
proposed Tampa Bypass Corridor. The study area
(about 40 miles long and 4 miles wide) is shown in
the figure. The corridor study was based on aerial
photographic interpretation with the goal of the
project being to locate and identify physical and
cultural features within the corridor .. to a degree
of detail consistent with the information needs for
preliminary location and design, and within a time
frame . more realistic than that required by ground
mapping methods."1 The study includes five separate
photo-map series delineating the following: land use,
key features, property boundaries, drainage, and
engineering soils. Except for the property boundaries
series, mapping was based exclusively on air photo
interpretation.
The land use maps show 53 different land uses
within 12 basic categories. The key feature maps


emphasize areas of special land use such as gravel,
sand and clay extractive industries, outdoor museums
and monuments, etc., which require special considera-
tion during the planning phase. Property boundaries
maps show the limits of individually owned land.
Drainage maps outline existing drainage patterns at
the time of mapping. Soils maps provide an indication
of the engineering soil types within the corridor.
These can be roughly correlated with the AASHO
classification. A portion of one of the engineering
soils maps along with the soils classification is shown
on this page.
The use of remote sensing can greatly facilitate
transportation planning. The potential of multiple-
sensor techniques (including black and white pan-
chromatic, black and white infrared, color, and color
infrared photography; multi-band photography; and
thermal and multi-spectral line scan imagery for
indicating thermal properties, vegetative patterns,
solution activity, permeability, physiography and
potential borrow pits is being investigated. It is hoped
that airborne data collection can be implemented to
provide rapid, accurate, economical, and detailed
information for use by transportation planners.

1Remote Sensing Section, Topographic Office, State of Fla.
D.O.T., July, 1970, Tampa By-Pass Corridor Study, p. 1


1000 0 1000


Source: DEPARTMENT of TRANSPORTATION


ENGINEERING SOILS MAP


3000 Feet


C~-~C~I I ,











GEOLOGIC FACTORS & CONSTRUCTION


In the Engineering Geology section of this study, a
detailed discussion of construction planning was
presented. Information from that section was
combined with information from the Water
Resources and Geology sections to produce this
overview of land suitability for construction.


I % t" *
s "


*e


The wetlands map was superimposed on


the flood prone area map which was superimposed on


the sinkholes and sinkhole-type lakes map which was superimposed on


the sand suitability for foundations map which was superimposed on


the depth to rock map.....


the clay conditions map which was superimposed on












LAND SUITABILITY FOR CONSTRUCTION


One unfavorable condition:
Flood prone and wetland areas

O sand poor for foundations
O clay poor for foundations
Areas of sinkhole occurence
Two unfavorable conditions:
Sfloodprone and wetland areas + poor sands
flood prone and wetland areas + poor clays
flood prone and wetland areas + sinks

O poor sands + poor clays
b poor sands + sinks
poor clays + sinks
Three unfavorable conditions:
Flood prone and wetland areas + poor sands + poor clays
flood prone and wetland areas + poor sands + sinks
flood prone and wetland areas + poor clays + sinks

poor sands + poor clays + sinks
* Four unfavorable conditions

Areas where rock lies near land surface
(suitable for seating piling for high rise structures)












GEOLOGIC FACTORS & SANITARY LANDFILLS


Solid waste disposal has become a topic of concern
in the Tampa area where population growth has
resulted in increasing production of waste and
decreasing undeveloped land areas suitable for waste
disposal.
In the past, few controls were placed on solid
waste disposal, and site selection was based largely on
convenience. Gradually, damaging environmental
effects resulting from indiscriminate waste disposal
become apparent and the concept of the sanitary
landfill was introduced.
The American Society of Civil Engineers defines
a sanitary landfill as: "A method of disposing of
refuse on land without creating nuisances or hazards
to public health or safety, by utilizing the principles
of engineering to confine the refuse to the smallest
practical area, to reduce it to the smallest practical
volume, and to cover it with a layer of earth at the
conclusion of each day's operation, or at such more
frequent intervals as may be necessary."
Essentially, a sanitary landfill consists of a series of
trenches which, in the Tampa area are excavated to
dimensions on the order of 400 feet long, 80 feet
wide and 10 feet deep. Trash and garbage emptied
into the trenches are compacted, then covered daily
with a thin layer of earth in order to minimize odor,
fire hazard, insect and rodent problems, etc.
Waterborne pollutants are also a significant poten-
tial problem of sanitary landfills. Rains infiltrate the
refuse in a sanitary landfill and pick up dissolved
solids. Under certain conditions this "leachate" may
find its way to a local water supply. For this reason,
certain geohydrologic factors must be thoroughly
investigated prior to selection of a landfill site.

Hillsborough County sanitary landfill trench
(photo by J.W. Stewart)


Among other things, sanitary landfill sites should
be relatively "dry" in terms of both surface and
ground water conditions, and surficial sediments
should be clayey and relatively impermeable. Under
these conditions, flow of the leachate may be L
retarded and potential pollutants filtered and ab- *
sorbed. *
The map presented on this page is based on 'P *
U.S.G.S.-F.B.G. Map Series 39 and on maps presented 0 l
earlier in this publication. Rating criteria are as
follows:
1. Type of unconsolidated material. Favorable:
clay, silty clay, clayey silt, and silt. Unfavorable: a
sand.
2. Thickness of unconsolidated materials. Favor- .
able: at least 25 feet. Unfavorable: less than 15 feet.
3. Site topography. Favorable: adequate drainage \
and not subject to flooding. Unfavorable: low
swampy areas; areas subject to flooding; sinkholes
and areas near sinkholes; along stream channels
hydraulically connected with Floridan aquifer. O L D
4. Ground-water levels. Nonartesian aquifer:
Favorable: greater than 15 feet below land surface.
Unfavorable: less than 5 feet below land surface. TA MPA
Artesian aquifer: Favorable: potentiometric surface
at least 5 feet above water table. Unfavorable:
potentiometric surface near or below the water table.
5. Character of limestone aquifer. Favorable:
dense, unfractured. Unfavorable: fractured and 1
cavernous.
6. Relation to public water supply wells. Favor-
able: at least several miles downgradient from large
pumping withdrawals. Unfavorable: adjacent to or
within the immediate cone of influence of large-scale
pumping.

UNFAVORABLE FACTORS IN SELECTING
SANITARY LANDFILL SITES

Q0 1 flood prone and wetland aiea

O 2 high water table
Q 3 rock surface at shallow depth
4 areas of sinkhole occurence

1-+. 1+2 01+3 @1t4

0 23t2+ 02+3 @2+4 03+4
S1+2+3 0 1+2+4

7 1 + @1+3+4 @2+3+4
- -J 9!J%- ".- 0







REFERENCES

INTRODUCTION

Committee of 100 of the Greater Tampa Chamber of Commerce
1970 Tampa Facts.

1971 Tampa's decade of development, the fabulous growth of a city: (table).

Florida Department of Natural Resources
1971 Outdoor recreation in Florida: Div. of Rec. and Parks, 349 p.

Florida Department of Transportation
1971 Average daily intensity map.

1971 Map of existing and proposed recreational facilities in the Tampa area: Bur. of
Planning.

Hillsborough County Planning Commission
1972 Hillsborough County, Florida population projections and environmental factors,
1960-1990: 42 p.

1970 1970 Census tracts (map).

Tampa Bay Regional Planning Council
1970 1970 Census of population and housing first count summary data.

1968 Parks and open spaces: Summary Rept. No. 6, 73 p.

The Greater Tampa Chamber of Commerce
1972 Highlights of Tampa history: (brochure).


TOPOGRAPHY

Menke, C. G.
1961 (and Meridith, E. W., Wetterhall, W. S.) Water resources of Hillsborough County,
Florida: Fla. Geol. Survey Rept. of Inv. 25, 101 p.

U.S. Geological Survey
1968 Index to topographic maps of Florida.

1971 Tools for planning: topographic maps (brochure).


WATER RESOURCES

Barraclough, J. T.
1962 (and Marsh, O. T.) Aquifers and quality of ground water along the gulf coast of
western Florida: Fla. Geol. Survey Rept. of Inv. 29, 28 p.

Beard, M. E.
1969 The Florida District Water Quality Laboratory: U.S. Geol. Survey, Water
Resources Division

Briley, Wild and Associates
1968 Comprehensive plan for water and sanitary sewer systems in the Tampa region of
Florida, (for): The Tampa Bay Regional Planning Council, 148 p.

Cherry, R. N.
1970 (and Stewart, J. W., and Mann, J. A.) General hydrology of the middle gulfarea,
Florida: Fla. Bur. of Geol. Rept. of Inv. 56, 96 p.

Federal Water Pollution Control Administration
1969 Problems and management of water quality in Hillsborough Bay, Florida: 86 p.

Ferguson, G. E.
1947 (and Lingham, C. W., Love, S. K., Vernon, R. 0.) Springs of Florida: Fla. Geol.
Survey Bull. 31, 196 p.


Florida Board of Conservation
1969 Florida lakes, part III gazetteer: Div. of Water Res., 145 p.

1966 Florida land and water resources southwest Florida: Div. of Water Res., 181 p.

Florida Bureau of Geology
1972 Environmental geology and hydrology Tallahassee area, Florida: Fla. Bur. of Geol.
Spec. Pub. 16,61 p.

Florida State Board of Health
1965 Biological, physical chemical study of Lake Apopka, 1962-64.

Hillsborough County Planning Commission
1972 Hillsborough County, Florida population projections and environmental factors,
1960-1990: 42 p.

Hillsborough Soil and Water Conservation District
1961 Work plan for upper Tampa Bay watershed Hillsborough, Pasco and Pinellas
Counties, Florida: 62 p.

1971 Work plan for Pemberton Creek Watershed Hillsborough County, Florida: 54 p.

Klein, H.
1971 Depth to base of potable water in the Floridan Aquifer, Florida: Bur. of Geol. Map
Series No. 42.

Peek, H. M.
1959 Record of wells in the Ruskin area of Hillsborough County, Florida: Fla. Geol.
Survey Inf. Circ. 22, 85 p.

Menke, C. G.
1964 (and Meridith, E. W., Wetterhall, W. S.) Water resources records of Hillsborough
County, Florida: Fla. Geol. Survey Inf. Circ. 44, 95 p.

Rickert, D. A.
1971 (and Spieker, A. M.) Real-estate lakes: U.S. Geol Survey Circ. 601-G, 19 p.

State Board of Conservation
1948 Observed rainfall in Florida, monthly totals from beginning of records to Dec. 31,
1947: Div. of Water Survey and Research, 427 p.

Stewart, J. W.
1970 (and Hanan, R. V.) Hydrologic factors affecting the utilization of land for sanitary
landfills in northern Hillsborough County, Florida: Dept. of Nat. Res., Bur. of'
Geol., Map Series No. 39.

1971 (and Mills, L. R., Knochenmus, D. D., Faulkner, G. L.) Potentiometric surface and
areas of artesian flow, May 1969, and change of potentiometric surface 1964 to
1969, Floridan Aquifer, Southwest Florida Water Management District, Florida:
U.S. Geol. Survey Atlas HA-440.

1968 Hydrologic effects of pumping from the Floridan Aquifer in northwest
Hillsborough, northeast Pinellas and southeast Pasco Counties, Florida: U.S. Geol.
Survey Open File Rept., 226 p.

Tampa Bay Regional Planning Council
1972 The interim comprehensive water quality and pollution abatement plan-Tampa
Bay region: 188 p.

Thornthwaite, C. W.
1957 (and Mather, J. R.) Instructions and tables for computing potential evapotran-
spiration and the water balance: Drexel Institute of Technology, Vol. X, No. 3.


U.S. Department of Agriculture
1965 Water and related land resources, Florida west coast tributaries: (Report).

1965 Water and related land resources, Florida west coast tributaries: (Appendix).

U.S. Army Engineer District, Southeast
1961 Comprehensive report on Four River Basins, Florida: Serial No. 185, 66 p.

1961 Comprehensive report on Four River Basins, Florida: (Appendices), Serial No.
185.

U.S. Department of Commerce
Climatological Data: Environmental Science Service Administration, monthly
records Jan. 1970-Dec. 1971; Vol. 74, No. 1-Vol. 75, No. 12.

Climatological Data, Florida: Annual Summary 1949 (vol. LIII, no. 13) to 1971
(Vol. 75, no. 13).

U.S. Geological Survey
1970 Water resources data for Florida: 303 p.

1972 1970 Water resource data for Florida, Part I, surface water records, Vol. 1;
Streams-Northern and Central Florida: 303 p.

1972 1970 Water resources data for Florida, Part I surface water records; Vol. 3, Lakes:
167 p.

1970 1968 Water resources data for Florida, Part II Water quality records: 251 p.


GEOLOGY

American Geological Institute
1962 Dictionary of Geological Terms: Doubleday and Co., Inc., 545 p.

Carr, W. J.
1959 (and Alverson, D. C.) Stratigraphy of Middle Tertiary rocks in part of west-central
Florida: U.S. Geol. Survey Bull. 1092, 111 p.

Cathcart, J. B.
1959 (and McGreevy) Results of geologic exploration by core drilling, 1953 land-pebble
phosphate district Florida: U.S. Geol. Survey Bull. 1046-K.

Cooke, C. W.
1945 Geology of Florida: Fla. Geol. Survey Bull. 29, 339 p.

Dunbar, C. O.
1969 (and Waage, K. M.) Historical Geology: John Wiley and Sons Inc., 556 p.

Florida Bureau of Geology
1972 Environmental geology and hydrology Tallahassee area, Florida: Bur. of Geol.
Spec. Pub. 16,61 p.

Mac Neil, F. S.
1949 Pleistocene shore lines in Florida and Georgia: U.S. Geol. Survey Pro. Paper 221-F.

Purl, H. S.
1964 (and Vernon, R. O.) Summary of the geology of Florida and a guidebook to classic
exposures: Fla. Geol. Survey Spec. Pub. 5, 312 p.

Shinn, E.
1963 Spur and groove formation of the Florida reef tract: Journal of Sed. Petrol. Vol.
33, No. 2, p. 295.


93











Southwest Florida Water Management District
1971 Aerial Mapping Index (northwest Hillsborough Basin).


Stewart, J. W.
1970 (and Hanan, R. V.) Hydrologic factors affecting the utilization of land for sanitary
landfills in northern Hillsborough County, Florida: Dept. of Nat. Res., Bur. of
Geol., Map Series No. 39.

White, W. A.
1970 The geomorphology of the Florida peninsula: Fla. Bur. of Geol. Bull. 51, 164 p.


MINERAL RESOURCES

Altschuler, Z. S.
1960 (and E. J. Young) Residual origin of the "Pleistocene" sand mantle in central
Florida uplands and its bearing on marine terraces and Cenozoic uplift: U.S.
Geological Survey Prof. Paper 400-B, pp. B 202-B 207.

1964 (and Cathcart, J. B., Young, E. J.) Geology and geochemistry of the Bone Valley
Formation and its phosphate deposits, West central Florida: Guidebook, Field Trip
No. 6, Geol. Soc. America Convention, Miami Beach, Fla., 68 p.

Bell, Olin G.
1924 A preliminary report on the clays of Florida (exclusive of Fuller's earth): Florida
Geol. Survey, 15th Annual Rept., p. 53-266.

Calver, James L.
1957 Mining and mineral resources: Florida Geological Survey, Bull. 39, 132 p.

Cathcart, J. B.
1950 Notes on the land-pebble phosphate deposits of Florida, in Symposium on mineral
resources of the southeastern United States: University of Tennessee Press, pp.
132-151.

1963 Economic geology of the Chicora quadrangle, Florida: U.S. Geol. Survey Bull.
1162-A, 66 p.

1963 Economic geology of the Keysville quadrangle, Florida: U.S. Geol. Survey Bull.
1128, 82 p.

1963 Economic geology of the Plant City quadrangle, Florida: U.S. Geol. Survey Bull.
1142-D, 56 p.

1964 Economic geology of the Lakeland quadrangle, Florida: U.S. Geol. Survey Bull.
1162-GG1-G128.

1966 Economic geology of the Fort Meade quadrangle, Polk and Hardee counties,
Florida: U.S. Geol. Survey Bull. 1207, 97 p.

1953 (and Blade, L. V., Davidson, D. F., Ketner, K. B.) The geology of the Florida
land-pebble phosphate deposits: 19th Internat. Geol. Cong., Algier, Comptes
rendus, sec. 11, fasc. 11, pp. 77-91.

Cooke, C. Wythe
1945 Geology of Florida: Florida Geol. Survey Bull. 29.

Davidson, W. B. M.
1892 Notes on the geological origin of phosphate of lime in the United States and
Canada: Am Inst. Mining Eng. Trans., v. 33, pp. 139-152.

Davis, John H.
1946 The peat deposits of Florida: Florida Geological Survey, Bull. 30, 247 p.

Fettke, C. R.
1926 American glass sands, their properties and preparations: Amer. Inst. Min. and Met.
Eng. Trans., Vol. LXIII, pp. 398-423.


Fountain, R. C.
1972 (and Zellers, M. E.) A program for ore control in the central Florida phosphate
district, in Seventh forum on geology of industrial minerals: Florida Bur. of
Geology Special Pub. 17, pp. 187-193.

Freas, D. H.
1968 (and Riggs, S. R.) Environments of phosphorite deposition in the central Florida
phosphate district, in Fourth forum on geology of Industrial minerals: Bureau of
Economic Geology, Univ. of Texas, pp. 117-128.

Ketner, K. B.
1959 (and McGreevy, L. J.) Stratigraphy of the area between Hernando and Hardee
counties, Florida: U.S. Geol. Survey Bull. 1074-C, pp. 49-124.

Martens, James H. C.
1928 Sand and gravel deposits of Florida: Florida Geol. Survey 19th Ann. Rept., pp.
33-123.

Maxwell, E. L.
1970 Mineral producers in Florida, 1968: Florida Bureau of Geology, Inf. Cir. 66, 40 p.

Pirkle, E. C.
1960 Kaolinitic sediments in peninsular Florida and origin of the kaolin: Economic
Geology, vol. 55, pp. 1382-1405.

1964 (and Yoho, W. H. Allen, A. T.) Origin of the silica sand deposits of the Lake Wales
Ridge area of Florida: Econ. Geol., Vol. 59, pp. 1107-1139.

1963 (and Yoho, W. H., Edgar, Allen C.) Citronelle sediments of peninsular Florida: Fla.
Acad. Sci., Vol. 26, pp. 105-149.

1967 (and Yoho, W. H., Webb, S. D,) Sediments of the Bone Valley Phosphate District
of Florida: Econ. Geology, Vol. 62, pp. 237-261.

Pride, R. W.
1966 (and Meyer, F. W., Cherry, R. N.) Hydrology of Green Swamp area in central
Florida: Florida Geol. Survey Rept. of Inv. 42, 137 p.

Reves, William D.
1962 Mineral resources adjacent to the proposed trans-Florida barge canal (revised):
Florida Geological Survey, 44 p.

Riggs, S. R.
1965 (and Freas, D. H.) Stratigraphy and sedimentation of phosphorite in the central
Florida phosphate district: Society of Mining Engineers, AIME, preprint 65H84,
17 p.

Sellards, E. H.
1915 The pebble phosphates of Florida: Florida Geol. Survey 7th Ann. Rept., pp.
25-116.

Timberlake, R. C.
1969 Building land with phosphate wastes: Min. Eng., v. 21, No. 12, pp. 38-40.

Vernon, Robert O.
1951 Geology of Citrus and Levy counties: Florida Geological Survey, Bull. 33, 256 p.

1943 Florida mineral industry: Florida Geological Survey, Bull. 24, 207 p.

Wahl, F. Michael
1972 (and Timmons, Bobby J.) Miocene clay deposits of peninsular Florida, in Seventh
forum on geology of industrial minerals: Florida Bureau of Geology Spec. Pub. 17,
pp. 109-116.

Yon, J. William
1972 (and Hendry, C. W., Jr.) Suwannee Limestone in Hernando and Pasco counties,
Florida: Florida Bureau of Geology, Bull. 54, part 1, pp. 1-42.


ENGINEERING GEOLOGY AND SOILS

Antil, J. M.
1967 (and Ryan, P.W.S.) Civil engineering construction: Angus and Robertson, Std,
Sydney, 631 p.

Hillsborough Soil and Water Conservation District
1972 Use and interpretations of soil surveys and engineering principles of water
management: (work shop).

Merritt, F. S.
1968 Standard Handbook for Civil Engineers: McGraw-Hill, Inc., ch. 7, 80 pp., and ch.
8, 94 pp.

U.S. Department of Agriculture, Soil Conservation Service
1958 Soil Survey: Hillsborough County, Florida: U.S. Government Printing Office,
Series 1950, No. 3, 68 p., 96 plates.


ENERGY RESOURCES

Florida Petroleum Council
1972 The Sun Below:

Garcia-Bengochea, J. I.
1970 Recharge of carbonaceous saline aquifer of South Florida with treated sanitary
wastewater: unpublished article, Artificial Groundwater Recharge Conference,
University of Reading, Berkshire, England (Sponsored by Water Research Assoc.,
Buckinghamshire, England, Sept. 21-24, 1970.)

National Petroleum Council
1972 U.S. Energy Outlook: A summary report, Dec. 1972.

Shell Oil Company
1973 The National Energy Outlook: March, 1973.

The Oil and Gas Journal
Weekly publication, Gulf Publishing Co.


World Oil


Monthly publication, Gulf Publishing Co.


LAND USE

American Society of Civil Engineers
1959 Sanitary landfill: Manuals of Engineering Practice no. 39, New York, Am. Soc. of
Civil Eng.

Florida Department of Transportation
1970 Tampa by-pass corridor study: (Remote Sensing Section, Topographic Office) p. 1.

1971 Soils and foundations:

Florida Land and Water Management Act of 1972
1972 House Bill 629

Hillsborough County Planning Commission
1972 Hillsborough County, Florida population projections and environmental factors:
42 p.

Leopold, L. B.
1971 (and Clarke, F. E., Hanshaw, B. B., Balsley, J. R.) A procedure of evaluating
environmental impact: U.S. Geol. Survey Circ. 645, 13 p.

McHarg, I. L.
1969 Design With Nature: Garden City, New York, Natural History Press, 197 p.




















































FLORIDA GEOLOGICAL SURVEY.
903 W. TENNESSEE STREET
TALLAHASSEE, FLORIDA 32304








3 9 '~1 0 5 4 5-
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FLORIDA GEOLOGICAL SURVEY