/ ll' -
Information Circular No. 2
.IPROVEMENT OF WATER QUALITY
THROUGH A COOPERATIVE WELL PLUGGING PROGRAM
"-: Douglas A. Munch
Water Resources Department
St. Johns River Water Management District
,": Palatka, Florida
Project Nuriber 2001801
STABLE OF CONTENTS
SINTRODUCTION . ...... . . . 1
Location . . . . . . 1
Problem . . . . . .... 3
Purpose and Objective . . . ...... 6
INTER-AGENCY COOPERATION .. . . . ....... 7
Planning . . . . . . 7
Program Responsibilities .. . .......... 7
WELL PLUGGING .. . . .............. 8
Previous Work . . . ........ 8
"Plugging Procedures . . . . .. 10
RESULTS ..................................... 11
SUMMARY .................................. 16
APPENDIX A . . . . . . . 18
A serious concern for the quality of water used for agricultural irrigation
in the State of Florida has developed in the past few years. In the late 1960's
and early 1970's, the practice of plugging artesian wells on a cost-sharing basis
was provided by the Agricultural Stabilization and Conservation Service (ASCS)
through the funding of the Federal Government. This cost-sharing program began
in the southern portion of the state, and now in certain counties in the St. Johns
"W; River Water Management District (SJRI-'MD) monies have been allocated by the ASCS
for this program. In most of the cost-sharing programs offered by the ASCS, the
technical expertise was provided by the agricultural engineers of the Soil Con-
servation Service (SCS), but in the case of well plugging programs, expertise
was provided by the Department of Natural Resources. Since the implementation
of Chapter 373, Florida Statutes, responsibility for providing well plugging
expertise has been delegated to the water management districts.
The plugging of these irrigation wells is specifically to restore the
hydrologic conditions which existed before the well was constructed and also to
eliminate the exchange of water between aquifers. Since this program was ini-
tiated in 1976, several deep irrigation wells have been plugged by methods pro-
vided by District staff in cooperation with the ASCS. The wells which have been
"corrected to date represent only a fraction of those which could benefit from
this program. Data that have been collected illustrates that this procedure
offers a practical method for controlling water quality problems in deep wells.
The agricultural community of Hastings, located in southwestern St. Johns
" County within the St. Johns River Water Management District (Figure 1), is the
largest producer of cabbage and potatoes in the southeastern United States.
Approximately 6,400 acres of land are irrigated by artesian wells in the Floridan
ST. JOHNS RIVER
WATER MANAGEMENT DISTRICT
o ?7 -a "
mnI DISTRICT BOUNDARY
N A SS AU t Fernandina -COUNTY OUNDA
GEORGIA B e a c n
S/Ko uE "- L.. HASTINGS
SAE Jacksonville AGRICULTURAL
...... L AREA
U UN1IONN I C
/ CL A Y
Green S T
f "tBRAD FORD Cove St. Augustine
Springs 0 H N S
A C H U A
Gainesvil.l J D PUTNAM M"
S:-T .. Bunnell
L. \ \FLAG LE R
SA R O N Daytona
..r \ V VOLUS IA
0 j^ DeLand
SUMMER SE M 0 L E
LAKE Tltusvl *
^^q I ^
!I .LA.-,N.G E
1l [ N DIAN
j --.. v ero Beach
. i KEF ,C. E
Figure 1. Location Map of the Hastings Agricultural Area
aquifer during the fall and winter months when insufficient amounts of rainfall
cannot meet the demands of the winter vegetables.
"All of the wells used for irrigation derive their water from the Floridan
aquifer. The Floridan aquifer consists of a series of porous Eocene limestone
formations (Figure 2) overlain in most areas by a semi-permeable clay unit known
AGE FORMATION THICKNESS DESCRIPTION
LU 0 to
Z 2 --.:" .--;100 ft Sand, Clay, and
S0 0 to Mixtures of the Two
z - HAWTHORN 180 ft Clay, with Sand, Sandy Clay
SI FORMATION 1 to and Sandy Limestone
2 55 m
I I I75 m
1I I 2501ft Soft, Pure Limestone
GROUP 30 to
"" '/ AVON PARK 250 ft Alternating Limestone and
Dolomite Beds with some
u LIMESTONE 45 to Disseminated Peat and
S75 m some Thin Peat Beds
Disseminated Peat and
E 120 t Distinct Peat Beds
Figure 2. Generalized Geologic Column, Hastings Area
/- / / / 150 m
:IZi I ZIZ Z 1
I / 1 / 1_ /]ZL
p" ~ ~ ~ ~ ~ ~ I ZIZ Z ZI i______________
as the Hawthorn Formation. Due to the nature of the confining clay unit, the
"Floridan aquifer is under artesian pressure which, under natural conditions,
allows many wells to freely flow above land surface. For the purpose of dis-
cussion, the Floridan aquifer is divided into two parts, the upper Floridan which
consists of the Ocala Group and the lower Floridan which consists of the Avon
Park, Lake City, and Oldsmar formations.
"C, An index used for the determination of salt contamination is the concen-
tration of chloride ions in the water. Irrigation water exceeding 1,000 parts
per million (ppm) in chloride concentration is damaging to vegetable crops.
The chloride content of water produced in the Hastings area (Figure 3) from the
upper Floridan ranges from 250-900 ppm. Typically, water derived from the deeper
zone exceeds 1,000 ppm and has been as high as 3,600 ppm in chloride concentra-
tion during low artesian levels.
Many of the irrigation wells located near the areas of denser crop culti-
vation become salt contaminated in two ways. A majority of the wells pre-
sently being used were drilled early in the agricultural history of the area.
..At that time, excessively deep wells were constructed to acquire greater quanti-
ties of natural artesian flow. By the late 1950's, water levels had steadily
"declined, and artesian flow from the wells could not supply the large quantities
of water needed for the increased irrigated acreage of the area. Various types
of power driven pumps were then installed on the wells to provide more water.
,, As the pumping duration and intensity increased, so did the salt content of the
water. In time these deeper wells become direct conduits for the upward migra-
tion of saltier water. Many acres of vegetables were ruined, and consequently,
these wells were either abandoned or used only when absolutely necessary.
The other mechanism which allows for the contamination of irrigation wells
is the process of salt water coning. This process involves overpumping of an
..=:'::::~::'' '='='=' -I:::'-:::: :::: ::~~~ii16~- \A ST JOT JHNS RIVERP
...... WATER MANAGEMENT DISTRICT
. ... .......
....... ..... ------ :l'i~';i;;:_
S 251--- 500..PPM
..........- -- - -- -
% ....... .......................... G R E A T E R T H A N 10(:::~
""*A I i i i i ; ': ;, } 2
Figr 3. pSoigteClrd Cocnrto ofte-pe-ord---f
.. rn March 1975
... .. ..
............ iii~~~ i~i~~ :::: ::::
::s ~~::~~~::~f::~::~i:~f (~:: ;s;:--::X::;.::r;::: 1*: 5"r. P )
r::-::~~t.. :5~~tl......... ::::::
.... ......; :: :: ::
.. .....==~=..='.. .'''....'=;'''
~~ i~:::B:~~:~~:'':;i:~::i~~L '~i_;251 50 PL
...........C'. .=r==; ''
ILL-- :':':'''.............''.....=r..,.... ~;
irrigation well during times of low artesian water levels, and thus inducing the
coning of salt contaminated water directly beheath the well (Figure 4). Slowly
the contaminated water migrates upward through the porous limestone aquifer until
i--- the general area that the well derives its water from is completely contaminated.
Purpose and Objective
The purpose of this program is to accomplish water management goals in
,pu _I GROUND SURFACE
.: -.T '- 3
-.' -. .... .. .". "" "-'-- : """ "-HAW TH O R N FM .
.. ,.... ;. _,.- UNCONNNSOLIDATED
FLO AND AQ
"". 3 ," ; I ..... ....... ... 4 ...* .
't; ... .. .. . ; : i : r R O C K A Q U I E R .
Figure 4. Generalized Diagram of Salt Water Coning Beneath
a Pumping Well
I.:.. HAWTHORN FM.
Figu-d FLRIA AQUIFERze -iga fSl atrCmn ee
a P'-qin ~l
hydrologically stressed areas through cooperation with other agencies. The ob-
jective is to upgrade ground water quality through methods of well rehabilitation
which prevent contamination of the fresh water layers of the Floridan aquifer
from deep wells which penetrate the saline zones below.
The initial outline and goals of the program were established after a
Series of workshops were held with local ASCS and SCS personnel in July 1976.
The Water Resources Department of the SJRWM was made responsible for outlining
a the program and procedures. The program focuses on the partial plugging of
irrigation wells to alleviate the interchange of water between aquifers. The
cost-sharing program will also apply if, after inspection, full plugging of a
well is recommended. Wells to be considered for the program could be abandoned
P wells or currently used wells. To date, this program has been confined to the
counties of Putnam, Flagler, and St. Johns in order to establish criteria and
precedents for other counties within the District.
The method for integrating the individual activities of the cooperating
agencies into a working program employ the following steps:
1. Upon receipt of a referral, the SCS District conservationist will notify
""" the appropriate water management district in writing. He will advise the
water management district of the name of the landowner, a general descrip-
tion of the location, and the date of availability of the well in suffi-
cient detail to enable a staff member of the water management district to
inspect the well.
"2. The water management district representative will geophysicalrv log the
well, then develop plans and specifications for plugging the well and
give a copy to the SCS District conservationist for delivery to the land-
3. The SCS District conservationist will complete the need and practicability
finding certification on the Agricultural Conservation Program (ACP) referral
4. The landowner will arrange for work to be done under the supervision of the
water management district representative, and will notify him by phone when
the work is completed.
5. The water management district representative will then inspect the well and
"state, in writing, to the SCS District conservationist that the well has or
has not been plugged according to plans and specifications.
"6. The SCS District conservationist will then so certify on the ACP-247 form
which authorizes reimbursement of funds to the owner.
i. Previous Work
Early attempts to grout irrigation wells in this area consisted of merely
"i pumping large quantities of neat cement down the well until either the driller
exhausted his supply of cement or the well was completely filled to the top.
At that time there was no possible way to determine any of the well character-
.,: istics except for total depth. Many wells could not be satisfactorily grouted
due to the large voids and cavities in the porous Floridan aquifer limestone
".. which could absorb tremendous quantities of cement. These early plugging
attempts were rarely successful.
In 1976 the Southwest Florida Water Management District initiated a quality
of water improvement program. Through this program, plugging techniques and a
device to shut off the flow of contaminated waters from aquifers were developed.
"These procedures assure proper placement of the plug and require less cement to
construct the plug within the cavities of the well. With confidence in this type
of plugging technique, the staff of the St. Johns River Water tManagement District
promoted these ideas to the local agricultural agencies.
Once a request for plugging has .----
been received by the District from the ,t:TE;R--:R- -fT Te- .
ASCS agent, arrangements are made with UNCO'NSOLIDATED
the owner to have the well made avail- .-.. c .,.. ..
i- able for geophysical logging. Through- -- :'-- :
- the sophisticated electronics of the --- wH AwORN F,,N
geophysical logger, important well -.
characteristics can be determined. RC -
Figures 5 and 6 are typical examples of
I the problem wells encountered during
the early stages of this program and
F RESH WATER-SALT WATER INTERFACE
S the possible placement of the plugs
Figure 5. This case exemplifies a
homogeneous aquifer in which the con-
struction of the well, being too deep,
GROUND SURFACE would cause salt water contamination.
7NC7NSOLIDE il Indicates area to be plugged
i .for correction. Well depth, amount of
-HAWTHORN ,F -- casing, flow zones, and water quality
-* .. CONFINING UNIT -
-FLORIDAN AUIFER -
;,-.- - - --_ of the various aquifers encountered are
N^^C J ROCK AQUIFER
_-__ taken into consideration when plugging
o OCAA L-SGROUP specifications are drawn up for each
individual well by the District geolo-
" ^^^^7-^^^,_i^_______ gists. This information is shown in
S--Figure 7. Specifications for the plug-
r ;'-:: r '. : ; *- -;--:' | ^ : FLORIDAN OAQUIFECR
SONEging, which include the location of the
---------^'r ---=--T--:- plug, the length and diameter of the
Figure 6. Well construction invol-
ving direct connection to the saline plug, and the amount of cement needed
zone. Partial plugging should be done
- to avoid contamination by the saline are derived from the interpretations of
zone, eliminating the exchange of water
"between aquifers. the geophysical data.
-:,- Indicates area to be plugged 9
F44 00 r(
,4 0 ;
- g '-------------^ ^ "^^ ^ ^------
I I 0
U U cu
0 0.-- ---
0 > 0
(N< > 4> 0
vo ,- o 6 -4
0* O u 0 0 0-
r-4 o4 < < 4 0
9 0 o 6m0E4E-
%.0__I I I I I I_
4 H I 4-iF-
S- E-0 E
I0H < 4
0 U rZ o 4 r
__ These specifications are promptly sent back to the ASCS, and arrangements are
made by the well owner for a water well drilling contractor to perform the
The plug is made to specifications using burlap material. This material
is inexpensive and easy to work with, and when placed within the well and filled
with cement, it conforms to the sides of the open borehole creating an effective
"At the well site, drilling equipment is set up over the existing well. The
burlap plug is then placed around the outside of the first length of hollow
drill stem (Figure 8). As the drill stem is lowered down the well, the burlap
is carefully fed down the hole making sure the drill rod does not rotate, with
the subsequent addition of more drill rod (Figure 9). Once the prescribed
length of plug has been fed down the well, it is attached in a manner which
will allow the drill stem to be pulled back out of the well without tearing the
"burlap. The plug is set into its proper place by the use of additional drill
rod and is now ready to be filled with cement.
The quantity of Portland Type II or Type III cement needed to fill and ex-
pand the plug is carefully mixed in a calibrated hopper (Figures 10 and 11).
After the grout has been mixed thoroughly, it is then pumped from the hopper
and down the hollow drill stem (Figure 12) by an auxiliary mud pump mounted on
the drill rig until the hopper has been completely emptied. As this process
occurs, the burlap plug expands and conforms to the sides of the open borehole.
The drill stem is then removed leaving an effective seal between the contamin-
ated and fresh water zones of the Floridan aquifer.
In order to appraise the effectiveness of the plugging operation, water
samples are taken from the well prior to and after the grouting. Sampling is
usually continued for several months thereafter followed by periodic checks
for the purpose of evaluating long term effects.
..h am i~P ,dY-.-" ~ tL~~,bl~h:ur:
" ": i r
"a "~'; ". . s
ss~i- 01 :
.. ,c .~ . ..... .
Figure 10. The Plugging Operation Involving the Geophysical Logging Van
and the Drilling Equi-pment
,, ,i' ,i': . .
9-: P, ~
r ,,- .~t .~ .f2.
Fiur ih i f n t a t p te
own th Well
~j~* f~~-i-: J ; P~; 1 .13
Figures 13 and 14 show the data collected from two irrigation wells that
have been plugged. Figure 13 illustrates the decrease in chloride concentration
of the water resulting from the plugging of the lower contaminated zone. Data
from the extended water sampling of this well over the past year shows the chloride
content has not exceeded 820 parts per million. Again, Figure 14 portrays similar
CEMENT SLURRY PUMPED
S- DOWN THE STEM UNDER
DRILL STEM FROM RIG, PRESSURE
. .. ^V :*, : ^- .. *. ....i .. i J -: --
:.i: -;: ,: ..- .. UNCONSOLIDATED
FW E :WELL CASING /,
CLAYS AND LS.
- OCALA LS.
mm _BURLAP SACK I A.'
Figure 12. Generalized Cross Section Showing the
| CEMENT SLURRY _
Ty' 'i'i^-^ T1-
i I | .:-
Figure 12. Generalized Cross Section Showing the
Placement of the Plug Within the Aquifer
"CHLORIDE CONCENTRATION IN PARTS PER MILLION
D CD CD 0 0 CD0 0 0 0 0
0 o o 0 o 0 0 0 0 0 0 0 0 0
"O 0 0 0 0 C\J ( 'O CO 0 C\J ') '.0 CO
o C % 0 CO r- r- r- r- r- C\ C\ C\J
It I I I t I I I I I I I I II i I I I I !
.. ..................... ;.,, .,.., ............................................................. 4
.Apri 1 ....... ... .... ... ... ..
,_ 1976 ,,,.,.1950
_AFebte rr6 Plugging
Feb. 650..... .......
1977 WELL no. SJ-147
Figure 13. Chloride Data Collected from Well SJ-147; chloride concen-
tration of this well before plugging attained 2800 ppm
"CHLORIDE CONCENTRATION IN PARTS PER MILLION
0 0 O 0 O O 0 O 0 r- < C- )
............ of t..wl al h u h..... ......... LOUd 0
0 '- C 0J C) X1 i 10N CO C" -- '-- i-
"I- I I I I I I I I I I I
pow_..... .. .....6........
...... .... .
1976 -c;,. =at~f~F~;:i~3~ol~i~ fnne
"=-',, du~,,"t Octber 197
data from another irrigation well rehabilitated through this program. Several
years prior to the establishment of the program, this well was unsuccessfully
plugged at the owner's expense. Since the well continued to produce contaminated
water, it was abandoned and capped. The owner made application to the St. Johns
County ASCS in October 1976 for corrective plugging. The well was inspected
by the District, and recommendations were followed by plugging in November. The
well is now being actively used for irrigation purposes.
The Floridan aquifer at the Hastings area of southwestern St. Johns County
is comprised of thick Eocene limestone formations. During the fall and winter
months, artesian water from this aquifer supply irrigation needs for the culti-
vation of cabbage and potatoes.
Water with less than 1,000 ppm chloride is supplied from wells penetrating
only the upper portion of the Floridan aquifer. Those wells which penetrate
both the lower and upper zones of the aquifer typically pump water exceeding
the salt tolerance of the plants. These salty wells also act as direct conduits
for the contamination of the upper fresh zone of the Floridan aquifer.
This program initiated with the Soil Conservation Service and the Agricul-
tural Stabilization and Conservation Service has shown that water resource man-
agement programs can be accomplished in cooperation with concerned agencies.
Chloride data obtained from the wells which have been plugged substantiates
that this well rehabilitation methodology provides an answer to water resource
and subsequent economic problems. The use of the fabricated plug insures proper
placement of the grout, decreases the amount of grout required, and provides an
alternative to the construction of a new well. In general, chloride concentra-
tions decreased substantially in those wells which were plugged according to
program specifications. When these wells were monitored on a monthly schedule,
chloride concentrations remained fairly stable even through times of increased
The plugging operation provides a method of improving regional water
- quality conditions by preventing salt contamination in individual wells. Irri-
gation wells which continue to allow the inter-aquifer exchange of contaminated
.. water will have a detrimental effect on those wells that have been plugged. In
order to accomplish any regional improvement of the resource in this area, all
such wells must be plugged to the proper specifications. The continuation of
this program will accomplish this regional improvement, and agriculturalists
.. are urged to take advantage of this program.
RECORD OF CHLORIDE CONCENTRATION IN PARTS PER MILLION
FROM PLUGGED WELLS
Date SJ-265 SJ-147 SJ-378 SJ-214 SJ-146 SJ-177
O- 8/76 720
9/76 720 Well collapse
due to casing
"11/76 1290* 1950* 970 not seated
12/76 760 740 840 aquifer.
1/77 660 580 760
.- 2/77 1070 650 790
3/77 670 590 670
"4/77 1120 820 960
6/77 820 900
7/77 620 850
11/77 870 725 790 1700* 1700*
1/78 710 580 670 -- --
2/78 790 -- --
3/78 560 660 670 340 1100
-, *Concentration of chloride before plugging.