STATUS and BACKGROUND
S: CHARLOTTE COUNTY,
STATUS AND BACKGROUND
THE QUALITY WATER IMPROVEMENT PROGRAM
A PROJECT OF THE
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
THE STAFF OF
SOUTHWEST FLORIDA WATER MANAGEMENT DISTRICT
SUMMARY . . . . . .. 1
INTRODUCTION AND BACKGROUND ................. 3
IMPROVEMENT OF WATER QUALITY. ............... 7
GEOHYDROLOGY OF CHARLOTTE COUNTY ............ 9
GEOPHYSICAL LOGGING .. ................ .14
METHODS OF PLUGGING ......... ..... ... 15
HISTORY OF TESTING. .................. 18
MONITORING PROGRAM. .................. 23
COSTS AND FINANCING ....... .......... .. .26
WHAT DIRECTION QWIP?. .................. 27
LIST OF ILLUSTRATIONS
Fig. 1 GEOLOGIC CROSS-SECTION OF CHARLOTTE COUNTY. ... 11
Fig. 2 GENERALIZED HYDROGEOLOGIC SECTION OF WESTERN
CHARLOTTE COUNTY. ... ............ 12
Fig. 3 VERTICAL HYDRAULIC GRADIENT ........... 13
Fig. 4 QWIP PLUG . . . . . 17
Fig. 5 CROSS SECTION OF WELL AT PUNTA GORDA CITY GARAGE. 22
Fig. 6 LOCATION OF CAVITIES AND CORRESPONDING CHANGES
IN WATER TEMPERATURE AND RESISTIVITY. ..... 25
Fig. 7 AREAS OF QWIP OPERATION IN CHARLOTTE COUNTY . 30
Deterioration of water quality, caused by salt water intrusion, will continue at
an accelerated rate as water and land use development in Charlotte County
intensifies; unless measures such as regulation of well construction, plugging
of multi-aquifer wells and recharge of the upper aquifers are implemented.
Geohydrological and geophysical studies provide data that allow selective plugging
of wells which prevents the vertical flow of salty water from deeper artesian
aquifers into shallower aquifers. Plugging of salty wells, coupled with recharge
of the upper aquifers from surplus water during periods of high stream flow, should
effect an improvement in water quality in a relatively short time.
Some wells can be plugged by backfilling with neat cement slurry, but most
must be plugged by other methods that prevent loss of cement into cavities.
A special device, the Quality Water Improvement Program (QWIP) plug, was
designed to facilitate selective plugging of these wells. It has now been
tested and shown to be effective. The techniques of well plugging will vary
with the characteristics of the wells and the rock strata into which they
! are drilled. Plugging costs will vary with the time, material and
equipment required to emplace the plugs. Presently high costs should
decrease as experience is gained and cost studies are made by the
The first target of the QWIP effort is the Alligator Creek drainage basin,
a potential source of water supply for Punta Gorda. Next, Shell Creek
drainage basin will be the principal area of operation. Other parts of
the County that lie within the SWFWMD boundaries are planned to follow.
A continuing program of monitoring chloride and artesian pressure in each
of the principal aquifers will allow evaluation of the effectiveness of
the program in improving water quality and further understanding of area
INTRODUCTION AND BACKGROUND
Since the early 1900's, wells have been drilled in Charlotte County without
knowledge of the local geohydrology nor concern about the damaging effects
that some of the wells were having on the quality of our fresh-water resource.
Citizens of today are paying the price for errors of the past through higher
costs for development, treatment and protection of their water supplies. Salt
water has gradually intruded into formerly useable sources of water. This
salt water intrusion has made necessary the development of new water sources
for public supplies and has virtually ruined many acres of formerly productive
agricultural land. Rapid land use development in the western part of the
County may tend -to compound water quality problems in the future.
Water supply problems tend to be most severe along the coast where the
proximity of the Gulf encourages urban development. Intense development
is occurring where the majority of surface water bodies are salty and
where the greatest potential for salt water intrusion exists. Many areas
along the southwest coast of Florida that have favorable climate, as well
as cultural and esthetic beauty, also have water quality problems of this
Most of the public supplies near the west coast of Florida south of Tampa
Bay originally had brackish, foul-tasting water. Some of the water
was so high in sulfates that it was laxative when consumed in
large quantities by people unaccustomed to it. Water of similar
quality was used to irrigate acreages that were under agricultural
As more wells were drilled to accommodate the water demand of the
burgeoning coastal development, the ground water became saltier and
public suppliers began to look for alternate sources. Well fields -
and streams farther inland furnished water that could be treated to
the desired level of quality. Agricultural interests, restricted by
economic considerations, were unable to develop new water supplies and
suffered when the soil and water became to salty to support healthy plants.
Large farm areas, vacated because of the water quality problems, were
considered desirable for residential development, and many square
miles have been acquired by land developers for that purpose.
Many wells that were drilled and used for public water supply and i
irrigation are now abandoned. Time, salt and hydrogen sulfide have worked
together to corrode the casings and valves. Wild artesian flow
from these wells has caused a decline in pressures in the entire system
of aquifers that was penetrated by the wells. The lowered pressures have
encouraged the lateral and vertical movement of salt water into the
If the salty wells are capped, interaquifer flow through the well j
bores will cause the shallower, lower-pressure aquifers to be
contaminated at an accelerated rate by water from the deeper and saltier J
higher-pressure aquifer. On the other hand, if the wells continue to i
flow without restraint, an increase in salt content will cause further
deterioration of water quality in the upper artesian aquifers and major
contamination of the water-table aquifer.
In 1953 a law (Florida Statute 373) was enacted that emphasized
regulation of wild flowing wells. This law recognized that stopping
the surface flow of a well could cause problems more serious than the waste
of water flowing to the surface. The control of flowing wells may include
capping, valving or plugging. This law also provided for the establishment
of well construction standards to prevent the mixing of poorer quality
water with that of a better quality. Later, the law was amended to provide
for the mandatory plugging of wells yielding nonpotable water. Horace
Sutcliffe (1973) described the layer-cake distribution of aquifers in
Charlotte County and the increase in both artesian pressure and mineralization
with depth below land surface. This information was used by Southwest
Florida Water Management District in developing the Quality Water Improvement
Program in this area.
The economic significance of salt water intrusion has long been appreciated
by government officials and many other citizens interested in water
conservation and management. Solutions have historically been sought in
finding new and replacement sources of water rather than remedying the cause
of the existing problems. The recent trend toward an increased public awareness
of finite resource quantities, environmental protection and conservation has allowed
consideration of a program designed to preserve or improve the quality of
water in Charlotte County.
This report presents the history, rationale and techniques of QWIP
and suggests companion projects that can improve the quality of water
in Charlotte County.
IMPROVEMENT OF WATER QUALITY
Ground water flows from one location to another because a hydraulic
gradient or difference in pressure exists. Flow is always from
higher to lower pressure. Pressure differential between aquifers
is possible because beds of lower permeability, or aquitards,
separate the aquifers. The rate of flow is controlled by
differences in pressure between locations in the aquifers system and
the permeability of the beds. Since salty water in the deeper aquifers is
under greater pressure than the fresher water in the shallower
aquifers, it will flow upwards and cause contamination if avenues
of flow exist. Many avenues of flow have been created by drilling wells
through the aquitards. The deterioration process has been accelerated by
withdrawal of water from the shallower aquifers which results in greater
differences in pressure between the shallow aquifer and the salt water
Improvement in the quality of water in the shallower aquifers depends
on reduction or elimination of this interaquifer flow of salty water.
This may be accomplished by any of three methods:
1. Increase the artesian pressure in the shallower aquifers;
2. Decrease the pressure in the deeper aquifers; or,
3. Plug wells that allow interaquifer flow through aquitards.
Increasing the pressure in the shallower aquifers would require injection
of fresh water through specially constructed wells. This would be possible
during high stream flow periods when large amounts of fresh water are
discharged to the Gulf. The double-barreled effect of introducing
fresh water into the shallower aquifer zones, thereby increasing pressure in
the upper aquifer; and at the same time inhibiting the upward movement of
salty water from the deeper aquifer, would soon improve the quality of water
in the shallower aquifers.
Decreasing the artesian pressure in the salty aquifers could be accomplished
by drilling flowing wells with bore holes open only to these aquifers, but
the outcome would result in disposal problems and a net waste of water. The
probable benefits to be realized make this procedure a possible course of action
that could be applied in areas of high natural interaquifer flow where plugging
of flow avenues would be virtually impossible.
The third method of reducing interaquifer flow of salty water involves
selective plugging of wells which contribute to aquifer contamination. This
method attacks the problem directly, involves no large-scale transfers
of water for injection and can be productive in proportion to almost any
level of program funding. Furthermore, it has the Distinct advantage of
being in concert with the natural system, thereby progressing towards
restoration of the hydrologic equilibrum that man's well-intentioned
activities have disrupted.
GEOHYDROLOGY OF CHARLOTTE COUNTY
Aquifers that supply water to wells in Charlotte County occur as
zones of high permeability separated by zones of lower permeability.
The geologic units in Charlotte County (Figures 1 and 2) slope to
the southwest at about five feet per mile on the southwest flank
of the Ocala uplift. The principal aquifers are in rocks of
Eocene to Miocene age and tend to follow the geology. As many
as eight water-yielding zones can be distinguished by geophysical
methods in the upper 750 feet, and eleven occur in the upper 1500
feet of geologic section in the southern part of Charlotte County;
where many beds of clay or "dirty" limestone separate beds of limestone.
Most of the aquifers are in the limestone layers which are both
permeable and competent to maintain solution cavities. Some of the
sandy marls in the upper 500 feet of section transmit enough water
to be called aquifers, but these are only poorly identified. Each
aquifer has a pressure, chemical quality and temperature that is
different from the aquifers above and below it.
The vertical distribution of aquifers, as determined from geophysical
logs in the upper 750 feet of the geologic section in southwest
Charlotte County, is shown in Figure 2. Among the more important
aquifers are those at depths of approximately 500 feet near the
Hawthorn-Tampa contact and at about 750 feet near the Tampa-Suwannee
contact. These aquifers are separated by rocks of very low
permeability that, in'the absence of open well bores, effectively
separate the salty water below from the fresher water above. A
high differential pressure across this confining layer serves to
emphasize its importance. A marked increase in flow usually occurs
when the higher pressure aquifer below this "tight" zone is
penetrated by the drill bit. Conversely, a well that is plugged
above the lower of the two aquifers suffers an abrupt loss in
artesian pressure as manifested by a reduction in flow.
Shown in Figure 3 is the hydraulic gradient in the rocks between
discrete cavities that were penetrated by a well located a few
miles north of the Charlotte-Desoto County line (Kaufman and Dion,
1968). This figure illustrates that if the rocks have a high vertical
permeability, the change in pressure for a given thickness would be
low. Conversely, an aquitard that separates aquifers would have a
low vertical permeability and a large change in pressure for a given J
thickness. The five artesian zones from which the well produces water
were determined during the drilling process. The artesian pressure
was measured soon after a change in flow at the ground surface was
GEOLOGIC CROSS-SECTION OF CHARLOTTE CO.
82015' j200' 8r45' 8135'
I I I I
2700 rF o CHARLOTTE COUNTY
2 6'- C __HAILOTTEE COUNTY
2%460- LEE CO.
MSL O _
-I od- Z. n
S500'- ^ 3WER AWTHO R
-I1- Ti E-RY DRU'Mi
GENERALIZED HYDROGEOLOGIC SECTION OF WESTERN
0 CALOOSAHATCHEE FORMATION................(Surface sand, shell, marl,
Sj TAMIAMI FOMATION......... ......... (Green and gray green clay,
tan limestone, gray limestone, and dark gray
clay with phosphorite at bottom).
UPPER HAWTHORN FORMATION......(Interbedded gray to gray-white
APPROX sandy clay and gray to gray- white sandy
limestone abundant phosphorite throughout )
LOWER HAWTHORN FORMATION...... (Interbedded gray to gray-white
DEPTH limestone and gray to green clay
with thin streaks of dolomite, clay
GO0 bed at bottom. Phosphorite is
STAMPA FORMATION...... (Interbedded gray to tan sandy limestone
IN FEET and gray and white clay).
AQUIFERS SUWANNEE LIMESTONE..... (Tan to creamy white limestone, sandy
limestone, and sand).
AND 1: j
1200 OCALA LIMESTONE ....... (Tan, chalky limestone -darker and
dolomitized near bottom).
AVON PARK LIMESTONE......(Tan to dark brown dolomite and |
j BEDS OF MODERATE PERMeALBILITY (AQUIFERS SMALL YIELD)
1 BEDS OF LOW PERMEABILITY (AQUITAROS) J
BEDS OF HIGH PERMEABLITY ( AQUIFERS LARE YIELD)
Modified after H.S. PurL, 1974. SWFWMD j
VERTICAL HYDRAULIC GRADIENT
300 -AQUITARD ----- -- .0386
a 400 ---....
0 .01 .02 .03 .04 .05 .06 .07
SWFWMD CHANGE IN PRESSURE(IN FEET OF WATER PER FOOT OF DEPTH)
Much useful information about the nature of the aquifer, the quality
of water and the distribution of pressure can be derived from on-site
study during the well drilling process. Such information is extremely
expensive to collect and, hence, has been collected from only a few
wells. The bulk of the information that is necessary to describe the
well, the aquifer and the water in the aquifer must be derived from
geophysical studies. These studies are based on logs (continuous
line graphs showing changes in measured parameters as a function of
depth) that result from lowering remote detection devices down an
existing well bore and recording the parameter that the device measures.
The indirect indications of physical or chemical changes in the
rocks, the well or the water in the well that are derived from
study of the various geophysical logs can be combined with
geologic and hydrologic data to yield a profile of the aquifers,
the well and the water. This information is of utmost importance,
because it makes the selection of a plugging interval for QWIP project
wells a rational exercise rather than a guess.
METHODS OF PLUGGING
A well that has only small cavities may be backfilled with a neat Portland
cement slurry, crushed limestone, sand or other materials that contain
enough fine material to assure a positive plug. The cement plug
may be interlayered with coarse fill material or emplaced as a
continuous neat cement slurry filling the entire well bore. All
materials must be emplaced by tremie (a pipe through which the
cement is pumped) into the well bore.
Where a large cavity occurs, a bridging plug may be used. Bridging plugs
are devices that allow a neat cement slurry to be emplaced only on
top of the plug. Many such devices are on the market, but most are
quite expensive and do not stop the flow of water in the well bore when
the differential pressure across the plug is as great as occurs in
the southern part of Charlotte County. A bridging plug is a variation
of the back filling method that allows the plugging of wells with
large cavities. Many non-commercial bridging plugs have been
invented by well drillers including such devices as a 3-limbed branch,
a bag full of beans, a sack full of cement, etc.
All bridging plugs have the same shortcomings: (1) The cement slurry
that is emplaced on top of the plug is not controlled as to the
length of the plug. This may allow some or all of the cement slurry to
disappear into a cavity that is connected to the well. (2) The bridge
may slip down the well when loaded with cement due to lack of bond to the
well bore walls. (3) The plug must be set in two stages with only a
few feet of cement on top of the bridge at first. Later, after the first
cement has set, another batch of cement must be emplaced to effect a plug.
The QWIP plug (Figure 4) was developed by SWFWMD to eliminate the problems
associated with other plugs. This plug consists of a burlap sock of such
length that the expected differential pressure across the plug can be more
than balanced by the column of heavy cement slurry that fills it. The
bottom 4 feet of the sock exterior is covered with a tough plastic material
that prevents tearing of the burlap and creates a tight seal when the cement
slurry fills the sock. The burlap is semi-permeable with respect to
cement slurry under low pressure, but it readily allows passage of the
slurry under the pressure that prevails at the bottom of the filled sock.
The sequence of events in the setting of a plug is as follows: (1) The
plug is assembled and lowered to the desired depth. (2) The cement
slurry is pumped through the tremie into the sock. (3) The sock fills
from the bottom and stops the flow of water in the well bore. (4) The
cement slurry leaks through the burlap to displace water from the bottom
of the burlap upward, filling any irregularities in the well bore. This
leaked slurry prevents the setting of a "cold" plug that does not tightly
seal the well in the plugged interval. (5) The tremie is immediately
disconnected, flushed and recovered. The resulting plug fills a controlled
length of bore with reliability and permanence not usually attained by
other plugs. 1
Cost of the plug materials in 1975 was $64.00 for the pipe, sock
and fittings. Cement and additives cost $84.00, bringing the total
cost of the plug materials to $148.00. Approximately 2 hours is
required to set the plug at 600 feet. This time includes assembly j
of the plug, lowering it into place, mixing and emplacing the cement
slurry, flushing the tremie and running out of the hole. i
LEFT-HAND THREAD NIPPLE
.I .-----21 PVC PIPE
Si I z
BURLAP SOCK ..... I 8o o
SI 4' PLASTIC BOOT
SI OUTSIDE BURLAP SOCK
I I '
DEC. 15, 1975
QWIP PLUG DRAWN BY:
HISTORY OF TESTING
In 1974 the SWFWMD staff designed and built a unit similar to a
commercially produced well service rig for the purpose of testing
the prototype method of QWIP well plugging. A used 12-foot trailer
was modified and equipped with a 17-foot aluminum boom, and a gasoline-
powered AC welding unit was installed as a source of electrical power.
A modified electric powered vehicle winch was used to winch and spool the
cable. An AC winch motor was substituted for the original DC motor and
the winch drum altered to allow it to handle over 600 feet of
3/16 inch aircraft cable. An 8 HP Barnes-Peabody trash pump was
mounted inside the trailer for mixing and handling the cement
The resulting rig proved to be inadequate for its intended use. -
The electric motor and the pump were subject to frequent
and considerable stress, often leading to interruptions during
operations. Due to the rig's limited capabilities, only plastic
PVC pipe could be used for pumping cement into the plug socks.
This type of pipe was soon found to be too light in weight
for the work. Breaks in the tremie were a common occurrence, and
retrieving the lost sections of pipe from the well was time consuming. i
The initial plugging operations began on October 10, 1974 and involved
a well 768 feet deep and 6 inches in diameter located near the west j
side of the Punta Gorda city garage. The first operational problem
encountered was the irregularity in the bore hole size. The irregularities
obstructed the passage of the pipe and plug assembly and the jagged
edges of the rusted-out casing often ripped the burlap sock.
Attempts were made to manually ream out the well to a uniform diameter,
but the light equipment that could be handled by the rig proved
inadequate. A professional well driller was then contracted to
perform the reaming operation.
When the first plug assembly was lowered into the well, another
problem became obvious. Because of the considerable upward force
of flowing water, it was difficult to force the PVC pipe, with
a large diameter plug assembly, into the well. An initial weight of
more than 200 pounds was required to start the plug into the well.
Only after more than 300 feet of pipe had been pushed down the hole did
the pipe begin to sink from its own weight. This problem recurred during
most of the subsequent plugging operations and suggested the desirability
of using heavier metal pipe for the tremie.
When the plug had been lowered into position, a neat cement slurry
was mixed in the proportion of 94 pounds of Portland cement to five
gallons of water and pumped into the burlap sock through the
tremie. Considerable loss of cement occurred due to the rapid upward
movement of water, but enough remained to effect a plug; and a
drop in water pressure and rate of flow was observed.
Plugs were set at four intervals in the well: the first from 620
feet to 660 feet; the second, 466 feet to 505 feet; the third, 302
feet to 327 feet; and the fourth, 103 feet to 118 feet. The placement
of these plugs isolated the major aquifers which were supplying the
well; namely the Tampa, Lower Hawthorn, Upper Hawthorn and Tamiami
formations (Figure 5). The casing above the fourth plug, 103 feet
to land surface, was filled with cement slurry.
Four piezometers were installed in the well by lowering 1-1/4 inch PVC
pipes in tandem with the tremie to extend below the bottom of each plug.
The purpose of the piezometers was to allow each aquifer to be monitored }
individually for water pressure and chemical quality. Unfortunately three
PVC pipes were melted by the heat of hydration of the cement. Only the deepest
piezometer remained open because the cap was faulty, and water leaked
through the pipe in sufficient quantities to cool it. The future use of
CPVC pipe should solve the heat of hydration problem.
The second well to be plugged was also the property of the City of
Punta Gorda. Located behind the City Hall, the well was 6 inches in
diameter and 475 feet deep. After the well bore was cleaned and reamed out
by a rotary drill rig, plugs were set at depths of 337 feet to 371 feet and 90
feet to 110 feet; and the top eleven feet of casing filled with cement slurry.
Efforts to fill the casing allowed a large amount of cement slurry to
escape to a cavity. The escaping cement stopped a small flow that had
persisted after the plug was emplaced in the 90 foot to 110 foot interval. -
In a third well plugging operation a 6-inch, 560-foot deep well owned
by Punta Gorda Isles Corporation was partially plugged and allowed _
to remain flowing at a reduced rate to provide water for livestock.
Two plugs were set in the well; the first at 500-560 feet and the
second at 415-460 feet. Analysis showed that the chloride content j
of the water from this well had dropped from 775 parts per million (ppm)
in December 1974, when the plugs were placed, to 650 ppm in August of 1975.
To what extent this change can be ascribed to improvement due to the plugging
of the well, rather than normal seasonal variation, has not yet been
A fourth well, also owned by Punta Gorda Isles, was plugged using
the same plugging methods as previously described. For the purpose
of experimentation, the work was performed by a private drilling contractor
with rotary drilling equipment. Under the supervision of District personnel,
two plugs were set in the well and the top of the casing cemented, effectively
stopping all flow of water.
CROSS SECTION OF WELL AT PUNTA GORDA CITY GARAGE
O LAND SURFACE
0 ____&SAND 1"Oft
CALOOSAHACH FORMATION WATER LEAVE LAppox.
5 FT ABOVE MS L
oo. 00 WATER TABLE SYSTEMt
MARKER ,-- --PULT G + ARTESIAN SYSTEM
--- CASING ENDS
UPPER WATER LEVEL: Approx.
-HAWTHORN 15 FT. ABOVE MSL
SLOWER WATER LEVEL: Aprox.
w HAWTHORN 20 FT ABOVE MSL
TAMPA PLUG WATER LEVEL:Approx.
-LIMESTONE -25 FT. ABOVE MSL
SUWANNE WATER LEVEL: Approx.
LIMESTONE 40 FT ABOVE MSL
800 --- *
10 8 6 4 2 24 6810
RADIUS OF WELLBORE
DEC. 15, 1975
The rationale for recharging aquifers, plugging wells and relieving
pressure with drain wells has been established. The expected results
should be well worth while if the systems involved behave generally as
predicted. It is only by monitoring of data from the complex natural
hydrogeologic system before, during and after corrective measures are
undertaken that the effectiveness of predicted results can be assessed
and the natural systems better understood.
An example of the occasional conflict between the logical application of
established hydrologic principles and real data occurs with the observed rapid
recovery of variation in temperature and quality of water with depth found,
when several following wells were uncapped after being capped a considerable
period of time previously.
Well-established laws of hydrodynamics require that water flow down the
hydraulic gradient, that is, from areas of high pressure to areas of low
pressure. Application of this principle would require water from the
higher pressure, deeper, salty aquifers to flow upward and laterally into
shallower aquifers in which pressures are lower. A well that has been
capped at the surface for a number of years would be expected to have
allowed permeation by large quantities of water from the higher pressure
salty aquifer into all of the upper aquifers in a large area around each
well. However, in some of the wells that have been logged, a few minutes
after uncapping the temperature and quality of the several aquifers are
found to be substantially different from each other, with the temperature
increasing stepwise as the depth increases. The fluid resistivity log
indicates that changes in quality of water occur in a similar steplike
pattern (Figure 6). This rapid return to segregated water parameters
implys a rapid purging of the shallower aquifer zones, further implying
less salt contamination than would be predicted by theoretical considerations.
The apparent paradox, a conflict between real and predicted models of
flow, results from insufficient geophysical information to fully understand
anomalies in the area geohydrology. Such paradoxical situations are
expected to be resolved by further data collection, analysis and study.
Further field study must verify the validity of the basic hydrologic
premises and of all plugging operations based on those premises. This
can be best accomplished by monitoring the changes that take place after
an area is plugged, recharged or otherwise treated.
Monitoring of changes in artesian pressure, quality of water and temperature 1
of water can be accomplished by the installation of small pipes in selected
wells as they are plugged. Multiple monitor pipes, (one extending a few
feet below the bottom of each plug) are the most convenient and effective
arrangement for monitoring of the several aquifers. Multiple monitors
in the same well also simplify processing and presentation of data.
The quality of water from each water bearing zone should be determined
by specific conductance measurements monthly, and a standard complete
chemical analysis should be made of the water from each aquifer annually. J
The monitoring program will begin in 1976 when multiple monitor tubes
will be installed in several wells. These tubes will serve as piezometers
to measure the artesian pressure and as sampling tubes to collect samples
from the several water bearing zones that have been isolated by plugs.
LOCATION OF WELL CAVITIES AND CORRESPONDING
CHANGES IN WATER TEMPERATURE AND RESISTIVITY
800CROSS-SECTION TEMPLOG FLUID RESISTIVITY
OF WELL (Decreasing) LOG
SHOWING CAVITIES --- (Increasing)
DEC. 15, 1975
-25- TERRY DRUM
COSTS AND FINANCING
Due to the experimental nature of the QWIP program to date, a
determination of the expenses involved thus far would not accurately
reflect the cost of plugging on a per-well basis. Total expenditures
for the project during the initial six months were approximately $32,500.
Much of this money used to purchase materials and capital equipment
which will be available for future use. This figure also includes the
cost of building the experimental plugging rig and the costs of
contracting private drillers to perform reaming and plugging operations.
Estimated costs of a large-scale well plugging program, based on
comparative costs of a ten well 1975 contract and adjusted to reflect
changes in plugging technique, competitive bidding and reduced Staff effort
through development of a routine program; are $1,750.00 per well.
The District, through the Peace River Basin Board, has paid for research
and development of the QWIP plugging system described in this report, and a
number of wells have already been plugged as a part of this program.
When the 1976 budget expires the funding of the QWIP effort will
require a broader base. However, attempts to locate outside sources 1
of funding for the project have thus far proved fruitless.
WHAT DIRECTION QWIP?
The QWIP program is implemented in several phases delineated as follows.
(1) Phase One involves an inventory of all wells within a specified area.
Wells are located from aerial photographs, old records and by talking with
local residents. Data pertaining to the water quality, depth, use, location and
ownership of the wells is collected and studied to determine which wells
might be beneficially plugged.
(2) In Phase Two the owners of wells that are considered suitable candidates
for plugging are contacted and informed of the District's intentions. The
desirability of plugging the wells is explained to them and permission to
proceed with the work is requested.
(3) If the owner's formal permission is obtained, Phase Three begins
with any necessary preparation of the site; then follows the reaming and
cleaning out of the well bore to better facilitate work within the well.
(4) After the well has been reamed and all obstructions removed, the
geophysical logger begins Phase Four, the logging of the well. The
data obtained from the logs is essential in determining the size of the
plugs and at what depths they will be placed. When this information
has been obtained and analyzed, actual plugging of the well may
By request of the City of Punta Gorda and the Charlotte County Regional
Planning Council initial plugging operations have been, and will continue
to be, directed towards the Alligator Creek drainage area (Section A,
Figure 7). This area is considered a possible future source of water
supply for the City. At least 25 wells remain to be plugged in this
area, and numerous others should be partially plugged. In October 1975,
a contract was awarded to Mixon Foundation and Drilling Inc. of Tampa
for plugging ten of these wells. As of this writing all ten of the
wells have been effectively plugged, and a new contract for plugging
ten more wells is being prepared.
By the second quarter of 1976, QWIP should be focusing its attention
on southwest Charlotte County (Section B. Fig. 7), where at least
a dozen contaminated and unused wells are known to exist. Operations
in the Shell Creek drainage area (Section C, Fig. 7) should be underway
by the third quarter of 1976. Unlike the first two sections, A and B,
the Shell Creek area has not yet been extensively inventoried; but at
least five wells that should be plugged have already been documented.
Port Charlotte and that portion of Charlotte County east of the
Myakka River (Section D, Fig. 7) and the EL Jobean area (Section F,
Fig. 7) have yet to be inventoried.
Throughout the Charlotte County area it is conservatively estimated that there
are several hundred contaminating wells which need to be completely plugged.
Additionally, it is estimated that there are several hundred other
contaminating wells which cannot be completely plugged, because they
are privately being used. Never-the-less, these wells tend to cause aquifer j
contamination, and they should be partially plugged to seal off the salty
water flowing from the deep salty aquifer zones upward into the fresher zones.
Results and activities of the QWIP program in Charlotte County have
thus far only begun to assess and develop corrective measures for the
ground water quality problems in this area. Continuance of the QWIP program
on an expanded scale, seem essential if local supplies of fresh water are J
to be provided from the aquifer system for present and future generations
of residents. Plugging, monitoring and prototype recharge efforts must be
continued and expanded as part of the QWIP program. However, to accelerate
these efforts a source of financial assistance must be found to compliment
the limited financial resources of the Peace Basin Board of SWFWMD. Without
such funding QWIP will continue to be essentially a small scale research
and development program.
SARASOT A COUNTY DESOT0 COUNTY
I CHARLOTTE COUNTY CHARLOTTEE COUNTY
E D C
MARCH 31, 1976
(DWLEE COUNTY 0 I 2 3 4i
(DWG. NO. -)
Kaufman, M.I., and Dion, N.P., 1968; Groundwater Resource
Data of Charlotte, DeSoto and Hardee Counties, Florida;
Florida Bureau of Geology, Information Circular #53.
Puri, H.S. and Winston, G.O., 1974: Geologic Framework of the
High Transmissivity Zones in South Florida; Florida Bureau of
Geology, Special Publication #20.
Sutcliffe, Jr. H. 1973: Appraisal of the Water Resources of
Charlotte County, Florida; U. S. Geological Survey. Open File