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 Abstract
 Introduction
 Geography
 Geology
 Ground water
 Conclusion
 References


FGS










STATE OF FLORIDA
STATE BOARD OF CONSERVATION
Ernest Mitts, Director


FLORIDA GEOLOGICAL SURVEY
Robert 0. Vernon, Director





REPORT OF INVESTIGATIONS NO. 22




THE GROUND-WATER RESOURCES
OF
VOLUSIA COUNTY, FLORIDA

By
GRANVILLE G. WYRICK,
U. S. Geological Survey



Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
FLORIDA GEOLOGICAL SURVEY

and the
CITIES OF DAYTONA BEACH, NEW SMYRNA BEACH,
AND PORT ORANGE


TALLAHASSEE, FLORIDA
1960







/Jo .22-23
4GRI-


FLORIDA STATE BOAi~AY

OF

CONSERVATION


LeROY COLLINS
Governor


R. A. GRAY
Secretary of State



RAY E. GREEN
Comptroller


RICHARD ERVIN
Attorney General



J. EDWIN LARSON
Treasurer


THOMAS D. BAILEY LEE THOMPSON
Superintendent of Public Instruction Commissioner of Agriculture (Acting)



ERNEST MITTS
Director of Conservation







LETTER OF TRANSMITTAL


iforia jCeological Sarvely

CEallakassee

February 20, 1960

MR. ERNEST MITTS, Director
FLORIDA STATE BOARD OF CONSERVATION
TALLAHASSEE, FLORIDA


DEAR MR. MITTS:


The Florida Geological Survey is pleased to publish as Report
of Investigations No. 22 a summary of "The Ground-Water
Resources of Volusia County, Florida," which was prepared by
the members of the U. S. Geological Survey. A portion of this
work was conducted by Mr. W. P. Leutze, but the principal in-
vestigation has been made by Mr. Granville G. Wyrick, Geologist
with the U. S. Geological Survey.
The report will present the information required for the
development of water supplies for the rapidly expanding Atlantic
SCoast area in the vicinity of Daytona Beach, Holly Hill, Edgewater,
DeLand and other major metropolitan areas of Volusia County.
A series of wells in which permanent water level recorders have
been installed will provide a continued monitoring of the water
resource trends in the county, and the Florida Geological Survey,
with the U. S. Geological Survey, will be kept aware of the inven-
tory of this county's ground-water resources.
Respectfully yours,
ROBERT 0. VERNON, Director




















































Completed manuscript received
January 21, 1960
Published by the Florida Geological Survey
E. O. Painter Printing Company
DeLand, Florida
March 16, 1960

iv









CONTENTS



Page
Abstract -....----....-.. --.-.......-------------------------....... .. --........-...------ 1
Introduction -......-------......--...---.--..-- ----..----------............ ........- ...-...... 2
Previous investigations --..----..------------............... --.-.........--...... 3
Acknowledgments .-.......---- ...---...-..---. ---- ---.......--..---- 4
Well-numbering system ......--....... --......-------.--- ..---- ..---.--.... 4
Geography ............... -----..... ...... ...---.......-- ...... ...-- .....-- ............. .....--- 5
Location and area ..--........-......------ -----------.... ...--....--......- 5
Climate ---...............-------- -- -------------.......... .. .. ---..........-....... .. 7
Population ---.....--......--..... .. ........---------------------- -.................. 7
Topography --------.............------....--....----------.....--.............-------------------..................-.... 7
Terraces --.............-..----...----. ---..------ ------ ............ 7
Karst topography --..................---------- -----.. ...-----..---...... 10
Drainage .-.....----............--------..-.------------- --------............-..-.....-----. 10
Geology ........--..-----..... ... -- ....---........ ------- 10
Test drilling .--.. --- --.............-----------------................----- ....-- ...--- 11
Formations .--......--...-...----.. .. .. ------- ..-- .......... 13------ 1
Lake City limestone ---..--.... --..- ----.--...--.......----- ..--....-- 13
Avon Park limestone -.-.........-..---....-....--.. ---- ------- ..... ..20
Ocala group --..----................ ----..... .....---------------------- 21
Miocene or Pliocene deposits -..--....----..... ..-.......--------.-... ---.....---. 23
Pleistocene and Recent deposits --.....-......-----. ..-------- ......------. 23
Structure ..--....................-.......--.... -------..........-..........-- .... ..----.---------- 23
Ground water ---....--.....-........ --..-..--... .----.--------.- ...-. ---------24
Nonartesian aquifer ---....---....---..............--------- --....--.......--- 25
Artesian aquifer -------------............... ---- ------------.. ........ 25
Quality of water .-..------..............--..------------- ..............---------------....-----... 35
W ells .-.........................------......... .... .... ---------------. ... ....----------. -----..---. 41
Salt-water contamination ............--------- ...--- ........-----..--- 41
Quantitative studies --....--.... ..-....------......--.........................-------- ..---... 48
Construction and location of test and observation wells -...-......---....-----. 49
Pumping test .---..........------- ------ ----------------- 50
Analyses of data --.....---------.........--..------....---...------ ........-------- ...-------- 50
Conclusion -........................------------._..---.. -- -.. -............... 6---------62
References ------...--.--.---- -----------..-.--.-------------..-........--...--- 63


ILLUSTRATIONS
Figure Page
1 Explanation of well-numbering system ......----.--..-- .....--.-.-------- 5
2 Location of Volusia County .------.........--..-..... ..--..-----..-..-.------............. 6
3 Pleistocene marine terraces .............-...-.....-------... --...---------------......................-------- 9
4 Altitude of the top of limestone of Eocene age ..--...--..--..---.......-.......--- 11
5 Locations of test wells in part of Volusia County -------..-................-.--- 12

V .







6 Data obtained from well 905-113-3 --......-......................................-....... 13
7 Data obtained from well 909-106-1 --.................-- .........------..------- ..-- 14
8 Data obtained from well 910-105-1 --...---.......---. ----..--..............-.. 14
9 Data obtained from well 911-104-4 ....--.........-...---..-...- ....-- ...-- ......--- .. -15
10 Data obtained from wells 911-103-5 and 914-102-6 -.......-..............----- .. 15
11 Materials penetrated by test wells in Tomoka State Park .-.............. 16
12 Geologic formations penetrated by wells in Volusia County ..-..... -- 19
13 Piezometric surface of Volusia County in November 1955 .......-.....--- 26
14 Hydrology along line A-A', figure 3, in November 1955 --................. 28
15 Hydrographs of wells 912-101-18 and 857-105-1 and monthly rain-
fall at Daytona Beach .----.....-........-- ..-- ..-- ......- ..-- ..- ...............----.............- 31
16 Hydrographs of wells measured periodically in Volusia County and
rainfall at Daytona Beach ..--....-----.......-..... ---....- .............-......-......-... 32
17 Hydrographs of wells 911-104-4 and 911-104-5 at Daytona Beach
airport well field .--..............-- --....-.....................-... .... ........---------..-- --- 33
18 Areas of artesian flow and depth of piezometric surface below land
surface in November 1955 ...--...--...-......--.---.....--........-..-- .......--- ...-- ... 35
19 Location of wells whose water was sampled for chemical analysis 36
20 Wells inventoried in Volusia County ..--..............-- between p. 40 and 41
21 Chloride content of water from wells penetrating upper part of
artesian aquifer --------..........--.--------------..........................-....-...... 42
22 Chloride content of artesian water along line A-A' in figure 3 ..-.... 44
23 Fluctuations of water level and chloride content of water from well
915-103-1 at Ormond Beach ....... ..... ..-....--.. .....---...---...---- .........-...... 46
24 Chloride content of water from wells in vicinity of Adams Street
well field --............---..-..- .---- -- ........ --..----------...-......................-.-- 47
25 Water levels in the pumped well, the nearby observation wells and
the drainage ditch, and graph of barometric pressure -..-............--...... 51
26 Water levels in nearby observation wells during pumping test .....-. 52
27 Log plot of the drawdowns, and first part of recovery, versus t/r' 55
28 Semilog plot of drawdowns versus t/r2 for well 909-106-6 showing
solution for transmissibility and storage coefficients ......................... 56
29 Predicted drawdowns in vicinity of a well discharging 1,000 gpm
for selected periods -...---... .....-.....---- -- ...----........----------........-...-...-. 59
30 Theoretical drawdowns after one year of pumping a group of
wells at a rate of 9,000 gpm ........... -----... ------.......... ......... --60

TABLES

Table Page
1 Data from geologic logs of wells in Volusia County1 ..-..-.......--....... --- 17
2 Analyses of water samples from wells in Volusia County ................ 37
3 Data from analysis of pumping tests in Volusia County ...--...-...--.--. 58
Figure Page
IAdditional records on wells in Volusia County, Florida have been published by the Florida
Geological Survey. P. O. Box 631, Tallahassee, Florida, as Information Circular 24. A copy of
this publication may be obtained for one dollar.








GROUND-WATER RESOURCES OF VOLUSIA
COUNTY, FLORIDA
By Granville G. Wyrick
ABSTRACT

Volusia County comprises approximately 1,200 square miles in
the central part of the east coast of Florida. Limestone underlies
this area at a depth of 40 to 100 feet and extends to a depth of
several thousand feet. The upper part of the limestone includes
the Lake City limestone, the Avon Park limestone, and the Ocala
group' of Eocene age. The limestone of Eocene age is overlain by
sand, clay, and shell sediments of Miocene or Pliocene age. These
sediments are overlain by Pleistocene and Recent sand deposits,
which blanket the area to a depth of 30 to 70 feet.
Ground water occurs under both water-table (nonartesian) and
artesian conditions in Volusia County. The nonartesian aquifer,
composed of sand beds of Pleistocene and Recent age and the upper-
most sand and shell beds of Miocene or Pliocene age, generally
furnishes sufficient water for domestic use. The artesian aquifer
is composed of limestone of Eocene age. Beds of relatively
impermeable clay of Miocene or Pliocene age overlie the artesian
aquifer and confine the water in the aquifer. Within the limestone
formations numerous thin beds of low permeability retard the
vertical movement of water between the highly permeable zones of
the artesian aquifer. The artesian aquifer supplies most of the
ground water used in Volusia County.
There has been no progressive lowering of water levels in the
artesian aquifer. Water levels have declined locally in areas of
heavy pumping.
Salt-water contamination of fresh-water zones in the artesian
aquifer occurs where heavy pumping lowers the artesian pressure
sufficiently to cause the underlying salt water to move upward.
Such encroachment can be prevented by developing wells only in
areas where salt water lies at a considerable depth, or where the
limestone beds of low permeability are continuous over large areas,
and also by avoiding large drawdowns.

'The stratigraphic nomenclature used in this report conforms to the usage
of the Florida Geological Survey and, with the exception of the Ocala group
and its subdivisions, to the usage of the U. S. Geological Survey.







FLORIDA GEOLOGICAL SURVEY


Pumping tests in Volusia County indicate that the upper zone
of the artesian aquifer has a storage coefficient of approximately
0.0007 and a transmissibility ranging from 30,000 to 370,000 gpd
(gallons per day) per foot. At one test site in Daytona Beach,
where salt-water encroachment has been a problem, an analysis of
pumping-test data indicates that, after 3 hours of pumping, leakage
to the upper part of the aquifer equaled the pumping rate. Pre-
sumably, this leakage was from a salty zone below the bottom of
the well. At another test site 6 miles west of Daytona Beach, salt
water occurred at a depth greater than 500 feet and was separated
from the fresh water of the aquifer by numerous layers of limestone
and dolomite of low permeability. This test indicates that if draw-
downs are not excessive salt-water contamination probably will
not occur in that locality.


INTRODUCTION

Salt-water contamination of fresh ground-water supplies is a
problem in many areas of Florida. It is especially serious in coastal
areas where there is danger of direct encroachment of salt water
from the ocean or where salt water occurs at relatively shallow
depths in the water-bearing formations. The problem has become
acute in certain coastal areas of Pinellas County and in parts of
the Miami area of Dade County.
During recent years the cities of Daytona Beach, Port Orange,
and New Smyrna Beach, in Volusia County, have experienced
salt-water contamination of their municipal supplies as a result of
the increased use of ground water. The greater use of ground
water is due to an increase in both population and per capital use
of water. Recognizing the problems of salt-water contamination,
the City Council of Daytona Beach requested that the U. S.
Geological Survey make an investigation of the ground-water
resources of Volusia County. In response to their request, an
investigation was begun in October 1953 by the U. S. Geological
Survey in cooperation with the Florida Geological Survey and the
cities of Daytona Beach, Port Orange, and New Smyrna Beach.
The purpose of the investigation was to make a detailed study
of the ground-water resources of the county, with special emphasis
on the problems of salt-water contamination. This report contains
the results of that investigation. The major phases of the investi-
gation included the following:







REPORT OF INVESTIGATIONS NO. 22


1. An inventory of existing wells to determine their location,
depth, distribution, diameter, yield, and other pertinent data.
2. The drilling of test wells in selected areas where sufficient
information could not be obtained from existing wells.
3. Chemical analyses to determine specific chemical
characteristics of the ground water.
4. The collection and study of water-level records to determine
seasonal fluctuations and progressive trends.
5. Geologic studies to determine the character and extent of
the various geologic formations as they relate to the occurrence
of ground water.
6. The determination of the water-transmitting and water-
storage capacities of the aquifers.

During the period 1953-55, the investigation was carried on by
the writer and W. P. Leutze. The results of this period of the
investigation were published in Florida Geological Survey
Information Circular no. 8, entitled "Interim Report on Ground-
Water Resources of the Northeastern Part of Volusia County,
Florida" by Granville G. Wyrick and Willard P. Leutze. Since
1955 the investigation has been carried on by the present writer.

PREVIOUS INVESTIGATIONS

The geology and ground-water resources of Volusia County are
discussed in several reports published by the U. S. Geological
Survey and the Florida Geological Survey.
Cooke (1945, p. 226-227, 272, 311) briefly discusses the
occurrence of the Caloosahatchee marl, Anastasia formation, and
Pamlico formation in Volusia County. A report by Vernon (1951,
figs. 13, 33, and pl. 2) includes Volusia County in maps of central
Florida, which show generalized geologic sections and the structure
of the Inglis member of the Moodys Branch formation.
A map of the piezometric surface of the principal artesian
(Floridan) aquifer in Florida (Stringfield 1936, pl. 12) includes
Volusia County. Stringfield (1936, p. 152, 162-163) discusses the
areas in which the artesian aquifer is recharged and areas in
which the chloride content of the water is low. Stringfield and
Cooper (1951, p. 71) discuss the occurrence of salty artesian water
in eastern Volusia County.






FLORIDA GEOLOGICAL SURVEY


Chemical analyses of water from wells in Volusia County are
included in a report by Collins and Howard (1928, p. 130-133) and
in one by Black and Brown (1951, p. 109-110).

ACKNOWLEDGMENTS

Appreciation is extended to the many residents of the county
who cooperated in the collection of data and who readily gave
information regarding their wells. Special acknowledgment is
given to the well drilling companies, consultants, and public
officials, whose cooperation assisted the investigation and facilitated
the preparation of this report. During the investigation the
Daytona Beach Water Department, Mr. J. R. Brennon,
superintendent, furnished office and storage space.
The investigation was made under the immediate supervision
of Ralph C. Heath, Acting District Geologist, from October 1953
until August 1955, and under M. I. Rorabaugh, District Engineer,
for the remainder of the study. The project was under the general
supervision of A. N. Sayre, former chief of the Ground Water
Branch, U. S. Geological Survey and of Herman Gunter, former
State Geologist and Director of the Florida Geological Survey.

WELL-NUMBERING SYSTEM

Positions on the earth's surface may be located by a system of
coordinates known as parallels of latitude and meridians of
longitude. The parallels of latitude circle the earth parallel to i
the equator and are numbered from the equator to the poles in
degrees, minutes, and seconds, depending upon the angular distance
between them and the equator. The meridians of longitude
traverse the earth north and south and are numbered east or west
from the Greenwich, England, prime meridian in degrees, minutes,
and seconds.
The well-numbering system, derived from latitude and longitude
coordinates, is based on a statewide grid of 1-minute parallels of
latitude and meridians of longitude. The wells in a 1-minute
quadrangle are numbered consecutively in the order inventoried.
The well number is a composite of three numbers separated by
hyphens: the first number is composed of the last digit of the
degree and the two digits of the minutes that define the latitude
on the south side of the 1-minute quadrangle; the second number
is composed of the last digit of the degree and the two digits o:.
the minutes that define the longitude on the east side of the






REPORT OF INVESTIGATIONS NO. 22


quadrangle; and the third numeral is that of the well inventoried.
The latitude and longitude prefix "N" and "W" and the first digit
of the degree number are not included in the well number (fig.
1).

GEOGRAPHY
LOCATION AND AREA

Volusia County is in the central part of the east coast of Florida
(fig. 2), and comprises approximately 1,200 square miles. It is
bounded on the north by Flagler County, on the south by Brevard
County, on the east by the Atlantic Ocean, and on the west by the
St. Johns River.
The largest cities in Volusia County are Daytona Beach,
DeLand, and New Smyrna Beach. Other incorporated munici-


Figure 1. Explanation of well-numbering system.






FLORIDA GEOLOGICAL SURVEY


Figure 2. Location of Volusia County.







REPORT OF INVESTIGATIONS NO. 22


palities include Ormond Beach, Holly Hill, South Daytona, Port
Orange, Edgewater, Oak Hill, Orange City, and Pierson.

CLIMATE

The climate of Volusia County is subtropical. The mean annual
temperature is about 71"F, according to the U. S. Weather Bureau.
The normal average rainfall at Daytona Beach is about 51 inches, at
DeLand is about 53 inches, and at New Smyrna Beach is about 50
inches. Generally, precipitation is greatest during early fall.

POPULATION

The total permanent population of Volusia County was about
74,000 in 1950, according to the U. S. Census Bureau. At that
time the population of Daytona Beach was about 30,000, DeLand
was about 9,000, New Smyrna Beach was about 6,000, and Port
Orange was about 1,200. The population of Volusia County
increased about 34 percent between the 1940 census and the 1950
census.

TOPOGRAPHY

Volusia County is in the topographic division described by
Cooke (1945, p. 10, 11) as the Coastal Lowlands. These lowlands
consist of essentially level marine terraces, which are especially
well defined in Volusia County. The topography is of two types:
leveled terraces and karst (solution) topography. In Volusia
County, karst topography occurs only on the highest terrace.

TERRACES

During Pleistocene time the sea fluctuated between levels both
above and below its present level, submerging greater or lesser
land areas according to its height. Whenever the height of the
sea remained relatively stationary for a long period, waves and
currents eroded the sea floor and formed an essentially level
surface, called a terrace. When the sea dropped to a lower level,
each terrace emerged as a level plain. The landward edge of such
a terrace became an abandoned shoreline, an abrupt scarp
separating it from the next higher terrace, and the seaward edge
became the new shoreline. Generally, sand dunes were built up
along the new shorelines.






FLORIDA GEOLOGICAL SURVEY


Discussions of Pleistocene terraces in Florida are included in
the report by Cooke (1945, p. 248). Four of these terraces-the
Penholoway, the Talbot, the Pamlico, and the Silver Bluff-are
recognizable in Volusia County. Figure 3 shows them as they were
mapped from topographic maps and altimeter surveys.
The Penholoway terrace in the western part of Volusia County
is the highest marine plain in the county. This terrace is believed
by Cooke (1945, p. 17) to have formed during the Sangamon inter-
glacial stage, when sea level stood 70 to 80 feet above present sea
level.
The Talbot terrace was formed toward the end of the Sangamon
interglacial stage, when sea level dropped to a height of about 45
feet above present sea level. During the formation of the Talbot
terrace, sand dunes built up along the seaward edge of the
Penholoway terrace, which at that time was an island. When the
sea receded after Talbot time, the seaward or eastern side of the
island emerged as a terrace about 10 miles wide and the western
side of the island emerged as a very narrow terrace, because it was
sheltered from strong wave and current action. The Talbot terrace
is the best preserved and therefore the most easily recognized
terrace in Volusia County.
The Pamlico terrace was formed during a recession of the ice
during the Wisconsin glacial stage. During this recession sea level
was 25 to 30 feet above its present level, and in Volusia County
the Penholoway and Talbot terraces formed an island. Sand dunes
built upon the seaward edge of the Talbot terrace, and the ocean
floor surrounding the terrace was leveled to a plain. When the
sea again receded, the Pamlico terrace emerged as a plain about
six miles wide on the seaward side of the island and one mile
wide on the landward or western side.
The Silver Bluff terrace also was formed during the Wisconsin
glacial stage. During Silver Bluff time the ocean was five to six
feet above present sea level. The eastern side of the Pamlico terrace
was subjected to erosion by the ocean, but the western side was
probably subjected to erosion by a river that was in approximately
the present channel of the St. Johns River. High sand dunes were
formed along the seaward side of the Pamlico terrace, and a river
terrace was formed along the western side. It is probable that
Spruce Creek and the Tomoka River started eroding channels in
the eastern edge of the Pamlico terrace during Silver Bluff time.
Figure 3 shows that these streams have eroded large. areas in the
eastern side of the Pamlico terrace.
Cooke (1945, p. 247) advances the theory that the formation






REPORT, OF INVESTIGATIONS NO. 22


of marine terraces was not a continuous process of sea level
dropping from the level of one terrace to the level of the next lower
terrace. He theorizes that between the formation of one terrace
and that of the next lower terrace sea level may have dropped to
as much as 200 feet below present sea level and then recovered
to the height of the next lower terrace.
At the present time, the ocean is building a terrace along the
east coast of Volusia County, and the St. Johns River is forming a
river terrace in the western part of Volusia County. Dunes are
being formed along the eastern edge of the Silver Bluff terrace.


Figure 3. Pleistocene marine terraces.






FLORIDA GEOLOGICAL SURVEY


KARST TOPOGRAPHY

Karst topography is the name applied to the irregular, pitted
land surface that occurs where sinkholes are numerous and drain-
age is underground. Sinkholes are formed by the collapes of surface
deposits into caverns created by the solution and removal of under-
lying limestone. Karst topography has been extensively developed
on the Penholoway terrace in Volusia County. The topographic
section along line A-A' in figure 3 shows that the surface deposits
at some places in DeLand have slumped as much as 40 feet below
the level of the Penholoway terrace. This karst topography extends
north and south for several miles from DeLand along the Pen-
holoway terrace, and it also occurs along the Penholoway terrace
near Pierson and Seville. Nearly all precipitation on the terrace
either drains downward into the underlying limestone or is
returned to the atmosphere by evaporation or plant transpiration.
The sinkholes often become clogged by nearly impermeable peaty
material which retards the downward movement of water, thus
forming sinkhole lakes. There is no evidence of karst topography
in other parts of Volusia County.

DRAINAGE

Surface drainage in Volusia County is poorly developed, re-
sulting in relatively large swampy areas. On the Penholoway
terrace all drainage is underground. Spruce Creek and the Tomoka
River drain the eastern part of the county, and small tributaries
of the St. Johns River drain the western part. These streams are
so poorly developed and inefficient that much of the county,
especially the eastern part of the Talbot terrace, is marshland.
The Halifax River is not a river but a lagoon that runs parallel
to the coast throughout most of the northeastern part of the county.
The Halifax River and its southern counterpart, Mosquito Lagoon,
are connected with the ocean by Ponce de Leon Inlet.

GEOLOGY

Sediments of Pleistocene and Recent age blanket Volusia
County. These sediments are generally beds of unconsolidated sand
and shell which overlie beds of clay and shell of Miocene or Pliocene
age. Limestone of Eocene age underlies the deposits.of Miocene or
Pliocene age. Figure 4 shows the altitude of the top of this lime-
stone in Volusia County.






REPORT OF INVESTIGATIONS NO. 22


In Volusia County the Pleistocene and Recent sediments are
ie reservoir for the nonartesian ground water, and the Miocene
r Pliocene clays tend to confine ground water under artesian
pressure in the underlying limestone of Eocene age. Nine test
rells were drilled and ten test holes were augered in Volusia
countyy as a part of this study, to obtain geologic and hydrologic
ata that could not be obtained from existing wells.
TEST DRILLING

The locations of the nine test wells, drilled along U. S. Highway


Figure 4. Altitude of the top of limestone of Eocene age.







FLORIDA GEOLOGICAL SURVEY


92 between DeLand and Daytona Beach, are shown in figure 5.
During the drilling the following were collected:
1. Rock cuttings at approximately 5-foot intervals.
2. Information on the length of time required to drill each layer of the
limestone formations.
3. Water samples for the determination of chloride content at intervals of
5 to 10 feet (from the bailer).
4. Water samples from isolated sections of the well.
5. Water-level measurements representing both the composite pressure
head in the entire open hole and the head in isolated sections of the
well.
Upon completion of the wells, traverses were made with a cur-
rent meter to locate the water-producing zones and to determine
the rate of internal flow in the wells. Also, water samples were
collected at different depths by use of a deep-well sampler.
The same type of data was collected during the construction of
public supply wells in the cities of Daytona Beach, Holly Hill, and
Edgewater. The most important information obtained during the
construction of the test and supply wells is shown diagrammatically
in figures 6-10.
A power auger was used to auger 10 test holes at Tomoka
State Park. Samples from these holes were used to determine the
thickness of the clay layers and the depth to the top of the lime-
stone. Figure 11 is a graphic representation of the data collected
during augering of the test holes.


Figure 5. Location of test wells in part of Volusia County.







REPORT OF INVESTIGATIONS NO. 22


FORMATIONS

The geology of Volusia County is described on the basis of rock
cuttings collected during the drilling of water wells (table 1) and
from a study of the topography. Rocks older than the Lake City
limestone are not described in this report because no water wells
in the county are known to penetrate them.

LAKE CITY LIMESTONE

The Lake City limestone (Applin and Applin, 1944), of early
middle Eocene age, does not crop out in Florida. According to
Cooke (1945, p. 46), this formation unconformably overlies the
Oldsmar limestone of Wilcox age. As may be seen in figure 12, well
901-117-2 penetrated 380 feet of the Lake City limestone without


Figure 6. Data obtained from well 905-113-3.








FLORIDA GEOLOGICAL SURVEY


Figure 7. Data obtained from well 909-106-1.


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Figure 8. Data obtained from well 910-105-1.


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REPORT OF INVESTIGATIONS NO. 22


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Figure 9. Data obtained iron- weBl 911 104 4.


90

100


EF-. REIATIVF PRILLIN TIME RELATIVE VELOCITY CHLORIDE CONTENT
RC$ R YIVITY J, OF WAIYR
AGCE PIOT ITHSTIVITY (mnute pr f (rJm; 1 of currnt me4l1r (pa.r pO mhln)
I0 ohm, 1S5 30 45 60 75 90 50 7 90
S1 914 11 I6, o t ollmptoken fH




iuo r
Figure 10. Data obtained from wells 911-103-5 and 914-102-6.









Figure 10. Data obtained from wells 911-103-5 and 914-102-6.







FLORIDA GEOLOGICAL SURVEY


Oj SAN- D i -- i ,c t i ft ft
II II I




SHELL
o H SHELL

S100 -
u L IIM STONE
z
1530-
S 000 2o00 eft
200 Note See inset C in figure 20 for well locolions

Figure 11. Materials penetrated by test wells in Tomoka State Park.

reaching older formations. Also, the top of this limestone is shown
to dip eastward from the high near DeLand at approximately
three feet per mile.
The Lake City limestone consists of layers of dark brown dolo-
mite separated by layers of chalky limestone. The dolomite is
crystalline and contains few fossils. The limestone is very
fossiliferous and, in places, seems to be composed entirely of
unconsolidated foraminiferal tests. The most distinctive fossil
in this limestone is Dictyoconus americanus (Cushman), regarded
as a guide fossil for the Lake City limestone (Applin and Applin,
1944). Fossils identified in well cuttings from this formation in
Volusia County are:

Amphistegina nas8auensis Applin and Jordan
Dictyoconus americanus (Cushman)
Fabularia vaughani Cole and Ponton
Lepidocyclina sp.

The unconformity separating the Lake City limestone from the
Avon Park limestone above it is marked, in some wells, by a thin
layer of well rounded phosphatic pebbles and in well 909-106-1
by a 6-foot layer of brown clay and peat.
The Lake City limestone was omitted in the interim report of
this investigation (Wyrick and Leutze, 1956) but a re-examination
of the well cuttings revealed that the section described in that
report as "Zone B" of the Avon Park limestone is actually the Lake
City limestone.





TABLE 1. Data From Geologic Logs of Wells in Volusia County

Depth of the formation penetrated by wells, in feet below land surface


V V2

:' *d Pliocene "-o 0
SS or Mio- Avon Lake g
U.S.G.S. e scene sed- Williston Inglis Park City 3 ? F.G.S.
well No. ,.5 s E iments formation formation limestone limestone a. E well No.

851-118-11 20 0-50 50-110 -_ 110-225 -90 W-1639
858-117-1 60 0-50 50- 65 --.. _. 65-125 5 W-3531
859-055-1 11 0-78 78- 89 89-131 131-195 195-226 -78 W-4464
859-117-1 52 0 -65 ........ 65-185 -13 W-3581
900-120-19 21 0-30 30- 45 .... 45- 60 -24 W-4164
900-120-20 21 .. ... -... -_ 55- 74 -34 W-4589
901-056-2 8 0 ...........-..... 86 86-115 115-126 -78 W-3475
901-117-2 38 ( .------.. .... sink102-118 118-163 163-280 --76
903-116-1 71 0-35 35- 90 .. 90-385 385-511 -19 W- 657
905-113-3 40 0-37 37- 67 .67- 93 93-351 -27 W-3527
905-119-1 99 ..- .-.. --... 91-231 -..--.. + 8 W-4588
907-121-2 24 0 -........... 34 .... 34- 60 -... .... -10 W- 487
908-059-2 11 0-70 70- 88 88-100 .... ......... -77 W-3529
909-100-7 8 0 ..... ...... 88 88-105 -.... ... -80 W-3525
909-106-1 27 0-41 41- 82 82- 90 90-119 119-370 370-496 -55 W-3476
909-122-3 28 0 ................... 95 ....... 95-100 320-400 -67 W- 490
910-105-1 26 0-37 37- 84 84 ......-........122 122-365 365-498 -58 W-3540
911-103-5 26 0-73 73-102 102-118 118-163 163-280 ........ -76 .. -
911-104-4 27 0-62 62- 94 94-110 110-127 127-365 365-501 -67 W-3477






TABLE 1. (Continued)

Depth of the formation penetrated by wells, in feet below land surface



.4 S3

Pliocene
aU.S.. or Mio- Avon Lake 12 '
U.S.G.S. OT g, cene sed- Williston Inglis Park City S, F.G.S.
well No. 04.5 t i iments formation formation limestone limestone : M S well No.

912-102-35 4 0-50 50- 95 95 ............180 180-200 ........ -91 W-3569
912-126-8 58 0-60 60-108 .... 108-126 ...... ........ -50 W- 451
918-100-5 19 0-97 97-103 103-151 151-185 ........ ........ -84 W-4227
918-127-1 71 0-88 88-110 ..... 110-140 140-270 ........ -39 W- 450
914-102-6 19 0-60 60- 98 98-122 122-185 185-190 ........ -79 W-8701
914-126-1 52 .0-65 65- 90 .... ....-. 90-150 .... -38 W- 492
916-182-1 8 0-45 45- 65 65 ............. 130 130-290 290-318 -57 W- 744
919-106-3 29 0-65 65- 95 95-130 130-190 ... .... -66 W-4578
920-105-8 11 0 ................... 91 91-147 ...- .... ...... -80 W-3473
921-105-2 19 0-41 41- 92 92-145 ..... ........ -73 W-3472


'
;1 ~e


,....i







REPORT OF INVESTIGATIONS No. 22


S_1__ ?.4% AVON PARK LIMESTONE


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O' PLEISTOCENE AND RECENT DEPOSITS
OCALA GROUP


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FLORIDA GEOLOGICAL SURVEY


AVON PARK LIMESTONE

The Avon Park limestone (Applin and Applin, 1944), of late
middle Eocene age, is the oldest deposit exposed at the surface in
any part of Florida. It crops out in Citrus and Levy counties.
Near DeLand, this formation is the first limestone penetrated by
wells. The top of the Avon Park limestone in Volusia County dips
gently eastward, and is overlain by younger limestones of Eocene
age in the eastern part of the county and along the St. Johns River.
The Avon Park limestone is about 280 feet thick where it is over-
lain by the Ocala group (fig. 12).
The color of the Avon Park limestone ranges from chalky white
to light brown or ashen gray but most of it is tan. Some beds,
especially near the top of the formation, are composed of a loose
coquina of cone-shaped Foraminifera, small echinoids-Peronella
dalli (Twitchell), and shells of other marine organisms. The
following fossils were identified in cuttings from wells in Volusia
County.

Coskinolina floridana Cole
Dictyoconus cookei (Moberg)
Dictyoconus gunteri Cole
Peronella dalli (Twitchell)
Spirolina coryensis Cole
The Avon Park limestone is almost invariably dolomitized in
Volusia County (see columnar sections on figs. 6-10). The process
of dolomitization (replacement of some of the calcium of limestone
by magnesium) often changes the permeability of a bed. The
change depends on the original form of the limestone and on the
mode of dolomitization. If the rock was originally a loosely packed
coquina limestone, dolomitization generally renders it dense and
less permeable. Other beds of dolomite are extremely porous,
having a spongy, "honeycomb" appearance due to selective
dolomitization of matrix rock. The Avon Park includes dolomite of
both types. The top of the Avon Park was eroded before the
overlying Ocala group (Puri, 1953) was deposited, and near
DeLand the formation was again eroded before beds of the late
Miocene or Pliocene age were deposited.
One of the most notable features of the Lake City, Avon Park,
and overlying limestones is the presence of dense, indurated beds.
These beds are readily detectable during drilling because they
greatly retard the drilling rate. Graphs of drilling time (figs.
6-10) show that sections ranging from 5 to 10 feet in thickness






REPORT OF INVESTIGATIONS NO. 22


required 15 minutes or more per foot of drilling. The 10-foot
section from 235 to 245 feet in well 909-106-1 (fig. 7) is one of
the most conspicuous in this respect.
Information collected during the drilling and testing of the wells
indicates that these dense zones are relatively impermeable. There-
fore, wherever these layers are continuous for a considerable
distance they greatly retard upward or downward movement of
water between the different permeable zones.
A study of the relative resistivity graphs on figures 6-10 show
that most of the dense layers also have a fairly high electrical
resistivity.
Chemical analyses of water from different depths in the same
well show that the hardness of water from isolated sections of
the Avon Park limestone is less than that of water from the over-
lying limestone. This may be due to the fact that dolomitic rocks
are commonly less soluble in water than limestone.
The Avon Park limestone is the principal source of artesian
water in the western part of the county, where the Ocala group of
Puri (1953) is thin or absent. Also, many of the deeper wells along
the coast draw part of their water from the Avon Park.

OCALA GROUP

The upper Eocene unit known elsewhere as the Ocala limestone
was established by Puri (1957) as a group composed of three
similar formations. The first two were named by Vernon (1951),
who, however, did not retain the name Ocala. These are, in
ascending order, the Inglis, the Williston, and the Crystal River
formations. All three are fragmental marine limestones which
are differentiated on the basis of fossil content and lithology.
In central and western Florida, where the Ocala group crops
out, its three formations have a different lithology and contain
distinctive faunas. In Volusia County, where data on the rocks
must be obtained from well cuttings, the formations cannot
readily be separated (Vernon, 1951, p. 122, 144, 157). The upper
part, the Crystal River formation of Puri (1957), has not been
recognized in Volusia County, and was probably removed through-
out the county by post-Eocene erosion (Vernon, 1951, pl. 2; Neill,
1955, fig. 4).
The Inglis formation, in its typical development, is a coarsely

"Applin and Jordan, 1945, p. 130; Cooke, 1945, p. 53; Vernon, 1951, p. 115,
118; Puri, 1953, p. 130.






FLORIDA GEOLOGICAL SURVEY


granular marine limestone containing abundant echinoid frag-
ments. Of these, pieces of Periarchus lyelli (Conrad) are the most
readily identifiable.
The fossils identified from well cuttings from the Inglis forma-
tion in Volusia County include:
Amphistegina pinarensis cosdct'i Applin and Jordan
Fabiania cubensis (Cushman and Bermudez)
Nonion ad'vnum (Cushman)
Periarchus lyelli (Conrad)
Rotalia cushmani Applin and Jordan
Sphaerogypsina globula (Reuss)
The color of the Inglis formation is cream to white, mottled with
gray. The gray color is due to finely divided iron sulfide. The
formation overlies with an angular unconformity the Avon Park
limestone. The thickness of the formation averages about 50 feet
but may be as much as 120 feet in some parts of the county
(Vernon, 1951, p. 118, 121-122). The Inglis formation is overlain by
the Williston formation. The Inglis has been removed from the
crest of the high near DeLand and has been thinned by erosion in
most, if not all, of the remainder of the county. It is very porous
and permeable, however, and yields a large part of the water
used in Volusia County.
The Williston formation as described by Vernon (1951) is a
soft granular marine limestone. It is generally finer grained than
the Inglis, and contains fewer echinoid plates. Some of its beds
consist of a loosely cemented mass of Foraminifera.
The Foraminifera identified from well cuttings from the Willis-
ton formation in Volusia County include:
A mphistegina pinarensis cosdeni Applin and Jordan
Heterostegina ocalana Cushman
Lepidocyclina ocalana Cushman
Operculinoid flides densis (Heilprin)
Operculinoides jacksoncnais (Gravell and Hanna)
Operculinoides moodybranchensis (Gravell and Hanna)
Sphaerogypsina globula (Reuss)
The lithology of the Williston indicates that it was deposited in
deeper water than the Inglis, which is essentially a beach oi
shallow sea deposit. The Williston averages about 30 feet in
thickness, but it has been entirely eroded from the high neai
DeLand and thinned by erosion throughout the rest of the county.
Owing to its finer texture, the Williston is less permeable than the
Inglis. Nevertheless, it is an important part of the artesian aquifer
in eastern Volusia County. Along the coast, many wells draw







REPORT OF INVESTIGATIONS No. 22


exclusively from this formation, but deeper wells draw also from
underlying beds. The hydrologic properties of the Williston and
the Inglis are very similar but may be modified locally by
dolomitization. The combined thickness of the two formations
reaches a maximum of about 80 feet along the eastern coast of
Volusia County (see Ocala group in fig. 12). These formations are
considered as the Ocala group in this report because of their
similar hydrologic properties.

MIOCENE OR PLIOCENE DEPOSITS

The unconsolidated beds of fine sand, shells, and calcareous
silty clay which overlie the artesian aquifer were classified by
Cooke (1945, p. 214, 226-227, pl. 1) as the Caloosahatchee marl
of Pliocene age. Vernon (1951, figs. 13, 33; and personal
communication, June 29, 1955) indicated that these beds were of
late Miocene age. In Volusia County they generally consist of a
basal shell bed overlain by calcareous clay, fine sand, and silty shell
beds. As the permeability of the clay beds in these deposits is
relatively low, they serve to confine water under pressure in the
artesian aquifer. The basal shell bed yields a small amount of
water and hence some wells are left open to it.

PLEISTOCENE AND RECENT DEPOSITS

Sediments of Pleistocene and Recent age blanket Volusia
County. Their contact with the underlying deposits is marked
by a bed of coarse sand grains, waterworn shells, clay, and, at a
few places, a combination of these materials cemented together
by calcium carbonate. The Pleistocene and Recent deposits are
chiefly fine to medium grained quartz sand, locally, mixed with
shells. In many parts of the county the sediments are stained
yellow or orange by iron oxide. Locally, the sand has been cemented
into "hardpan" by deposition of iron oxide at the water table.
The Pleistocene and Recent deposits yield small quantities of
water to shallow wells. They are an important source of water in
those areas in which the artesian water is too salty for domestic
use. Many domestic wells in the county draw from these deposits.

STRUCTURE

The structure contours in figure 4 show the altitude of the top
of limestone of Eocene age in Volusia County. The top of the
limestone is an eroded surface which dips eastward from a high


23







FLORIDA GEOLOGICAL SURVEY


near DeLand at the rate of about three feet per mile. In the
northwestern part of the county the top of the limestone is domec
near Pierson.
Two important features on the map are the faults in the
western and southern parts of the county.
The east-west fault which passes through the north end of
Lake Monroe is part of a graben. The other side of this graben
is in the northern part of Seminole County (Barraclough, J. T.,
written communication, 1959). The top of the limestone is
displaced vertically from 60 to 100 feet near Lake Monroe.
The north-south fault which passes through DeLeon Springs,
Lake Beresford, and Lake Monroe separates the geologic high near
DeLand from the domed high near Pierson. The vertical dis-
placement along this fault is about 80 feet near DeLeon Springs
and at Lake Beresford.
The hydrologic effect of these faults will be discussed in the
sections on ground-water and salt-water contamination.

GROUND WATER

Ground water is the water in the zone of saturation, the zone
in which all pore spaces are filled with water under positive
hydrostatic head. The water in the zone of saturation is derived
from precipitation. Not all the precipitation soaks into the ground,
however; part evaporates and a part drains overland into lakes
and streams. Of the part that does filter into the earth, some is
later evaporated or is transpired by plants, and the rest reaches the
zone of saturation. Water that has reached the zone of saturation
is available to supply springs and wells and is referred to as
ground water.
Water in the zone of saturation moves under the influence of
gravity toward a place of discharge, such as a spring or well.
Where ground water only partially fills a permeable formation, its
surface, which is at atmospheric pressure, is free to rise and fall,
and the water is said to be under water-table conditions. However,
if ground water completely fills a permeable formation that is
overlain by a relatively impermeable bed, its surface is not free t,
rise and fall and the water is said to be under artesian conditionE.
The term "artesian" is applied to water that is under sufficient
pressure to rise above the top of the permeable formation
containing it, although not necessarily above the land surface.
A formation in the zone of saturation that is permeable enough
to transmit usable quantities of water to wells and springs i3







REPORT OF INVESTIGATIONS NO. 22


called an aquifer. Areas in which aquifers are replenished are
called recharge areas. Areas in which water is lost from aquifers
are called discharge areas.

NONARTESIAN AQUIFER

Ground water occurs in Volusia County under both water-table
and artesian conditions. The nonartesian, or shallow, aquifer is
composed of Pleistocene and Recent sediments. The upper portion
of the deposits of Miocene or Pliocene age also may constitute a
part of the nonartesian aquifer in some parts of the area. The
aquifer ranges in thickness from about 25 feet near the Halifax
and St. Johns rivers to as much as 80 feet in the central part of the
area (fig. 12).
The nonartesian aquifer is recharged chiefly by local rainfall.
It receives also a small amount of recharge by upward seepage of
artesian water in the area of artesian flow.
Water is lost from the nonartesian aquifer by natural discharge
into surface streams, such as the St. Johns River; by discharge into
the ocean; by downward seepage into the artesian aquifer, in those
areas in which the water table stands higher than the artesian
pressure head; and by evaporation and the transpiration of plants.
In addition, small quantities of water are withdrawn from the
aquifer through wells for domestic use and lawn irrigation.
The water from the nonartesian aquifer is generally less
mineralized than that from the artesian aquifer. However, in many
areas water from the nonartesian aquifer contains an excessive
amount of iron which gives the water a disagreeable taste and
stains clothes and fixtures. In areas immediately adjacent to the
St. Johns River and the ocean the nonartesian aquifer contains
salt water.
Temperature measurements of water from the nonartesian
aquifer range from 660 to 740F, and most of them are between 680
and 700F.

ARTESIAN AQUIFER

The artesian aquifer of Volusia County has a vital bearing on
the economy of the county. It is used by all communities that have
public water supplies, is the major source of irrigation water, and
is used by nearly all commercial and industrial consumers that
have their own wells. It is the source for many home supplies, air-
conditioning systems, and stock wells. Thus, most of the







FLORIDA GEOLOGICAL SURVEY


information collected and studied during this investigation concerns
the artesian water supply.
The artesian aquifer in Volusia County consists mainly of
limestone of Eocene age. In some parts of the county it also
includes a thin, permeable shell bed at the base of the Miocene or
Pliocene deposits. The water in the aquifer is confined under
artesian pressure by beds of clay in the Miocene or Pliocene
deposits.
The piezometric surface is an imaginary surface to which water
from a given artesian aquifer will rise in tightly cased wells that
penetrate the aquifer. The piezometric surface is generally


Figure 13. Piezometric surface of Volusia County in November 1955.






REPORT OF INVESTIGATIONS NO. 22


represented on a map by contour lines that connect points of equal
altitude. Water in the artesian aquifer moves from areas of high
artesian pressure toward areas of lower artesian pressure at right
angles to the contour lines representing the piezometric surface.
The map in figure 13 indicates the piezometric surface of Volusia
County in November 1955, when it was at about an average stage.
Volusia County differs from most counties in Florida in that
most, if not all, of the fresh water in the artesian aquifer is de-
rived from rain falling on the recharge areas within the county.
These recharge areas appear as piezometric highs within the closed
contours on figure 13. The principal recharge area is within the
closed 40-foot contour along the eastern edge of the Penholoway
terrace near DeLand. A smaller recharge area is within the
closed 35-foot contour along the Penholoway terrace near Pierson.
As was pointed out in the section on "Karst Topography," the sink-
holes in the Penholoway terrace have caused breaks in the confining
beds overlying the artesian aquifer. Thus, water may move
downward from the nonartesian aquifer to the artesian aquifer
through the sand and shell-filled sinkholes, where the water table
is higher than the piezometric surface. Near DeLand the water
table is as much as 30 feet higher than the piezometric surface.
The artesian aquifer is recharged also by the small amount of
water that seeps through the confining layers where the water
table is considerably higher than the piezometric surface even
though there are no sinkholes or breaks in the confining layers.
Figure 14 is a generalized section showing the hydrology along
line A-A' in figure 3. The figure shows an exaggerated profile of
the land surface, the position of the water table, the piezometric
surface of the upper part of the artesian aquifer, and the piezo-
metric surface of the lower part of the artesian aquifer in
November 1955. As may be seen, the water table stands higher
than the piezometric surface in all the area between Daytona
Beach and the St. Johns River, except for a small area about nine
miles west of Daytona Beach. Therefore, the artesian aquifer is
being recharged through sinkholes and by leakage through the
confining beds as shown by the arrows in figure 14.
From the Tomoka River westward almost to the St. Johns
River the pressure in the upper part of the artesian aquifer is
greater than the pressure in the lower part. Within this area,
water moves downward from the upper part of the aquifer to re-
charge the lower part. As pointed out in the discussion of
"Geology," dense, relatively impermeable layers of limestone were
penetrated in all the test wells. Although these layers are not at








FLORIDA GEOLOGICAL SURVEY


the same depth in each well, some of the thicker layers-fo:.
example, the layer between about 220 and 240 feet shown in
figures 7, 8, and 9-appear to be parallel to the bedding planes and
to be continuous over large areas. These layers doubtless retard
the downward movement of water from the upper part of the
aquifer.
In the area where the hydrologic gradient is downward, where
deep wells such as 909-106-1 penetrate different zones of the
aquifer, there is a substantial movement of water down the well
bore. This can be seen in figure 7 by comparing the relative
velocities while the well was standing idle with those while the
well was being pumped. While the well was standing idle, water
entered the hole between 150 and 160 feet below the land surface,
moved down the well, and entered the formations below a depth of
about 225 feet. The graph of relative velocities during pumping
of the well at a rate of 143 gpm shows an upward flow of water
above 155 feet and a downward flow below that depth. A
comparison of the graphs shows that the quantity of water flowing
down the well bore was reduced approximately two-thirds by
the pumping.

01t AND W M A t '.f1 ; r1I P 1'- 4,11 2 1 l rf,( ur.,-Af 2.11.i
PSA R 1I['o.AN Ufl*121 P111 of AAQU

I ItONAR IIIAN

.. J. .
-50 ._.l,2 N 'ol? 12 ia
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< L


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5J Y00 Aj 112 2222 r2 2 T 2
1 i-50 U, H r o Ir 19
T 2



-4200 r'ro 2:2

.250 r ji9'
Fur Tr Hn AN 1

Figur 14. ydrolgy alng lie A-A, figre 3,in Noember1955







REPORT OF INVESTIGATIONS NO. 22


The quantity of water moving from the upper part of the
aquifer to the lower zones through the well bore cannot be
determined from the relative velocity graphs because the diameter
of the well bore is not known. Although the open hole was drilled
with a 51-inch bit, its diameter is doubtless somewhat greater
than 51/ inches everywhere and may be a foot or more where
the well penetrated unconsolidated limestone.
After water reaches the artesian aquifer it moves down the
hydraulic gradient toward points of discharge. In general, the
movement of artesian water in the county is eastward and west-
ward from the piezometric high near DeLand to the piezometric
lows near the Atlantic Ocean and the St. Johns River.
Water is discharged from the artesian aquifer through
submarine springs where the limestone formations crop out
beneath the ocean, by upward seepage through the confining bed
where the piezometric surface stands higher than the water table,
and by leakage along faults where the confining layers are
displaced. Large quantities of water are also withdrawn from the
aquifer through wells.
East of the Tomoka River, the pressure in the lower part of
the artesian aquifer is greater than the pressure in the upper part
(fig. 14). Consequently, water moves upward from the lower
zones of the aquifer. However, this movement probably is not
appreciable in areas undisturbed by heavy pumping because the
natural upward gradient, which is only about one foot in 80 feet
at well 911-104-4, is not adequate to move large quantities of
water through the beds of very low permeability that serve as
confining beds between the different zones of the aquifer. In
areas of heavy pumping, as, for example, in the Adams Street
well field of the city of Daytona Beach, the pressure in the upper
part of the aquifer is drawn down as much as 20 feet. As a result,
the upward gradient in this area is many times greater than it is
elsewhere, and upward flow from the lower zones is correspondingly
much larger.
Wherever the pressure in the lower zones of the aquifer is
greater than that in the upper zones, water enters the lower part
of the open hole and flows up the well to recharge the upper zones
of the aquifer. Thus, the vertical direction of movement of water
in the deep wells east of the Tomoka River is opposite to that in
wells west of the river. Current-meter traverses made in wells
910-104-1 and 911-104-4 after their completion showed a large up-
ward flow (figs. 8, 9). Two traverses were made in well 910-105-1,
one while the well was standing idle and the other while it was







30 FLORIDA GEOLOGICAL SURVEY

being pumped at a rate of 250 gpm. A comparison of the results
of the two shows that the upward flow of water in the well while
the well was not being pumped was probably between 150 and
200 gpm. Most of this water entered the well below a depth of 430
feet, flowed up the well bore, and entered the upper part of the
artesian aquifer between the depths of 150 and 160 feet.
The graphs of relative velocities in well 911-104-4 (fig. 9)
show that while the well was not being pumped water entered it
between 395 and 485 feet. The decrease in relative velocity between
300 and 310 feet shows that a small quantity of water probably left
the well between those depths. Most of the flow, however left the
well between the depths of 225 and 230 feet. The remaining flow
entered the upper part of the artesian aquifer between the depths
of 165 and 180 feet.
The collection of data on the altitude, fluctuations, and progres-
sive trends of water levels is an essential part of the investigation.
In order to determine the altitude of water levels and pressure
heads throughout the county, the water levels in all open nonflowing
wells and the pressures in flowing wells are measured when the
wells are first visited. The fluctuations and progressive trends
are determined by measuring the water levels in a relatively large
number of wells periodically and by maintaining continuous-
recording gages on a few selected wells.
Water levels were observed periodically in 22 wells in Volusia
County, seven of which were equipped with recording gages.
Hydrographs showing the water-level fluctuations in two of the
wells equipped with recording gages are shown in figure 15.
Observations were begun on well 857-105-1, at Alamania, 11 miles
southwest of New Smyrna Beach, in 1936. As the water level in
this well is not affected by the withdrawal from other wells, and as
the well is near the area in which the artesian aquifer is being
recharged, the hydrograph shows the natural fluctuations of
artesian pressure head caused by changing rates of recharge. The
heaviest rainfall generally occurs in Volusia County from June
through October. Accordingly, the water level in well 857-105-1
is generally highest in the summer or early fall. As a result of
low rainfall in the period November to May, the water level begins
to decline near the end of the year and generally is lowest in June
or July. The hydrograph for this well does not show any pro-
gressive trend, either up or down, during the 22-year period from
1936 to 1957.
Observations of the water level in well 912-101-18, which is at
the west end of Main Street Bridge in Daytona Beach, were begun







REPORT OF INVESTIGATIONS NO. 22


20
Monthly rainfall at Daytona Beach

5 I

16 937 938 939 1940 1941 1942 1943 1944 t945 9 947 8 1949 1950 1951 1952 1953 1954 1955 1956-194 7
Figure 15. Hydrographs of wells 912-101-18 and 857-105-1 and monthly
rainfall at Daytona Beach.
in 1948. Thus, the record for this well is much shorter than that
for well 857-105-1. The water level in well 912-101-18 responds to
the heavy pumping in the Daytona Beach area and to seasonal
changes in the rate of recharge. The hydrograph of well 857-105-1
shows that the natural decline of water levels during each spring
and summer since 1951 has been about average for the period of
record, 1936 to date. On the other hand, the hydrograph of well
912-101-18 shows that the decline of water levels during the
summer at Daytona Beach has been substantially greater than
average since 1951. This doubtless reflects a substantial increase
in the use of ground water at Daytona Beach.
The hydrographs in figure 16 show the fluctuations of water
level in artesian wells that were measured periodically during the
investigation. These wells were selected from the group of 22 wells
that were measured periodically, because of their areal distribution.
As may be seen from figure 16, the water levels fluctuate in
response to rainfall. The magnitude of the fluctuations depends on
the location of the well with respect to recharge and discharge near
the well. During 1953, rainfall in Volusia County exceeded the
yearly average by about 25 inches. The years 1954, 1955, and 1956
were considered drought years, and in 1957 rainfall was about
normal.






32 FLORIDA GEOLOGICAL SURVEY


-59 . i| : I:



-60
-63
-64 r- ---



*3--^ J^ I\-----1








-4 .. .
-2








-. i '-... ...... ...



-2-
_: :-9 ... i :\ .. I.... .. .




1i Z je ,h 0i N8 SmI na \ I



F -I ,u,1,6;. .yir h io w l ,mie;;u e i pe ri odi ca ll i IoI ii i i I io





S Wel 908r-059-i '
._- __

0 i' Hof Par Oronql _







and rainfall at Daytona Beach.
and rainfall at Daytona Beach.





REPORT OF INVESTIGATIONS No. 22 33

Well 855-117-1 is very near the principal recharge area and
shows the greatest amount of fluctuation. Well 851-114-1 is near
or on the edge of the graben at Lake Monroe and shows the
smallest amount of fluctuation. The other wells in figure 16 are
along the east coast where there is apparently little recharge or
discharge.
The hydrographs in figure 17 represent water levels in the
nonartesian aquifer, in the upper part of the artesian aquifer,
and in the lower part of the artesian aquifer at the Daytona Beach
airport well field. The Daytona Beach airport well field started
pumping at about 4 million to 7 million gallons a day in February
1957. These water levels were measured in order to determine
whether this pumping from the upper part of the artesian aquifer

261 11 1 i


24
w Water level in nonartesian well
S__911-104-5
22

LJ
S20
z
w
18
w

16
I Water level in lower port of
Sthe artesian aquifer (480-500ft)
z well 911-104-4
-J
> 12
w
-J

W 10
< Water level in upper part of the
Sartesian aquifer (100-235ft)
8 ---- well 911- 104-4


6 IllitlI I1III__11 ll _II_ i


1955


1956


1957


Figure 17. Hydrographs of wells 911-104-4 and 911-104-5 at Daytona Beach
airport well field.






FLORIDA GEOLOGICAL SURVEY


would appreciably affect water levels in the nonartesian aquifer
and in the lower part of the artesian aquifer. As may be seen from
the record prior to February 1957, the three hydrographs correlate
very well. However, after January 1957, the net drawdown in
the upper part of the artesian aquifer was about two feet, there
being no corresponding drawdown in either the nonartesian aquifer
or the lower part of the artesian aquifer. This indicates that the
pumping from the upper part of the artesian aquifer did not, in
a period of nine months, induce additional recharge from the
nonartesian aquifer or from the lower part of the artesian aquifer.
Where the artesian pressure head stands higher than the land
surface, wells penetrating the artesian aquifer will flow. The
approximate area of artesian flow in Volusia County is shown
on the map in figure 18. As may be seen, wells will flow in most
of a belt two to three miles wide adjacent to the coast and in the
lowlands adjacent to the Tomoka River and Spruce Creek. Wells
will flow in another belt, several miles wide, along the St. Johns
River from Brevard County to Lake George. This belt is about
eight miles wide near DeLeon Springs.
Figure 18 shows also the areas in which artesian wells do not
flow, where the piezometric surface is below the land surface.
In areas where the piezometric surface is less than 20 feet below
the land surface most domestic wells are equipped with centrifugal
pumps. Where the depth of the piezometric surface is more than
20 feet below the land surface, most wells are equipped with either
jet-type or vertical turbine pumps.
The area of artesian flow expands and contracts in response to
seasonal changes in water levels. Thus, during periods of low
water levels, many wells cease to flow. In a few instances, owners
of intermittently flowing wells have found that their wells will
flow continuously if deepened, because the pressures in the lower
zones of the artesian aquifer are greater than in the upper zones.
In order to obtain the full benefit of the higher pressures, it would
be necessary to case off the upper zones of the aquifer. It should
be noted, however, that in most parts of the coastal area th
mineralization of the artesian water increases with depth. Thus.,
the advantage derived from the increase in pressure resulting fror?
deepening a well may be offset by a deterioration in quality of the
water.
The temperature of water from the upper parts of the artesia 1
aquifer ranges from 71 to 740F. Water from most of the wells
inventoried had a temperature between 720 and 730F.







REPORT OF INVESTIGATIONS NO. 22


QUALITY OF WATER

Rainwater, when it falls on the earth, is only slightly
mineralized. However, as it travels through the soil and rocks be-
neath the earth's surface it gradually dissolves some of the soluble
minerals from them. Thus, the chemical character of ground
water is dependent, in part, on the type of material through which
the water flows. The quartz sand that constitutes most of the
shallow aquifer in Volusia County is relatively insoluble. Lime-
stone and dolomite, which compose the artesian aquifer, are among
the most soluble of the common rocks.


'igure 18. Areas of artesian flow and depth of piezometric surface below
land surface in November 1955.







FLORIDA GEOLOGICAL SURVEY


The limestone, sand, and clay that underlie Volusia County
were deposited in the ocean. When these sediments were laid
down, and when they were under the sea at later times, they
became saturated with sea water. Part of the present mineral
content of the ground water in Volusia County, especially in the
coastal areas and along the St. Johns River, is a result of this
saturation of the formations with salty water many millenniums
ago.
Water from wells located in figure 19 was sampled for chemical
analysis during the present study. The analyses which show the


Figure 19. Locations of wells whose water was sampled for chemical analysis.





TABLE 2. Analyses of Water Samples from Wells in Volusia County



ST4 "
l S" S ona
_____~~4 .1 1Wji
Well 'A a 1 4 a I f a
number aj 2 4 = i P'S 4 C. Re
n^L~8 IQ %I0 a a 1 i s 8 AS ds a'a' Ns I %g| Remarks __


900-113-1

1/900-120-18-

1/900-120-19
Do--------

901-055-6

901-056-1

901-102-1

901-109-1

902-059-4

904-057-2

905-113-3

Do--------

Do---- ...

Do-------

Do--------

906-111-2

907-058-1

908-107-2

909-059-11

909-106-1

Do-----


2- 3.55

1-14.57

1-22.57

2- 7.57

2- 3.55

2- 3-55

2- 3-55

2- 3-55

2- 3-55

2- 3-55

4- 8-55

4-11-55

4-11-55

4-12-55

4-14-55

2- 2-55

2- 2-55

2- 2-55

2' 3-55

2" 9-55

2-11-55


_1/ Samples anolyase by lack Labfrator;


.43






.34








1.0

.24

ae8, I


127

56.'

11

8.1

11

48

8.6

18

22

28

17

8.8

55

6.8

21

10

17


0.8

17

18

16

.5








.5

1.4


200

100

15

20

15

75

2.5

3.5

3.5

2,5

7.2

10

85

15

18

8,0

10


8.01


Sample collected after
pumping 200,000 gallons
Sample collected after
pumping 33,000 gallons











Hydrogen sulfide, 0.0






Hydrogen sulfide, 1.2








Aluminum, 0,18


--













I


Wull
number


909-106-1




909-106-4

Do------

Do........

910-105-1

Do-........

Do-- -.**

Do------

Do-........


911-103-2

911-103-5

911-104-4

Do--------

Do-........

Do--------

Do--------

912-101-17

912-103-1

913-115-1


w,,,l !
numbmr


i s

il, i'


*a


''


38

4

44

23

23

23

13

26

36

43

49

49

20

28

14

26

38

501

504

191

17(

15


la1;,


14 377 2-17-55

96 481 2-23-55

96 102 4-15-55

14 102 5-24-55

4 102 5-26-55

4 102 5-28-55

10 113 3-17-55

0 246 3-22-55

0 344 3-25-55

5 426 3-30-55

8 487 4- 1-55

8 152 4-18-55

5 110 3-21-57

0 135 3-21-57

0 115 3- 2-55

5 244 3- 4-55

4 366 3- 8-55

0 489 3-11-55

3 115 4- 1-55

0 84 2- 3-55

0 111 2- 3-55

8 74 2 -2 55


16 0.8

14 .2


15 .3:

16 .0

17 .1I

18 .9:

17 1.5

16 3.9

17 .45

8.8 6.1


22 .32

19 .09

31 .54

29 1.1

21 1.1

21 1.3

. *


3 101

9 99

110

2 108

5 108

7 108

3 114

101

70

99

85

99

106

93

107

101

100

55

82

110

104

86 1


12

19

10

6.4

6.4

6.7

9.6

16

41

25

25

25

9.1

17

15

14

4.5

40

33

17

11

.1


32 1.0

42 1.7

2d

19 ,7

19 .7

19 .7

22 1.0

30 1.3

49 '1,7

23 2,2

16 '2.4

119


++ ,


2U6

390

366

360

365

378

364

274

21J4

242

292

368

360

308

352

331

307

302
-


5.5
5,0

7.0

4.5

4,5

3.2

1.2

3,2

3.8

16

8.8

28

12

2.0

1.5

1.2

2.0

6.0

22

18

10

10


r
r'i. i
*h". ,


HRmarks


'T'Al.E 'i, (Co101iiMiVl)


701 7.3


435 302


526


382

380

380

394

417

566

792

717


390

454

437

374

389

395

684

526

402

340


22

37

27

21

25

20

98
*


1- . -- .----C---~ ~j~---------


302 653

340 110

344 852

304 646

258 553


I


7,4 Hydrogen sulfide, 0,3

7.3

7,3 Manganess, 001; hydrogen
sulfide, 0.0
7,5 Manganese, 0.00; hydrogen
sulfide, 0,3
7.5 Manganes*,0.01; hydrogen
sulfide, 0.6
7.6 HMnganese,0.00; hydrogen
sulfide, 1.3
7.5 Mangeanse,0,02; hydrogen
sulfide, 0.6
7.4

7.3 Hydrogen sulfide, 0.2

7.5 Hydrogen sulfide, 1.I

7.5 Hydrogen sulfide, 0.3

7.4 Hydrogen sulfide, 0.2

7.5 Hydrogen sulfide, 0.4

7.7 Hydrogen sulfide, 0.7


I





J-ABLE Z;~C

vSo 4
In b I A ,
tu t|ber I_ I I 3 g j A


v"
B S
o
s
pq Q Ifi, k1~1


324
357


7.0
4.0
10
10
30
10
180


0
.r j


-53
.7,
67
53
171
92
;860


,914-102-6
Do--------
915-107-3
916-112-1
918-103-4
920-106-1
921-104-3


'U
'U3


I


13
15
16
18
24
14
132


3.
hr


1


- I


I


23


*


--


I


107 9-16-55
157 9-20-55
- 24 355
- 2- 3-55
89 2- 3-55
- 2- 3-55
107 2- 2-55


1.7 95
- 101
- 107
- 87
- 102
- 120
- 208


u


0.8


go R
marks
Foo


II


315
314
332
292
354
358
1,060


397
478
442
448
628
542
3780


n .... qP___


L'



0

0/2

-4

I3


I I I I


I I






FLORIDA GEOLOGICAL SURVEY


principal chemical constituents of these samples are contained in
table 2. All results given in the table are in parts per million
(ppm) unless otherwise stated.
One part per million is a very small quantity, equal to only
8.34 pounds of the constituent in a million gallons of water. How-
ever, even this small quantity of certain constituents, such as iron,
imparts objectionable characteristics to water.
The dissolved-solids content of a water is an index to the degree
of mineralization. If all the dissolved constituents in a water
sample were added together, the bicarbonate being included as
equivalent carbonate, the sum would equal the total dissolved solids.
However, because many of the rarer constituents are not generally
determined, and because of the water of crystallization, there is
usually a slight discrepancy between the total obtained by
evaporation of a water sample and the total obtained by summation
of the determined constituents.
The chloride (Cl) content of water in Volusia County is
discussed in detail under the heading "Salt-Water Contamination."
As determinations of chloride content can be made readily in the
field, this constituent is commonly used as an index of how "salty"
a water is. Water having a chloride content of less than 500 ppm
does not taste objectionably salty to most people, and water having
a chloride content of not more than 250 ppm is acceptable for a
public supply, if otherwise satisfactory, according to the standards
of the Florida State Board of Health.
Hydrogen sulfide (H2S), a gas, imparts the taste and odor to
the water that is commonly referred to as "sulfur water."
Hydrogen sulfide has an objectionable odor, but many people
become accustomed to drinking water that contains it. The gas
can be removed from water by aeration. Analyses of samples
(see "Remarks" in table 2) show that where hydrogen sulfide
was present its concentration did not exceed 1.3 ppm.
The hardness of a water is caused chiefly by the basic ions
calcium (Ca) and magnesium (Mg). These constituents are dis-
solved from the limestone (CaCO3) and dolomite (CaMg(CO,)z)
that compose the artesian aquifer. Water having a hardness of
more than 150 ppm is rated as hard and is commonly softened for
household and certain other uses. The hardness of artesian water
in Volusia County ranges from about 200 ppm to more than 1,000
ppm.























I.



















I I





UNITED STATES DEPARTMENT" OF 1HI" IN1(EHIOR
GEOLOGICAL SURVEY


FLORIDA GEOLOGICAL SURVEY
R 0 Vernon, Director


I I
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^ ,(F-


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81*5 29'25'







- 29=20'


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29'20'


81*15'

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81015'


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yur= lulllll 111,111 UrllVg IVIVIUI:IIUIII+ VI
U, S, Department of Agriculturet


BREVARD COUNTY

80955, 80050 8045V
2845' 2'45'-









20 1 *1.
2840t Iml
SI I I I I I1 I I
at


Well Inventory by Granville G. Wyrlck.


Figure 20. Wells inventoried in Volusia County.


I 1


.......


9u


-ei .I- a' s eT; -. . .
J I







-
-81 A 105' a "'







'o a
/NS"r r
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EXPLANATION

Well( number Is well number)


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-- ---






REPORT OF INVESTIGATIONS NO. 22


WELLS

The inventory of wells consists of the collection of information
on their location, depth, diameter, length of casing, yield, and
use. Figure 20 shows the distribution of more than 900 wells that
have been inventoried in the county. About 95 percent of these
wells draw water from the artesian aquifer, and five percent draw
from the nonartesian aquifer. Approximately half the wells are in
the area of artesian flow.
Most nonartesian wells are 11/4 inches in diameter and 15 to
50 feet in depth. As the sedimentary rocks that compose the non-
artesian aquifer consist predominantly of unconsolidated sands,
most nonartesian wells are equipped with screened drive points.
Most artesian wells are 11/2 to 6 inches in diameter and 9 to 180
feet deep. Wells for domestic use, lawn irrigation, and watering
stock are commonly 11/2 to 2 inches in diameter. These wells are
generally constructed by driving casing to the top of the limestone
and drilling an open hole to a depth of 25 to 50 feet below the
bottom of the casing. Wells for farm and grove irrigation,
municipal supply, and air conditioning are generally larger than
four inches in diameter and range in depth from 125 feet to 175
feet. Records of these wells are published separately by the Florida
Geological Survey as Information Circular No. 24, which may be
obtained from that department at P. 0. Box 631, Tallahassee,
Florida.

SALT-WATER CONTAMINATION

Saline water is present in the principal artesian aquifer in
many areas of Florida. Although the presence of saline water
could result from several causes, in Volusia County it appears to
be due to the infiltration of sea water into the artesian aquifer at
times during Pleistocene time when the sea stood higher than it
is now. After the high seas declined, fresh water entering the
aquifer began diluting and flushing out the salty water. The salty
water has been completely flushed out of the aquifer in the recharge
areas, but in areas distant from the recharge areas the flushing is
still incomplete.
More than 90 percent of the dissolved solids in ocean water are
chloride salts. Therefore, the concentration of chloride in artesian
water constitutes a reliable index to the degree of salt-water
contamination. A map (fig. 21) was prepared which shows the
chloride content of water from wells penetrating the upper part







FLORIDA GEOLOGICAL SURVEY


Figure 21. Chloride content of water from wells penetrating upper part of
artesian aquifer.

of the artesian aquifer. As may be seen from this map, the chloride
content of water in the recharge areas is less than 25 ppm, which
indicates that flushing is virtually complete in that area. Eastward
and westward, however, the aquifer has been flushed less, and the
chloride content of the water is greater.
A noticeable feature on the map is the fresh-water zone about
eight miles west of U.S. Highway 1 in Daytona. In this area the
aquifer is probably being recharged by seepage through the
confining layers. The water table .is about 15 feet above the
piezometric surface in the dunes along the eastern edge of the







REPORT OF INVESTIGATIONS No. 22


Talbot terrace. This difference in head would cause fresh water
to move downward from the nonartesian aquifer to the artesian
aquifer even though there are no sinkholes or other breaks in the
confining layers.
The zones in which the chloride content of the artesian water
exceeds 1,000 ppm also are very noticeable on the map. The
eastern, southern, and western sides of the county are almost
entirely within these zones. The zones in which the chloride is
highest are near Lake Beresford, DeLeon Springs, and Lake
Harney.
The concentrations of chloride in water samples collected from
wells of different depths indicate that the lower zones of the
artesian aquifer have been flushed less completely than the upper
zones. Thus, as a general rule, the deeper a well is drilled the
higher is the chloride content of the water produced by the well.
Figures 6-10 contain graphs showing the chloride content of
water samples obtained from the bailer during construction of
the supply and deep test wells, and from different depths in the
well bore after the wells had been undisturbed for several weeks.
The plot of the chloride content of the bailer samples from well
909-106-1 in figure 7 shows a saw-tooth pattern. This effect is
believed to result from the flow of water, low in chloride content,
down the well bore at night while drilling was not in progress.
Therefore, a line connecting the highest chloride values probably
would give a fairly accurate picture of the chloride content of the
water in the different layers of the aquifer. As may be seen from
figure 7, the chloride content of the water at a depth of 497 feet
was 150 ppm. After the well had been undisturbed for several
weeks, the downward flow of water of low chloride content from
the upper zones decreased the chloride content in the lower part
of the well. The high chloride content still present in the casing
apparently represents salty water that leaked from the bailer while
the lower portion of the well was being drilled.
As pointed out in a previous section, there was an upward
flow of water in wells 910-105-1 and 911-104-4. Therefore, the
chloride content of the bailer samples probably represents rather
closely the actual chloride content of the water in the producing
aquifers. As may be seen from figures 8 and 9, the chloride con-
tent in both wells began to increase at a depth of about 250 feet.
Well 910-905-1 reached water containing more than 250 ppm
of chloride at a depth of 435 feet, whereas well 911-104-4, which
is nearer the coast, drew water containing more than 250 ppm
at about 385 feet, or 50 feet less. Figure 9 shows a marked decrease






FLORIDA GEOLOGICAL SURVEY


in chloride content in well 911-104-4 below a depth of about 465
feet. A study of the data collected during construction of the well
strongly indicates that the water samples were diluted by fresh
water in the upper part of the well during drilling.
The chloride content of samples obtained with a deep-well
sampler from different depths in wells 910-105-1 and 911-104-4
is shown on figures 8 and 9. At the time these samples were
collected the wells had not been pumped for several days. There-
fore, as may be seen from the graphs, the chloride content was
relatively high throughout the well bore as a result of the upward
flow of salty water from the lower zones penetrated by the wells.
Figure 22 is a generalized section showing the chloride content
of the water in the artesian aquifer along line A-A' in figure 3.
As may be seen from the figure, the chloride content increases
with depth except for a thin section at the top of the aquifer west
of well 907-110-1. The effects of the fault near well 900-120-2
also show very clearly in figure 22; near the well water is lost
from the upper part of the artesian aquifer by leakage to the
nonartesian aquifer along the fault. This loss of water from the
upper part of the aquifer lowers the artesian pressure and allows
salty water to move upward from lower zones of the aquifer.
The quantity of water that may be safely withdrawn from the
artesian aquifer in Volusia County is limited by the extent to
which the artesian pressure can be lowered without causing
encroachment of salt water from either the sea or the lower zones
of the aquifer. Sea water, so far as is known, has not encroached


Figure 22. Chloride content of artesian water along line A-A' in figure 3.







REPORT OF INVESTIGATIONS NO. 22


into any part of the artesian aquifer in the county as a result of
heavy pumping. It appears entirely likely, however, that such
encroachment would occur if the artesian pressure in the area
immediately adjacent to the coast were lowered excessively by
heavy pumping.
The upward movement of salty water from the lower zones of
the artesian aquifer is the principal water-supply problem along
the St. Johns River and in the coastal areas of the county. As
shown in figure 22, the depth to salty water in the aquifer is much
less in these areas than in the recharge areas. Therefore, the
extent to which water levels can be safely lowered is less. As pointed
out in the section headed "Ground Water," the pressure in the
lower zones of the aquifer in the coastal areas and near the St.
Johns River is higher than the pressure in the upper zones. Where
the natural conditions have not been disturbed by pumping, the
small difference in pressure probably results in only a small upward
movement of salty water from the lower zones of the aquifer,
except along the fault through Lake Beresford and DeLeon Springs
and the graben in Lake Monroe. However, when pumping begins,
the difference in pressure becomes greater and the quantity of
upward flow is increased. If the pumping remains constant for
a relatively long period, the chloride content of the water will
become stabilized at some level above the initial concentration. If
the rate of pumping is later increased, the chloride content also
will increase.
An increase in chloride content in response to a decline in
artesian pressure has been observed in most of the coastal areas
of the county. During the spring of 1954, the chloride content
in a well at the Riviera Hotel in Ormond Beach increased about
50 ppm as a result of a decline in artesian pressure of about two
feet (fig. 23). Figure 23 shows the water levels and the chloride
content of water from well 915-103-1. From November 1953
through October 1954 the well flowed continuously from a leak in
the casing. The rate of leakage was three to.nine gpm, according
to the height of the water level. In October 1954 the casing was
repaired and the well was allowed to flow for only about 10 minutes
when each water sample was collected. The increase in chloride
content which accompanied a decline in water levels correlated
very closely when the well flowed continuously but was delayed by
about four months when the well did not flow continuously. Records
of the Daytona Beach Water Department show that the chloride
content of water from the Adams Street well field increases as the
water level declines. Between January and April 1954 the artesian







FLORIDA GEOLOGICAL SURVEY


z
LL
C
C
3


1953 1954 1955 1956 1957

Figure 23. Fluctuations of water level and chloride content of water from well
915-103-1 at Ormond Beach.


pressure in the vicinity of the field declined about one foot in
response to an increase of about 1,600,000 gallons in the average
daily pumpage. The average daily chloride content increased
during the same period from 132 to 162 ppm.
The upward coning of salty water beneath the Daytona Beach
well field is shown diagrammatically on figure 22. The chloride
content of the water from the individual wells in the Adams Street
and a part of the Canal well fields during a period of average
pumping in February 1954 is shown on figure 24. The area of
highest chloride content was centered around well 912-102-19 in
the south-central part of the field.
The chloride content of the Port Orange city wells increased
by as much is 50 to 75 ppm each year from 1951 until 1955. An
analyses of samples from other wells between the city well field and
the coast show no appreciable increase in chloride content during
this time, and as the chloride increase in the center well is greater
than in the end wells, it appears that salt water has moved upward
from the lower zones of the aquifer as a result of pumping. The
rapid increase in the chloride content of the Port Orange city well
field may indicate that the zone from which the wells draw is not
effectively separated from the lower, saltier zones of the aquifer.
In 1955 the increase in chloride content of water from this well


JPMF AMJJASONDJFMAMJJ ASONDJFMAMJJASONDJFMAMJJASONDJ F M A MJJA S ND
S --tell flowing Well not flowing--
1 continuously ot 3 to n
150- 9
M

S W 9 ell 915 3- 1











- 4
I-- --- --

a: -4-
tL







REPORT OF INVESTIGATIONS No. 22


If



Li


0 500 feet


Note: All wells


EXPLANATION
Public-supply well
@
Well equipped with recording gage
0
Privately owned well

Contour line connects points of equal chloride
content of. water, in parts per million
186
Upper number is well number. Lower number is
chloride content of water in parts per million,
February 1954
( )
Chloride content in June 1955

Volusio Avenue ^(


Figure 24. Chloride content of water from wells in vicinity of Adams Street
well field.





FLORIDA GEOLOGICAL SURVEY


field became relatively stable at 425 to 450 ppm. It is expected
that so long as the pumpage is approximately 210,000 gpd the
chloride content of the water will remain approximately the same.
A decrease in pumpage will probably result in a decrease in
chloride content of the water, and an increase in pumpage will
doubtless result in an increase in the chloride content of the water.

QUANTITATIVE STUDIES

The withdrawal of water from an aquifer causes water levels
to decline in the vicinity of the point of withdrawal. As a result
of this decline, the water table or piezometric surface assumes the
approximate shape of an inverted cone having its apex at the
center of withdrawal. The size, shape, and rate of growth of this
"cone of depression" depend on several factors. Among these are:
(1) the water-transmitting and water-storing capacities of the
aquifer; (2) the rate of pumping; (3) any increase in recharge
resulting from the decline in water levels; and (4) the amount of
natural discharge salvaged by the pumping. The distance that
water levels are lowered at any point by the pumping is termed
"drawdown." The drawdown is approximately proportional to the
pumping rate.
The quantity of water that may be pumped perennially from a
a well or group of wells in Volusia County is limited by the draw-
down that may be maintained without causing the mineral content
of the water to become intolerably high. In the areas immediately
adjacent to the coast, the perennial yield is determined by the
extent to which water levels may be lowered without causing sea
water to move into the aquifer. In areas more remote from the
coast, the yield is determined by the extent to which water levels
may be lowered without inducing an excessive upward movement
of salty water from the lower zones of the aquifer.
As the depth to salty water increases with increasing distance
from the coast, the perennial yield of a well or wells also increases.
However, the perennial yield of wells depends also on other factors.
Most important of these in the stratification of the aquifer. As
has already been pointed out, the limestone formations that
compose the aquifer consist of permeable zones separated by thin
zones of low permeability that appear to be continuous over
relatively large areas. Where zones of low permeability underlie
the fresh-water-bearing parts of the aquifer, they retard or prevent
the upward movement of salty water. Thus, wherever such zones





REPORT OF INVESTIGATIONS No. 22


occur, larger drawdowns may be maintained and the perennial
yield is greater than it otherwise would be.
Other factors affecting the perennial yield of the aquifer are
recharge and discharge. Withdrawals from the artesian aquifer
in recharge areas increase the gradient between the water table
and artesian aquifer and results in increased recharge. With-
drawals salvage a part of the natural discharge.
One phase of this investigation was devoted to the collection
of data needed in an evaluation of the yield of the upper part of
the artesian aquifer. Data pertaining to this phase were collected
during the construction of test wells along U.S. Highway 92 and
during a pumping test on well 909-106-4. Other data were collected
during the construction and testing of public supply wells and
privately owned wells.

CONSTRUCTION AND LOCATION OF
TEST AND OBSERVATION WELLS
Three 6-inch test wells (wells 905-113-3, 910-105-1, and
911-104-4) were drilled west of Daytona Beach along U.S. High-
way 92 (fig. 5) to a depth of approximately 500 feet to
determine the depth to salt water at different distances from the
coast, the pressure head at different depths in the aquifer, and
other significant data. Studies made during the construction of
the wells indicate that the depth to salt water at well 909-106-1
was greater than 500 feet beneath the surface. Also, as this well
was between a recharge and a discharge area, the site appeared to
be well suited to studies of the perennial yield of the aquifer.
At this site an 8-inch discharge well (well 909-106-4), four 2-
inch observation wells (wells 909-106-2, 3, 5, 6), and two l/4-inch
observation wells (wells 909-106-7, 8) were drilled. The 6-inch test
well 909-106-1 previously drilled at the site was in effect converted
into two observation wells, ending at different depths. First a
string of 2-inch casing, perforated between the depths of 416 and
496 feet, was inserted inside the 51/2-inch well. Next, a concrete
plug was poured between the 51/-inch open hole and the 2-inch
casing from a depth of 355 feet to 416 feet, and sand and gravel
was poured on top of the plug to a depth of 234 feet (the depth
of the discharge well, 909-106-4). The 8-inch discharge well and
the four 2-inch observation wells were cased to a depth of
approximately 102 feet and drilled as open holes to 234 feet. The
two 11-inch observation wells (wells 909-106-7 and 909-106-8)
were equipped with 60-mesh screen points and driven to a depth of







FLORIDA GEOLOGICAL SURVEY


approximately 15 feet below the land surface. One 2-inch well
and one 11/-inch well were constructed southeast of the discharge
well. The remaining wells were constructed southwest of the
discharge well (see inset in fig. 5).
The discharge well was equipped with a centrifugal pump
having a capacity of approximately 2,000 gpm. Automatic water-
level recorders were installed on wells 905-113-3 (5.2 miles east
of DeLand) and 910-105-1 (4.6 miles west of Daytona Beach)
several weeks prior to the pumping test to establish regional water-
level trends before and during the test. Also, a microbarograph
was installed at well 910-105-1 to record barometric changes
during the test.

PUMPING TEST

In order to determine the water-transmitting and water-storing
properties of the upper part of the artesian aquifer, a pumping
test was started at 1:10 p.m. on May 24, 1955. Well 909-106-4
was pumped at a rate of 1,100 gpm for a period of 100 hours.
During the test, measurements of the changes of water level in
the observation wells were made periodically. In addition, changes
in the water level in the drainage ditch immediately north of the
observation wells were measured by means of a staff gage.
Measurements of water levels were made also in the deep 2-inch
observation well 909-106-1 to determine how pumping from the
upper part of the artesian aquifer would affect the pressure head in
the lower part of the artesian aquifer. Throughout the test,
automatic water-level recorders were in operation on wells
910-105-1 and 905-113-3 and the microbarograph was in operation
at well 910-105-1. After the pumping was stopped, measurements
of the recovery of the water level in each well were made
periodically for five days.

ANALYSIS OF DATA

The 3,100 measurements of water levels made during the
pumping test are not tabulated in this report. However,
hydrographs of each well were plotted from these data and are
presented as figures 25 and 26. The hydrographs show a decline in
water level during the afternoon of May 23. This decline resulted
from pumping well 909-106-4 approximately 25 minutes to
determine the throttle setting of the pump motor for the pumping
test. The brief rise in water levels in wells 909-106-1 and 909-106-3








REPORT OF INVESTIGATIONS NO. 22


9

I0

I I
9 ---------------
11 1-- -- ----



139 --- -.

14 -






15


0
-I
LJ


LJ
LL

Z

-I
LJ
LJ
_-j


'i


.. 'Well 909-106-4, 6 miles
southwest of Daytona
Beach


ii i LLi i


i1 I


__ __ __ __ i~l


8 /-1 Well 909-10i6-, 5 ft--
-- southwest of well 909-106 -'
9 ---- o (U r rt of artesian
I quter) ,

Well 909-106-1, 25 ft
____ southwest of well 909-106-4
(Lower part of artesion
j aquifer)





15 _

16

9 .. ... -- n __"-_-- --;*
Well 909-106-3, 40 ft
SI southwest of well 909-106-4
10 -----,1_- --




13
+1n d
Drinoge. ditch


I I I ----4 ...
-I
U_ 304
0>- Barometric pressure


- 19 300
19 20 21 22 23 24 .25 26 27 28 29 30 31 I 2


Figure 25. Water levels in the pumped well, the nearby observation wells
and the drainage ditch, and graph of the barometric pressure.


HI L K 1





T


MAY 1955


uUNl I


\.







52 FLORIDA GEOLOGICAL SURVEY

on May 25 (fig. 25) resulted when the pump motor stopped for
1 minute 40 seconds. Wells 909-106-1 and 909-106-3 were the only
wells measured during the time the pump was stopped; therefore
this rise is not recorded on the other hydrographs. As may be seen
in figures 25 and 26, the drawdowns at the end of the pumping
period in the pumped well (well 909-106-4) and in well 909-106-6,



7 Well 909-106-2,
9 I 179 ft southeast of
SI well 909-106-4
8-


10 -



179 ft southeast
: ,




Well 910 -10, 4.6miles
Zof well 909-106-4





2u 9 ~'~\/ **' Well 909-106-6, 450 ft "
S .' southes of well 909-06-4
,10 -- --2 "2 .9 I ...... .. .
-J 1 II


LL I I Well 910-105-I, 4.6 miles
S i i west of Daylono Beach

: 1 ---'--L I-MY9-...
lLI Well 911-104-4, 3.2 miles
-> --- --- ,----w---... west of Doylona Bench

2 I &(Upper port of ortcsion oquiter)
S;ll 911 104-4, 32 miles west of Doytona Beach
6 15i I I o-wer I n a

7 -I ~Well 905-113-3. 5 2 miles eost of land |
S-Well 909-106-8 179fYi soulheost of well


Well 909-106-7, 179 ft
_______ __ ____ southestof awl 09-106-4
6 ---- ----- '----1- w- ---- '----

19 20 21 22 23 24 25 26 27 28 29 30 31 1 2 3
MAY 1955 JUNE
Figure 26. Water levels in nearby observation wells during pumping test.






REPORT OF INVESTIGATIONS NO. 22


450 feet southwest of the pumped well, were about 9.5 feet and 3
feet, respectively. An indication of the extent of the cone of depres-
sion is shown on the hydrographs for wells 910-105-1 and 911-104-4.
The drawdown in well 910-105-1, 1.4 miles northeast of the
pumped well, was approximately 0.9 foot. The drawdown in well
911-104-4, 3.0 miles northeast, was approximately 0.8 foot.
In addition to the record of barometric-pressure fluctuations,
figures 25 and 26 contain hydrographs of shallow wells 909-106-8
and 909-106-7 and of the drainage ditch. The decline of the water
level in well 909-106-7 on May 24 and 25 was a result of the slow
drainage of water poured into the well on May 23. The water level
in the drainage ditch was raised approximately 0.7 foot on May
24 by the discharge from the pump. As a result, the water level
in well 909-106-7, approximately 30 feet from the ditch, was held
up higher than it would have been if the ditch had not risen, as
is shown by the decline that occurred on May 28 at the end of the
test. However, the rise in the water table resulting from the rise
in stage of the ditch was apparently restricted to a narrow zone
adjacent to the ditch, as there was no detectable change in the
level of well 909-106-8, approximately 200 feet away.
In any analysis of pumping-test data it is necessary to
determine the regional trend of water levels during the test in
order to determine true drawdowns. On May 23, the first day of
the pumping test, rain fell, resulting in an upward trend of water
levels in the artesian aquifer. To correct for this trend, a compari-
son was made of the hydrographs compiled prior to the pumping
test for well 905-113-3 and the wells at the pumping-test site. This
comparison showed that the water-level fluctuation at well
909-106-4 lags three days behind the fluctuation at well 905-113-3.
The drawdowns during the pumping test were corrected by taking
into account the time lag and applying the rise in water level at
well 905-113-3 to the drawdowns measured in the observation
wells. Changes in barometric pressure were relatively small during
the test, and therefore no correction was made for changes in
water level due to them.
The corrected drawdowns were analyzed by two methods to
determine the coefficients of transmissibility and storage of the
artesian aquifer. The coefficient of transmissibility, which is a
measure of the capacity of an aquifer to transmit water, is the
quantity of water, in gallons per day, that will move through a
vertical section of the aquifer one foot wide under a hydraulic
gradient of one foot per foot. The coefficient of storage, which is
a measure of the capacity of an aquifer to store water, is defined







FLORIDA GEOLOGICAL SURVEY


by the Geological Survey as the volume of water released from or
taken into storage per unit surface area of the aquifer per unit
change in the component of head normal to that surface.
Computations of the coefficients of transmissibility and storage
were first made by the Theis graphical method (Wenzel, 1942, p.
87-89). This method involves the following formula, which relates
the drawdowns in the vicinity of a discharging well to the rate and
duration of discharge.

114.6Q e-u 114.6Q W
s= du= W(u)
T Ju T

u
1.87r2S
where u= 1 r-
Tt
s=drawdown, in feet, at distance r and time t
r= distance, in feet, from pumped well
Q=discharge, in gallons per minute
t=time since pumping began, in days
T=coefficient of transmissibility, in gallons per day
per foot
S=coefficient of storage, a dimensionless fraction
The formula is based on certain simplifying assumptions-that
the aquifer is constant in thickness, infinite in areal extent,
homogeneous, and isotropic (transmits water with equal facility
in all directions). It is assumed also that there is no recharge to
the formation or discharge other than that from the one well within
the area of influence of the well, and that water may enter the
well throughout the full thickness of the aquifer.
When T and S are to be determined, the log of the drawdown
in the wells is plotted against the log of t/r2. The resulting curve
is a segment of the type curve produced by plotting the log of the
exponential integral W(u) against the log of the quantity u. The
curve of observed data is then superposed on the type curve and
the values of u, W(u), s, and t/r2 are selected at any convenient
match point. These values are next inserted in the formulas for s
and u, given above, in order to determine the coefficients of
transmissibility and storage.
A match of the type curve with a mass plot of the observed
data (fig. 27) yielded the following values:
where W (u) = 1.0, s=0.41
and where u=0.1, t/r2=4.6x10-s







REPORT OF INVESTIGATIONS NO. 22


Inserting these values in the formulas T= 114.6QW (u) and S=-
s
uTt
72 gives a transmissibility of 310,000 gpd per foot and a
1.87r2
storage coefficient of 7.5 x 10-4 for the upper part of the artesian
aquifer.
To check the results of the Theis graphical method, the data
from well 909-106-6 were analyzed also by a method devised by
Cooper and Jacob (1946). In this method the corrected draw-
downs are plotted against the log of t/r2 and the transmissibility
and storage coefficient are computed from the following formulas:

T 264Q
As
S=0.301Tt/r
where Q is discharge, in gallons per minute
As is the change in drawdown, in feet, over one logarithmic
cycle of the t/r2 scale
t/r, is the value of t/r2 at the point of no drawdown.

A plot of the data for well 909-106-6 is shown in figure 28
Use of above formulas gave coefficients of transmissibility and
storage of 300,000 gpd per foot and 7.2x10- respectively.
Drawdowns in the vicinity of discharging wells penetrating
the upper part of the artesian aquifer near Daytona Beach can be






I -0 ,100 qP-





-. 114 6 'I






t/r. ( PER FEET2)
figure 27 Log plot of the drawdowns and first part of recovery, versus t/
.T = F








trt (DANl& PER FEET!)

Figure 27. Log plot of the drawdowns, and first part of recovery, versus t/r2.







56 FLORIDA GEOLOGICAL SURVEY


O0 +" ..-.. ... : ,, ... --
:: :--- : : '.'::::::--::'::::-'---.^~t ; i -. Well 909-106-- 6
I. 1. "- ^.- -i ---l T. 240 300,000 gpd/t
-- ---- **-- ---- : .........;... .... --.--- ...... Where:
S= .301 T (I/r2). 7. 2X 10 -
. : Where:
o --- Q= 1,100 gpm







S. ....-- :-- -- --- ..... --, ..LOG CYCLE ,+"-+i":.^: ,. .


S_ (DAYS _PER FEET_)8.0
















by the test. Also, with time, recharge will occur which will vitiate
















aquifer and consequently would show higher values.
S- --___




















FiThure 28. Sperennial yieldot of dradown versus t/r for wells at the pumping-test106-, showiteng



whereas in the other cacteristical areas of the aqcounty, is limited those quantityed
.... .. .... . .'.. ....+ .. .+1.. .. ..... . 1' +Q ; +] . ++-








































as in the other coastal areas of the county, is limited to the quantity







REPORT OF INVESTIGATIONS NO. 22 57

f water that can be pumped from the aquifer without producing
excessive drawdowns that will result in an upward movement of
.alty water. Water containing 150 ppm of chloride was en-
ountered at a depth of about 500 feet in well 909-106-1, 25 feet
southwest of the pumped well. Therefore, water containing more
1 han 250 ppm of chloride, the suggested upper limit for water to be
used in a municipal supply, is probably present in the area at a
depth of less than 600 feet. In order to determine if the drawdowns
during the pumping test would result in an upward movement of
this salty water, water-level measurements were made in well
909-106-1 in the interval between 416 and 496 feet. These measure-
ments did not show any detectable change in water level, although
drawdowns of approximately 6 feet in this well in the interval
between 102 and 234 feet and 10 feet at the pumped well were
maintained for a period of four days. In view of this, it appears
safe to assume that, in pumped wells, drawdowns of approximately
10 feet could be maintained without inducing an upward flow of
salty water.
The results of the analysis of data from other tests in Volusia
County are given in table 3. As may be seen from the table, the
hydrologic character of the aquifer is different in different parts
of the county. Therefore, in designing a well field, the coefficients
of transmissibility and storage determined from pumping tests
nearest the proposed well field should be used.
In order to show the drawdowns that will result from different
rates of pumping and different well spacings, computations were
made by use of the Theis formula and coefficients of transmissibility
and storage of 300,000 and 7 x 10-4, respectively. The Theis
formula involves several simplifying assumptions. Among these
is the assumption that all the discharge is derived from storage in
the aquifer. However, after pumping begins, the downward
gradient will be increased as a result of the drawdowns produced
by the pumping, and the rate of recharge will be increased. As
the cone of depression expands it will intersect recharge, and
ultimately the recharge within the cone of depression will equal
the pumping rate. Thus, it is expected that the actual drawdowns
generally would closely approximate the drawdowns computed from
the Theis formula during the initial period of pumping, but would
be smaller than the computed drawdowns after the cone of
depression began to intercept recharge. It is not possible to
determine from the available data the length of time that would
be required for the cone of depression to become stabilized. How-
ever, in similar areas in other parts of the State, stabilized



















TABLE 3. Data from Analysis of Pumping Tests in Volusia County


aill
(ocsi)


T'llk1.r.a
of .;uth;r
penatratwd
by wfel
(feec)


178 Sd 6

327 87 b

298 88 6

0.5 233 5

10 9 5

5 16 5

27 and 28)

0.4 145 6

1,000 92 8

1,000 95 8

1,000 100 8

2,000 100 8

500 66 8


Lwngth Li
pulping
period
(hCurs) tate f tet


1- 7-58

1- 7-58

1- 7-58

4-23-57

2- 4-57

2- 4-57



11- 7-56

8- 9-36

8- 9-56

8- 7-56

8-15-56

10-12-55


Tranjmis l-
bility
(gTid/ft)


46,000

55,000

55,000

190,000

57,000

40,000


160,000

350,000

330,000

310,000

370,000

28,000


Coafitctant of
storage


2.0 x 10'4

3.4 x 10"-

3.4 x 10'4



1.1 x 10-4

2.7 x 10"4







2.2 x 10'4

1.8 x 10-4

1.1 x 10'4

2.3 x 10-4


Remarks


Analyzed according to Ccopar--Jacrb ilmtlug method

Analyzed according to Iheis nonequlllbriun method

Do

Analyzed accordtra to Cooper--Jacob samilog method

Analyzed according to Theis nonequillbrium method

Do.



Analyzed according to Coopcr--Jacob zemilog muthod

Analyzed according to Theis nonequiibrium method

Do.

no.

Do.

Analyzed by using an unpublished "Typa curve for non-
steady radial flbw in an infinite leaky aquifer" by
H. H. Cooper, Jr. (Leakage equaled discharge of
pumped well in 3 hours.)


Discharge
Well o ruFmprd
number well (gpn)


859-055-1

859-055-2

859-055-3

859-117-2

900-120-18

900-120-19

909-106-1-6

911-103-5

911-104-6

911-103-2

911-104-7

911-104-7

912-102-36


350



.50

550

110

110

ee figs.

550

800

aoo

800

1,100

200


I --


-r --------- -





-


[







REPORT OF INVESTIGATIONS NO. 22


conditions have been reached within a matter of months, and
vertical leakage caused well 912-102-35, in Daytona Beach, to
stabilize in about three hours.
Figure 29 shows the drawdowns that would be produced by one
well discharging at a rate of 1,000 gpm for different lengths of
time. As the drawdowns outside the pumped well vary directly
with the discharge, drawdowns for greater or lesser rates of
discharge can be computed from these curves. For example, under
the assumed conditions the drawdown 100 feet from a well dis-
charging at 1,000 gpm would be 5.4 feet after 100 days of
discharge. If the well had discharged at 100 gpm for the same
length of time, the drawdown at the same distance would have
been only one-tenth as much, or 0.54 foot.
Computed profiles of the water levels in the vicinity of several
discharging wells after one year of pumping are illustrated in
figure 30. The values used to construct these profiles were obtained
by summing the drawdowns from the 1-year curve in figure 29 and
applying a factor for the efficiency of the discharging wells. The
factor for the efficiency of the discharging well was applied to
the profile only at the well not along the entire profile. One profile
MANCE. N EET D.ISCH.INN .WE .
........ ......vo0 MDo


Figure 29. Predicted drawdowns in vicinity of a well discharging 1,000 gpm
Sfor selected periods.








60 FLORIDA GEOLOGICAL SURVEY


was computed for the center line of a group of nine wells arranged
in three parallel lines of three wells each, with 500 feet between
lines and 500 feet between adjacent wells in each line, forming
a square grid. Each of the other profiles is for a group of nine
wells in a straight line, spaced at the distances indicated in the
figure. Although the number of wells and amount of total discharge


THOUSANDS OF FEET
5 0 5


DISTANCE, IN FEET, BETWEEN PUMPING WELLS
500 1O00 500 200500500 3000 3500 400


4500 5D00


SI s 200 -30gn ea-
: ^' J (p .. -"! -












/ ( S = 0.0007
o / ,Well diaoeter; 8 inches

Figure 30. Theoretical drawdowns after one year of pumping a group of wells
at a rate of 9,000 gpm.

at a rate of 9,000 gpr.


0007 I. J Single line wells 500 feel aporl
ihomeler 8 inches i I I I
S"-Center line of three lnes-wells 500 feel apart
-lines 500 feel apart
A. Drawdowns in the vicinity of a group of nine wells.







REPORT OF INVESTIGATIONS NO. 22


corresponding to the four profiles are the same, the drawdowns are
different owing to differences in the spacing and arrangement of
the wells.
Two of the profiles in figure 30A represent drawdown in wells
500 feet apart. In one system, the wells are arranged in a square
grid and in the other they are spaced along a straight line. The
maximum drawdown under the grid system exceeds the maximum
drawdown under the straight-line system by 3.5 feet. This shows
that with the same number of wells, discharging at the same rate,
spaced at the same distance, less maximum drawdown will result
if the wells are in a straight line.
Three of the profiles in figure 30A represent the drawdowns
resulting from straight-line well systems. In each system, each of
the nine wells is assumed to have discharged 1,000 gpm for one
year. The maximum drawdown for each system varies according
to the distance between adjacent wells in the system. The greatest
maximum drawdown occurs in the system having the least distance
(500 feet) between adjacent wells, and the smallest maximum
drawdown occurs in the system having the greatest distance
(2,000 feet) between adjacent wells.
The curves in figure 30B represent the change in drawdown,
at the center well of straight-line well systems, as the distance
between adjacent wells is changed. The total discharge of each
line of wells was arbitrarily set at 9,000 gpm and the period of
discharge at one year. An example of the use of this graph is as
follows: If a well system were required to yield 9,000 gpm with a
maximum drawdown of 30 feet, one would follow across the 30-foot
drawdown line to its intercepts of the curves to determine the
number of wells, discharge rate for each well, and spacing between
adjacent wells. The 30-foot drawdown line intersects the curve for
45 wells discharging at 200 gpm each at a point corresponding to
a spacing of 400 feet. The 30-foot drawdown line intersects the
curve for 19 wells discharging at 474 gpm each where the spacing
is 1,150 feet between wells, and intersects the curve for nine wells
discharging at 1,000 gpm each where the wells are spaced 4,500
feet apart. The 30-foot drawdown line is above the curve for three
wells discharging at 3,000 gpm each; thus such a group could not
be used if the drawdown were to be restricted to 30 feet. The
graph could be used in a similar manner for any given maximum
drawdown. The drawdowns are almost directly proportional to the
total discharge. Therefore, for greater or lesser rates of discharge,
proportionately lesser or greater maximum drawdown lines should
be used. Thus, in the example above, if the discharge rate had been







FLORIDA GEOLOGICAL SURVEY


18,000 gpm and the maximum drawdown 30 feet, the 15-foot draw-
down line would have been used.

CONCLUSION

1. Volusia County is underlain by limestone of Eocene age. The
oldest formation penetrated by water wells in the county is the
Lake City limestone. Overlying the Lake City limestone is the
Avon Park limestone. The top of the Avon Park limestone ranges
in depth from about 80 feet below the land surface in the central
part of the county to about 200 feet along the east coast. The top
of the Ocala group, which overlies the Avon Park, is about 50 feet
below the land surface in the central part of the county and about
100 feet at the coast. The Ocala group is the first limestone pene-
trated by wells in most of Volusia County. Overlying the limestone
of Eocene age are 40 to 60 feet of shelly sand and clay beds of
Miocene or Pliocene age. Sands of Pleistocene and Recent age
blanket the deposits of Miocene or Pliocene age and form the land
surface.
2. Two sources of ground-water supplies in Volusia County are
a nonartesian aquifer and an artesian aquifer.
The nonartesian aquifer is composed of sand beds of Pleistocene
and Recent age and sand or shell beds in the sediments of late
Miocene or Pliocene age. The nonartesian aquifer is recharged
locally by precipitation on the land surface, which percolates down-
ward. The nonartesian aquifer usually supplies sufficient water for
domestic use.
The artesian aquifer is composed of limestone and dolomite of
Eocene age. Water is confined in the rocks of Eocene age by clay
beds in the deposits of Miocene or Pliocene age. The artesian
aquifer is recharged principally in the central part of the county
and to a lesser extent elsewhere in the county, wherever the water
table stands at a higher elevation than the piezometric surface.
The permeable limestone and dolomite beds of the artesian
aquifer are separated by numerous thin beds of low permeability
which retard the upward or downward movement of water. The
artesian aquifer furnishes sufficient quantities of water for mu-
nicipal, agricultural, industrial, and commercial needs in Volusia
County.
3. The chemical character of artesian water in the northeastern
part of the county varies considerably, according to the location
and depth of the point of sampling. Chemical analyses indicate







REPORT OF INVESTIGATIONS NO. 22


that the dissolved solids range from 136 ppm to 3,780 ppm;
hardness, from 120 ppm to 1,060 ppm; and chloride content, from
8 ppm to 18,000 ppm.
4. Records of water-level measurements indicate that there
has been no progressive areal decline of water levels in recent
years, although heavy pumping has caused some local decline.
5. Analysis of data collected during one pumping test indicates
that the upper part of the artesian aquifer west of Daytona Beach
has a transmissibility of about 300,000 gpd/ft and a storage
coefficient of about 0.0007. It indicates also that drawdowns of 10
feet or so in the upper part of the aquifer do not appreciably
affect water levels in the lower part of the aquifer in that area,
presumably because of the presence of layers of low permeability
which separate the different zones of the aquifer. Probably water-
level drawdowns somewhat greater than 10 feet also would not
have a significant effect. Tests in other parts of the county indicate
that the transmissibility may be as low as 28,000 gpd/ft and as
high as 370,000 gpd/ft and that salt-water encroachment may
occur within a few hours if pumping is excessive.
6. Salt-water contamination of artesian water supplies of
Volusia County results from the upward movement of saline water
into the overlying fresh-water zones of the aquifer. This occurs
where heavy pumping or leakage along faults lowers the artesian
pressure in the fresh-water portion sufficiently to cause the under-
lying salt water, which then has a greater pressure head than the
fresh water, to move upward. Salt-water encroachment can be
partially controlled in Volusia County by developing areas where
limestone beds of low permeability below the freshwater zones are
relatively continuous and where the upper part of the artesian
aquifer is neither faulted nor immediately underlain by salt water,
and by using proper well spacing and pumping rates in well fields
drawing heavily from the upper zone of the artesian aquifer.

REFERENCES

Applin, Esther R. (see also Applin, Paul L.)
1945 (and Jordan, Louise) Diagnostic Foraminifera from subsurface
formations in Florida: Jour. Paleontology, v. 19, no. 2, p. 129-148.
Applin, Paul L.
1944 (and Applin, Esther R.) Regional subsurface stratigraphy and
structure of Florida and southern Georgia: Am. Assoc. Petroleum
Geologists Bull., v. 28, no. 12, p. 1673-1753.








64 FLORIDA GEOLOGICAL SURVEY

Barraclough, Jack T. (see Heath, Ralph C.)
Black, A. P.
1951 (and Brown, Eugene) Chemical character of Florida's waters-
1951: Florida State Board of Cons., Water Survey and Research,
Paper 6.
Brown, Eugene (see Black, A. P.)
Collins, W. D.
1928 (and Howard, C. S.) Chemical character of waters of Florida:
U. S. Geol. Survey Water-Supply Paper 596-G.
Cooke, C. W.
1945a Geology of Florida: Florida Geol. Survey Bull. 29.
1945b Cenozoic echinoids of eastern United States: U. S. Geol. Survey
Prof. Paper 321.
Cooper, H. H., Jr. (see also Stringfield, V. T., 1951)
1946 (and Jacob, C. E.) A generalized graphical method for evaluating
formation constants and summarizing well-field history: Am.
Geophys, Union Trans., 1946, v. 27, no. 4, p. 526-534.
Heath, Ralph C.
1954 (and Barraclough, Jack T.) Interim report on the ground-water
resources of Seminole County, Florida: Florida Geol. Survey
Inf. Cir. 5.

Howard, C. S. (see Collins, W. D., 1928)

Jacob, C. E. (see Cooper, H. H., Jr.)

Jordan, Louise (see Applin, Esther R.)

Leutze, Willard P. (see Wyrick, Granville G.)

MacNeil, F. Stearns
1947 Correlation chart of the outcropping Tertiary formations of the
eastern Gulf region: U. S. Geol. Survey Oil and Gas Inv. Pre-
liminary Chart 29.

Neill, Robert M.
1955 Basic data of the 1946-47 study of ground-water resources of
Brevard County, Florida: U. S. Geol. Survey open-file release.

Purl, Harbans S.
1953 Zonation of the Ocala group in peninsular Florida (abstract):
Jour. Sed. Petrology, v. 23.

1957 Stratigraphy and zonation of the Ocala group: Florida Geol.
Survey Bull. 38.

Stringfield, V. T.
1936 Artesian water in the Florida peninsula: U. S. Geol. Survey
Water-Supply Paper 773-C.








REPORT OF INVESTIGATIONS NO. 22


1951 (and Cooper, H. H., Jr.) Geologic and hydrologic features of an
artesian spring east of Florida: Florida Geol. Survey Rept. Inv.
7.

Vernon, R. 0.
1951 Geology of Citrus and Levy counties, Florida: Florida Geol.
Survey Bull. 33.
Wenzel, L. K.
1942 Methods for determining permeability of water-bearing materials,
with special reference to discharging-well methods: U. S. Geol.
Survey Water-Supply Paper 887.

Wyrick, Granville G.
1956 (and Leutze, Willard P.) Interim report on ground-water
resources of the northeastern part of Volusia County, Florida:
Florida Geol. Survey Inf. Cir. 8.




The ground-water resources of Volusia County, Florida ( FGS: Report of investigations 22 )
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 Material Information
Title: The ground-water resources of Volusia County, Florida ( FGS: Report of investigations 22 )
Series Title: ( FGS: Report of investigations 22 )
Physical Description: vi, 65 p. : maps (1 fold.) diagrs., tables. ; 24 cm.
Language: English
Creator: Wyrick, Granville G
Geological Survey (U.S.)
Publisher: s.n.
Place of Publication: Tallahassee
Publication Date: 1960
 Subjects
Subjects / Keywords: Groundwater -- Florida -- Volusia County   ( lcsh )
Water-supply -- Florida -- Volusia County   ( lcsh )
Genre: non-fiction   ( marcgt )
 Notes
General Note: "Prepared by the United States Geological Survey in cooperation with the Florida Geological Survey and the cities of Daytona Beach, New Smyrna Beach and Port Orange."
General Note: "References": p. 63-65.
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Table of Contents
    Copyright
        Copyright
    Front Cover
        Page i
    Florida State Board of Conservation
        Page ii
    Transmittal letter
        Page iii
        Page iv
    Table of contents
        Page v
        Page vi
    Abstract
        Page 1
        Page 2
    Introduction
        Page 2
        Page 3
        Page 4
        Page 5
    Geography
        Page 6
        Page 7
        Page 5
        Page 8
        Page 9
        Page 10
    Geology
        Page 11
        Page 12
        Page 13
        Page 14
        Page 10
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
    Ground water
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 24
        Page 38
        Page 39
        Page 40
        40a
        Page 41
        Page 42
        Page 43
        Page 44
        Page 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
        Page 60
        Page 61
        Page 62
    Conclusion
        Page 63
        Page 62
    References
        Page 63
        Page 64
        Page 65
Full Text






FLRD GEOLIOWC( ICA SURflViEWY~


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STATE OF FLORIDA
STATE BOARD OF CONSERVATION
Ernest Mitts, Director


FLORIDA GEOLOGICAL SURVEY
Robert 0. Vernon, Director





REPORT OF INVESTIGATIONS NO. 22




THE GROUND-WATER RESOURCES
OF
VOLUSIA COUNTY, FLORIDA

By
GRANVILLE G. WYRICK,
U. S. Geological Survey



Prepared by the
UNITED STATES GEOLOGICAL SURVEY
in cooperation with the
FLORIDA GEOLOGICAL SURVEY

and the
CITIES OF DAYTONA BEACH, NEW SMYRNA BEACH,
AND PORT ORANGE


TALLAHASSEE, FLORIDA
1960







/Jo .2 2-z2
4GRI-


FLORIDA STATE BOAgU"A

OF

CONSERVATION


LeROY COLLINS
Governor


R. A. GRAY
Secretary of State



RAY E. GREEN
Comptroller


RICHARD ERVIN
Attorney General



J. EDWIN LARSON
Treasurer


THOMAS D. BAILEY LEE THOMPSON
Superintendent of Public Instruction Commissioner of Agriculture (Acting)



ERNEST MITTS
Director of Conservation







LETTER OF TRANSMITTAL


florida CeoIoqical Sarvel

Callakassee

February 20, 1960

MR. ERNEST MITTS, Director
FLORIDA STATE BOARD OF CONSERVATION
TALLAHASSEE, FLORIDA


DEAR MR. MITTS:


The Florida Geological Survey is pleased to publish as Report
of Investigations No. 22 a summary of "The Ground-Water
Resources of Volusia County, Florida," which was prepared by
the members of the U. S. Geological Survey. A portion of this
work was conducted by Mr. W. P. Leutze, but the principal in-
vestigation has been made by Mr. Granville G. Wyrick, Geologist
with the U. S. Geological Survey.
The report will present the information required for the
development of water supplies for the rapidly expanding Atlantic
Coast area in the vicinity of Daytona Beach, Holly Hill, Edgewater,
DeLand and other major metropolitan areas of Volusia County.
A series of wells in which permanent water level recorders have
been installed will provide a continued monitoring of the water
resource trends in the county, and the Florida Geological Survey,
with the U. S. Geological Survey, will be kept aware of the inven-
tory of this county's ground-water resources.
Respectfully yours,
ROBERT 0. VERNON, Director



















































Completed manuscript received
January 21, 1960
Published by the Florida Geological Survey
E. 0. Painter Printing Company
DeLand, Florida
March 16, 1960

iv









CONTENTS


Page
Abstract ....-............-................ ......... ...... -... -.. ...... ...........- 1
Introduction ..............-------------............. ----....----------................... ......................-.. 2
Previous investigations --.........------------------------------............--..................-..........------ 3
Acknowledgments ......-.......--.-- ...--.....-------.. ---------..-----.--.---.--...........-- --------.. 4
Well-numbering system .............-....----- ----..---------......-- ---------.......---......-- --.... 4
Geography .--......-------------------..............................................-------------................................ 5
Location and area ..-------------.............--..... ------.-....---------------... ---.... --..-....... 5
Climate ..---........-...--- .....-------------..... --------------................-.....---------................--..... 7
Population ---------------------............................-----------------................................-----------............... 7
Topography --------............------.. --....----------..... --.............-------------------.....................-- 7
Terraces .---.....................--------------------------.......----------------........ --.... --...... 7
Karst topography .--..........-----------..----------.......------..-.....---------..-..---........ 10
Drainage .-.....----.......----.. ..----------- --------- -----------..............-.....-----. 10
Geology -....--......-----.. ......-- -----............-- ......------- 10
Test drilling ...................................................................................------------------------------------------------. 11
Formations .--........--.........--------.. ....-----...........---- -- -- ..............1------ 13
Lake City limestone ...........----------.--.---...------....------..-..-..-----..-...----..... 13
Avon Park limestone -------..-..-......... ----------.......................-----------.--..--....---- 20
Ocala group ..----.. --.................----- ----------........--------- ...--..-...............-----------.... 21
Miocene or Pliocene deposits .......--........-- ..........----------------........-. 23
Pleistocene and Recent deposits ...............-....... .......------------ ............---- .-----23
Structure ..----------------................................-....-.........................----------------................---------- 23
Ground water ..--..- --------------.....------...... .......... ---------..----.....---.-- -------........ 24
Nonartesian aquifer .-----------...... -----................. --..... -------------.... ----.............---. 25
Artesian aquifer -....------------......... ----------......----...........------------------- ........... 25
Quality of water .---....-.....---.....--..... ---- --..--- ...............----------- .....----.-- 35
Wells .-..-.....-.............-----...................-----------------------------------..... .........-----..---.......-- 41
Salt-water contamination .......-------........ -------....---...---.--------...............-----.--- 41
Quantitative studies --.--..--..........................................................--------------------.....................---- 48
Construction and location of test and observation wells .....-.......---.....-------...... 49
Pumping test .---.............--....................-----------------...------...------- ------------ 50
Analyses of data --.....---------.........--.. ------ ....--------- ...........----..----.-------- 50
Conclusion ---------------------.................................................................--.............------- 62
References -...-...-........-- ......-----.-----..----..... ----- -------....-----................--- 63


ILLUSTRATIONS
Figure Page
1 Explanation of well-numbering system ......----. ..--- ..... ..-----..-------- 5
2 Location of Volusia County ..------------------..................................-.........-- ........------ 6
3 Pleistocene marine terraces .............-...-.....-------... --...---------------......................-------- 9
4 Altitude of the top of limestone of Eocene age ..-...-.......................--------........--------11
5 Locations of test wells in part of Volusia County .......-..-................----------...... 12







6 Data obtained from well 905-113-3 .................................---------------------------........................ 13
7 Data obtained from well 909-106-1 -------............-.......-......-..---------------....................--...-..-. 14
8 Data obtained from well 910-105-1 --............-...........--------------------......--....-...-.......--..-.. 14
9 Data obtained from well 911-104-4 ......-..........-------.-.......-...---...-.........----------....-......--.. 15
10 Data obtained from wells 911-103-5 and 914-102-6 ....-...-........----------....-....-....... 15
11 Materials penetrated by test wells in Tomoka State Park .-...............--------16
12 Geologic formations penetrated by wells in Volusia County ..-.........------- 19
13 Piezometric surface of Volusia County in November 1955 -...-..-..-....... 26
14 Hydrology along line A-A', figure 3, in November 1955 --...-.........-........ 28
15 Hydrographs of wells 912-101-18 and 857-105-1 and monthly rain-
fall at Daytona Beach .-.....--....-....------..-...-..-........-.....-...-.................--------------.....-....-.........- 331
16 Hydrographs of wells measured periodically in Volusia County and
rainfall at Daytona Beach ..-------------..--..-..........--...................------------....................-......---... 32
17 Hydrographs of wells 911-104-4 and 911-104-5 at Daytona Beach
airport well field .--...........-........---- -...--------........-...........................-.........------------..-...-..-..... 33
18 Areas of artesian flow and depth of piezometric surface below land
surface in November 1955 -...-----------.........--........--..-....--......-....................---.......-......-------... 35
19 Location of wells whose water was sampled for chemical analysis 36
20 Wells inventoried in Volusia County --...-.......--------......... between p. 40 and 41
21 Chloride content of water from wells penetrating upper part of
artesian aquifer --.--.....-------------..............--------..............................................----------------..............--.... 42
22 Chloride content of artesian water along line A-A' in figure 3 .....-... 44
23 Fluctuations of water level and chloride content of water from well
915-103-1 at Ormond Beach ....... ........- ..- .....------- ----------..... ....................... 46
24 Chloride content of water from wells in vicinity of Adams Street
well field -....-..--.....................---...-------------------------............-.........-.....-.......-...-..-......--.... 47
25 Water levels in the pumped well, the nearby observation wells and
the drainage ditch, and graph of barometric pressure -..-............--.-.......--------. 51
26 Water levels in nearby observation wells during pumping test -....... 52
27 Log plot of the drawdowns, and first part of recovery, versus t/r' 55
28 Semilog plot of drawdowns versus t/r2 for well 909-106-6 showing
solution for transmissibility and storage coefficients ......................... --------------56
29 Predicted drawdowns in vicinity of a well discharging 1,000 gpm
for selected periods ---.............-..-.....---------------------.......--..........-.......------........-....... 59
30 Theoretical drawdowns after one year of pumping a group of
wells at a rate of 9,000 gpm ............ ---. -- --------... .......... ................ 60

TABLES

Table Page
1 Data from geologic logs of wells in Volusia County ..-..-...-.....--.......-...... 17
2 Analyses of water samples from wells in Volusia County ................ 37
3 Data from analysis of pumping tests in Volusia County -..-.--..-..........--.--. 58
Figure Page
IAdditional records on wells in Volusia County, Florida have been published by the Florida
Geological Survey, P. 0. Box 631, Tallahassee, Florida, as Information Circular 24. A copy of
this publication may be obtained for one dollar.








GROUND-WATER RESOURCES OF VOLUSIA
COUNTY, FLORIDA
By Granville G. Wyrick
ABSTRACT

Volusia County comprises approximately 1,200 square miles in
the central part of the east coast of Florida. Limestone underlies
this area at a depth of 40 to 100 feet and extends to a depth of
several thousand feet. The upper part of the limestone includes
the Lake City limestone, the Avon Park limestone, and the Ocala
group' of Eocene age. The limestone of Eocene age is overlain by
sand, clay, and shell sediments of Miocene or Pliocene age. These
sediments are overlain by Pleistocene and Recent sand deposits,
which blanket the area to a depth of 30 to 70 feet.
Ground water occurs under both water-table (nonartesian) and
artesian conditions in Volusia County. The nonartesian aquifer,
composed of sand beds of Pleistocene and Recent age and the upper-
most sand and shell beds of Miocene or Pliocene age, generally
furnishes sufficient water for domestic use. The artesian aquifer
is composed of limestone of Eocene age. Beds of relatively
impermeable clay of Miocene or Pliocene age overlie the artesian
aquifer and confine the water in the aquifer. Within the limestone
formations numerous thin beds of low permeability retard the
vertical movement of water between the highly permeable zones of
the artesian aquifer. The artesian aquifer supplies most of the
ground water used in Volusia County.
There has been no progressive lowering of water levels in the
artesian aquifer. Water levels have declined locally in areas of
heavy pumping.
Salt-water contamination of fresh-water zones in the artesian
aquifer occurs where heavy pumping lowers the artesian pressure
sufficiently to cause the underlying salt water to move upward.
Such encroachment can be prevented by developing wells only in
areas where salt water lies at a considerable depth, or where the
limestone beds of low permeability are continuous over large areas,
and also by avoiding large drawdowns.

'The stratigraphic nomenclature used in this report conforms to the usage
of the Florida Geological Survey and, with the exception of the Ocala group
and its subdivisions, to the usage of the U. S. Geological Survey.







FLORIDA GEOLOGICAL SURVEY


Pumping tests in Volusia County indicate that the upper zone
of the artesian aquifer has a storage coefficient of approximately
0.0007 and a transmissibility ranging from 30,000 to 370,000 gpd
(gallons per day) per foot. At one test site in Daytona Beach,
where salt-water encroachment has been a problem, an analysis of
pumping-test data indicates that, after 3 hours of pumping, leakage
to the upper part of the aquifer equaled the pumping rate. Pre-
sumably, this leakage was from a salty zone below the bottom of
the well. At another test site 6 miles west of Daytona Beach, salt
water occurred at a depth greater than 500 feet and was separated
from the fresh water of the aquifer by numerous layers of limestone
and dolomite of low permeability. This test indicates that if draw-
downs are not excessive salt-water contamination probably will
not occur in that locality.


INTRODUCTION

Salt-water contamination of fresh ground-water supplies is a
problem in many areas of Florida. It is especially serious in coastal
areas where there is danger of direct encroachment of salt water
from the ocean or where salt water occurs at relatively shallow
depths in the water-bearing formations. The problem has become
acute in certain coastal areas of Pinellas County and in parts of
the Miami area of Dade County.
During recent years the cities of Daytona Beach, Port Orange,
and New Smyrna Beach, in Volusia County, have experienced
salt-water contamination of their municipal supplies as a result of
the increased use of ground water. The greater use of ground
water is due to an increase in both population and per capital use
of water. Recognizing the problems of salt-water contamination,
the City Council of Daytona Beach requested that the U. S.
Geological Survey make an investigation of the ground-water
resources of Volusia County. In response to their request, an
investigation was begun in October 1953 by the U. S. Geological
Survey in cooperation with the Florida Geological Survey and the
cities of Daytona Beach, Port Orange, and New Smyrna Beach.
The purpose of the investigation was to make a detailed study
of the ground-water resources of the county, with special emphasis
on the problems of salt-water contamination. This report contains
the results of that investigation. The major phases of the investi-
gation included the following:







FLORIDA GEOLOGICAL SURVEY


Pumping tests in Volusia County indicate that the upper zone
of the artesian aquifer has a storage coefficient of approximately
0.0007 and a transmissibility ranging from 30,000 to 370,000 gpd
(gallons per day) per foot. At one test site in Daytona Beach,
where salt-water encroachment has been a problem, an analysis of
pumping-test data indicates that, after 3 hours of pumping, leakage
to the upper part of the aquifer equaled the pumping rate. Pre-
sumably, this leakage was from a salty zone below the bottom of
the well. At another test site 6 miles west of Daytona Beach, salt
water occurred at a depth greater than 500 feet and was separated
from the fresh water of the aquifer by numerous layers of limestone
and dolomite of low permeability. This test indicates that if draw-
downs are not excessive salt-water contamination probably will
not occur in that locality.


INTRODUCTION

Salt-water contamination of fresh ground-water supplies is a
problem in many areas of Florida. It is especially serious in coastal
areas where there is danger of direct encroachment of salt water
from the ocean or where salt water occurs at relatively shallow
depths in the water-bearing formations. The problem has become
acute in certain coastal areas of Pinellas County and in parts of
the Miami area of Dade County.
During recent years the cities of Daytona Beach, Port Orange,
and New Smyrna Beach, in Volusia County, have experienced
salt-water contamination of their municipal supplies as a result of
the increased use of ground water. The greater use of ground
water is due to an increase in both population and per capital use
of water. Recognizing the problems of salt-water contamination,
the City Council of Daytona Beach requested that the U. S.
Geological Survey make an investigation of the ground-water
resources of Volusia County. In response to their request, an
investigation was begun in October 1953 by the U. S. Geological
Survey in cooperation with the Florida Geological Survey and the
cities of Daytona Beach, Port Orange, and New Smyrna Beach.
The purpose of the investigation was to make a detailed study
of the ground-water resources of the county, with special emphasis
on the problems of salt-water contamination. This report contains
the results of that investigation. The major phases of the investi-
gation included the following:







REPORT OF INVESTIGATIONS NO. 22


1. An inventory of existing wells to determine their location,
depth, distribution, diameter, yield, and other pertinent data.
2. The drilling of test wells in selected areas where sufficient
information could not be obtained from existing wells.
3. Chemical analyses to determine specific chemical
characteristics of the ground water.
4. The collection and study of water-level records to determine
seasonal fluctuations and progressive trends.
5. Geologic studies to determine the character and extent of
the various geologic formations as they relate to the occurrence
of ground water.
6. The determination of the water-transmitting and water-
storage capacities of the aquifers.

During the period 1953-55, the investigation was carried on by
the writer and W. P. Leutze. The results of this period of the
investigation were published in Florida Geological Survey
Information Circular no. 8, entitled "Interim Report on Ground-
Water Resources of the Northeastern Part of Volusia County,
Florida" by Granville G. Wyrick and Willard P. Leutze. Since
1955 the investigation has been carried on by the present writer.

PREVIOUS INVESTIGATIONS

The geology and ground-water resources of Volusia County are
discussed in several reports published by the U. S. Geological
Survey and the Florida Geological Survey.
Cooke (1945, p. 226-227, 272, 311) briefly discusses the
occurrence of the Caloosahatchee marl, Anastasia formation, and
Pamlico formation in Volusia County. A report by Vernon (1951,
figs. 13, 33, and pl. 2) includes Volusia County in maps of central
Florida, which show generalized geologic sections and the structure
of the Inglis member of the Moodys Branch formation.
A map of the piezometric surface of the principal artesian
(Floridan) aquifer in Florida (Stringfield 1936, pl. 12) includes
Volusia County. Stringfield (1936, p. 152, 162-163) discusses the
areas in which the artesian aquifer is recharged and areas in
which the chloride content of the water is low. Stringfield and
Cooper (1951, p. 71) discuss the occurrence of salty artesian water
in eastern Volusia County.






FLORIDA GEOLOGICAL SURVEY


Chemical analyses of water from wells in Volusia County are
included in a report by Collins and Howard (1928, p. 130-133) and
in one by Black and Brown (1951, p. 109-110).

ACKNOWLEDGMENTS

Appreciation is extended to the many residents of the county
who cooperated in the collection of data and who readily gave
information regarding their wells. Special acknowledgment is
given to the well drilling companies, consultants, and public
officials, whose cooperation assisted the investigation and facilitated
the preparation of this report. During the investigation the
Daytona Beach Water Department, Mr. J. R. Brennon,
superintendent, furnished office and storage space.
The investigation was made under the immediate supervision
of Ralph C. Heath, Acting District Geologist, from October 1953
until August 1955, and under M. I. Rorabaugh, District Engineer,
for the remainder of the study. The project was under the general
supervision of A. N. Sayre, former chief of the Ground Water
Branch, U. S. Geological Survey and of Herman Gunter, former
State Geologist and Director of the Florida Geological Survey.

WELL-NUMBERING SYSTEM

Positions on the earth's surface may be located by a system of
coordinates known as parallels of latitude and meridians of
longitude. The parallels of latitude circle the earth parallel to
the equator and are numbered from the equator to the poles in
degrees, minutes, and seconds, depending upon the angular distance
between them and the equator. The meridians of longitude
traverse the earth north and south and are numbered east or west
from the Greenwich, England, prime meridian in degrees, minutes,
and seconds.
The well-numbering system, derived from latitude and longitude
coordinates, is based on a statewide grid of 1-minute parallels of
latitude and meridians of longitude. The wells in a 1-minute
quadrangle are numbered consecutively in the order inventoried.
The well number is a composite of three numbers separated by
hyphens: the first number is composed of the last digit of the
degree and the two digits of the minutes that define the latitude
on the south side of the 1-minute quadrangle; the second number
is composed of the last digit of the degree and the two digits o:
the minutes that define the longitude on the east side of the






REPORT OF INVESTIGATIONS NO. 22


quadrangle; and the third numeral is that of the well inventoried.
The latitude and longitude prefix "N" and "W" and the first digit
of the degree number are not included in the well number (fig.
1).

GEOGRAPHY
LOCATION AND AREA

Volusia County is in the central part of the east coast of Florida
(fig. 2), and comprises approximately 1,200 square miles. It is
bounded on the north by Flagler County, on the south by Brevard
County, on the east by the Atlantic Ocean, and on the west by the
St. Johns River.
The largest cities in Volusia County are Daytona Beach,
DeLand, and New Smyrna Beach. Other incorporated munici-


Figure 1. Explanation of well-numbering system.






FLORIDA GEOLOGICAL SURVEY


Figure 2. Location of Volusia County.






REPORT OF INVESTIGATIONS NO. 22


palities include Ormond Beach, Holly Hill, South Daytona, Port
Orange, Edgewater, Oak Hill, Orange City, and Pierson.

CLIMATE

The climate of Volusia County is subtropical. The mean annual
temperature is about 71 7F, according to the U. S. Weather Bureau.
The normal average rainfall at Daytona Beach is about 51 inches, at
DeLand is about 53 inches, and at New Smyrna Beach is about 50
inches. Generally, precipitation is greatest during early fall.

POPULATION

The total permanent population of Volusia County was about
74,000 in 1950, according to the U. S. Census Bureau. At that
time the population of Daytona Beach was about 30,000, DeLand
was about 9,000, New Smyrna Beach was about 6,000, and Port
Orange was about 1,200. The population of Volusia County
increased about 34 percent between the 1940 census and the 1950
census.

TOPOGRAPHY

Volusia County is in the topographic division described by
Cooke (1945, p. 10, 11) as the Coastal Lowlands. These lowlands
consist of essentially level marine terraces, which are especially
well defined in Volusia County. The topography is of two types:
leveled terraces and karst (solution) topography. In Volusia
County, karst topography occurs only on the highest terrace.

TERRACES

During Pleistocene time the sea fluctuated between levels both
above and below its present level, submerging greater or lesser
land areas according to its height. Whenever the height of the
sea remained relatively stationary for a long period, waves and
currents eroded the sea floor and formed an essentially level
surface, called a terrace. When the sea dropped to a lower level,
each terrace emerged as a level plain. The landward edge of such
a terrace became an abandoned shoreline, an abrupt scarp
separating it from the next higher terrace, and the seaward edge
became the new shoreline. Generally, sand dunes were built up
;along the new shorelines.
i






REPORT OF INVESTIGATIONS NO. 22


quadrangle; and the third numeral is that of the well inventoried.
The latitude and longitude prefix "N" and "W" and the first digit
of the degree number are not included in the well number (fig.
1).

GEOGRAPHY
LOCATION AND AREA

Volusia County is in the central part of the east coast of Florida
(fig. 2), and comprises approximately 1,200 square miles. It is
bounded on the north by Flagler County, on the south by Brevard
County, on the east by the Atlantic Ocean, and on the west by the
St. Johns River.
The largest cities in Volusia County are Daytona Beach,
DeLand, and New Smyrna Beach. Other incorporated munici-


Figure 1. Explanation of well-numbering system.






FLORIDA GEOLOGICAL SURVEY


Discussions of Pleistocene terraces in Florida are included in
the report by Cooke (1945, p. 248). Four of these terraces-the
Penholoway, the Talbot, the Pamlico, and the Silver Bluff-are
recognizable in Volusia County. Figure 3 shows them as they were
mapped from topographic maps and altimeter surveys.
The Penholoway terrace in the western part of Volusia County
is the highest marine plain in the county. This terrace is believed
by Cooke (1945, p. 17) to have formed during the Sangamon inter-
glacial stage, when sea level stood 70 to 80 feet above present sea
level.
The Talbot terrace was formed toward the end of the Sangamon
interglacial stage, when sea level dropped to a height of about 45
feet above present sea level. During the formation of the Talbot
terrace, sand dunes built up along the seaward edge of the
Penholoway terrace, which at that time was an island. When the
sea receded after Talbot time, the seaward or eastern side of the
island emerged as a terrace about 10 miles wide and the western
side of the island emerged as a very narrow terrace, because it was
sheltered from strong wave and current action. The Talbot terrace
is the best preserved and therefore the most easily recognized
terrace in Volusia County.
The Pamlico terrace was formed during a recession of the ice
during the Wisconsin glacial stage. During this recession sea level
was 25 to 30 feet above its present level, and in Volusia County
the Penholoway and Talbot terraces formed an island. Sand dunes
built upon the seaward edge of the Talbot terrace, and the ocean
floor surrounding the terrace was leveled to a plain. When the
sea again receded, the Pamlico terrace emerged as a plain about
six miles wide on the seaward side of the island and one mile
wide on the landward or western side.
The Silver Bluff terrace also was formed during the Wisconsin
glacial stage. During Silver Bluff time the ocean was five to six
feet above present sea level. The eastern side of the Pamlico terrace
was subjected to erosion by the ocean, but the western side was
probably subjected to erosion by a river that was in approximately
the present channel of the St. Johns River. High sand dunes were
formed along the seaward side of the Pamlico terrace, and a river
terrace was formed along the western side. It is probable that
Spruce Creek and the Tomoka River started eroding channels in
the eastern edge of the Pamlico terrace during Silver Bluff time.
Figure 3 shows that these streams have eroded large. areas in the
eastern side of the Pamlico terrace.
Cooke (1945, p. 247) advances the theory that the formation






REPORT, OF INVESTIGATIONS NO. 22


of marine terraces was not a continuous process of sea level
dropping from the level of one terrace to the level of the next lower
terrace. He theorizes that between the formation of one terrace
and that of the next lower terrace sea level may have dropped to
as much as 200 feet below present sea level and then recovered
to the height of the next lower terrace.
At the present time, the ocean is building a terrace along the
east coast of Volusia County, and the St. Johns River is forming a
river terrace in the western part of Volusia County. Dunes are
being formed along the eastern edge of the Silver Bluff terrace.


Figure 3. Pleistocene marine terraces.






FLORIDA GEOLOGICAL SURVEY


KARST TOPOGRAPHY

Karst topography is the name applied to the irregular, pitted
land surface that occurs where sinkholes are numerous and drain-
age is underground. Sinkholes are formed by the collapes of surface
deposits into caverns created by the solution and removal of under-
lying limestone. Karst topography has been extensively developed
on the Penholoway terrace in Volusia County. The topographic
section along line A-A' in figure 3 shows that the surface deposits
at some places in DeLand have slumped as much as 40 feet below
the level of the Penholoway terrace. This karst topography extends
north and south for several miles from DeLand along the Pen-
holoway terrace, and it also occurs along the Penholoway terrace
near Pierson and Seville. Nearly all precipitation on the terrace
either drains downward into the underlying limestone or is
returned to the atmosphere by evaporation or plant transpiration.
The sinkholes often become clogged by nearly impermeable peaty
material which retards the downward movement of water, thus
forming sinkhole lakes. There is no evidence of karst topography
in other parts of Volusia County.

DRAINAGE

Surface drainage in Volusia County is poorly developed, re-
sulting in relatively large swampy areas. On the Penholoway
terrace all drainage is underground. Spruce Creek and the Tomoka
River drain the eastern part of the county, and small tributaries
of the St. Johns River drain the western part. These streams are
so poorly developed and inefficient that much of the county,
especially the eastern part of the Talbot terrace, is marshland.
The Halifax River is not a river but a lagoon that runs parallel
to the coast throughout most of the northeastern part of the county.
The Halifax River and its southern counterpart, Mosquito Lagoon,
are connected with the ocean by Ponce de Leon Inlet.

GEOLOGY

Sediments of Pleistocene and Recent age blanket Volusia
County. These sediments are generally beds of unconsolidated sand
and shell which overlie beds of clay and shell of Miocene or Pliocene
age. Limestone of Eocene age underlies the deposits.of Miocene or
Pliocene age. Figure 4 shows the altitude of the top of this lime-
stone in Volusia County.







REPORT OF INVESTIGATIONS NO. 22


In Volusia County the Pleistocene and Recent sediments are
the reservoir for the nonartesian ground water, and the Miocene
or Pliocene clays tend to confine ground water under artesian
pressure in the underlying limestone of Eocene age. Nine test
wells were drilled and ten test holes were augered in Volusia
County as a part of this study, to obtain geologic and hydrologic
data that could not be obtained from existing wells.

TEST DRILLING

The locations of the nine test wells, drilled along U. S. Highway


Figure 4. Altitude of the top of limestone of Eocene age.







FLORIDA GEOLOGICAL SURVEY


92 between DeLand and Daytona Beach, are shown in figure 5.
During the drilling the following were collected:
1. Rock cuttings at approximately 5-foot intervals.
2. Information on the length of time required to drill each layer of the
limestone formations.
3. Water samples for the determination of chloride content at intervals of
5 to 10 feet (from the bailer).
4. Water samples from isolated sections of the well.
5. Water-level measurements representing both the composite pressure
head in the entire open hole and the head in isolated sections of the
well.
Upon completion of the wells, traverses were made with a cur-
rent meter to locate the water-producing zones and to determine
the rate of internal flow in the wells. Also, water samples were
collected at different depths by use of a deep-well sampler.
The same type of data was collected during the construction of
public supply wells in the cities of Daytona Beach, Holly Hill, and
Edgewater. The most important information obtained during the
construction of the test and supply wells is shown diagrammatically
in figures 6-10.
A power auger was used to auger 10 test holes at Tomoka
State Park. Samples from these holes were used to determine the
thickness of the clay layers and the depth to the top of the lime-
stone. Figure 11 is a graphic representation of the data collected
during augering of the test holes.


Figure 5. Location of test wells in part of Volusia County.








REPORT OF INVESTIGATIONS NO. 22


FORMATIONS

The geology of Volusia County is described on the basis of rock
:uttings collected during the drilling of water wells (table 1) and
irom a study of the topography. Rocks older than the Lake City
limestone are not described in this report because no water wells
in the county are known to penetrate them.

LAKE CITY LIMESTONE

The Lake City limestone (Applin and Applin, 1944), of early
middle Eocene age, does not crop out in Florida. According to
Cooke (1945, p. 46), this formation unconformably overlies the
Oldsmar limestone of Wilcox age. As may be seen in figure 12, well
901-117-2 penetrated 380 feet of the Lake City limestone without

SELF- RELATIVE DRILLING TIME CHLORIDE CONTENT
AGE POTENTIAL LITHOLOGY RESISTIVITY (minutes per fool) ( parts pr million)
I P m 5MV5 10 15 25 50 75
0


50 LoAl IociN -- --
0 4HOCCOC .PI.









250
0 0


Figure 6. Data obtained from well 905-113-3.









FLORIDA GEOLOGICAL SURVEY


Figure 7. Data obtained from well 909-106-1.


pp* fp.u


CHOO CONWNT
ppwt P" -)


ISOI




-A ---



t\ t



4.LL%- 161 o


Figure 8. Data obtained from well 910-105-1.


I-M'


__


M"4010f v"WkeV






FLORIDA GEOLOGICAL SURVEY


KARST TOPOGRAPHY

Karst topography is the name applied to the irregular, pitted
land surface that occurs where sinkholes are numerous and drain-
age is underground. Sinkholes are formed by the collapes of surface
deposits into caverns created by the solution and removal of under-
lying limestone. Karst topography has been extensively developed
on the Penholoway terrace in Volusia County. The topographic
section along line A-A' in figure 3 shows that the surface deposits
at some places in DeLand have slumped as much as 40 feet below
the level of the Penholoway terrace. This karst topography extends
north and south for several miles from DeLand along the Pen-
holoway terrace, and it also occurs along the Penholoway terrace
near Pierson and Seville. Nearly all precipitation on the terrace
either drains downward into the underlying limestone or is
returned to the atmosphere by evaporation or plant transpiration.
The sinkholes often become clogged by nearly impermeable peaty
material which retards the downward movement of water, thus
forming sinkhole lakes. There is no evidence of karst topography
in other parts of Volusia County.

DRAINAGE

Surface drainage in Volusia County is poorly developed, re-
sulting in relatively large swampy areas. On the Penholoway
terrace all drainage is underground. Spruce Creek and the Tomoka
River drain the eastern part of the county, and small tributaries
of the St. Johns River drain the western part. These streams are
so poorly developed and inefficient that much of the county,
especially the eastern part of the Talbot terrace, is marshland.
The Halifax River is not a river but a lagoon that runs parallel
to the coast throughout most of the northeastern part of the county.
The Halifax River and its southern counterpart, Mosquito Lagoon,
are connected with the ocean by Ponce de Leon Inlet.

GEOLOGY

Sediments of Pleistocene and Recent age blanket Volusia
County. These sediments are generally beds of unconsolidated sand
and shell which overlie beds of clay and shell of Miocene or Pliocene
age. Limestone of Eocene age underlies the deposits.of Miocene or
Pliocene age. Figure 4 shows the altitude of the top of this lime-
stone in Volusia County.








REPORT OF INVESTIGATIONS NO. 22


fliiI IM-N IE MTIVC VY1,05ITY CjoORIOf CONTFENT
C I"O NILLT(-4 RfSITIVIY 0 ;."w-Of WATER
(MINIIIII ~ ~ ~ O P1W(01ATFR P1% .









200*N

H" L/
I50 ____ ____ __ _21
EAF -h

I. /














Figure 9. Data obtained from- well 911-104-4.


9
50
100


EF- RfItLATIVE PRILLIPN TIME RELATIVE VELOCITY CHLORIDE CONTEND
AGCE PIOTNTI EIT1HOISTIVITY ( ,nute1 % r fo (, fmw of c nt erl ,. (pOa p A hc)
.0 ch0.$ I15 30 45 60 75 90 50 70 90
SS 119 I 6 0 2 t1 oll 2 Smp$t0 oken fHo m













Figure 10. Data obtained from wells 911-103-5 and 914-102-6.






FLORIDA GEOLOGICAL SURVEY


O- SAND
SHELL
o H S HELL
LUL
S100
L LIMESTONE

4' 150-
100 2o00 leet
0 Note See inset C in figure 20 for well locations

Figure 11. Materials penetrated by test wells in Tomoka State Park.

reaching older formations. Also, the top of this limestone is shown
to dip eastward from the high near DeLand at approximately
three feet per mile.
The Lake City limestone consists of layers of dark brown dolo-
mite separated by layers of chalky limestone. The dolomite is
crystalline and contains few fossils. The limestone is very
fossiliferous and, in places, seems to be composed entirely of
unconsolidated foraminiferal tests. The most distinctive fossil
in this limestone is Dictyoconuis americanus (Cushman), regarded
as a guide fossil for the Lake City limestone (Applin and Applin,
1944). Fossils identified in well cuttings from this formation in
Volusia County are:

Amphistegina na8sauensis Applin and Jordan
Dictyoconus americanus (Cushman)
Fabular-ia vaughani Cole and Ponton
Lepidocyclina sp.

The unconformity separating the Lake City limestone from the
Avon Park limestone above it is marked, in some wells, by a thin
layer of well rounded phosphatic pebbles and in well 909-106-1
by a 6-foot layer of brown clay and peat.
The Lake City limestone was omitted in the interim report of
this investigation (Wyrick and Leutze, 1956) but a re-examination
of the well cuttings revealed that the section described in that
report as "Zone B" of the Avon Park limestone is actually the Lake
City limestone.




iligi nm im ----
TABLE 1. Data From Geologic Logs of Wells in Volusia County

Depth of the formation penetrated by wells, in feet below land surface


V V2


4'. o Pliocene 1-o
SU.S. or Mio- Avon Lake g
U.S.G.S. e scene sed- Williston Inglis Park City n ?g F.G.S.
well No. ,.5 s E iments formation formation limestone limestone .s p well No.

851-118-11 20 0-50 50-110 __ 110-225 -90 W-1639
858-117-1 60 0-50 50- 65 --.. -_. 65-125 _- 5 W-3531
859-055-1 11 0-78 78- 89 89-131 131-195 195-226 -78 W-4464
859-117-1 52 0 65 ........ -. 65-185 -13 W-3581
.900-120-19 21 0-30 30- 45 ..... 45- 60 -24 W-4164
900-120-20 21 .. ... -.... 55- 74 -34 W-4589
901-056-2 8 0 ..--............... 86 86-115 115-126 ... -78 W-3475
901-117-2 38 ( ------.- -.-.. sink102-118 118-163 163-280 -76 -.
903-116-1 71 0-35 35- 90 90-385 385-511 -19 W- 657
905-113-3 40 0-37 37- 67 .. 67- 93 93-351 -27 W-3527
905-119-1 99 .. .-... ...... 91-231 -..--... + 8 W-4588
907-121-2 24 0 -.......... 34 ...... 34- 60 ... ...... -10 W- 487
908-059-2 11 0-70 70- 88 88-100 .... .......... -77 W-3529
909-100-7 8 0 .-............ 88 88-105 -. ... .... -80 W-3525
909-106-1 27 0-41 41- 82 82- 90 90-119 119-370 370-496 -55 W-3476
909-122-3 28 0 .................... 95 ....... 95-100 320-400 -67 W- 490
910-105-1 26 0-37 37- 84 84 ..............-122 122-365 365-498 -58 W-3540
911-103-5 26 0-73 73-102 102-118 118-163 163-280 ........ -76 ..- ---
911-104-4 27 0-62 62- 94 94-110 110-127 127-365 365-501 -67 W-3477






TABLE 1. (Continued)

Depth of the formation penetrated by wells, in feet below land surface


.4 S3

Pliocene W
aU.S.S. or Mio- Avon Lake 12 '
U.S.G.S. OT g, cene sed- Williston Inglis Park City S, F.G.S.
well No. 04.5 ia iments formation formation limestone limestone : MS well No.

912-102-35 4 0-50 50- 95 95 .............180 180-200 ........ -91 W-3569
912-126-8 58 0-60 60-108 ... 108-126 ........ ........ -50 W- 451
918-100-5 19 0-97 97-103 103-151 151-185 ........ ........ -84 W-4227
918-127-1 71 0-88 88-110 ..-... 110-140 140-270 ........ -39 W- 450
914-102-6 19 0-60 60- 98 98-122 122-185 185-190 ........ -79 W-8701
914-126-1 52 .0-65 65- 90 -..-.. .-.... 90-150 .... -38 W- 492
916-182-1 8 0-45 45- 65 65 ................130 130-290 290-318 -57 W- 744
919-106-3 29 0-65 65- 95 95-130 130-190 ... ... -66 W-4578
920-105-8 11 0 ................... 91 91-147 .....- ... ...... -80 W-3473
921-105-2 19 0-41 41- 92 92-145 .............. -73 W-3472


'







ALTITUDE, IN FEET REFERRED TO MEAN SEA LEVEL


rf
zo









I~ -l






rq
-n I I
'M14 909-C2-3 0i


I C)
z 1 0n

0 1-3

WON 93152-3 -9z




00
4,4~~ ~ '043-494 -


04 0
'Ma 85"7-1





-~W '.39>'72 44


do -- wil0t- -l


IT 0

Figur 12 Googcfomainspnerte b elsinVouiaCuny






FLORIDA GEOLOGICAL SURVEY


AVON PARK LIMESTONE

The Avon Park limestone (Applin and Applin, 1944), of late
middle Eocene age, is the oldest deposit exposed at the surface in
any part of Florida. It crops out in Citrus and Levy counties.
Near DeLand, this formation is the first limestone penetrated by
wells. The top of the Avon Park limestone in Volusia County dips
gently eastward, and is overlain by younger limestones of Eocene
age in the eastern part of the county and along the St. Johns River.
The Avon Park limestone is about 280 feet thick where it is over-
lain by the Ocala group (fig. 12).
The color of the Avon Park limestone ranges from chalky white
to light brown or ashen gray but most of it is tan. Some beds,
especially near the top of the formation, are composed of a loose
coquina of cone-shaped Foraminifera, small echinoids-Peronella
dalli (Twitchell), and shells of other marine organisms. The
following fossils were identified in cuttings from wells in Volusia
County.

Coskinolina floridana Cole
Dictyoconus cookei (Moberg)
Dictyoconus gunteri Cole
Peronella dalli (Twitchell)
Spirolina coryensis Cole
The Avon Park limestone is almost invariably dolomitized in
Volusia County (see columnar sections on figs. 6-10). The process
of dolomitization (replacement of some of the calcium of limestone
by magnesium) often changes the permeability of a bed. The
change depends on the original form of the limestone and on the
mode of dolomitization. If the rock was originally a loosely packed
coquina limestone, dolomitization generally renders it dense and
less permeable. Other beds of dolomite are extremely porous,
having a spongy, "honeycomb" appearance due to selective
dolomitization of matrix rock. The Avon Park includes dolomite of
both types. The top of the Avon Park was eroded before the
overlying Ocala group (Puri, 1953) was deposited, and near
DeLand the formation was again eroded before beds of the late
Miocene or Pliocene age were deposited.
One of the most notable features of the Lake City, Avon Park,
and overlying limestones is the presence of dense, indurated beds.
These beds are readily detectable during drilling because they
greatly retard the drilling rate. Graphs of drilling time (figs.
6-10) show that sections ranging from 5 to 10 feet in thickness






REPORT OF INVESTIGATIONS NO. 22


required 15 minutes or more per foot of drilling. The 10-foot
section from 235 to 245 feet in well 909-106-1 (fig. 7) is one of
the most conspicuous in this respect.
Information collected during the drilling and testing of the wells
indicates that these dense zones are relatively impermeable. There-
fore, wherever these layers are continuous for a considerable
distance they greatly retard upward or downward movement of
water between the different permeable zones.
A study of the relative resistivity graphs on figures 6-10 show
that most of the dense layers also have a fairly high electrical
resistivity.
Chemical analyses of water from different depths in the same
well show that the hardness of water from isolated sections of
the Avon Park limestone is less than that of water from the over-
lying limestone. This may be due to the fact that dolomitic rocks
are commonly less soluble in water than limestone.
The Avon Park limestone is the principal source of artesian
water in the western part of the county, where the Ocala group of
Puri (1953) is thin or absent. Also, many of the deeper wells along
the coast draw part of their water from the Avon Park.

OCALA GROUP

The upper Eocene unit known elsewhere as the Ocala limestone
was established by Puri (1957) as a group composed of three
similar formations. The first two were named by Vernon (1951),
who, however, did not retain the name Ocala. These are, in
ascending order, the Inglis, the Williston, and the Crystal River
formations. All three are fragmental marine limestones which
are differentiated on the basis of fossil content and lithology.
In central and western Florida, where the Ocala group crops
out, its three formations have a different lithology and contain
distinctive faunas. In Volusia County, where data on the rocks
must be obtained from well cuttings, the formations cannot
readily be separated (Vernon, 1951, p. 122, 144, 157). The upper
part, the Crystal River formation of Puri (1957), has not been
recognized in Volusia County, and was probably removed through-
out the county by post-Eocene erosion (Vernon, 1951, pl. 2; Neill,
1955, fig. 4).
The Inglis formation, in its typical development, is a coarsely

2Applin and Jordan, 1945, p. 130; Cooke, 1945, p. 53; Vernon, 1951, p. 115,
118; Puri, 1953, p. 130.






FLORIDA GEOLOGICAL SURVEY


granular marine limestone containing abundant echinoid frag-
ments. Of these, pieces of Periarchus lyelli (Conrad) are the most
readily identifiable.
The fossils identified from well cuttings from the Inglis forma-
tion in Volusia County include:
Amphistegina pinarensis cosdct'i Applin and Jordan
Fabiania cubensis (Cushman and Bermudez)
Nonion advenum (Cushman)
Periarchus lyelli (Conrad)
Rotalia cushmani Applin and Jordan
Sphaerogypsina globula (Reuss)
The color of the Inglis formation is cream to white, mottled with
gray. The gray color is due to finely divided iron sulfide. The
formation overlies with an angular unconformity the Avon Park
limestone. The thickness of the formation averages about 50 feet
but may be as much as 120 feet in some parts of the county
(Vernon, 1951, p. 118, 121-122). The Inglis formation is overlain by
the Williston formation. The Inglis has been removed from the
crest of the high near DeLand and has been thinned by erosion in
most, if not all, of the remainder of the county. It is very porous
and permeable, however, and yields a large part of the water
used in Volusia County.
The Williston formation as described by Vernon (1951) is a
soft granular marine limestone. It is generally finer grained than
the Inglis, and contains fewer echinoid plates. Some of its beds
consist of a loosely cemented mass of Foraminifera.
The Foraminifera identified from well cuttings from the Willis-
ton formation in Volusia County include:
A mphistegina pinarensis cosdeni Applin and Jordan
Heterostegina ocalaina Cushman
Lepidocyclina ocalana Cushman
Operculinoides floridensis (Heilprin)
Operculinoides jacksoncnais (Gravell and Hanna)
Operculinoides wmoodybranchensis (Gravell and Hanna)
Sphaerogypsina globula (Reuss)
The lithology of the Williston indicates that it was deposited in
deeper water than the Inglis, which is essentially a beach o01
shallow sea deposit. The Williston averages about 30 feet in
thickness, but it has been entirely eroded from the high neai
DeLand and thinned by erosion throughout the rest of the county.
Owing to its finer texture, the Williston is less permeable than the
Inglis. Nevertheless, it is an important part of the artesian aquifer
in eastern Volusia County. Along the coast, many wells draw







REPORT OF INVESTIGATIONS NO. 22


exclusively from this formation, but deeper wells draw also from
underlying beds. The hydrologic properties of the Williston and
the Inglis are very similar but may be modified locally by
dolomitization. The combined thickness of the two formations
reaches a maximum of about 80 feet along the eastern coast of
Volusia County (see Ocala group in fig. 12). These formations are
considered as the Ocala group in this report because of their
similar hydrologic properties.

MIOCENE OR PLIOCENE DEPOSITS

The unconsolidated beds of fine sand, shells, and calcareous
silty clay which overlie the artesian aquifer were classified by
Cooke (1945, p. 214, 226-227, pl. 1) as the Caloosahatchee marl
of Pliocene age. Vernon (1951, figs. 13, 33; and personal
communication, June 29, 1955) indicated that these beds were of
late Miocene age. In Volusia County they generally consist of a
basal shell bed overlain by calcareous clay, fine sand, and silty shell
beds. As the permeability of the clay beds in these deposits is
relatively low, they serve to confine water under pressure in the
artesian aquifer. The basal shell bed yields a small amount of
water and hence some wells are left open to it.

PLEISTOCENE AND RECENT DEPOSITS

Sediments of Pleistocene and Recent age blanket Volusia
County. Their contact with the underlying deposits is marked
by a bed of coarse sand grains, waterworn shells, clay, and, at a
few places, a combination of these materials cemented together
by calcium carbonate. The Pleistocene and Recent deposits are
chiefly fine to medium grained quartz sand, locally, mixed with
shells. In many parts of the county the sediments are stained
yellow or orange by iron oxide. Locally, the sand has been cemented
into "hardpan" by deposition of iron oxide at the water table.
The Pleistocene and Recent deposits yield small quantities of
water to shallow wells. They are an important source of water in
those areas in which the artesian water is too salty for domestic
use. Many domestic wells in the county draw from these deposits.

STRUCTURE
The structure contours in figure 4 show the altitude of the top
of limestone of Eocene age in Volusia County. The top of the
limestone is an eroded surface which dips eastward from a high







FLORIDA GEOLOGICAL SURVEY


near DeLand at the rate of about three feet per mile. In the
northwestern part of the county the top of the limestone is domec
near Pierson.
Two important features on the map are the faults in the
western and southern parts of the county.
The east-west fault which passes through the north end of
Lake Monroe is part of a graben. The other side of this graben
is in the northern part of Seminole County (Barraclough, J. T.,
written communication, 1959). The top of the limestone is
displaced vertically from 60 to 100 feet near Lake Monroe.
The north-south fault which passes through DeLeon Springs,
Lake Beresford, and Lake Monroe separates the geologic high near
DeLand from the domed high near Pierson. The vertical dis-
placement along this fault is about 80 feet near DeLeon Springs
and at Lake Beresford.
The hydrologic effect of these faults will be discussed in the
sections on ground-water and salt-water contamination.

GROUND WATER

Ground water is the water in the zone of saturation, the zone
in which all pore spaces are filled with water under positive
hydrostatic head. The water in the zone of saturation is derived
from precipitation. Not all the precipitation soaks into the ground,
however; part evaporates and a part drains overland into lakes
and streams. Of the part that does filter into the earth, some is
later evaporated or is transpired by plants, and the rest reaches the
zone of saturation. Water that has reached the zone of saturation
is available to supply springs and wells and is referred to as
ground water.
Water in the zone of saturation moves under the influence of
gravity toward a place of discharge, such as a spring or well.
Where ground water only partially fills a permeable formation, its
surface, which is at atmospheric pressure, is free to rise and fall,
and the water is said to be under water-table conditions. However,
if ground water completely fills a permeable formation that is
overlain by a relatively impermeable bed, its surface is not free to
rise and fall and the water is said to be under artesian conditionE.
The term "artesian" is applied to water that is under sufficient
pressure to rise above the top of the permeable formation
containing it, although not necessarily above the land surface.
A formation in the zone of saturation that is permeable enough
to transmit usable quantities of water to wells and springs i3







REPORT OF INVESTIGATIONS NO. 22


called an aquifer. Areas in which aquifers are replenished are
called recharge areas. Areas in which water is lost from aquifers
are called discharge areas.

NONARTESIAN AQUIFER

Ground water occurs in Volusia County under both water-table
and artesian conditions. The nonartesian, or shallow, aquifer is
composed of Pleistocene and Recent sediments. The upper portion
of the deposits of Miocene or Pliocene age also may constitute a
part of the nonartesian aquifer in some parts of the area. The
aquifer ranges in thickness from about 25 feet near the Halifax
and St. Johns rivers to as much as 80 feet in the central part of the
area (fig. 12).
The nonartesian aquifer is recharged chiefly by local rainfall.
It receives also a small amount of recharge by upward seepage of
artesian water in the area of artesian flow.
Water is lost from the nonartesian aquifer by natural discharge
into surface streams, such as the St. Johns River; by discharge into
the ocean; by downward seepage into the artesian aquifer, in those
areas in which the water table stands higher than the artesian
pressure head; and by evaporation and the transpiration of plants.
In addition, small quantities of water are withdrawn from the
aquifer through wells for domestic use and lawn irrigation.
The water from the nonartesian aquifer is generally less
mineralized than that from the artesian aquifer. However, in many
areas water from the nonartesian aquifer contains an excessive
amount of iron which gives the water a disagreeable taste and
stains clothes and fixtures. In areas immediately adjacent to the
St. Johns River and the ocean the nonartesian aquifer contains
salt water.
Temperature measurements of water from the nonartesian
aquifer range from 660 to 740F, and most of them are between 680
and 700F.

ARTESIAN AQUIFER

The artesian aquifer of Volusia County has a vital bearing on
the economy of the county. It is used by all communities that have
public water supplies, is the major source of irrigation water, and
is used by nearly all commercial and industrial consumers that
have their own wells. It is the source for many home supplies, air-
conditioning systems, and stock wells. Thus, most of the







FLORIDA GEOLOGICAL SURVEY


information collected and studied during this investigation concerns
the artesian water supply.
The artesian aquifer in Volusia County consists mainly of
limestone of Eocene age. In some parts of the county it also
includes a thin, permeable shell bed at the base of the Miocene or
Pliocene deposits. The water in the aquifer is confined under
artesian pressure by beds of clay in the Miocene or Pliocene
deposits.
The piezometric surface is an imaginary surface to which water
from a given artesian aquifer will rise in tightly cased wells that
penetrate the aquifer. The piezometric surface is generally


Figure 13. Piezometric surface of Volusia County in November 1955.







REPORT OF INVESTIGATIONS NO. 22


represented on a map by contour lines that connect points of equal
altitude. Water in the artesian aquifer moves from areas of high
artesian pressure toward areas of lower artesian pressure at right
angles to the contour lines representing the piezometric surface.
The map in figure 13 indicates the piezometric surface of Volusia
County in November 1955, when it was at about an average stage.
Volusia County differs from most counties in Florida in that
most, if not all, of the fresh water in the artesian aquifer is de-
rived from rain falling on the recharge areas within the county.
These recharge areas appear as piezometric highs within the closed
contours on figure 13. The principal recharge area is within the
closed 40-foot contour along the eastern edge of the Penholoway
terrace near DeLand. A smaller recharge area is within the
closed 35-foot contour along the Penholoway terrace near Pierson.
As was pointed out in the section on "Karst Topography," the sink-
holes in the Penholoway terrace have caused breaks in the confining
beds overlying the artesian aquifer. Thus, water may move
downward from the nonartesian aquifer to the artesian aquifer
through the sand and shell-filled sinkholes, where the water table
is higher than the piezometric surface. Near DeLand the water
table is as much as 30 feet higher than the piezometric surface.
The artesian aquifer is recharged also by the small amount of
water that seeps through the confining layers where the water
table is considerably higher than the piezometric surface even
though there are no sinkholes or breaks in the confining layers.
Figure 14 is a generalized section showing the hydrology along
line A-A' in figure 3. The figure shows an exaggerated profile of
the land surface, the position of the water table, the piezometric
surface of the upper part of the artesian aquifer, and the piezo-
metric surface of the lower part of the artesian aquifer in
November 1955. As may be seen, the water table stands higher
than the piezometric surface in all the area between Daytona
Beach and the St. Johns River, except for a small area about nine
miles west of Daytona Beach. Therefore, the artesian aquifer is
being recharged through sinkholes and by leakage through the
confining beds as shown by the arrows in figure 14.
From the Tomoka River westward almost to the St. Johns
River the pressure in the upper part of the artesian aquifer is
greater than the pressure in the lower part. Within this area,
water moves downward from the upper part of the aquifer to re-
charge the lower part. As pointed out in the discussion of
"Geology," dense, relatively impermeable layers of limestone were
penetrated in all the test wells. Although these layers are not at







FLORIDA GEOLOGICAL SURVEY


the same depth in each well, some of the thicker layers-fo:.
example, the layer between about 220 and 240 feet shown in
figures 7, 8, and 9-appear to be parallel to the bedding planes and
to be continuous over large areas. These layers doubtless retard
the downward movement of water from the upper part of the
aquifer.
In the area where the hydrologic gradient is downward, where
deep wells such as 909-106-1 penetrate different zones of the
aquifer, there is a substantial movement of water down the well
bore. This can be seen in figure 7 by comparing the relative
velocities while the well was standing idle with those while the
well was being pumped. While the well was standing idle, water
entered the hole between 150 and 160 feet below the land surface,
moved down the well, and entered the formations below a depth of
about 225 feet. The graph of relative velocities during pumping
of the well at a rate of 143 gpm shows an upward flow of water
above 155 feet and a downward flow below that depth. A
comparison of the graphs shows that the quantity of water flowing
down the well bore was reduced approximately two-thirds by
the pumping.

01t AII WAN II IADI. 1'. '1 rf1tt 11e 0l f lM Id 1( ur,.-Af A11fit! ,
Vm0 Ill r.
50 /sv.1 1

J oh





150 -.l


-00
r r-350 r 1 1 3 1 I1





u200 4 t i tdroloi aln li A A' 1 re ri Fw ii oF, In( Im 19 I
S1 RT FSIAN AQUIER


0 :'-03--00.0-1,r
r A-. 0WF R ,,ARro-







Figure 14. Hydrology along line A-A', figure L, in November 1955.







REPORT OF INVESTIGATIONS NO. 22


The quantity of water moving from the upper part of the
aquifer to the lower zones through the well bore cannot be
determined from the relative velocity graphs because the diameter
of the well bore is not known. Although the open hole was drilled
with a 51-inch bit, its diameter is doubtless somewhat greater
than 51/1 inches everywhere and may be a foot or more where
the well penetrated unconsolidated limestone.
After water reaches the artesian aquifer it moves down the
hydraulic gradient toward points of discharge. In general, the
movement of artesian water in the county is eastward and west-
ward from the piezometric high near DeLand to the piezometric
lows near the Atlantic Ocean and the St. Johns River.
Water is discharged from the artesian aquifer through
submarine springs where the limestone formations crop out
beneath the ocean, by upward seepage through the confining bed
where the piezometric surface stands higher than the water table,
and by leakage along faults where the confining layers are
displaced. Large quantities of water are also withdrawn from the
aquifer through wells.
East of the Tomoka River, the pressure in the lower part of
the artesian aquifer is greater than the pressure in the upper part
(fig. 14). Consequently, water moves upward from the lower
zones of the aquifer. However, this movement probably is not
appreciable in areas undisturbed by heavy pumping because the
natural upward gradient, which is only about one foot in 80 feet
at well 911-104-4, is not adequate to move large quantities of
water through the beds of very low permeability that serve as
confining beds between the different zones of the aquifer. In
areas of heavy pumping, as, for example, in the Adams Street
well field of the city of Daytona Beach, the pressure in the upper
part of the aquifer is drawn down as much as 20 feet. As a result,
the upward gradient in this area is many times greater than it is
elsewhere, and upward flow from the lower zones is correspondingly
much larger.
Wherever the pressure in the lower zones of the aquifer is
greater than that in the upper zones, water enters the lower part
of the open hole and flows up the well to recharge the upper zones
of the aquifer. Thus, the vertical direction of movement of water
in the deep wells east of the Tomoka River is opposite to that in
wells west of the river. Current-meter traverses made in wells
910-104-1 and 911-104-4 after their completion showed a large up-
ward flow (figs. 8, 9). Two traverses were made in well 910-105-1,
one while the well was standing idle and the other while it was







FLORIDA GEOLOGICAL SURVEY


being pumped at a rate of 250 gpm. A comparison of the results
of the two shows that the upward flow of water in the well while
the well was not being pumped was probably between 150 and
200 gpm. Most of this water entered the well below a depth of 430
feet, flowed up the well bore, and entered the upper part of the
artesian aquifer between the depths of 150 and 160 feet.
The graphs of relative velocities in well 911-104-4 (fig. 9)
show that while the well was not being pumped water entered it
between 395 and 485 feet. The decrease in relative velocity between
300 and 310 feet shows that a small quantity of water probably left
the well between those depths. Most of the flow, however left the
well between the depths of 225 and 230 feet. The remaining flow
entered the upper part of the artesian aquifer between the depths
of 165 and 180 feet.
The collection of data on the altitude, fluctuations, and progres-
sive trends of water levels is an essential part of the investigation.
In order to determine the altitude of water levels and pressure
heads throughout the county, the water levels in all open nonflowing
wells and the pressures in flowing wells are measured when the
wells are first visited. The fluctuations and progressive trends
are determined by measuring the water levels in a relatively large
number of wells periodically and by maintaining continuous-
recording gages on a few selected wells.
Water levels were observed periodically in 22 wells in Volusia
County, seven of which were equipped with recording gages.
Hydrographs showing the water-level fluctuations in two of the
wells equipped with recording gages are shown in figure 15.
Observations were begun on well 857-105-1, at Alamania, 11 miles
southwest of New Smyrna Beach, in 1936. As the water level in
this well is not affected by the withdrawal from other wells, and as
the well is near the area in which the artesian aquifer is being
recharged, the hydrograph shows the natural fluctuations of
artesian pressure head caused by changing rates of recharge. The
heaviest rainfall generally occurs in Volusia County from June
through October. Accordingly, the water level in well 857-105-1
is generally highest in the summer or early fall. As a result of
low rainfall in the period November to May, the water level begins
to decline near the end of the year and generally is lowest in June
or July. The hydrograph for. this well does not show any pro-
gressive trend, either up or down, during the 22-year period from
1936 to 1957.
Observations of the water level in well 912-101-18, which is at
the west end of Main Street Bridge in Daytona Beach, were begun







REPORT OF INVESTIGATIONS NO. 22


20
Monthly rainfall at Daytona Beach


5 I
16 937 938 1939 1940 194 942 1943 1944 1945 1946 947 1948 1949 1950 195 952 195 4 1955 195 197
Figure 15. Hydrographs of wells 912-101-18 and 857-105-1 and monthly
rainfall at Daytona Beach.
in 1948. Thus, the record for this well is much shorter than that
for well 857-105-1. The water level in well 912-101-18 responds to
the heavy pumping in the Daytona Beach area and to seasonal
changes in the rate of recharge. The hydrograph of well 857-105-1
shows that the natural decline of water levels during each spring
and summer since 1951 has been about average for the period of
record, 1936 to date. On the other hand, the hydrograph of well
912-101-18 shows that the decline of water levels during the
summer at Daytona Beach has been substantially greater than
average since 1951. This doubtless reflects a substantial increase
in the use of ground water at Daytona Beach.
The hydrographs in figure 16 show the fluctuations of water
level in artesian wells that were measured periodically during the
investigation. These wells were selected from the group of 22 wells
that were measured periodically, because of their areal distribution.
As may be seen from figure 16, the water levels fluctuate in
response to rainfall. The magnitude of the fluctuations depends on
the location of the well with respect to recharge and discharge near
the well. During 1953, rainfall in Volusia County exceeded the
yearly average by about 25 inches. The years 1954, 1955, and 1956
were considered drought years, and in 1957 rainfall was about
normal.






FLORIDA GEOLOGICAL SURVEY


3



0


I 1
- .. --. ----- 4 -A
A.1> ~
I ~ ;
I' L~' '~c -


C


Figure 16. Hydrographs of wells measured periodically in Volusia
and rainfall at Daytona Beach.


County


-4-





-8 Coy mai of Pa t -.nq
.... K ... I


02 a- K M L2M /6
1`5 19j1 c N 19ie ~'~


L-,U
_ ti


............. I





REPORT OF INVESTIGATIONS No. 22 33

Well 855-117-1 is very near the principal recharge area and
shows the greatest amount of fluctuation. Well 851-114-1 is near
or on the edge of the graben at Lake Monroe and shows the
smallest amount of fluctuation. The other wells in figure 16 are
along the east coast where there is apparently little recharge or
discharge.
The hydrographs in figure 17 represent water levels in the
nonartesian aquifer, in the upper part of the artesian aquifer,
and in the lower part of the artesian aquifer at the Daytona Beach
airport well field. The Daytona Beach airport well field started
pumping at about 4 million to 7 million gallons a day in February
1957. These water levels were measured in order to determine
whether this pumping from the upper part of the artesian aquifer

26 i i i i i 1 1 1 1 i 1 1 I l i


2 \ 4s--
wJ Water level in nonartesian well
> _911-104-5
22
LJ
20
z

18



W Water level in lower port of
l..u_ 14 the artesian aquifer (480-500ft)
4 well 911-104-4
-J
> 12
-J

u 10
< Water level in upper part of the
W artesian aquifer (100-235ft)
8 --well 911- 104-4


6 1 1 1 1 1 1 1 1 1 1 1 11I1 1I1 1 1 1 l l I I I l i


1955


1956


1957


Figure 17. Hydrographs of wells 911-104-4 and 911-104-5 at Daytona Beach
airport well field.






FLORIDA GEOLOGICAL SURVEY


would appreciably affect water levels in the nonartesian aquifer
and in the lower part of the artesian aquifer. As may be seen from
the record prior to February 1957, the three hydrographs correlate
very well. However, after January 1957, the net drawdown in
the upper part of the artesian aquifer was about two feet, there
being no corresponding drawdown in either the nonartesian aquifer
or the lower part of the artesian aquifer. This indicates that the
pumping from the upper part of the artesian aquifer did not, in
a period of nine months, induce additional recharge from the
nonartesian aquifer or from the lower part of the artesian aquifer.
Where the artesian pressure head stands higher than the land
surface, wells penetrating the artesian aquifer will flow. The
approximate area of artesian flow in Volusia County is shown
on the map in figure 18. As may be seen, wells will flow in most
of a belt two to three miles wide adjacent to the coast and in the
lowlands adjacent to the Tomoka River and Spruce Creek. Wells
will flow in another belt, several miles wide, along the St. Johns
River from Brevard County to Lake George. This belt is about
eight miles wide near DeLeon Springs.
Figure 18 shows also the areas in which artesian wells do not
flow, where the piezometric surface is below the land surface.
In areas where the piezometric surface is less than 20 feet below
the land surface most domestic wells are equipped with centrifugal
pumps. Where the depth of the piezometric surface is more than
20 feet below the land surface, most wells are equipped with either
jet-type or vertical turbine pumps.
The area of artesian flow expands and contracts in response to
seasonal changes in water levels. Thus, during periods of low
water levels, many wells cease to flow. In a few instances, owners
of intermittently flowing wells have found that their wells will
flow continuously if deepened, because the pressures in the lower
zones of the artesian aquifer are greater than in the upper zones.
In order to obtain the full benefit of the higher pressures, it would
be necessary to case off the upper zones of the aquifer. It should
be noted, however, that in most parts of the coastal area th
mineralization of the artesian water increases with depth. Thus.,
the advantage derived from the increase in pressure resulting frori
deepening a well may be offset by a deterioration in quality of the
water.
The temperature of water from the upper parts of the artesia 1
aquifer ranges from 710 to 740F. Water from most of the wells
inventoried had a temperature between 720 and 730F.







REPORT OF INVESTIGATIONS NO. 22


QUALITY OF WATER

Rainwater, when it falls on the earth, is only slightly
mineralized. However, as it travels through the soil and rocks be-
Leath the earth's surface it gradually dissolves some of the soluble
ninerals from them. Thus, the chemical character of ground
vater is dependent, in part, on the type of material through which
:he water flows. The quartz sand that constitutes most of the
shallow aquifer in Volusia County is relatively insoluble. Lime-
;tone and dolomite, which compose the artesian aquifer, are among
he most soluble of the common rocks.


18. Areas of artesian flow and depth of piezometric surface below
land surface in November 1955.







FLORIDA GEOLOGICAL SURVEY


The limestone, sand, and clay that underlie Volusia County
were deposited in the ocean. When these sediments were laid
down, and when they were under the sea at later times, they
became saturated with sea water. Part of the present mineral
content of the ground water in Volusia County, especially in the
coastal areas and along the St. Johns River, is a result of this
saturation of the formations with salty water many millenniums
ago.
Water from wells located in figure 19 was sampled for chemical
analysis during the present study. The analyses which show the


Figure 19. Locations of wells whose water was sampled for chemical analysis.





TABLE 2. Analyses of Water Samples from Wells in Volusia County



S2 3i I s 1 IS^ i a ','^ l ise
a aM u
I 1 I o a
well ja. a2e P5 ;A "4 0 Remarks~
number au U ~ m3- mz ~ &.w -~ .m ~ e eak


_1/ Samples an lyzea by Black Labtrator:


900-113-1

1/900-120-18.

1/900-120-19

Do--------


901-055-6

901-056-1

901-102-1

901-109-1

902-059-4

904-057-2

905-113-3

Do --------

Do---- ........

Do--------

Do--------

906-111-2

907-058-1

908-107-2

909-059-11

909-106-1
Do ........-


2- 3.55

1-14-57

1-22.57

2- 7-57


2- 3.55

2- 3-55

2- 3-55

2- 3-55

2- 3-55

2- 3-55

4- 8-55

4-11-55

4-11-55

4-12-55

4-14-55

2- 2-55

2- 2-55

2- 2-55

2- 3-55

2- 9-55

2-11-55


5.5







127

56 '

11

8.1

11

48

8.6

18

22

28

17

8.8

55

6.8

21

10

17


Sample collected after
pumping 200,000 gallons
Sample collected after
pumping 33,000 gallons












Hydrogen sulfide, 0.0






Hydrogen sulfide, 1.2








Aluminum, 0.18 *


200

100

15

20

15

75

2.5

3.5

3.5

2.5

7.2

10

85

15

18

8.0

10


.43






.34








1.0

.24

,es,







FLORIDA GEOLOGICAL SURVEY


near DeLand at the rate of about three feet per mile. In the
northwestern part of the county the top of the limestone is domec
near Pierson.
Two important features on the map are the faults in the
western and southern parts of the county.
The east-west fault which passes through the north end of
Lake Monroe is part of a graben. The other side of this graben
is in the northern part of Seminole County (Barraclough, J. T.,
written communication, 1959). The top of the limestone is
displaced vertically from 60 to 100 feet near Lake Monroe.
The north-south fault which passes through DeLeon Springs,
Lake Beresford, and Lake Monroe separates the geologic high near
DeLand from the domed high near Pierson. The vertical dis-
placement along this fault is about 80 feet near DeLeon Springs
and at Lake Beresford.
The hydrologic effect of these faults will be discussed in the
sections on ground-water and salt-water contamination.

GROUND WATER

Ground water is the water in the zone of saturation, the zone
in which all pore spaces are filled with water under positive
hydrostatic head. The water in the zone of saturation is derived
from precipitation. Not all the precipitation soaks into the ground,
however; part evaporates and a part drains overland into lakes
and streams. Of the part that does filter into the earth, some is
later evaporated or is transpired by plants, and the rest reaches the
zone of saturation. Water that has reached the zone of saturation
is available to supply springs and wells and is referred to as
ground water.
Water in the zone of saturation moves under the influence of
gravity toward a place of discharge, such as a spring or well.
Where ground water only partially fills a permeable formation, its
surface, which is at atmospheric pressure, is free to rise and fall,
and the water is said to be under water-table conditions. However,
if ground water completely fills a permeable formation that is
overlain by a relatively impermeable bed, its surface is not free to
rise and fall and the water is said to be under artesian conditionE.
The term "artesian" is applied to water that is under sufficient
pressure to rise above the top of the permeable formation
containing it, although not necessarily above the land surface.
A formation in the zone of saturation that is permeable enough
to transmit usable quantities of water to wells and springs i3













I


WWI I
number


909-106-1

Do........

Do.......

909-106-4

Do------
Do........
0-






910-105-1

Do-........

Do---*

Do----
D-








Do-........


911-103-2

911-103-5

911-104-4

Do--------

Do-........

Do--------

Do------

912-101-17

912-103-1

913-115-1


w,,,l !
numbmr


I

i~', 'i'~


*a


''


3

4

4

23

23

2

13

26

36

43

49

49

20

28

14

26

38

50

50

19

17

15


14 377 2-17-55

96 481 2-23-55

96 102 4-15-55

14 102 5-24-55

4 102 5-26-55

4 102 5-28-55

10 113 3-17-55

0 246 3-22-55

0 344 3-25-55

5 426 3-30-55

8 487 4- 1-55

8 152 4-18-55

5 110 3-21-57

0 135 3-21-57

0 115 3- 2-55

5 244 3- 4-55

4 366 3- 8-55

0 489 3-11-55

0 115 4- 1-55

0 84 2- 3-55

0 111 2- 3-55

8 74 2 -2 455


16 0.8

14 .2


15 .3:

16 .0

17 .1I

18 .9:

17 1.5

16 3.9

17 .45

8.8 6.1


22 .32

19 .09

31 .54

29 1.1

21 1.1

21 1.3

. *


3 101

9 99

110

2 108

5 108

7 108

3 114

101

70

99

85

99

106

93

107

101

100

55

82

110

104

86 1


12

19

10

6.4

6.4

6.7

9.6

16

41

25

25

25

9.1

17

15

14

4.5

40

33

17

11

.1


32 1.0

42 1.7

2d

19 .7

19 .7

19 .7

22 1.0

30 1.3

49 '1,7

23 2,2

16 '2.4

119


++ ,


2U6

390

366

360

365

378

364

274

214

242

292

368

360

308

352

331

307

302
-


5.5

5.0

7.0

4.5

4,5

3.2

1.2

3,2

3.8

16

8.8

28

12

2.0

1.5

1.2

2.0

6.0

22

18

10

10


HRmarks


'T'Al.E 'i, (Co101iiMiVl)


701 7.3


435 302


526


382

380

380

394

417

566

792

717


390

454

437

374

389

395

684

526

402

340


22

37

27

21

25

20

98
*


1- . -- .----C---~ ~j~---------


302 653

340 1110

344 852

304 646

258 553


I


7,4 Hydrogen sulfide, 0,3

7.3

7,3 Manganess, a01; hydrogen
sulfide, 0.0
7,5 Manganese, 0.00; hydrogen
sulfide, 0,3
7.5 Manganes*,0.01; hydrogen
sulfide, 0.6
7.6 Manganese,0.00; hydrogen
sulfide, 1.3
7.5 Mangeanse,0.02, hydrogen
sulfide, 0.6
7.4

7.3 Hydrogen sulfide, 0.2

7.5 Hydrogen sulfide, 1.1

7.5 Hydrogen sulfide, 0.3

7.4 Hydrogen sulfide, 0.2

7.5 Hydrogen sulfide, 0.4

7.7 Hydrogen sulfide, 0.7


I




TABLE 2. (CUontinued)


Well
number g


,914-102-6
Do--------
915-107-3
916-112-1
918-103-4
920-106-1
921-104-3


-I- I --- -


9-16-55
9 20" 55
2- 3-55
2- 3-55
2- 3-55
2- 3-55
2- 2-55


23


o- 0
1.7 95
S 101
107
87
102
120
208


* *


L w
J ^ 11


324
367


13
15
16
18
24
14
132


AU


.-53
.7,
67
53
171
92
;860


7.0
4.0
10
10
30
10
180


o'A
04-


397
478
442
448
628
542
3780


K8


315
314
332
292
354
358
1,060


L'J
0

0.
-4


U



0


z
P


I I I I I .. I I


I


l asilk i vW\ 2v 1 0 B a. | mKa
I--r


Igo


.V -1


I I I I I I I I I


i


k






FLORIDA GEOLOGICAL SURVEY


principal chemical constituents of these samples are contained in
table 2. All results given in the table are in parts per million
(ppm) unless otherwise stated.
One part per million is a very small quantity, equal to only
8.34 pounds of the constituent in a million gallons of water. How-
ever, even this small quantity of certain constituents, such as iron,
imparts objectionable characteristics to water.
The dissolved-solids content of a water is an index to the degree+
of mineralization. If all the dissolved constituents in a water
sample were added together, the bicarbonate being included as
equivalent carbonate, the sum would equal the total dissolved solids.
However, because many of the rarer constituents are not generally
determined, and because of the water of crystallization, there is
usually a slight discrepancy between the total obtained by
evaporation of a water sample and the total obtained by summation
of the determined constituents.
The chloride (Cl) content of water in Volusia County is
discussed in detail under the heading "Salt-Water Contamination."
As determinations of chloride content can be made readily in the
field, this constituent is commonly used as an index of how "salty"
a water is. Water having a chloride content of less than 500 ppm
does not taste objectionably salty to most people, and water having
a chloride content of not more than 250 ppm is acceptable for a
public supply, if otherwise satisfactory, according to the standards
of the Florida State Board of Health.
Hydrogen sulfide (H2S), a gas, imparts the taste and odor to
the water that is commonly referred to as "sulfur water."
Hydrogen sulfide has an objectionable odor, but many people
become accustomed to drinking water that contains it. The gas
can be removed from water by aeration. Analyses of samples
(see "Remarks" in table 2) show that where hydrogen sulfide
was present its concentration did not exceed 1.3 ppm.
The hardness of a water is caused chiefly by the basic ions
calcium (Ca) and magnesium (Mg). These constituents are dis-
solved from the limestone (CaCO3) and dolomite (CaMg (CO) 2)
that compose the artesian aquifer. Water having a hardness of
more than 150 ppm is rated as hard and is commonly softened for
household and certain other uses. The hardness of artesian water
in Volusia County ranges from about 200 ppm to more than 1,000
ppm.





UNITED STATES DEPARTMFNI' OF 'HI-" INEHIIOR
GEOLOGICAL SURVEY


FLORIDA GEOLOGICAL SURVEY
R 0 Vernon, Director


I I
S.292S' -- o i' .--. -







S VILLA
TAN L'F-


-F L
-FLAGLE


81* 29'25







- 29=20'


0 I 53 4 mll1


29'20


81Bl5

- COUNTY.
-i r-71


EsoN _


1)61


I^ I_?
-( '23^8
-- ---. '* ^^
-4otj^


S I I II


81'30


ao-"-8 'o 5



90 l 8'0'









.^ 1 5 -.7



I-oI


in 4



[0 ^WiTe 28500'
a1 0
2 ts5~I


+-s i i irS, 2 It


VLICI)ELO N SRlNdS 1N


I du02 t 1


--I--W Il -


-IiJIlJI.IIflrtt


-; i f, JI J . [ -I 2I Y


DELI ND


i.~~ ~'.-W


I 44~{4


S ORAIk


l-i-e


81020'


LA K


IIILAN
L Ur


I I I- --T


WI ow


LLY HILL.


I.4\,




14


2 -' 2iI0' -






8 2' 9250d
INSET C




29800-






. IUTH "NA 2l 55'
Is lq 11106 INS r


.Ni-


I)


OSTEN+4


-SL L I C OUNTy


I II I III


81015'


81610


-*IA a pi,'




61l04' INST '


284d0


f


SS Department of Agriculture


--BREVARD -- COUNTY

80955, 80050 8045V
2845' 28'45'-


29*02 -9BO a.





O0-? 00"5 81 .
,o.*,' N T -


INSt F ml
0 1 1


Well Inventory by Granville G. Wyrlck.


Figure 20. Wells inventuried in Volusia County.


I 1


.......


9u


-e .Io-. wa' eT; -. . .
0 l 00'









Sir --
-.*oly ^6 .


_"] '^^^." 2L-XL-""""is


EXPLANATION

Well( number Is well number)


.


---


ID


::r~:~:^ LLZ~ ~~::?'A


I


I )


_no p s-11i : --72


.. .. .. I J


I1 I


I


--


'


I '


I


~ ~ .nP~-t----ltf-rC--C


_1


I l l l" "


I-


1 ..


"-~`~~b~


92,J


I


. ni


I I \--r I


t----t-----hd~i~fi


I


I L .. .I l


~


"'


8125


~ ~ir~ J~9~k:;tNlbPRIIE I ~IP~/j_ ~


I


m


-4






REPORT OF INVESTIGATIONS NO. 22


WELLS

The inventory of wells consists of the collection of information
on their location, depth, diameter, length of casing, yield, and
use. Figure 20 shows the distribution of more than 900 wells that
have been inventoried in the county. About 95 percent of these
wells draw water from the artesian aquifer, and five percent draw
from the nonartesian aquifer. Approximately half the wells are in
the area of artesian flow.
Most nonartesian wells are 11/4 inches in diameter and 15 to
50 feet in depth. As the sedimentary rocks that compose the non-
artesian aquifer consist predominantly of unconsolidated sands,
most nonartesian wells are equipped with screened drive points.
Most artesian wells are 11/2 to 6 inches in diameter and 9 to 180
feet deep. Wells for domestic use, lawn irrigation, and watering
stock are commonly 11/2 to 2 inches in diameter. These wells are
generally constructed by driving casing to the top of the limestone
and drilling an open hole to a depth of 25 to 50 feet below the
bottom of the casing. Wells for farm and grove irrigation,
municipal supply, and air conditioning are generally larger than
four inches in diameter and range in depth from 125 feet to 175
feet. Records of these wells are published separately by the Florida
Geological Survey as Information Circular No. 24, which may be
obtained from that department at P. 0. Box 631, Tallahassee,
Florida.

SALT-WATER CONTAMINATION

Saline water is present in the principal artesian aquifer in
many areas of Florida. Although the presence of saline water
could result from several causes, in Volusia County it appears to
be due to the infiltration of sea water into the artesian aquifer at
times during Pleistocene time when the sea stood higher than it
is now. After the high seas declined, fresh water entering the
aquifer began diluting and flushing out the salty water. The salty
water has been completely flushed out of the aquifer in the recharge
areas, but in areas distant from the recharge areas the flushing is
still incomplete.
More than 90 percent of the dissolved solids in ocean water are
chloride salts. Therefore, the concentration of chloride in artesian
water constitutes a reliable index to the degree of salt-water
contamination. A map (fig. 21) was prepared which shows the
chloride content of water from wells penetrating the upper part







FLORIDA GEOLOGICAL SURVEY


Figure 21. Chloride content of water from wells penetrating upper part of
artesian aquifer.

of the artesian aquifer. As may be seen from this map, the chloride
content of water in the recharge areas is less than 25 ppm, which
indicates that flushing is virtually complete in that area. Eastward
and westward, however, the aquifer has been flushed less, and the
chloride content of the water is greater.
A noticeable feature on the map is the fresh-water zone about
eight miles west of U.S. Highway 1 in Daytona. In this area the
aquifer is probably being recharged by seepage through the
confining layers. The water table .is about 15 feet above the
piezometric surface in the dunes along the eastern edge of the







REPORT OF INVESTIGATIONS No. 22


Talbot terrace. This difference in head would cause fresh water
to move downward from the nonartesian aquifer to the artesian
aquifer even though there are no sinkholes or other breaks in the
confining layers.
The zones in which the chloride content of the artesian water
exceeds 1,000 ppm also are very noticeable on the map. The
eastern, southern, and western sides of the county are almost
entirely within these zones. The zones in which the chloride is
highest are near Lake Beresford, DeLeon Springs, and Lake
Harney.
The concentrations of chloride in water samples collected from
wells of different depths indicate that the lower zones of the
artesian aquifer have been flushed less completely than the upper
zones. Thus, as a general rule, the deeper a well is drilled the
higher is the chloride content of the water produced by the well.
Figures 6-10 contain graphs showing the chloride content of
water samples obtained from the bailer during construction of
the supply and deep test wells, and from different depths in the
well bore after the wells had been undisturbed for several weeks.
The plot of the chloride content of the bailer samples from well
909-106-1 in figure 7 shows a saw-tooth pattern. This effect is
believed to result from the flow of water, low in chloride content,
down the well bore at night while drilling was not in progress.
Therefore, a line connecting the highest chloride values probably
would give a fairly accurate picture of the chloride content of the
water in the different layers of the aquifer. As may be seen from
figure 7, the chloride content of the water at a depth of 497 feet
was 150 ppm. After the well had been undisturbed for several
weeks, the downward flow of water of low chloride content from
the upper zones decreased the chloride content in the lower part
of the well. The high chloride content still present in the casing
apparently represents salty water that leaked from the bailer while
the lower portion of the well was being drilled.
As pointed out in a previous section, there was an upward
flow of water in wells 910-105-1 and 911-104-4. Therefore, the
chloride content of the bailer samples probably represents rather
closely the actual chloride content of the water in the producing
aquifers. As may be seen from figures 8 and 9, the chloride con-
tent in both wells began to increase at a depth of about 250 feet.
Well 910-905-1 reached water containing more than 250 ppm
of chloride at a depth of 435 feet, whereas well 911-104-4, which
is nearer the coast, drew water containing more than 250 ppm
at about 385 feet, or 50 feet less. Figure 9 shows a marked decrease






FLORIDA GEOLOGICAL SURVEY


in chloride content in well 911-104-4 below a depth of about 465
feet. A study of the data collected during construction of the well
strongly indicates that the water samples were diluted by fresh
water in the upper part of the well during drilling.
The chloride content of samples obtained with a deep-well
sampler from different depths in wells 910-105-1 and 911-104-4
is shown on figures 8 and 9. At the time these samples were
collected the wells had not been pumped for several days. There-
fore, as may be seen from the graphs, the chloride content was
relatively high throughout the well bore as a result of the upward
flow of salty water from the lower zones penetrated by the wells.
Figure 22 is a generalized section showing the chloride content
of the water in the artesian aquifer along line A-A' in figure 3.
As may be seen from the figure, the chloride content increases
with depth except for a thin section at the top of the aquifer west
of well 907-110-1. The effects of the fault near well 900-120-2
also show very clearly in figure 22; near the well water is lost
from the upper part of the artesian aquifer by leakage to the
nonartesian aquifer along the fault. This loss of water from the
upper part of the aquifer lowers the artesian pressure and allows
salty water to move upward from lower zones of the aquifer.
The quantity of water that may be safely withdrawn from the
artesian aquifer in Volusia County is limited by the extent to
which the artesian pressure can be lowered without causing
encroachment of salt water from either the sea or the lower zones
of the aquifer. Sea water, so far as is known, has not encroached


Figure 22. Chloride content of artesian water along line A-A' in figure 3.







REPORT OF INVESTIGATIONS NO. 22


into any part of the artesian aquifer in the county as a result of
heavy pumping. It appears entirely likely, however, that such
encroachment would occur if the artesian pressure in the area
immediately adjacent to the coast were lowered excessively by
heavy pumping.
The upward movement of salty water from the lower zones of
the artesian aquifer is the principal water-supply problem along
the St. Johns River and in the coastal areas of the county. As
shown in figure 22, the depth to salty water in the aquifer is much
less in these areas than in the recharge areas. Therefore, the
extent to which water levels can be safely lowered is less. As pointed
out in the section headed "Ground Water," the pressure in the
lower zones of the aquifer in the coastal areas and near the St.
Johns River is higher than the pressure in the upper zones. Where
the natural conditions have not been disturbed by pumping, the
small difference in pressure probably results in only a small upward
movement of salty water from the lower zones of the aquifer,
except along the fault through Lake Beresford and DeLeon Springs
and the graben in Lake Monroe. However, when pumping begins,
the difference in pressure becomes greater and the quantity of
upward flow is increased. If the pumping remains constant for
a relatively long period, the chloride content of the water will
become stabilized at some level above the initial concentration. If
the rate of pumping is later increased, the chloride content also
will increase.
An increase in chloride content in response to a decline in
artesian pressure has been observed in most of the coastal areas
of the county. During the spring of 1954, the chloride content
in a well at the Riviera Hotel in Ormond Beach increased about
50 ppm as a result of a decline in artesian pressure of about two
feet (fig. 23). Figure 23 shows the water levels and the chloride
content of water from well 915-103-1. From November 1953
through October 1954 the well flowed continuously from a leak in
the casing. The rate of leakage was three to.nine gpm, according
to the height of the water level. In October 1954 the casing was
repaired and the well was allowed to flow for only about 10 minutes
when each water sample was collected. The increase in chloride
content which accompanied a decline in water levels correlated
very closely when the well flowed continuously but was delayed by
about four months when the well did not flow continuously. Records
of the Daytona Beach Water Department show that the chloride
content of water from the Adams Street well field increases as the
water level declines. Between January and April 1954 the artesian







FLORIDA GEOLOGICAL SURVEY


L-

3


1953 1954 1955 1956 1957
Figure 23. Fluctuations of water level and chloride content of water from well
915-103-1 at Ormond Beach.

pressure in the vicinity of the field declined about one foot in
response to an increase of about 1,600,000 gallons in the average
daily pumpage. The average daily chloride content increased
during the same period from 132 to 162 ppm.
The upward coning of salty water beneath the Daytona Beach
well field is shown diagrammatically on figure 22. The chloride
content of the water from the individual wells in the Adams Street
and a part of the Canal well fields during a period of average
pumping in February 1954 is shown on figure 24. The area of
highest chloride content was centered around well 912-102-19 in
the south-central part of the field.
The chloride content of the Port Orange city wells increased
by as much is 50 to 75 ppm each year from 1951 until 1955. An
analyses of samples from other wells between the city well field and
the coast show no appreciable increase in chloride content during
this time, and as the chloride increase in the center well is greater
than in the end wells, it appears that salt water has moved upward
from the lower zones of the aquifer as a result of pumping. The
rapid increase in the chloride content of the Port Orange city well
field may indicate that the zone from which the wells draw is not
effectively separated from the lower, saltier zones of the aquifer.
In 1955 the increase in chloride content of water from this well


JPMAMJJASONDJFMAMJJ ASONDJFMAMJJASONDJFMAMJJASONDJ F M A MJJ A S 0 N D
-- '--Itell flowing -Well not flowing--
1 "- cotinuously ot 3 to not flowing
150 9 t m
M

Well 9153- 10-1 Ho











SiI IIIIIII--III I IIIIIIIIII IIIIII
r -








REPORT OF INVESTIGATIONS NO. 22


If


0 500 feet


wells


EXPLANATION

Public-supply well
@
Well equipped with recording gage

Privately owned well

Contour line connects points of equal chloride
content of. water, in parts per million
186
Upper number is well number. Lower number is
chloride content of water in parts per million,
February 1954
( )
Chloride content in June 1955

ioluso ..-- Avenue 10


Figure 24. Chloride content of water from wells in vicinity of Adams Street
well field.





FLORIDA GEOLOGICAL SURVEY


field became relatively stable at 425 to 450 ppm. It is expected
that so long as the pumpage is approximately 210,000 gpd the
chloride content of the water will remain approximately the same.
A decrease in pumpage will probably result in a decrease in
chloride content of the water, and an increase in pumpage will
doubtless result in an increase in the chloride content of the water.

QUANTITATIVE STUDIES

The withdrawal of water from an aquifer causes water levels
to decline in the vicinity of the point of withdrawal. As a result
of this decline, the water table or piezometric surface assumes the
approximate shape of an inverted cone having its apex at the
center of withdrawal. The size, shape, and rate of growth of this
"cone of depression" depend on several factors. Among these are:
(1) the water-transmitting and water-storing capacities of the
aquifer; (2) the rate of pumping; (3) any increase in recharge
resulting from the decline in water levels; and (4) the amount of
natural discharge salvaged by the pumping. The distance that
water levels are lowered at any point by the pumping is termed
"drawdown." The drawdown is approximately proportional to the
pumping rate.
The quantity of water that may be pumped perennially from a
a well or group of wells in Volusia County is limited by the draw-
down that may be maintained without causing the mineral content
of the water to become intolerably high. In the areas immediately
adjacent to the coast, the perennial yield is determined by the
extent to which water levels may be lowered without causing sea
water to move into the aquifer. In areas more remote from the
coast, the yield is determined by the extent to which water levels
may be lowered without inducing an excessive upward movement
of salty water from the lower zones of the aquifer.
As the depth to salty water increases with increasing distance
from the coast, the perennial yield of a well or wells also increases.
However, the perennial yield of wells depends also on other factors.
Most important of these in the stratification of' the aquifer. As
has already been pointed out, the limestone formations that
compose the aquifer consist of permeable zones separated by thin
zones of low permeability that appear to be continuous over
relatively large areas. Where zones of low permeability underlie
the fresh-water-bearing parts of the aquifer, they retard or prevent
the upward movement of salty water. Thus, wherever such zones





REPORT OF INVESTIGATIONS No. 22


occur, larger drawdowns may be maintained and the perennial
yield is greater than it otherwise would be.
Other factors affecting the perennial yield of the aquifer are
recharge and discharge. Withdrawals from the artesian aquifer
in recharge areas increase the gradient between the water table
and artesian aquifer and results in increased recharge. With-
drawals salvage a part of the natural discharge.
One phase of this investigation was devoted to the collection
of data needed in an evaluation of the yield of the upper part of
the artesian aquifer. Data pertaining to this phase were collected
during the construction of test wells along U.S. Highway 92 and
during a pumping test on well 909-106-4. Other data were collected
during the construction and testing of public supply wells and
privately owned wells.

CONSTRUCTION AND LOCATION OF
TEST AND OBSERVATION WELLS
Three 6-inch test wells (wells 905-113-3, 910-105-1, and
911-104-4) were drilled west of Daytona Beach along U.S. High-
way 92 (fig. 5) to a depth of approximately 500 feet to
determine the depth to salt water at different distances from the
coast, the pressure head at different depths in the aquifer, and
other significant data. Studies made during the construction of
the wells indicate that the depth to salt water at well 909-106-1
was greater than 500 feet beneath the surface. Also, as this well
was between a recharge and a discharge area, the site appeared to
be well suited to studies of the perennial yield of the aquifer.
At this site an 8-inch discharge well (well 909-106-4), four 2-
inch observation wells (wells 909-106-2, 3, 5, 6), and two ll/4-inch
observation wells (wells 909-106-7, 8) were drilled. The 6-inch test
well 909-106-1 previously drilled at the site was in effect converted
into two observation wells, ending at different depths. First a
string of 2-inch casing, perforated between the depths of 416 and
496 feet, was inserted inside the 51/2-inch well. Next, a concrete
plug was poured between the 51-inch open hole and the 2-inch
casing from a depth of 355 feet to 416 feet, and sand and gravel
was poured on top of the plug to a depth of 234 feet (the depth
of the discharge well, 909-106-4). The 8-inch discharge well and
the four 2-inch observation wells were cased to a depth of
approximately 102 feet and drilled as open holes to 234 feet. The
two 11,-inch observation wells (wells 909-106-7 and 909-106-8)
were equipped with 60-mesh screen points and driven to a depth of







FLORIDA GEOLOGICAL SURVEY


approximately 15 feet below the land surface. One 2-inch well
and one 11/4-inch well were constructed southeast of the discharge
well. The remaining wells were constructed southwest of the
discharge well (see inset in fig. 5).
The discharge well was equipped with a centrifugal pump
having a capacity of approximately 2,000 gpm. Automatic water-
level recorders were installed on wells 905-113-3 (5.2 miles east
of DeLand) and 910-105-1 (4.6 miles west of Daytona Beach)
several weeks prior to the pumping test to establish regional water-
level trends before and during the test. Also, a microbarograph
was installed at well 910-105-1 to record barometric changes
during the test.

PUMPING TEST

In order to determine the water-transmitting and water-storing
properties of the upper part of the artesian aquifer, a pumping
test was started at 1:10 p.m. on May 24, 1955. Well 909-106-4
was pumped at a rate of 1,100 gpm for a period of 100 hours.
During the test, measurements of the changes of water level in
the observation wells were made periodically. In addition, changes
in the water level in the drainage ditch immediately north of the
observation wells were measured by means of a staff gage.
Measurements of water levels were made also in the deep 2-inch
observation well 909-106-1 to determine how pumping from the
upper part of the artesian aquifer would affect the pressure head in
the lower part of the artesian aquifer. Throughout the test,
automatic water-level recorders were in operation on wells
910-105-1 and 905-113-3 and the microbarograph was in operation
at well 910-105-1. After the pumping was stopped, measurements
of the recovery of the water level in each well were made
periodically for five days.

ANALYSIS OF DATA

The 3,100 measurements of water levels made during the
pumping test are not tabulated in this report. However,
hydrographs of each well were plotted from these data and are
presented as figures 25 and 26. The hydrographs show a decline in
water level during the afternoon of May 23. This decline resulted
from pumping well 909-106-4 approximately 25 minutes to
determine the throttle setting of the pump motor for the pumping
test. The brief rise in water levels in wells 909-106-1 and 909-106-3








REPORT OF INVESTIGATIONS NO. 22


9

I0






14 -

15 --




o
z I


0 18 -
^ 19 __-.. .. -


0
_I
LJ


LJ
LL



--
LJ
LJ
_j


LJ
I


'I


.. 'Well 909-106-4, 6 miles
southwest of Daytona _
Beach


ii i LLj i


i1 I


__ __ __ __~ i~~i


8 /-1 Well 909-10i6-, 5 ft--
-- southwest of well 909-106 -'
9 ---- (Uppe(Upp of artesian
I j -aqu ter

Well 909-106-1, 25 ft
____ southwest of well 909-106-4
(Lower part of artesion
j aquifer)

-----


913 ------- -- ---- -h... Ii,^- I L -rI -
13I
14-

15 _
16 1


Well 909-106-3, 40 ft
I0 I southwest of well 909-106-4


1 ------ 1-- -- --- -- -_.


13
+1
Drainage ditch


I P I I 1 4 .....
-I
_ 304 ,-
0>- Barometric pressure


S 300 0 21 22 23 24 25 2 27 28 29 30 31
19 20 21 22 23 24 .25 26 27 28 29 30 31 I 2


Figure 25. Water levels in the pumped well, the nearby observation wells
and the drainage ditch, and graph of the barometric pressure.


HKI L 1 1 _





T


MAY 1955


uUNl I


\







52 FLORIDA GEOLOGICAL SURVEY


on May 25 (fig. 25) resulted when the pump motor stopped for
1 minute 40 seconds. Wells 909-106-1 and 909-106-3 were the only
wells measured during the time the pump was stopped; therefore
this rise is not recorded on the other hydrographs. As may be seen
in figures 25 and 26, the drawdowns at the end of the pumping
period in the pumped well (well 909-106-4) and in well 909-106-6,



S Well 909-106-2
179 ft southeast of
well 909-106-4
8- ..-


10 -








012
SW Well 909-106-6. 450 ft




.0 southwest of well 909-106 4




2\ I I Well 910 -105-1, 4.6 miles
west of Daytona Beach
13

SLLI Well 9 104-, no4.3 miles
LLt west of Daytona Beach
h 19 ---------...--- ----.. -


SI I Upper port of, ortleson oqlitfer)
I-- ; iWcll 911 04-4. 32 miles west of Daoyona Beach


I I i Well 905-t13-3. 5 2 mies east f Delnd


5


I _.---t-.I--______I Well 909-106-8. 179fti southeast of well
SI ---T -'---~'-F"--r--- 9--9 '06-4


Well 909-106-7, 179 ft
U_______ th eso wel 09 -106 4



19 20 21 22 23 24 25 26 27 28 29 30 31 I 2 3
MAY 1955 JUNE

Figure 26. Water levels in nearby observation wells during pumping test.






REPORT OF INVESTIGATIONS NO. 22


450 feet southwest of the pumped well, were about 9.5 feet and 3
feet, respectively. An indication of the extent of the cone of depres-
sion is shown on the hydrographs for wells 910-105-1 and 911-104-4.
The drawdown in well 910-105-1, 1.4 miles northeast of the
pumped well, was approximately 0.9 foot. The drawdown in well
911-104-4, 3.0 miles northeast, was approximately 0.8 foot.
In addition to the record of barometric-pressure fluctuations,
figures 25 and 26 contain hydrographs of shallow wells 909-106-8
and 909-106-7 and of the drainage ditch. The decline of the water
level in well 909-106-7 on May 24 and 25 was a result of the slow
drainage of water poured into the well on May 23. The water level
in the drainage ditch was raised approximately 0.7 foot on May
24 by the discharge from the pump. As a result, the water level
in well 909-106-7, approximately 30 feet from the ditch, was held
up higher than it would have been if the ditch had not risen, as
is shown by the decline that occurred on May 28 at the end of the
test. However, the rise in the water table resulting from the rise
in stage of the ditch was apparently restricted to a narrow zone
adjacent to the ditch, as there was no detectable change in the
level of well 909-106-8, approximately 200 feet away.
In any analysis of pumping-test data it is necessary to
determine the regional trend of water levels during the test in
order to determine true drawdowns. On May 23, the first day of
the pumping test, rain fell, resulting in an upward trend of water
levels in the artesian aquifer. To correct for this trend, a compari-
son was made of the hydrographs compiled prior to the pumping
test for well 905-113-3 and the wells at the pumping-test site. This
comparison showed that the water-level fluctuation at well
909-106-4 lags three days behind the fluctuation at well 905-113-3.
The drawdowns during the pumping test were corrected by taking
into account the time lag and applying the rise in water level at
well 905-113-3 to the drawdowns measured in the observation
wells. Changes in barometric pressure were relatively small during
the test, and therefore no correction was made for changes in
water level due to them.
The corrected drawdowns were analyzed by two methods to
determine the coefficients of transmissibility and storage of the
artesian aquifer. The coefficient of transmissibility, which is a
measure of the capacity of an aquifer to transmit water, is the
quantity of water, in gallons per day, that will move through a
vertical section of the aquifer one foot wide under a hydraulic
gradient of one foot per foot. The coefficient of storage, which is
a ,measure of the capacity of an aquifer to store water, is defined






FLORIDA GEOLOGICAL SURVEY


by the Geological Survey as the volume of water released from or
taken into storage per unit surface area of the aquifer per unit
change in the component of head normal to that surface.
Computations of the coefficients of transmissibility and storage
were first made by the Theis graphical method (Wenzel, 1942, p.
87-89). This method involves the following formula, which relates
the drawdowns in the vicinity of a discharging well to the rate and
duration of discharge.

114.6Q e-u 114.6Q
s= du= W(u)
T u T

u
1.87r-S
where u- 1.87r-
Tt
s= drawdown, in feet, at distance r and time t
r= distance, in feet, from pumped well
Q=discharge, in gallons per minute
t=time since pumping began, in days
T= coefficient of transmissibility, in gallons per day
per foot
S=coefficient of storage, a dimensionless fraction
The formula is based on certain simplifying assumptions-that
the aquifer is constant in thickness, infinite in areal extent,
homogeneous, and isotropic (transmits water with equal facility
in all directions). It is assumed also that there is no recharge to
the formation or discharge other than that from the one well within
the area of influence of the well, and that water may enter the
well throughout the full thickness of the aquifer.
When T and S are to be determined, the log of the drawdown
in the wells is plotted against the log of t/r2. The resulting curve
is a segment of the type curve produced by plotting the log of the
exponential integral W(u) against the log of the quantity u. The
curve of observed data is then superposed on the type curve and
the values of u, W (u), s, and t/r2 are selected at any convenient
match point. These values are next inserted in the formulas for s
and u, given above, in order to determine the coefficients of
transmissibility and storage.
A match of the type curve with a mass plot of the observed
data (fig. 27) yielded the following values:
where W (u) = 1.0, s=-0.41
and where u=-0.1, t/r2=-4.6x10-s







REPORT OF INVESTIGATIONS NO. 22


Inserting these values in the formulas T= 114.6QW (u) and S--
s
uTt
172 -gives a transmissibility of 310,000 gpd per foot and a
1.87r
storage coefficient of 7.5 x 10-4 for the upper part of the artesian
aquifer.
To check the results of the Theis graphical method, the data
from well 909-106-6 were analyzed also by a method devised by
Cooper and Jacob (1946). In this method the corrected draw-
downs are plotted against the log of t/r2 and the transmissibility
and storage coefficient are computed from the following formulas:

T 264Q
As
S=-0.301Tt/r 2
where Q is discharge, in gallons per minute
As is the change in drawdown, in feet, over one logarithmic
cycle of the t/r2 scale
t/r, is the value of t/r2 at the point of no drawdown.
A plot of the data for well 909-106-6 is shown in figure 28
Use of above formulas gave coefficients of transmissibility and
storage of 300,000 gpd per foot and 7.2x10- respectively.
Drawdowns in the vicinity of discharging wells penetrating
the upper part of the artesian aquifer near Daytona Beach can be


-T T 114 60Wt. M
S __30 310.000 gpd/U f : : F
-____- jI S-TH- j J j


I i -,
--TS







o- 10-' a'a -4 -- I 0 'I0'
t/rt (DA & PER FEET!)
Figure 27. Log plot of the drawdowns, and first part of recovery, versus t/r2.








56 FLORIDA GEOLOGICAL SURVEY




i2640
.. l T-24 300,000 gpd/t
: : : .. S= .301 T(t/r2), 7. 2x l0- 4
..... -- .. Where:










10o 10' 10= 100 109m

S(DAYS (/PER FEET80X)










Figure 28. Semilog plot of drawdown versus t/r for well 909-106-6, showing
.. .-..... I LOG CYCLE .. -i- ;j ---







REPORT OF INVESTIGATIONS No. 22 57

f water that can be pumped from the aquifer without producing
excessive drawdowns that will result in an upward movement of
.alty water. Water containing 150 ppm of chloride was en-
ountered at a depth of about 500 feet in well 909-106-1, 25 feet
southwest of the pumped well. Therefore, water containing more
I han 250 ppm of chloride, the suggested upper limit for water to be
used in a municipal supply, is probably present in the area at a
depth of less than 600 feet. In order to determine if the drawdowns
during the pumping test would result in an upward movement of
this salty water, water-level measurements were made in well
909-106-1 in the interval between 416 and 496 feet. These measure-
ments did not show any detectable change in water level, although
drawdowns of approximately 6 feet in this well in the interval
between 102 and 234 feet and 10 feet at the pumped well were
maintained for a period of four days. In view of this, it appears
safe to assume that, in pumped wells, drawdowns of approximately
10 feet could be maintained without inducing an upward flow of
salty water.
The results of the analysis of data from other tests in Volusia
County are given in table 3. As may be seen from the table, the
hydrologic character of the aquifer is different in different parts
of the county. Therefore, in designing a well field, the coefficients
of transmissibility and storage determined from pumping tests
nearest the proposed well field should be used.
In order to show the drawdowns that will result from different
rates of pumping and different well spacings, computations were
made by use of the Theis formula and coefficients of transmissibility
and storage of 300,000 and 7 x 10-4, respectively. The Theis
formula involves several simplifying assumptions. Among these
is the assumption that all the discharge is derived from storage in
the aquifer. However, after pumping begins, the downward
gradient will be increased as a result of the drawdowns produced
by the pumping, and the rate of recharge will be increased. As
the cone of depression expands it will intersect recharge, and
ultimately the recharge within the cone of depression will equal
the pumping rate. Thus, it is expected that the actual drawdowns
generally would closely approximate the drawdowns computed from
the Theis formula during the initial period of pumping, but would
be smaller than the computed drawdowns after the cone of
depression began to intercept recharge. It is not possible to
determine from the available data the length of time that would
be required for the cone of depression to become stabilized. How-
ever, in similar areas in other parts of the State, stabilized



















TABLE 3. Data from Analysis of Pumping Tests in Volusia County


21.J~r


of dqu,.r
penatratwd
by wfell
(feec)


178 Sd 6

327 87 b

298 88 6

0.5 233 5

10 9 5

5 16 5

27 and 28)

0.4 145 6

1,000 92 8

1,000 93 8

1,000 100 8

2,000 100 8

500 66 8


Lwngth di
pulping
period
(hMurs) tate f test


1- 7-58

1- 7-58

1- 7-58

4-23-57

2- 4-57

2- 4-57



It1- 7-56

8- 9-36

8- 9-56

8- 7-56

8-15-56

10-12-55


Tranjmis l-
bility
(gTid/ft)


46,000

55,000

55,000

190,000

57,000

40,000


160,000

350,000

330,000

310,000

370,000

28,000


Coafitctant of
storage


2.0 x 10,4

3.4 x 10"-

3.4 x 10.4



1.1 x 10-4

2.7 x 10"4







2.2 x 10"4

1.8 x 10-4

1.1 x 10"4

2.3 x 10-4


Remarks


Analyzed according to Ccopar--Jacrb imtuilg method

Analyzed according to Theis nonequilibriun method

Do

Analyzed accordtra to Coopor--Jacob samilog method

Analyzed according to Theis nonequllibrium method

Do.



Analysed according to Coopcr--Jacob zcmilog method

Analyzed according to Theis nonequiLibrLum method

Do.

Do.

Do.

Analyzed by using an unpublished "Typo curve for non-
steady radial flbw in an infinite leaky aquifer" by
H. H. Cooper, Jr. (Leakage equaled discharge of
pumped well in 3 hours.)


-I
Discharge
Well 1 ruFmped
number well (gpm)


859-055-1

859-055-2

859-055-3

859-117-2

900-120-18

900-120-19

909-106-1-6

911-103-5

911-104-6

911-103-2

911-104-7

911-104-7

912-102-36


350



.50

550

110

110

ee figs.

550

800

800

800

1,100

200


I -- -


-r -I --------------- -


'


--


[







REPORT OF INVESTIGATIONS NO. 22


conditions have been reached within a matter of months, and
vertical leakage caused well 912-102-35, in Daytona Beach, to
stabilize in about three hours.
Figure 29 shows the drawdowns that would be produced by one
well discharging at a rate of 1,000 gpm for different lengths of
time. As the drawdowns outside the pumped well vary directly
with the discharge, drawdowns for greater or lesser rates of
discharge can be computed from these curves. For example, under
the assumed conditions the drawdown 100 feet from a well dis-
charging at 1,000 gpm would be 5.4 feet after 100 days of
discharge. If the well had discharged at 100 gpm for the same
length of time, the drawdown at the same distance would have
been only one-tenth as much, or 0.54 foot.
Computed profiles of the water levels in the vicinity of several
discharging wells after one year of pumping are illustrated in
figure 30. The values used to construct these profiles were obtained
by summing the drawdowns from the 1-year curve in figure 29 and
applying a factor for the efficiency of the discharging wells. The
factor for the efficiency of the discharging well was applied to
the profile only at the well not along the entire profile. One profile
M A-NE, F -- DSCA .GIN .WE ..
. . . v0 MO-


Figure 29. Predicted drawdowns in vicinity of a well discharging 1,000 gpm
Sfor selected periods.









60 FLORIDA GEOLOGICAL SURVEY


was computed for the center line of a group of nine wells arranged
in three parallel lines of three wells each, with 500 feet between
lines and 500 feet between adjacent wells in each line, forming
a square grid. Each of the other profiles is for a group of nine
wells in a straight line, spaced at the distances indicated in the
figure. Although the number of wells and amount of total discharge


THOUSANDS OF FEET
5 0 5


DISTANCE, IN FEET, BETWEEN PUMPING WELLS
500 1O00 500 200500 500 3000 3500 4000


4500 5000


I I \ 1 s eeL1-s 200 i each- ...--
20





Sooogao eacc
630










Computalions based on:
T=300,000 gpd/f I
/ S=0.0007



at a rate of 9,000 gpm.


0007 I.l J'-- Single line wells 500 feel aporl
ihometer 8 inches I I
1 -Center line of three lines-wells 500 feet apart
Lines 500 feet apart
A. Drawdowns in the vicinity of a group of nine wells.







REPORT OF INVESTIGATIONS NO. 22


corresponding to the four profiles are the same, the drawdowns are
different owing to differences in the spacing and arrangement of
the wells.
Two of the profiles in figure 30A represent drawdown in wells
500 feet apart. In one system, the wells are arranged in a square
grid and in the other they are spaced along a straight line. The
maximum drawdown under the grid system exceeds the maximum
drawdown under the straight-line system by 3.5 feet. This shows
that with the same number of wells, discharging at the same rate,
spaced at the same distance, less maximum drawdown will result
if the wells are in a straight line.
Three of the profiles in figure 30A represent the drawdowns
resulting from straight-line well systems. In each system, each of
the nine wells is assumed to have discharged 1,000 gpm for one
year. The maximum drawdown for each system varies according
to the distance between adjacent wells in the system. The greatest
maximum drawdown occurs in the system having the least distance
(500 feet) between adjacent wells, and the smallest maximum
drawdown occurs in the system having the greatest distance
(2,000 feet) between adjacent wells.
The curves in figure 30B represent the change in drawdown,
at the center well of straight-line well systems, as the distance
between adjacent wells is changed. The total discharge of each
line of wells was arbitrarily set at 9,000 gpm and the period of
discharge at one year. An example of the use of this graph is as
follows: If a well system were required to yield 9,000 gpm with a
maximum drawdown of 30 feet, one would follow across the 30-foot
drawdown line to its intercepts of the curves to determine the
number of wells, discharge rate for each well, and spacing between
adjacent wells. The 30-foot drawdown line intersects the curve for
45 wells discharging at 200 gpm each at a point corresponding to
a spacing of 400 feet. The 30-foot drawdown line intersects the
curve for 19 wells discharging at 474 gpm each where the spacing
is 1,150 feet between wells, and intersects the curve for nine wells
discharging at 1,000 gpm each where the wells are spaced 4,500
feet apart. The 30-foot drawdown line is above the curve for three
wells discharging at 3,000 gpm each; thus such a group could not
be used if the drawdown were to be restricted to 30 feet. The
graph could be used in a similar manner for any given maximum
drawdown. The drawdowns are almost directly proportional to the
total discharge. Therefore, for greater or lesser rates of discharge,
proportionately lesser or greater maximum drawdown lines should
be used. Thus, in the example above, if the discharge rate had been







FLORIDA GEOLOGICAL SURVEY


18,000 gpm and the maximum drawdown 30 feet, the 15-foot draw-
down line would have been used.

CONCLUSION

1. Volusia County is underlain by limestone of Eocene age. The
oldest formation penetrated by water wells in the county is the
Lake City limestone. Overlying the Lake City limestone is the
Avon Park limestone. The top of the Avon Park limestone ranges
in depth from about 80 feet below the land surface in the central
part of the county to about 200 feet along the east coast. The top
of the Ocala group, which overlies the Avon Park, is about 50 feet
below the land surface in the central part of the county and about
100 feet at the coast. The Ocala group is the first limestone pene-
trated by wells in most of Volusia County. Overlying the limestone
of Eocene age are 40 to 60 feet of shelly sand and clay beds of
Miocene or Pliocene age. Sands of Pleistocene and Recent age
blanket the deposits of Miocene or Pliocene age and form the land
surface.
2. Two sources of ground-water supplies in Volusia County are
a nonartesian aquifer and an artesian aquifer.
The nonartesian aquifer is composed of sand beds of Pleistocene
and Recent age and sand or shell beds in the sediments of late
Miocene or Pliocene age. The nonartesian aquifer is recharged
locally by precipitation on the land surface, which percolates down-
ward. The nonartesian aquifer usually supplies sufficient water for
domestic use.
The artesian aquifer is composed of limestone and dolomite of
Eocene age. Water is confined in the rocks of Eocene age by clay
beds in the deposits of Miocene or Pliocene age. The artesian
aquifer is recharged principally in the central part of the county
and to a lesser extent elsewhere in the county, wherever the water
table stands at a higher elevation than the piezometric surface.
The permeable limestone and dolomite beds of the artesian
aquifer are separated by numerous thin beds of low permeability
which retard the upward or downward movement of water. The
artesian aquifer furnishes sufficient quantities of water for mu-
nicipal, agricultural, industrial, and commercial needs in Volusia
County.
3. The chemical character of artesian water in the northeastern
part of the county varies considerably, according to the location
and depth of the point of sampling. Chemical analyses indicate







REPORT OF INVESTIGATIONS NO. 22


;that the dissolved solids range from 136 ppm to 3,780 ppm;
hardness, from 120 ppm to 1,060 ppm; and chloride content, from
8 ppm to 18,000 ppm.
4. Records of water-level measurements indicate that there
has been no progressive areal decline of water levels in recent
years, although heavy pumping has caused some local decline.
5. Analysis of data collected during one pumping test indicates
that the upper part of the artesian aquifer west of Daytona Beach
has a transmissibility of about 300,000 gpd/ft and a storage
coefficient of about 0.0007. It indicates also that drawdowns of 10
feet or so in the upper part of the aquifer do not appreciably
affect water levels in the lower part of the aquifer in that area,
presumably because of the presence of layers of low permeability
which separate the different zones of the aquifer. Probably water-
level drawdowns somewhat greater than 10 feet also would not
have a significant effect. Tests in other parts of the county indicate
that the transmissibility may be as low as 28,000 gpd/ft and as
high as 370,000 gpd/ft and that salt-water encroachment may
occur within a few hours if pumping is excessive.
6. Salt-water contamination of artesian water supplies of
Volusia County results from the upward movement of saline water
into the overlying fresh-water zones of the aquifer. This occurs
where heavy pumping or leakage along faults lowers the artesian
pressure in the fresh-water portion sufficiently to cause the under-
lying salt water, which then has a greater pressure head than the
fresh water, to move upward. Salt-water encroachment can be
partially controlled in Volusia County by developing areas where
limestone beds of low permeability below the freshwater zones are
relatively continuous and where the upper part of the artesian
aquifer is neither faulted nor immediately underlain by salt water,
and by using proper well spacing and pumping rates in well fields
drawing heavily from the upper zone of the artesian aquifer.

REFERENCES

Applin, Esther R. (see also Applin, Paul L.)
1945 (and Jordan, Louise) Diagnostic Foraminifera from subsurface
formations in Florida: Jour. Paleontology, v. 19, no. 2, p. 129-148.
Applin, Paul L.
1944 (and Applin, Esther R.) Regional subsurface stratigraphy and
structure of Florida and southern Georgia: Am. Assoc. Petroleum
Geologists Bull., v. 28, no. 12, p. 1673-1753.







FLORIDA GEOLOGICAL SURVEY


18,000 gpm and the maximum drawdown 30 feet, the 15-foot draw-
down line would have been used.

CONCLUSION

1. Volusia County is underlain by limestone of Eocene age. The
oldest formation penetrated by water wells in the county is the
Lake City limestone. Overlying the Lake City limestone is the
Avon Park limestone. The top of the Avon Park limestone ranges
in depth from about 80 feet below the land surface in the central
part of the county to about 200 feet along the east coast. The top
of the Ocala group, which overlies the Avon Park, is about 50 feet
below the land surface in the central part of the county and about
100 feet at the coast. The Ocala group is the first limestone pene-
trated by wells in most of Volusia County. Overlying the limestone
of Eocene age are 40 to 60 feet of shelly sand and clay beds of
Miocene or Pliocene age. Sands of Pleistocene and Recent age
blanket the deposits of Miocene or Pliocene age and form the land
surface.
2. Two sources of ground-water supplies in Volusia County are
a nonartesian aquifer and an artesian aquifer.
The nonartesian aquifer is composed of sand beds of Pleistocene
and Recent age and sand or shell beds in the sediments of late
Miocene or Pliocene age. The nonartesian aquifer is recharged
locally by precipitation on the land surface, which percolates down-
ward. The nonartesian aquifer usually supplies sufficient water for
domestic use.
The artesian aquifer is composed of limestone and dolomite of
Eocene age. Water is confined in the rocks of Eocene age by clay
beds in the deposits of Miocene or Pliocene age. The artesian
aquifer is recharged principally in the central part of the county
and to a lesser extent elsewhere in the county, wherever the water
table stands at a higher elevation than the piezometric surface.
The permeable limestone and dolomite beds of the artesian
aquifer are separated by numerous thin beds of low permeability
which retard the upward or downward movement of water. The
artesian aquifer furnishes sufficient quantities of water for mu-
nicipal, agricultural, industrial, and commercial needs in Volusia
County.
3. The chemical character of artesian water in the northeastern
part of the county varies considerably, according to the location
and depth of the point of sampling. Chemical analyses indicate







REPORT OF INVESTIGATIONS NO. 22


;that the dissolved solids range from 136 ppm to 3,780 ppm;
hardness, from 120 ppm to 1,060 ppm; and chloride content, from
8 ppm to 18,000 ppm.
4. Records of water-level measurements indicate that there
has been no progressive areal decline of water levels in recent
years, although heavy pumping has caused some local decline.
5. Analysis of data collected during one pumping test indicates
that the upper part of the artesian aquifer west of Daytona Beach
has a transmissibility of about 300,000 gpd/ft and a storage
coefficient of about 0.0007. It indicates also that drawdowns of 10
feet or so in the upper part of the aquifer do not appreciably
affect water levels in the lower part of the aquifer in that area,
presumably because of the presence of layers of low permeability
which separate the different zones of the aquifer. Probably water-
level drawdowns somewhat greater than 10 feet also would not
have a significant effect. Tests in other parts of the county indicate
that the transmissibility may be as low as 28,000 gpd/ft and as
high as 370,000 gpd/ft and that salt-water encroachment may
occur within a few hours if pumping is excessive.
6. Salt-water contamination of artesian water supplies of
Volusia County results from the upward movement of saline water
into the overlying fresh-water zones of the aquifer. This occurs
where heavy pumping or leakage along faults lowers the artesian
pressure in the fresh-water portion sufficiently to cause the under-
lying salt water, which then has a greater pressure head than the
fresh water, to move upward. Salt-water encroachment can be
partially controlled in Volusia County by developing areas where
limestone beds of low permeability below the freshwater zones are
relatively continuous and where the upper part of the artesian
aquifer is neither faulted nor immediately underlain by salt water,
and by using proper well spacing and pumping rates in well fields
drawing heavily from the upper zone of the artesian aquifer.

REFERENCES

Applin, Esther R. (see also Applin, Paul L.)
1945 (and Jordan, Louise) Diagnostic Foraminifera from subsurface
formations in Florida: Jour. Paleontology, v. 19, no. 2, p. 129-148.
Applin, Paul L.
1944 (and Applin, Esther R.) Regional subsurface stratigraphy and
structure of Florida and southern Georgia: Am. Assoc. Petroleum
Geologists Bull., v. 28, no. 12, p. 1673-1753.








64 FLORIDA GEOLOGICAL SURVEY

Barraclough, Jack T. (see Heath, Ralph C.)
Black, A. P.
1951 (and Brown, Eugene) Chemical character of Florida's waters-
1951: Florida State Board of Cons., Water Survey and Research,
Paper 6.
Brown, Eugene (see Black, A. P.)
Collins, W. D.
1928 (and Howard, C. S.) Chemical character of waters of Florida:
U. S. Geol. Survey Water-Supply Paper 596-G.
Cooke, C. W.
1945a Geology of Florida: Florida Geol. Survey Bull. 29.
1945b Cenozoic echinoids of eastern United States: U. S. Geol. Survey
Prof. Paper 321.
Cooper, H. H., Jr. (see also Stringfield, V. T., 1951)
1946 (and Jacob, C. E.) A generalized graphical method for evaluating
formation constants and summarizing well-field history: Am.
Geophys, Union Trans., 1946, v. 27, no. 4, p. 526-534.
Heath, Ralph C.
1954 (and Barraclough, Jack T.) Interim report on the ground-water
resources of Seminole County, Florida: Florida Geol. Survey
Inf. Cir. 5.
Howard, C. S. (see Collins, W. D., 1928)

Jacob, C. E. (see Cooper, H. H., Jr.)

Jordan, Louise (see Applin, Esther R.)

Leutze, Willard P. (see Wyrick, Granville G.)

MacNeil, F. Stearns
1947 Correlation chart of the outcropping Tertiary formations of the
eastern Gulf region: U. S. Geol. Survey Oil and Gas Inv. Pre-
liminary Chart 29.

Neill, Robert M.
1955 Basic data of the 1946-47 study of ground-water resources of
Brevard County, Florida: U. S. Geol. Survey open-file release.

Puri, Harbans S.
1953 Zonation of the Ocala group in peninsular Florida (abstract):
Jour. Sed. Petrology, v. 23.

1957 Stratigraphy and zonation of the Ocala group: Florida Geol.
Survey Bull. 38.

Stringfield, V. T.
1936 Artesian water in the Florida peninsula: U. S. Geol. Survey
Water-Supply Paper 773-C.








REPORT OF INVESTIGATIONS NO. 22


1951 (and Cooper, H. H., Jr.) Geologic and hydrologic features of an
artesian spring east of Florida: Florida Geol. Survey Rept. Inv.
7.
Vernon, R. 0.
1951 Geology of Citrus and Levy counties, Florida: Florida Geol.
Survey Bull. 33.
Wenzel, L. K.
1942 Methods for determining permeability of water-bearing materials,
with special reference to discharging-well methods: U. S. Geol.
Survey Water-Supply Paper 887.
Wyrick, Granville G.
1956 (and Leutze, Willard P.) Interim report on ground-water
resources of the northeastern part of Volusia County, Florida:
Florida Geol. Survey Inf. Cir. 8.


TRACE ROUTE

Total Execution Time: 4 Milliseconds

MILLISECOND   CLASS.METHODMESSAGE
0sobekcm_page_globals.constructor
0sobekcm_page_globals.constructorApplication State validated or built
0sobekcm_database.verify_item_lookup_object
0sobekcm_page_globals.constructorNavigation Object created from URI query string
0sobekcm_database.verify_item_lookup_object
0sobekcm_page_globals.display_itemRetrieving item or group information
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0sobekcm_assistant.get_entire_collection_hierarchy
0cached_data_manager.retrieve_item_aggregation
0cached_data_manager.retrieve_item_aggregationFound item aggregation on local cache
0item_aggregation_builder.get_item_aggregationFound 'all' item aggregation in cache
0system.web.ui.page.page_load (ufdc.page_load)
0sobekcm_page_globals.constructor.on_page_load
0html_echo_mainwriter.add_style_referencesAdding style references to HTML
0html_echo_mainwriter.add_text_to_pageReading the text from the file and echoing back to the output stream
4html_echo_mainwriter.add_text_to_pageFinished reading and writing the file