Equipment and Controls 

Used in Studies of 

Artificial Recharge in the 

Grand Prairie Region 

Arkansas

By R. T. SNIEGOCKI, F. H. BAYLEY 3o, and KYLE ENGLER

ARTIFICIAL RECHARGE OF GROUND WATER GRAND PRAIRIE 

REGION, ARKANSAS

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1615-C

Prepared in cooperation with the Corps 

of Engineers, United States Army, and 

the Agricultural Experiment Station, 

Un iv ersity of Ark ansas

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1963
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington 25, D.G.
CONTENTS

Page

Abstract. _________________________________________________________ Cl

Introduction. _____________________________________________________ 1

Purpose of this report-_________________________________________ 1

Location of the area___________________________________________ 2

Acknowledgments. ____________________________________________ 3

Recharge wells____________________________________________________ 4

Recharge well l__________-_-__________________________________ 4

Accessory equipment.______________________________________ 6

Summary of recharge tests__________________________________ 9

Recharge well 2_______________________________________________ 9

Accessory equipment_______________________________________ 13

Summary of recharge tests_-----____________________________ 15

Hydrologic instrumentation and control ______________________________ 15

Observation wells______________________________________________ 15

Water meters_________________________________________________ 16

Measurement of atmospheric pressure ____________________________ 17

Water-quality instrumentation and control___________________________ 17

pH and residual chlorine. ______________________________________ 17

Turbidity. ____________________________________________________ 17

Temperature. _ ________________________________________________ 18

Micro-organism counts.________________________________________ 19

Millipore filter. _______________________________________________ 19

Coagulant testing._____________________________________________ 19

Bacteriological sampling and testing _____________________________ 19

Sampling wells._______________________________________________ 21

Water-treatment equipment and procedures- _________________________ 21

Water supply.________________________________________________ 21

Micro-organism control_______________________________________ 21

Coagulation__ _ ______________________________________________ 24

Settling basin_ ________________________________________________ 26

Chlorination_ _________________________________________________ 28

Filtration___________________________________________________ 28

Clear well._-__-_-______--_-_--__-_-___-_-_--_-___-_-_---_--__ 29

Supplemental equipment and controls._______________________________ 31

Testing seasons______________________________________________ 31

Timing of observations and note keeping.________________________ 32

Specific-capacity tests.__-_-_____-___________-__----_--_--__---_ 32

Project layout.__________________________________________________ 34

Conclusions._ ________________________________-------_------__-__ 35

References cited_____________________-_-_____-___-----_--__------_- 39

HI
IV CONTENTS

ILLUSTEATIONS

Page 

FIGURE ]. Map of Arkansas showing location of Grand Prairie-____-____ C2

2. Map showing site of tests___-_----_---_-____-_____________ 3

3. Construction of recharge well l_-____-_________--__--___-__ 5

4. Sketch of screen used in recharge well l_____-_____-________ 6

5. Photograph of screen used in recharge well l-______________- 7

6. Preparing the asphalt-burlap well seal ______________________ 8

7. Construction of recharge well 2___.________________________ 10

8. Photograph of screen used in recharge well 2________________ 11

9. Tailpipe and washring assembly-__________________________ 14

10. Completed observation well and gage______________________ 16

11. Flow meter used to measure rates _________________________ 17

12. Graph from temperature-recording gage ____________________ 18

13. Sketch of Millipore filter assembly-___-------_-_----------- 20

14. Aerial photograph of the test site, I960-----_---_-------_--_ 22

15. View of water-handling facilities at pickup point____________ 25

16. Installation of pretreatment equipment at pickup point _ _____ 25

17. Mechanical feeder in operation at pickup point--____________ 26

18. Construction of baffle in settling basin_-_-_-_____-_________ 27

19. Installation of baffle in settling basin-__-___________________ 27

20. Filter tank before placing of filter medium._________________ 28

21. Primer installed on filter-intake line___. ____________________ 29

22. View of the clear well used to collect filtered water, showing 

discharge line from filter and line from clear well to recharge 

well. Note meters used for measuring rates and quantity of 

water flow____________________________________________ 30

23. Electric pump for cleaning and emptying clear well__________ 30

24. Curves obtained during a step-drawdown test of the recharge

well --___-______-___-____-__-___---_---.--_--_----- 33

25. Map or artificial-recharge site showing layout of equipment. __ 34
ARTIFICIAL RECHARGE OF GROUND WATER GRAND PRAIRIE REGION,

ARKANSAS

EQUIPMENT AND CONTROLS USED IN STUDIES OF 

ARTIFICIAL RECHARGE IN THE GRAND PRAIRIE 

REGION, ARKANSAS

By R. T. SNIEGOCKI/ F. H. BAYLEY 3d,2 and KYLE ENGLER

ABSTRACT

Studies of artificial recharge have been underway in the Grand Prairie region 

since 1953. The studies have required the use of many different kinds of 

equipment and control procedures.

Recharge-well specifications were not available; therefore, well design was 

considered to be an integral part of this investigation. Certain generalities 

regarding well construction may be stated, but this study does not conclusively 

establish a design for recharge wells.

Much of the equipment and control used have been adapted to field conditions 

from standard methods. The practicality of recharge operations, with special 

regard for simplicity and cost, has been considered as much as possible in the 

field layout.

Essentially, the equipment and procedures used were satisfactory for conducting an experimental recharge operation. Some difficulty was experienced when 

attempting to repeat test conditions or maintain constant testing conditions for 

a prolonged period of time.

INTRODUCTION

PURPOSE OF THIS REPORT

In 1953 the Grand Prairie region of Arkansas was selected for an 

investigation of fundamental principles of recharging ground-water 

reservoirs through wells. Since that time, the work has consisted of 

collecting detailed hydrogeologic information in the vicinity of the 

recharge site, drilling two recharge wells, constructing'water-treatment and conveyance facilities, and making a series of injection tests 

using the two wells. This report is one of a series covering distinct

1 District Geologist, U.S. Geol. Survey, Water Resources Division, Branch of Ground 

Water, Little Rock, Ark.

2 Civil engineer, Corps of Engineers, U.S. Army Engineer District, Vicksburg, Vicksburg, 

Miss.

3 Head, Department of Agriculture Engineering, University of Arkansas, Fayetteville, 

Ark.

Ol
C2 ARTIFICIAL RECHARGE, GRAND. PRAIRIE REGION

elements of the project; the reports have been prepared and released 

as the data and interpretative analyses became available. The purpose 

of this report is to present information about the equipment, controls, 

and control procedures used during a series of recharge tests using 

waters of different quality and two differently constructed injection 

wells.

LOCATION OF THE AREA

The Grand Prairie region in east-central Arkansas is in the Mississippi Alluvial Plain, a subdivision of the Coastal Plain. The 

region is an irregular, but continuous, tract of prairie lying between 

the White River and Bayou Meto. It extends northwestward, from 

near the confluence of the White and Arkansas Rivers, to a short 

distance beyond Lonoke, Lonoke County. Nearly all of Arkansas 

County and parts of Lonoke, Prairie, and Monroe Counties are included in the Grand Prairie region. (See fig. 1.) The Prairie inr

10 0 100 Miles

luul I I I I I I I I I I

INDEX MAP OF ARKANSAS 

FIGURE 1. Map of Arkansas showing the location of the Grand Prairie region.
EQUIPMENT AND CONTROLS C3

eludes approximately 1,000 square miles, of which roughly TOO square 

miles or 450,000 acres is developed riceland.

The project area includes about 210 square miles of land in Arkansas 

county (areas A, B, and C fig. 2). The Rice Branch Experiment 

Station of the University of Arkansas is near the center of the area 

and is the site of the artificial-recharge tests.

R. 5 W. R. 4 w

Area A, University of 

Arkansas, Rice Branch 

Experiment Station, 

site of the recharge 

tests

EXPLANATION

Area B, area arbitrarily 

considered as likely to 

be affected by the 

^artificial recharge test

Area C, area outside B 

that is being studied 

for control

FIGURE 2. Map of the artificial-recharge area showing the site of the tests.

ACKNOWLEDGMENTS

The cooperation, assistance, and advice given by many Federal, 

State, and city agencies, companies, and individuals are gratefully 

acknowledged. A detailed account of assistance is in the report 

"Studies of artificial recharge in the Grand Prairie region, Arkansas, environment and history" (Engler, Bayley, and Sniegocki, 1963).
C4 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION 

RECHARGE WELLS

Research into the literature concerning artificial recharge through 

wells discloses meager data on recharge-well design. Closed-system 

'recharge has been practiced for several years in New York, and 

return-well specifications are available. However, most of these wells 

are not used for recharge of a completely alien water they return 

 water to the same aquifer from which it has been pumped.

A recharge-well design has been patented, but, so far as is known, 

it has not been tested in the field and is considered by its inventor to 

make the cost of recharged water for irrigation too expensive for 

most users (Ross, Nebolsine, written communication, 1958).

Several recharge projects throughout the United States were visited 

by personnel working on the Arkansas project (Steinbrugge and 

others, 1954). Helpful suggestions and opinions were given, but 

definite recharge-well specifications were not available.

Aquifer collapse around recharge wells, clogging resulting from 

improper screen selection, and other operational difficulties caused 

by faulty well design were observed in previous studies of artificial 

recharge through wells. Experimentation with differently constructed 

recharge wells was made an integral phase of the investigation because 

recharge-well-design data were not available, and part of the failure 

of previous recharge attempts was caused by faulty well construction.

RECHARGE WELL 1

Two major considerations based on the aspect of practicability 

controlled the design of the first recharge well. First, a conventional 

irrigation well such as those now in use in the Grand Prairie region 

is economical to construct because material, equipment, and drillers 

experienced in the area are readily available. Second, if a well typical 

of many already in existence were found to be suitable as a recharge 

well, it would be a simple and economical matter for an irrigator to 

recharge through a production well during the nonirrigation season. 

Consequently, the construction of recharge well 1 is similar to many 

of the producing irrigation wells now in use in the Grand Prairie 

region (figs. 3-5). The design of a typical Grand Prairie irrigation 

well is discussed and illustrated in another report of this series (Engler, Bayley, and Sniegocki, 1960).

Construction of recharge well 1 was begun February 14,1955, using 

a reverse-hydraulic rotary rig. The hole was drilled through the 

aquifer to the top of underlying clay deposits, and the screen and 

casing were set firmly on the clay.

About 3 cubic yards of gravel grains % to 1/4 inch in diameter 

was backfilled in the annular space around the screen. Sand was
H

FIGURE 3. Diagram showing construction of recharge well 1.
C6 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

Circumference:

12-gauge steel plate, punched, 

rolled, and welded to form 

the punched blank

oooooooooo

oooooooooo

oooooooooo--.

oooooooooo

oooooooooo

oooooooooo

oooooooooo

oooooooooo

OOO O OO O O O O

qooooooooo 

oooooooooo 

oooooooooo 

oooooooooo

OOO OOOOOOO

oooooooooo 

oooooooooo 

oooooooooo

O OO OOOOOOO

oooooooooo 

oooooo oooo 

oooooooooo 

oooooooooo 

oooooo oooo 

oooooo oooo 

oooooooooo 

oooooooooo 

oooooooooo 

oooooooooo 

oooooooooo

TOJ

T-H J5/s" holes on 2' 

centers

Number 12 brass wire screen 

wrapped and soldered over 

punched blank

hardware cloth wrapped 

over number 12 screen and 

soldered

7CM -I

Plate welded over 

end of screen -

FIGURE 4. Sketch of the screen used in recharge well 1.

used to backfill the remaining annular space to above the top of the 

aquifer, and clay was used to fill it from there to the surface.

Recharge well 1 was developed by surging and bailing. Sodium 

hexametaphosphate was added to aid in dispersing and removing clay 

particles. Final development was by surge pumping with a deep-well 

turbin pump temporarily installed for the purpose. The specific 

capacity of the well after development was about 21 gpm (gallons 

per minute) per foot of drawdown, and the static water level was 

about 95 feet below the land surface.

ACCESSORY EQUIPMENT

To obtain water-level measurements inside the recharge well, a 

stilling well of %-inch pipe was installed through a hole cut in the side 

of the upper part of the recharge-well casing. The pipe, slotted with
EQUIPMENT AND CONTROLS C7

 WzHiEHS.'SSSKsSiSS'Briiwtaitf-a*

FIGURE 5. Photograph showing the screen used in recharge well 1.

a hacksaw in the lower 3 feet, extended to the bottom of the recharge 

well. A collar on the upper part of the -%-inch pipe was attached 

to the recharge-well casing, effectively sealing the casing and preventing surface wT ater from leaking into the recharge well. This stilling 

well was designated as "I."

Before backfilling, a li/^-inch galvanized pipe, finished with 5 feet 

of slotted brass pipe, was lowered into the annular space outside the 

screen to provide access for water-level measurements in the gravel 

pack. This observation well was designated as "O."

A backflush or redevelopment pump and power unit were the last 

items required to complete construction of the recharge well. Susjpended matter in the recharge water will eventually clog the interstices of an aquifer. Available evidence indicates that this clogging 

may occur at or very near the recharge-well screen and takes place 

rapidly or slowly, depending upon the recharge rate and the amount 

of suspended matter in the recharge water. Part of or all the clogging 

material can be removed by redevelopment of the well by pumping at 

twice the recharge rate or at higher rates (California Water Pollution 

Control Board, 1954, p. 8).

The redevelopment pump was a 3-stage, 12-inch bowl, deep-well 

turbine pump using 12 sections of threaded-coupling pump column, 

8 inches in diameter; a tailpipe 0.1 foot long was installed. The tailpipe was approximately 1.3 feet from the bottom of the well. The 

pump has a rated capacity of 2,000 gpm against a total head of 130
C8 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

feet. By limiting the recharge rate to 400 gpm or less, it was possible 

to pump the well at least 800 gpm for short periods during redevelopment.

The redevelopment pump was sealed in the recharge well by forming a tapered plug of burlap and hot asphalt around the pump column 

next to the pump base (fig. 6). The diameter of the plug at its widest 

part wT as a few inches greater than the diameter of the well. As the 

pump was lowered into place, the asphalt-burlap plug was squeezed 

into the well, making an airtight seal at the top of the well casing.

FIGURE 6. Preparing the asphalt-burlap well seal.

A right-angle drive (gear ratio 2:8), with a nonreversing ratchet 

was installed to transmit power from an electric motor to the pump. 

Water was introduced into the well through the pump column, and 

the ratchet was necessary to prevent the pump shaft and impellers 

from rotating backwards as the injected water passed through the 

well.

A variable-speed electric motor was connected to the right-angle 

drive. A 3-phase, 200/440-volt, 60-hp motor provided a variation of 

1,190 rpm to 1,755 rpm at the pump. With a static water level of 

about 96 feet, the equipment pumped approximately 200 gpm at 1,190 

rpm, 550 gpm at 1,325 rpm, 815 gpm at 1,560 rpm, and 855 gpm at 

1,755 rpm. The motor was not an all-weather type and therefore was 

protected by a wellhouse.
EQUIPMENT AND CONTROLS C9

Four "feeder wells," 2 inches in diameter with 10-foot screens, were 

drilled equidistant from each other within 60 inches of the recharge 

well. (See fig. 25.) These wells were drilled primarily to introduce 

chemicals into the aquifier just outside the gravel pack of the recharge 

well for redevelopment if the recharge well were to become plugged. 

The feeder wells also furnished additional control points for waterlevel measurements and water-sample collection.

SUMMARY OF RECHARGE TESTS

A total of 17 tests were made using recharge well 1, the first test 

being made in March 1955 and the last in March 1958. Approximately 46 acre-feet of water treated in various ways was recharged at 

rates of 117 to 900 gpm in about 20 days. The specific capacity of 

the well was diminished as much as 19 gpm per ft by plugging during 

recharge. As a result of redevelopment after injection tests, the specific capacity ranged from 22 to 33 gpm per ft, indicating that the 

original specific capacity of the well (21 gpm) could be restored or 

even exceeded, although at times with difficulty.

During the latter part of the test series the screen was ruptured. 

Severe pumping and surging commonly brought up small quantities 

of the gravel-pack material. Rather than completely destroy well 1, 

a new recharge well was constructed, and well 1 was converted into a 

water-level control point by installing a recording gage.

KECHARGE WELL 2

The design of recharge well 2 was based on experience gained by the 

injection tests in recharge well 1. The construction of well 2 and 

some of the accessory equipment is shown in figure 7.

A comparison of the construction of recharge wells 1 and 2 shows 

very few similarities. Well 2 has a diameter of 26 inches. This was 

considered desirable for two reasons. Additional space was needed 

inside the well to install accessory equipment such as the butterfly 

valve. Also, the larger diameter allowed the installation of a shorter 

screen with no decrease in the area of screen opening, as compared 

to well 1.

The screen, of the wire-wrapped type, was about 5 feet in length 

and 26 inches in diameter with slot openings of 0.016 inch. (See 

fig. 8.) Stainless-steel screen was selected to prevent as much corrosion as possible, thus increasing well life. The wire-wrapped construction permitted more exact control over the size of screen openings 

as well as more open area per foot of screen length.

The longer screen of recharge well 1 permitted the injected water 

to be distributed over a greater vertical section of the aquifer. When 

a cone of depression was created around recharge well 1 during re-

EQUIPMENT AND CONTROLS Cll

FIGDBB 8. Photograph showing the screen used in recharge well 2. Screen and casing are 

ready for lowing into the drill hole. Note observation well "O" attached to the side of 

the screen and casing.

development at the maximum pumping rate, the part of the aquifer 

in contact with the upper part of the screen was unwatered. Water 

could be moved through the upper part of the screen only by decreasing the pumping rate, thus decreasing velocity of flow and probably 

diminishing the effectiveness of backflushing.

Concrete was grouted in place around the casing just above the 

screen of recharge well 2 to insure that the flow of water was through 

the screen into the acquifer. The gravel pack of recharge well 1 

extended several feet above the screen, and because of less resistance 

to flow, much of the injected water probably moved out through the 

screen, up the gravel pack, and out into the aquifer. This condition 

increased the section of acquifer through which the injected water 

moved and further diminished potential backflushing effectiveness. 

The concrete grout used hi recharge well 2 insured the movement of 

water through the section of the aquifer adjacent to the screen, 

whether recharging or pumping.

So far as could be determined, the gravel pack of recharge well 1 

permitted injected water to move sediment to the gravel pack-aquifer 

interface, where plugging was more severe than it was farther out 

in the aquifer. Velocity of water flow at the gravel pack-aquifer 

interface was not as great as at the screen, and redevelopment possibilities by backflushing were diminished. High permeability and
C12 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

maximum filterability of the gravel pack very near or at the screen 

should be desirable features to incorporate in a recharge well. In 

achieving these features, the aquifer should be completely stabilized 

to prevent aquifer collapse and shifting and mixing with any pack 

material used.

Two methods of obtaining an optimum balance between permeability and filterability of the material adjacent to the screen of recharge well 2 were considered natural development in the aquifer 

and sand packing. The aquifer section at which the screen would 

be placed ranged in composition from fine to coarse sand (0.125 to 2 

mm), consisting predominantly of quartz ranging in diameter from 

0.25 to 0.5 mm. The well could have been developed by removing 

the fines from the aquifer close to the screen, leaving a medium to 

coarse sand in contact with the screen. This would have created a 

zone of relatively higher permeability adjacent to the screen and would 

have provided higher filterability than the gravel pack of recharge 

well 1. However, natural development would have prevented concrete grouting and other desirable constructional features designed to 

establish and maintain aquifer stability.

Measurements of water levels in observation wells "I" and "O" 

showed a significant head loss, increasing with time, between the two 

wells during certain recharge tests utilizing recharge well 1. This 

was interpreted as indicating plugging between wells "I" and "O," 

probably on the interior of the screen.

A degree of success in development of newly installed wells has 

been experienced by various drillers using a high-pressure jetting tool. 

The jet head is lowered into the well, and a stream of water is directed 

against the interior of the screen by rotating the jet nozzles at different 

depths. Chemicals may be used in this procedure to further accelerate 

well development. Development generally is effective as much as 1 

foot into the aquifer where wire-wrapped or similar types of screens 

are used.

Because the injection characteristics of recharge well 1 indicated 

that most of the plugging was on the inside and within a few inches 

of the outside of the screen, a jetting device was installed in recharge 

well 2. If the jetting device (washring) proved effective in well 

redevelopment, it would reduce the amount of water pumped from 

the well when removing clogging material.

A carefully graded sand, such as that utilized in rapid sand filters, 

was placed next to the screen in well 2. The sand was composed of 

subangular to well-rounded quartz grains ranging in diameter from 

about 0.7 to 1.4 mm with a uniformity coefficient of less than 1.6. 

Thus, in the section in which the screen was placed, the aquifer consisted principally of quartz sand 0.25 to 0.5 mm in diameter, the sand
EQUIPMENT AND CONTROLS C13

pack consisted of quartz grains 0.7 to 1.4 mm in diameter, and the 

screen had slot openings of 0.41 mm. These conditions provided the 

best compromise possible in achieving maximum permeability and 

filterability at the pack-screen interface and maximum stability of the 

aquifer.

Construction of recharge well 2 was begun July 7, 1958, using an 

auger and bailer for drilling. A large-diameter hole was augered to 

a depth of about 78 feet, and a 36-inch diameter casing, extending 

from the land surface to the bottom of the hole, was installed (fig. 7). 

A 34-inch-diameter casing about 39 feet long was placed inside the 

36-inch casing. By bailing inside the 34-inch casing, it was possible 

to place the lower end about 92 feet below the land surface, thus, 

creating an overlap of about 25 feet between the bottom of the 36-inchdiameter and the top of the 34-inch-diameter casing. A section of 

32-inch-diameter casing was placed inside the 34-inch casing. By 

bailing and adding additional lengths as the hole was deepened, the 

32-inch-diameter casing was placed to extend from the land surface 

to the bottom of the aquifer. A 26-inch-diameter casing with the 

screen attached to the lower end was carefully centered inside the 

32-inch casing. After sand packing and concrete grouting, the 32- 

inch casing was pulled.

Recharge well 2 was developed by block surging and bailing. 

Sodium hexametaphosphate was added to aid in dispersing and removing clay particles. Final development was by surge pumping 

with a turbine pump. The specific capacity of the well after development was about 27 gpm per foot, and the static water level was about 

97 feet below the land surface.

ACCESSORY EQUIPMENT

To obtain water-level measurements inside recharge well 2, a stilling 

well similar to that used in well 1 was installed. A 1-injch pipe 

finished with a brass well screen was attached by brackets to the pump 

column. The screen, number 7 slot, was 5 feet in length and 1% inches 

in diameter. The saw-slotted pipe used for the stilling-well screen in 

recharge well 1 caused difficulty after about 2 years7 use when it became encrusted with rust; hence, the use of a longer brass screen with 

more open area per foot of length in well 2. This observation well 

was designated as "I."

A well identical to "I" was attached by brackets to the outside of 

the final well casing before backfilling to provide access for waterlevel measurements in the sand pack. This observation well was 

designated as "O."

The pump column was used to convey recharge water into recharge 

well 2 as in well 1. However, two notable changes in the tailpipe

668522 O 63 3
C14 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

assembly in recharge well 2 were made to accomodate a washring and 

a butterfly valve. (See figs. 7 and 9.)

The butterfly valve was added to provide more adequate control 

of injection rates. A shaft attached to the valve and extending to 

the surface provided full-range manual valve control.

A washring and attendant facilities, as shown in figures 7 and 9, 

were installed in well 2 at the same time the deep-well turbine was 

lowered into place. A large crank was attached to the washring feed 

pipes by cables to permit raising and lowering the ring the length of 

the screen. A high-pressure centrifugal pump was used to force 

water through the washring. Redevelopment chemicals could be recirculated in the recharge well by pumping the chemical solution from 

the well with the turbine and forcing the solution back through the 

washring with the high-pressure centrifugal pump.

The tailpipe extended to the bottom of well 2 to provide a means of 

guiding the washring as it was raised and lowered. Holes were 

drilled in the sides of the tailpipe to permit free movement of water 

in and out of the pump column (fig. 9).

The electric motor, right-angle drive, and deep-well turbine used 

for recharge well 1 were reassembled and used for recharge well 2. 

The well casing extended above the land surface sufficiently high to 

prevent any surface water from draining into the well, and sealing 

was not necessary.

FIGURE 9. View of the tailpipe and the washring assembly used in recharge well 2, 

showing tailpipe with washring in raised position.
EQUIPMENT AND CONTROLS CIS

"Feeder wells" were not drilled near recharge well 2; however, an 

observation well not more than 10 feet from the recharge well was 

considered a necessity. Kecharge well 2 was drilled near a well that 

had been cased with 2-inch galvanized pipe and screened with an 

80-mesh drive point.

SUMMARY OF RECHARGE TESTS

Five injection tests have been made using recharge well 2, the first 

test being made in January 1959 and the last in January 1960. Approximately 26 acre-feet of water treated in various ways was recharged at rates of 37 to 313 gpm. The time spent in injecting the 

water was about 37 days. Testing procedures were similar to those 

used on recharge well 1, except that fewer but much longer tests were 

completed.

The specific capacity of the well was diminished as much as 18 gpm 

per foot by plugging. As a result of redevelopment after injection 

tests, the specific capacity ranged from about 13 to 21 gpm per foot, 

never regaining the original specific capacity of 27 gpm per foot.

HYDROLOGIC INSTRUMENTATION AND CONTROL

OBSERVATION WELLS

Several observation wells (5S, 4S, 3S, and 2N, fig. 14; and 2SW, 

2SE, 1SW, 1SE, IN, and PW, fig. 25) provide for observation of 

hydrologic and chemical changes in the aquifer during recharge tests. 

Each hole was drilled to the bottom of the acquif er to provide details 

on the character of the entire section. Twelve of the wells were cased 

with 2-inch galvanized pipe and finished with 60- or 80-mesh drive 

points, 2 inches in diameter and 48 inches in length.

Three wells were drilled and cased with 5-inch galvanized-iron 

24-gage casing. Each of these wells was screened at the bottom of 

the aquifer with a 30-inch slotted section of the casing. The larger 

diameter casing was used to permit the installation of a recording 

gage having a 4-inch float (fig. 10).

Recharge well 1 was equipped with a recording gage after recharge 

well 2 was completed. The gage was installed with a 12-inch float 

and proper gearing for an expanded time scale.

One additional well (so-called dry-sand well) was installed about 

20 feet from recharge well 1. This well was cased to a depth of 78 

feet with l^-inch galvanized-iron pipe. The lower 3 feet was slotted 

with a hacksaw, and a pipe cap was placed on the end. This well was 

screened in the unwatered part of the aquifer intentionally to permit 

measurements of any changes in air pressure in the dry zone above 

the ground-water surface. If the aquifer could be recharged for a 

sufficient period of time, the cone of elevation would saturate this
C16 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

FIGURE 10. View of a completed observation well In which a recording gage has

been Installed.

part of the unwatered aquifer. The dry-sand well would furnish 

access for water-level measurements under such conditions. Thus, 

this well was installed for a dual purpose.

Three irrigation wells (designated as east, middle, and west irrigation well, fig. 14) were drilled on the Eice Branch Experiment Station 

before beginning this project. These wells also furnished access for 

water-level measurements.

WATER METERS

Whether recharging or discharging, control and observation of rates 

of water transfer were necsssary during all tests. It was decided to 

recharge at a rate as constant as possible while measuring changes in 

water levels rather than to recharge at a constant head and observe 

rate changes. This method was chosen to allow more latitude for 

experimental variation. Furthermore, high rates of recharge, such 

as those at the beginning of a constant-head test, seemed undesirable, 

because backflushing and well redevelopment apparently would be 

more difficult.

Impeller-type flow meters were coupled into the injection-discharge 

lines where needed (fig. 11). The cumulative gallons of water transferred during a test were read directly from the meter, and a stopwatch used in conjunction with the sweep hand on the meter dial made 

spot checks of rates possible.
EQUIPMENT AND CONTROLS C17

FIGURE 11. Impeller-type flow meter used during recharge tests to measure rates and

quantities of water Injected.

MEASUREMENT OF ATMOSPHERIC PRESSURE

Widespread and continuous fluctuations of the water levels in wells 

in the Grand Prairie are due to changes in the atmosphreric pressure 

(Sniegocki, 1959). Water levels fluctuate from a fraction of an inch 

to about a foot over periods ranging from a few hours to several days. 

To correct water-level measurements for changes in atmospheric 

pressure, a barograph was maintained at the test site.

I

WATER-QUALITY INSTRUMENTATION AND CONTROL

pH AND RESIDUAL CHLORINE

In all recharge tests the water was chlorinated before injection, 

samples were, collected, and a colorimetric comparator was used in 

conjunction with ortho-tolidine solution to determine total chlorine 

residual. The pH of water samples was determined in the field using 

the same equipment as used for chlorine residual, with a change in 

indicators. Samples of water collected for chemical analyses were 

retested for pH, but this was done at a later date in a laboratory.

TURBIDITY

Turbidity of recharged or discharged water was measured during 

tests by a Hellige turbidimeter. The measurement of turbidity with
CIS

this instrument is based on the comparison of a beam of transmitted 

light with the scattered light produced by a lateral illumination of the 

water sample by the same light source (Eainwater, and Thatcher, 

1960, p. 70). All results were recorded in parts per million. One or 

more turbidity determinations generally were made on the raw surface 

water before pretreatment and on the pretreated settled water. More 

frequent determinations were made on the water after chlorination 

and filtration, just before it entered the recharge well.

Recharge tests were made under specified, controlled conditions. 

In some tests, the turbidity of the recharge water was not limited, 

and the turbidity data were collected and recorded as the test progressed. In other tests, injection was discontinued when the turbidity 

exceeded a specified test limit.

TEMPERATURE

An automatic temperature-recording gage was used to obtain records of the temperature of the injected and recovered water. Generally, the injected water was removed from the aquifer after a 

particular test. The difference between the chloride and sulfate content of the ground water and recharge water was useful in indicating 

when this removal was essentially complete. Recharge tests were 

made when the temperature of the recharge water was less than that 

of the ground water. A comparison of the temperature observations 

with the chloride and sulfate content established the dependability 

of temperature differences in distinguishing between the two waters. 

An example of the type of record obtained during and after a recharge test is shown in figure 12.

Midn 

100

80 

ii60

40

ight Noon Midnight No 

1-30-57 1-31

 

 

 

A^JUL.V

/^~

f

 

__ 0C

EXPLANATION

A

Start recharge. 0930, 

1-30-57, 41.5T

B

Stop recharge.start pumping, 

1445, 1-30-57, 42 "F

c

Stop pumping, 0920,1-31-57, 64 

ground-water temperature,64"F

FIGURE 12. Graph taken from the temperature-recording gage showing changes in water 

temperature during recharge and discharge.
EQUIPMENT AND CONTROLS C19 

MICRO-ORGANISM COUNTS

The identification and number of micro-organisms in recharged 

water are essential control data where the quality of injected water 

and test results are compared. Sedgewick-Raf ter equipment was used 

in the field laboratory to identify and count micro-organisms as tests 

progressed.

MILLIPORE FILTER

A portable apparatus was developed by Felsenthal and Carlberg 

for testing the quality of oilfield injection waters (Felsenthal, and 

Carlberg, November 1956, p. B-53-55, B-58). The apparatus was 

especially useful for evaluating how effectively suspended solids are 

removed from oilfield injection waters by field-treating systems.

Need for additional data on the quality of injected water used 

during recharge tests in this project was recognized, and an apparatus 

based oil specifications by Felsenthal and Carlberg was constructed.

The components of the apparatus are shown in figure 13. The unit 

may be tied into a field water system at any desired point, but in these 

studies it was attached to a sampling valve in the injection line at a 

point where the recharge water entered the well.

The filter element, a disk 47mm in diameter and having 0.45 micron 

pore openings, permitted collection of practically all suspended material in the water.

COAGULANT TESTING

From the analysis of a water, it is not possible to predict the quantity of coagulant required for optimum coagulation of injection water. 

Coagulation problems were varied because of changing raw water 

characteristics such as temperature and pH differences, changes in 

bacterial and micro-organism content, and varying amounts of suspended solids. A standard variable-speed laboratory stirring device 

was used to determine optimum coagulant concentration. A procedure similar to that used in standard water-treatment plants 

was followed, thus providing efficient and economical coagulation 

treatment.

BACTERIOLOGICAL SAMPLING AND TESTING

Samples of the injected water and ground water were collected each 

time a recharge test was made. These samples were collected according to methods prescribed by the Arkansas State Health Department. 

Each sample was tested by the State Health Department to determine 

whether or not the sample contained coliform organisms. Presumptive and confirmatory tests were the only examinations made.

Special water-handling facilities were needed to obtain representative water samples for bacteriological examination. The depth to
C20 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

Hole in overflow line 

to prevent syphoning

To drain

 Water reservoir

C ) Needle valve

Water line

Screw for venting air 

at start of test

FIGURE 13. Diagrammatic sketch of the Millipore-fllter test assembly.

water exceeded the suction limit of centrifugal pumps, and bailer 

samples were difficult to obtain without the sample becoming contaminated from the bailer. Small single-pipe jet jumps were installed 

in three of the 2-inch observation wells. These wells were less critically needed for water-level measurements and were readily convertible to water-sampling control points. Each pump was sealed inside 

the well casing, and contamination by seepage of water down the outside of the casing was prevented by a concrete apron at ground level 

and a small shelter over the entire assembly. Total yield of these
EQUIPMENT AND CONTROLS C21

pumps was less than 5 gpm, but the yield was adequate for sampling 

for bacteriological examination as well as chemical quality.

Kerosene lanterns and, later, thermostatically controlled heat lamps, 

were used to prevent freezing during the winter; therefore, it was not 

necessary to drain the pumps and risk contamination from an outside 

source when repriming the pumps for the next test.

The injected water was sampled for bacteriological examination by 

installing a small valve in the injection line at the point where the 

water entered the recharge wells.

SAMPLING WELLS

Samples of water from many points around the recharge wells were 

occasionally needed for chemical analysis. These were obtained by use 

of a small bailer that would operate inside a 2-inch well. Later work 

indicated the need for at least one permanent sampling point within 

a 20-foot radius of the recharge wells. All inexpensive pump capable 

of pumping about 3 gpm was installed in one of the 2-inch wells.

WATER-TREATMENT EQUIPMENT AND PROCEDURES

The equipment and procedures described herein were not necessarily 

used in all injection tests. Generally, every effort was made to 

"polish" the surface water to be injected to the highest degree possible, 

whereas in other tests, one or more of the treatment steps were varied 

or omitted. In general, the equipment used and procedures followed 

were field adaptations of conventional water-treatment practices.

WATER SUPPLY

Reservoirs on the Fred Hoskyn farm adjacent to the Rice Branch 

Experiment Station were used as the source of surface water for the 

recharge tests. A tributary of Little LaGrue Bayou collects runoff 

water from about a 4-square mile area. Mr. Hoskyn pumps this water 

into his reservoirs, where it is stored for rice irrigation. (See fig. 14.) 

The Hoskyn canal system was connected to that on the experiment 

station by a new canal about 1,200 feet long, providing gravity flow 

of water from the reservoir to the recharge wells.

MICRO-ORGANISM CONTROL

Knowledge and control of microscopic organisms are important to 

waterworks officials because of the effect these organisms have upon 

the taste and odor of water. Nearly all the domestic supplies of 

water in the Grand Prairie region are pumped from the same aquifer 

in which the recharge wells are screened; therefore, palatability of 

the ground water should be maintained. However, with respect to
C22 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

FIGURE 14. Aerial photo
EQUIPMENT AND CONTROLS C23

well

Recharge wri area " 

(see fig. 25)

;

e test site, 1960.
C24 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

recharge operations, an additional important consideration is the 

potential plugging of the well and aquifer that could be caused by 

microscopic organisms in the injected water. Synedra ulna, one of 

the Diatomaceae is an example of a microscopic organism that can 

cause serious trouble in rapid-sand filters by plugging the filter bed, 

thus increasing the frequency of backwashing operations. Similar 

plugging could occur in an aquifer when artificial recharge is 

attempted.

Several methods of micro-organism control have been used throughout the testing periods at the recharge project. The simplest manner 

of control was to drag burlap bags containing copper sulf ate through 

the water in the canals and reservoir. Copper sulfate, dissolved in 

water, also was sprayed over the surface of the water.

Other control methods utilized a small pump, such as those used 

in chlorinating swimming pools, to inject calcium hypochlorite solution into the water supply. This treatment was done before coagulation at a point in the supply canal where water velocity furnished 

mixing.

The variety and numbers of micro-organisms in the water were 

checked to determine effectiveness of the treatment. The best treatment was achieved when copper sulfate and calcium hypochlorite were 

used together.

COAGULATION

The canal facilities on the Rice Branch Experiment Station were 

used as much as possible in the water-treatment process. A relift 

pump was installed (fig. 15) to pump water from the Hoskyn canal 

into the canal on the experiment station. This afforded a means of 

controlling the level of the water in the canal and also provided a 

convenient place for mixing the coagulating agent with the turbid 

water. A dry chemical feeder was installed in a shelter spanning the 

canal (figs. 16 and 17). Two sections of 48-inch concrete culvert 

were placed on end in the canal adjacent to the feeder as an initial 

mixing chamber. By operating the relift pump and feeder simultaneously, the coagulating agent and raw water were thoroughly 

mixed. Alum was used as the coagulant in all tests involving pretreatment of the surface water.

Recent tests in the High Plains region of Texas indicated excellent 

results when using a product called Separan AP 30 as a coagulating 

agent (The Cross Section, June 1959, p. 2-3). Separan AP 30 was 

spread over lakes by crop-dusting methods; 1 pound per acre-foot of 

water produced relatively clear water in 24 hours. Water tested in 

the laboratory at the project site apparently was of a different character than that in the High Plains, and alum proved to be a cheaper 

and more effective coagulant than Separan AP 30.
EQUIPMENT AND CONTKOLS C25

FIGURE 15.- -View of the water-handling facilities at the raw-water pickup point, showing 

the complete relift and pretueatment installation.

FIGURE 16. Pretreatment equipment used at raw-water pickup point, showing pretreatment installation with culvert mixing chamber in operation.
C26 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

FIGCBE 17. Pretreatment equipment used at raw-water pickup point, 

showing the mechanical feeder In operation, using alum as a coagulating agent.

SETTLING BASIN

The suspended material in the water was flocculated and settled in 

the canal after the addition of alum, as the water slowly moved to other 

treatment facilities near the recharge wells.

Wave action against the levee banks caused a change in turbidity 

from 3 or 4 ppm (parts per million), after pretreatment, to as much as 

15 to 20 ppm. Cypress lumber was used to build 18 baffles, each one 

long enough to span the width of the canal. Each baffle was constructed so that a strip of wood 4 inches wide projected above the 

surface of the water as the baffle floated in the canal. They were 

anchored at about 100-foot intervals, at right angles to the length of 

the canal, by means of nylon cords and stakes driven into the levee 

banks. This arrangement allowed the baffles to rise and fall with the 

change in stage of the water in the canal and prevented wind from 

forming large waves.

The removal of accumulated floe from the settling basin was considered. If the floe could not be pumped or flushed into ad j acent fields, 

the problem would be serious. Several agricultural authorities were 

interviewed and a search was made of related literature, but no information was available as to whether alum floe applied to cultivated 

fields would be detrimental to crops.
EQUIPMENT AND CONTKOLS C27

Greenhouse facilities were used to test the germination and growing 

of rice on soils treated with various percentages of alum floe. No 

detrimental effects were observed, and the floe may actually improve 

the soils under some conditions (Dr. Kenneth Olson, oral communication, 1957).

A sketch of the construction details and view of a completed baffle 

are shown in figures 18 and 19.

- Screw /» for anchoring

FIGURE 18. Construction of baffle used to subdue wind action in settling basin.

FIGURE 19. Photograph showing baffle as installed In settling basin.
C28 ARTIFICIAL RECHARGE, GRANP PRAIRIE REGION

The Rice Branch Experiment Station used ground water for irrigation of rice each growing season. Consequently, it was necessary to 

empty the canal distribution system each recharge-testing season and 

replace the ground water with surface water before testing could be 

started. A low-lift pump, weighing 100 pounds and driven by a 

small air-cooled gasoline engine, was used to remove ground water 

from the dead storage space in the canals. The pump, mounted on 

wheels for portability, had a 6-inch discharge pipe and a maximum 

pumping rate of 700 gpm.

CHLOBINATION

After flocculation and settling, the water was chlorinated before 

filtration with a vacuum-type solution-feed chlorinator. This type 

was chosen because it is of medium capacity and will treat a relatively 

uniform, continuous, or interrupted flow of water. Records of chlorine 

weight were maintained. These data provided a means for computing 

the total chlorine supply on hand, as well as furnishing a check on 

the quantity of chlorine used during a particular test.

FILTRATION

Final treatment of the surface water was passage of the water 

through a rapid-sand filter (fig. 20). The filter had a radius of 8 feet, 

4% inches, was 9 feet 6 inches high, and had a manifold-type underFIGUEE 20. View of the Interior of filter tank before placing of filtering medium, showing 

the manifold, laterals, and wash troughs.
EQUIPMENT AND CONTROLS C29

FIOUEE 21. Primer installed on the filter-Intake line.

drain system. The maximum capacity was approximately 600 gpm. 

The coarse filtering material consisted of siliceous pebbles, graded 

with a 5-percent tolerance as follows: 1-inch to :%-inch (8 cubic yards, 

gravel); '%-inch to i/^-inch (4 cubic yards, gravel); and %-inch to 

%-inch (4 cubic yards, gravel). The fine filtering material consisted 

of quartz sand and was graded as follows: 0.45 mm- to 0.55 mm- grain 

size, with a uniformity coefficient of less than 1.6 (16 cubic yards). 

The various sizes of filtering media were placed in the filter, grading 

upward from coarse to fine, without separating screens.

A 10-inch centrifugal pump, with a rated capacity of about 3,000 

gpm against a head of 60 feet, and a 180-hp industrial 8-cylinder 

engine, with carburetion arranged so that Butane could be used as 

fuel, were installed to lift the water into the filter and backflush the 

filter when the medium became plugged.

All waterlines were fitted in place by welding or with couplings. 

Because the testing periods were not continuous and winter temperatures frequently were low enough to cause freezing, it was necessary 

to drain the pumps and pipelines. Priming of the pumps was necessary after each draining and was difficult until the diaphragm-priming 

devices shown in figure 21 were installed.

CLEAR WELL

A later addition to the water-treatment facilities was a clear well 

(figs. 22 and 23), which was 5 feet deep and 13 feet in diameter, and
C30 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

FIGURE 22. View of the clear well used to collect filtered water, showing discharge Hue 

from filter and line from clear well to recharge well. Note meters used for measuring 

rates and quantity of water flow.

FIGDKB 23. View showing electric pump (far side of tank) used for cleaning ard 

emptying clear well shown in figure 22.
EQUIPMENT AND CONTROLS C31

was made of steel. The purpose of the clear well was to receive filtered 

water and provide a break in the closed system in the injection line 

when the filter was connected directly to the recharge well. By moving 

water from the clear well into the recharge well, the siphon effect 

created during injection was not operative on the filter.

SUPPLEMENTAL EQUIPMENT AND CONTROLS

TESTING SEASONS

Many ground-water projects are controlled somewhat by weather, 

accessibility of the project site, the length of the pumping season, time 

of the year, and other factors. The testing season on the artificialrecharge project was rigidly controlled by hydraulic conditions within 

the aquifer, the availability of surface water for injection, and farming 

activities on the Rich Branch Experiment Station.

The rice-growing season in the Grand Prairie region occurs from 

April through October. During this period most of the irrigation 

wells in the region, as well as those on the experiment station, are 

pumped. The season drawdown of the regional water level varies 

from place to place according to the concentration of wells, well yields, 

and the hours of pumping. The complexities of hydraulic conditions 

within the acquifer, caused by pumping, make it difficult to analyze 

recharge results.

Water used during recharge tests was taken from a reservoir in 

which runoff water had been stored for crop irrigation. Rainfall is 

distributed unevenly in the region, and the reservoir owner must conserve his water supply during the irrigation season to insure the availability of water for crops. Consequently, a supply of surface water 

for recharge tests was not available during the rice-growing season.

Many of the structures on the Rice Branch Experiment Station, 

particularly the canal system, were utilized during recharge tests. 

The canal system was designed for distribution of irrigation water to 

the various plant-testing plots and had to be used for this purpose 

during the growing season.

Recharge work during the nongrowing season (November through 

March) did not interfere seriously with experiment station activities. 

Rainfall generally was adequate during these months, and, because 

water was not needed for irrigation, an ample supply of surface water 

was available for injection tests. By the latter part of December, hydraulic conditions within the aquifer generally were stabilized, and 

pumping influence on water levels was at a minimum. This period, 

November through March, constituted the testing season.

The cyclic nature of the testing period was advantageous in that 

the summer was used for equipment maintenance and revision, and 

time was available for analysis of results and test planning.
C32 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION 

TIMING OP OBSERVATIONS AND NOTE KEEPING

During each test, all activities and observations were recorded in 

a log of operations. This log contained filtration, chlorination, and 

turbidity data, as well as any other information that might be helpful 

in analyzing test results.

A stopclock with an 8-inch face was used to time all water-level 

measurements made by the wetted-steel-tape method. The flow meters 

were timed with stopwatches to make spot checks of the injection or 

discharge rates. All time notes made in the log of operations were 

based on the 24-hour clock. This was particularly advantageous when 

a test period covered several days.

SPECIFIC-CAPACITY TESTS

Specific-capacity tests were used throughout the project to determine the effectiveness of redevelopment procedures after injection 

tests. The specific capacity of the recharge wells was as low as 2 

gpm per foot at the end of a recharge test and as high as 33 gpm 

per foot after redevelopment.

A specific-capacity test was started by making a series of waterlevel measurements in the recharge well several minutes before starting the pump. This established any short-term trend of the nonpumping water level in the vicinity of the recharge well and was 

used to indicate the static water level during the specific-capacitytest period.

For most tests, pumping was started at about 300 gpm and held 

constant for 1 hour. The pumping rate was then increased to about 

500 gpm and again held constant for 1 hour. Water-level measurements in the recharge well were made throughout the pumping period. 

Figure 24 illustrates the manner in which collected data were plotted. 

Note that the drawdown curves were extrapolated to 100 minutes so 

that the effect of time of pumping on drawdown would be cancelled 

out. The performance of the well during each step and each test 

was then compared with the previous test.

Specific capacity is expressed as follows:

sc=2- 

in which *°

S(7= Specific capacity in gallons per minute per foot of drawdown or

buildup,

Q=Pumping or recharge rate in gallons per minute, 

8c=Drawdown or buildup, in feet, corrected for fluctuation of the water 

level caused by atmospheric-pressure changes.

From figure 24, the specific capacity during the first step at 300 gpm 

was 23.6 gpm per foot. During the second step, when the rate was 

increased by 248 gpm, the specific capacity was 23.2 gpm per foot.
I 3

5'

!» 

I S

8

8

sea SIOH-LXOO
C34 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

PROJECT LAYOUT

A project layout map (fig. 25) shows the location of the various 

control and water-treatment facilities used during injection tests. 

The pretreatment equipment had been placed over the canal about 1,800

10"steel pipe 

6"steel pipe 

End of 6"discharge pipe

%"water pipe j 

Chlorinates

Powerline,a3 cables

Pipe enters 

ground

Base electric motor

Powerline, 3 wires 

Switch box <C 

1 ¥2"steel pipe \J

Middle irregation well ^U 

and electric pump

Observation well PW

Filter pump and

power unit 

Valve /

Observation well 1 SE~ 

Observation well 1 SW

Feeder well NE 

Feeder well NW 

Recharge well 1

26"casing 

Feeder well SW

Feeder well SE

Valve-type 

~ gate

6"steel discharge pipe 

8"steel discharge pipe 

Steel storage tank

0-0bservation well 2 SE

Observation well 2 SW ^. 

FIGURE 25. Map of the artificial-recharge site showing layout of equipment.
EQUIPMENT AND CONTROLS C35

feet from the recharge wells. Experience proved the distance too 

great. Coagulation results were excellent, but wind action and fish 

and turtles in the settling basin caused the clarified water to regain 

a suspended-solids load almost equal to that of the raw water by the 

time it reached the filter pickup point. The dry chemical feeder, 

mixing culverts, and relift pump were moved down the canal toward 

the recharge wells, making the settling basin approximately 900 feet 

long. This distance proved satisfactory, and water of greatest clarity 

was observed at the filter pickup point.

CONCLUSIONS

The recharge tests have not conclusively established the proper construction for a recharge well. However, certain generalities may be 

stated.

All recharge wells should include a means of measuring the water 

level or well-head pressure inside the well and immediately outside. 

The Grand Prairie tests have shown that the first and most severe 

plugging was in or very near the injection well. Measurements of 

water levels inside the recharge well will permit early detection of 

plugging. Observations noted only at a distance from the recharge 

well will not show evidence of plugging until recharge has been in 

progress for long periods of time, and by then redevelopment becomes 

difficult.

The backflush pump did not completely restore intake or discharge 

capacities of the recharge wells but was a definite aid that could not 

be omitted. The 2-inch holes drilled in the side of the tailpipe used 

in recharge well 2 prevented maximum drawdown inside the well, and 

redevelopment by use of the pump was less effective.

Most irrigation wells in the Grand Prairie have the pump sealed 

in the well. Suction lift created by the pump is supposed to increase 

the well yield and retard breaking suction. Sealing the recharge well 

was of no apparent benefit except in preventing runoff surface water 

from gaining entry around the pump

The use of the pump column as a means of introducing recharge 

water to the well was satisfactory and perhaps furnishes additional 

justification for installing a backflush pump. Unless recharge is 

practiced at a constant head with the water level at the ground surface, 

an entry line should be used to prevent free fall of recharge water 

into the well.

The effectiveness of the "feeder wells" in redevelopment procedures 

cannot be stated with certainty. Less trouble was experienced in 

redevelopment of recharge well 1 where the feeder wells were located. 

However, for the most part, the character of the water injected in 

recharge well 1 was significantly different from that of the water
C36 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

injected into recharge well 2, as was duration of the tests. At least 

in theory, the use of feeder wells is sound, and positioning them closer 

to the recharge well may have made their utility more apparent. The 

use of feeder wells as control points for water-level observations and 

sample collection justifies installation in an experimental operation, 

but their value in an operational project is questionable.

If water is to be recharged at a controlled rate, some means of eliminating the siphon effect in the injection system should be included. 

The butterfly valve installed in well 2 served this purpose.

The use of the wire-wrapped stainless-steel screen is recommended. 

Rigorous procedures that may be needed to redevelop an injection well 

require a screen of structural strength and of a composition to withstand surging, bailing, acidizing, and the addition of other chemicals. 

The life of a recharge well generally will be less than that of a production well. Corrosion and erosion should be minimized as much as 

possible by using a screen of suitable material that has an optimum 

open area.

Perhaps initial development of recharge well 2 was more complete than that of recharge well 1, but development differences can 

account for only part of the initially higher specific capacity of 

recharge well 2. The well and screen diameters, screen type, and 

method of installing and finishing the well were the major factors 

resulting in the higher specific capacity.

The sand pack used in recharge well 2 was more effective than the 

gravel pack used in recharge well 1 in confining or trapping clogging 

material near the screen. However, the sand-pack well was more 

difficult to redevelop. Apparently, the clogging material became more 

tightly embedded in the pack interstices. Test duration was longer 

and injected water "polish" generally was poorer when using recharge 

well 2. This may have caused most of the greater redevelopment 

difficulties with recharge well 2. Consequently, conclusive data are 

not available to establish the relative merits of gravel-pack versus 

sand-pack recharge wells.

No apparent beneficial results in redevelopment were obtained by 

the use of the jetting device installed in recharge well 2. The quantity 

and pressure of the jetted water may not have been great enough to be 

effective in removing clogging material. No malfunctions in manipulations of the washring were encountered. N

All other accessory equipment used in the recharge wells, such 

as the electric motor, right-angle drive, and nonreversing ratchet, was 

satisfactory in operation and amply served its purpose.

Arrangements for observation of water levels inside and immediately 

outside a recharge well are considered mandatory in specifications 

whether a project is operational or experimental. Observation wells
EQUIPMENT AND CONTROLS C37

in the recharged aquifer also are required at greater distances from 

the injection well. Well spacing should be based on hydrologic characteristics of the aquifer and injection procedures. These wells should 

be designed for collection of water samples as well as for making 

water-level measurements. A minimum of three wells are required, 

the first well being close enough to the injection well to be influenced 

at least 2 or 3 feet by the cone of elevation. These wells will be useful 

in long-term observations of recharge operations. Most of the suspended matter in the injected water affects the aquifer in the immediate vicinity of the recharge well. However, chemical changes 

in the water and bacterial contamination may cause plugging at 

greater distances. Unless water levels and water-quality data are 

available at a distance from the injected well, long-term recharge 

effects cannot be determined or predicted, and procedures to overcome undesirable effects cannot be formulated.

Measurements of rates and quantities of water are major factors in 

the development of any ground-water supply and are essential in 

recharge operations. Several types of metering equipment are available and should be as satisfactory as those used on this project.

The turbidimeter used during the tests was satisfactory except when 

samples of the raw water were examined. The suspended solids of raw 

water frequently exceeded 200 or 300 ppm, and in this range the 

possibility of observer error is great.

The temperature-recording gage was satisfactory; however, the 

instrument should have been calibrated to allow readings to the nearest 

one-tenth degree.

It may be inferred from temperature changes observed during recharge and pumping that very little native ground water remained 

near the recharge well after a few minutes of injection. The injected 

water merely replaced the native ground water. Even so, the usefulness of temperature data as a method of distinguishing between two 

waters may be limited under certain conditions. Obviously, this is 

true when the temperature of the recharge water and the ground 

water are nearly the same. Also, differentiation between waters would 

be difficult if the recharge water is left in the aquifer for a long 

period of time and allowed to become warmed or cooled to a temperature near that of the ground water. No systematic attempt was made 

to collect data regarding the rate of temperature change of the two 

waters in the aquifer after recharge. A 2-week contact period resulted 

in approximately 2° rise in the temperature of the injected water when 

the temperature differential between the two waters was about 7° F.

One not so obvious limitation to the usefulness of temperature data 

as a method for distinguishing between recharge and ground water 

has been observed during the recharge studies made in California
C38 ARTIFICIAL RECHARGE, GRAND PRAIRIE REGION

(California Water Pollution Control Board, 1954). Bacterial contamination and activity in the injected water may cause a significant 

rise in the temperature of the water after injection into the aquifer.

In the Grand Prairie recharge studies, reliance has been placed upon 

temperature differences as a means of distinguishing between recharge 

and ground water when recovery of the injected water is started immediately upon completion of a recharge test. Immediate withdrawal 

of the injected water should preclude most of the warming effects of 

bacterial action and contact with warmer rocks and water. Precise 

identification of injected water and native ground water would require finer calibrated temperature observations or the use of other 

methods such as water tracers.

The Millipore filter apparatus was not used until several tests had 

been completed. In an experimental project of this type, it is highly 

recommended that the apparatus or an adaptation of the apparatus 

be considered for use,

The Millipore filter permits collection of practically all suspended 

material in the water. This material then becomes available for chemical, bacteriological, X-ray, or other types of examination. In a long 

series of tests, the data soon become voluminous and unwieldy to 

examine. The Millipore filter unit makes it possible to rate water 

quality with a single number by observing the decline of flow percent 

in a given period of time (Felsenthal and Carlberg, 1956).

The equipment and controls regarding coagulant testing, bacteria 

sampling, chlorination, and water supply were adequate. Some of 

the effectiveness of copper sulf ate as a micro-organism control chemical was nullified, presumably by precipitation as insoluble copper carbonate and hydroxide. Copper sulfate and chlorine used together 

were more effective than either chemical used alone, although chlorine 

provided acceptable control.

The baffles, installed in the settling canal, prevented the formation 

of large waves, but their effectiveness in reducing pickup of turbidity 

was not as great as anticipated. Maintenance difficulties such as waterlogging of the wooden baffles, collection and entrapment of algae, and 

interference with the Rice Branch Experiment Station's normal 

irrigation activities were encountered. The baffle system did not 

reduce the pickup of turbidity in the coagulated water enough to justfy 

maintenance or continued use. A more permanent baffle extending 

to the bottom of a settling canal might be considerably more effective.

The filter was satisfactory in most respects. Even distribution of 

the backflush water would have been more easily obtained in a rectangular tank. Proper wash-trough spacing also was difficult in 

the cylindrical tank. The clear well, which received filter effluent 

served its purpose satisfactorily.
EQUIPMENT AND CONTROLS C39

Recharge facilities should be kept as compact as possible. Economical use of space and transportation of water by gravity flow will reduce 

the cost of the recharge operation, permit the use of more automatic 

controls, and minimize difficulties in manipulating recharge equipment.

In general, the equipment and operation procedures used were satisfactory. Some difficulty was encountered when attempting to repeat 

testing conditions and maintain constant injection conditions for a 

prolonged period of time. Many problems were created by weather; 

however, weather changes would affect any field recharge operation.

REFERENCES CITED

California Water Pollution Control Board, 1954, Report on the investigation of 

travel of pollution: Sacramento, California, Sanitary Engineering Research 

Laboratory, Pub. 11, 218 p.

Cross Section, 1959, High Plains underground water conservation district No. 1, 

June 1959, Data reveal flocculating chemical clears lake water of most suspended matter: The Cross Section, v. 6, no. 1, p. 2-3.

Engler, Kyle, Bayley, F. H., 3d, and Sniegocki, R. T., 1962. Studies of artificial 

recharge in the Grand Prairie region, Arkansas environment and history: 

U.S. Geol. Survey Water-Supply Paper 1615-A. (In press.)

Felsenthal, Martin, and Carlberg, B. L., 1956, Measuring quality of injection 

waters: Petroleum Engineer, November, p. B-53-55, B-58.

Rainwater, F. H., and Thatcher, L. L., 1960, Methods for collection and analysis 

of water sample: U.S. Geol. Survey Water-Supply Paper 1454, 301 p.

Sniegocki, R. T., 1962, Hydrogeology of a part of the Grand Prairie region, 

Arkansas: U.S. Geol. Survey Water-Supply Paper 1615-B. (In press.)

Steinbrugge, G. W., Heiple, L. R., Rogers, Nickerson, and Sniegocki, R. T., 1954, 

Ground water recharge by means of wells, an abstract of literature and report 

of project visits: Arkansas Univ. Agr. Expt. Sta., mimeo. rept., 119 p.

U.S. GOVERNMENT PRINTING OFFICE: 1963 O 668522