AQUIFER TESTS -NORTHEAST CORNER AHD EASTERN BOUNDARY

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VolumeUnited Nuclear Corp.Administrative Record0000013502/12/82

BILLINGS & ASSOCIATES, INC.

00000135

AQUIFER TESTS -NORTHEAST CORNER AHD EASTERN BOUNDARY

FOR

we FINING A13D BILLINGCHURCHROCK OPERATION

C H U R C H R O C F , KEV; M E X I C O

DYBILLINGS & ASSOCIATES, INC.

ALDUOUEROUE, NEW MEXICO

«^

w4^-- • uJ^&6^yytftyr^. Dillings^- t _ ' ^ _ * - ^ ^ * ^ r t f t ^ yruary 12, 1982

TABLE OF CONTENTS

i2£££rlp-Lion

Introduction

Section 1: Northeast Corner Zone 3 -Aquifer Test Design

Section 2: Auxiliary ^ell Nest LocationFor Detern.ination of The Extent

' of Contamination In Zone 1 end theTorrivio Sandstone - NortheastCorner^ WC Tailings

Section 3: Eest Borrow Pit Zone 1 -Extraction and Aquifer TestDesign

Appendix A

Appendix B

Appendix C

Appendix D

Appendix E

References Cited

11

LIST OF FIGURES

Figure A

1

. 2

3

4

5

Description

Zone 3 ~ Northeast Tail-ings Area (Drawdown vs. Radius)

Pump Test Layout

Typical ObservdtJion WellLayout

Zone 1 " East Borrow Pit(Drawdown vs. Radius)

Cross-Section of TypicalPumping Well

Cross-Section of TypicalObservation Well

LIST OF APPENDICES

Appendix A

Appendix E

Appendix C

Appendix D

Appendix E

Well ConstructionSpecifications

Well Development Procedures

Well Construction MaterialsSpecifications Supplied byUI3C

Pump Test Materials Suppliedby UI3C

UNC Participation

LIST OF PLATES

XlAtfLJL

1

E^CJ-Jp.tlPB

Well Locations

INTRODUCTION

This report details additional aquifer -..-sting and

drilling of the groundwater decontanination systems required

at the United nuclear Corp. (UMC) Churchrock Mill Site. The

report is divided into three sections. The first section

deals with the contamination existing in Zone 3 in the

northeast corner of the tailings area. The second section

deals with the contamination occurring in Zone 1 and the*

Torrivio Sandstone^ in the northeast corner of the tailings

area* Finally? the third section describes the extraction

syster. needed for the Zone 1 contamination on the east side

of the Borrow Pits. Contaminationy as a term used in this

report, refers solely to that related to tailings operation

and not to "natural contamination.tt

SECTION 1:

NORTHEAST CORHERZONE 3 - AQUIFER TEST DESIGN

INTRODUCTION

Previous water quality investigations (SAIr 1981 and BAIr

^982) / have identified groundwater contamination existing to

"the northeast of the United Nuclear Corp. (UNO tailings

area. The dispersion of the contamination appears to be in a

northeast flowpath.

It is UNC's intent that the contamination in this area be

removed^ Thereforor an aquifer test is proposed in order to

establish aquifer parameters in this area- These aquifer

parameters will then be used in the development and

installation of a permanent decontamination system.

: .'*';,.•••'. i;*. :' r. ' .,,1,:..'"'' •,.;'. ,1-S

A Q U I F E R TEST

The aquifer test will consist of one pumping well and

three observation wells (See Plate tl for well locations).

However/ other wells in the area will be periodically

monitored during the test. Appendix A describe? the

procedure of and presents the specifications for well

construction. Appendix B presents the well development

procedures- Appendix C lists the estimated material

specifications for veil construction. Presently available

data indicate that the construction and development^of these

wells should be completed in such a manner that they may be

p&rfc of the permanent decontamination system*

A preliminary discharge range of 0.9 gal./min. to 1 4 . 5

gal./min. for a minimum test pumping time of 10 days was

established for the aquifer test. This discharge range and

minimum test time allows for a radius of influence of at

least 150 feet. The pumping time, discharges^ drawdowns and

radii of influences were computed from the solution of the

Theis equation ( 1 9 3 5 ) . The Theis equation in its simplest

foryr. is (Johnson Division? UOP Inc., 1980) :

where s

s =-

0 -

T ^

W ( u )

s == ( 1 1 4 . 6 x Q/T) x W ( u )

drawdown, in ft. at any point in the vicinity of a

well discharging at a constant rat

pumping rate/ in gal./min.

transrr.issivity of the aquifer^ in gal./day/ft*

the well function and is approximated by the

equation below:

7 3W ( u ) ^ -0.5772 - log. u+u - u / ( 2 x 2 ! ) + u / ( 3 x 3 ! )e

u 4 / ( 4 x 4 ! ) . . .

In this express ion,

u = 1.87 x r2 x S/(Txt)

where?

r =

s ^

T ==

t ^

distance^ in ft-y from the center of the pumped

well to a point where drawdown is measured,

coefficient of storage, dimensionless

transmissivity? in gal./day/ft.

time since pumping Btartedy in days^

If the transmissivity and storage coefficient are known,

values for these and other terms can be substituted in the

formula to obtain a desired unknown.

«

For example, using a transmissivity equal to 822.9

gal./day/ft* and a storage coefficient of 0 .015 (typical Zone

3 aquifer parameters in the 400 well series, SAI, 1 9 8 1 ) ,

various values of drawdown may be computed for correspondingrf-"^-

values of pumping times and distances from the pumping well

(radi i )<

Using a radius of 0.1 ft. (approximate radius of pump),

and a limiting drawdown value of 50 feet (average thickness

of Zone 3 is 58 feet as deter^i^e^ Jf^gJp site^eophysic&l

logs? leaving 8 feet to accomodate pump height), a maximum

purr.ping rate of 22 gal./min. was detern.ined for a 10 day

pumping tirr.e. A pumping time of 10 days was chosen because

it yielded a sufficient radius of influence for the purposes

of the test* Once the discharge of 2 2 * 0 gal./rr.in. had been

determined, drawdowns at various distances from the pumping

well were then computed. These drawdowns are presented

graphically on Figure <1 .

Using the s$me procedure for the solution of. the Theis

equation as that presented above, the second curve an Figure

?1 was generated for a transmissivty value of 35-2

gal./day/ft, and a coefficient of storage of 0 . 0 1 5 , This

5

FiQUre Sl

ZONE 3 - NORTHERST TRILINGS

T I M E -. 10 CRTS

bc-

•X.»0Q»(X(E:

a

300

1 » (0- 22 (GRLJMIt^l

RND T » 9Z2.9 (GRL.^&flT/FT.U

• « tQ « 1.1 [GOL. /MIN.1 SNO

T - 3S.2 EGRL. /DPT/FT . ! )

JL \ 1 i ? i H I I I M H

DESTFtMCE FRO^I PUMPING VFI.L t fT . l

100 IODQ

BILLINGS & PSSOCIRTES

PROJECT 9 1 2

DPTE 920210

!NC

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curve represents the drawdowns at various distances from the

pumped well for a discharge of 1*1 gal*/min. This discharge

produces the upper value of drawdown for a 10 day test. The

transmissivity value of 35.2 gal./day/ffc. was determined from

data obtained from a slug test on well TWQ-124 (SAI, 1 9 8 0 ) .

k

These calculations serve only as guidelines in enabling a

more accurate design of the aquifer test. The final

discharge rate and pumping fcin-.e for the aquifer test will be

determined in the field. The discharge rate will be set by

conducting a step drawdown test prior to the initialization

of the aquifer test- For the step drawdown test and the

aquifer test/ the measurement of discharge will be

accomplished by the use of a flowmeter. See Appendix C for

the needed testing materials* See Figures S2 and S3 for the

testing arrangement of both the pumping well and the

observation wells, respectively* Water level measurements

will be obtained by pressure transducers for wells 600, 517,

518, 124 and 505-B, and by water marker for wells TWO-123,

125, 126 and 127. See Appendix E for UKC participation.

Every 24 hours after the start of the test, water samples

from the pumping well will be taken. These samples will be

analyzed for the following parameters:

f» pHe ECft S04« TDSQ N03

7

2" Flowmeter

To TailingsGate Value

(Not to Scale)

Figure < 2: Pump Test Layout

Cable ClampTo Pumping Well

Pressure Transducer

(Not to Scale)

Fi9ure <3: Typical Observation Well Layout

9

CONCLUSIONS

Groundwater contamination has been identified in Zone 3

near the northeast corner of UNC's tailings. This

'contamination is to be removed by a permanent deconfcamination

system. In order to establish the size of the needed

decontamination system, the parameters of the contaminated

aquifer must be determined.

Therefore, an aquifer test is proposed in order to

establish the transmissivity and storage coefficient of the

contaminated aquifer. Once these aquifer parameters are

determined, a permanent system to decontaminate the aquifer

will be designed and constructed.

10

SECTION 2

AUXILLARY WELL NEST LOCATION FORDETERMINATION OP THE EXTENT OF

CONTAMINATION IN ZONE 1 ANDTHE TORRIVIO SANDSTONE -

NORTHEAST CORNER, UNC TAILINGS. AREA

11

INTRODUCTION

Water quality data from Well 450-A and 505-A indicate

contamination in Zone 1 in this area. If Zone 1 is

.contaminated in this area, the plume of contamination appears

to be small in size. For instance? other wells screened in

Zone 1 such as 448 and TWQ-120^ show no signs of

contamination.

Water quality data from Well 449 and 505-C suggests C

contamination in the Torrivio sandstone in this area.

CONCLUSION

Two pumping wells similar in design and completion to

Well 600 should be drilled at the locations shown on Plate

^1. Should contamination be identified in this area, in Zone

1 and the Torrivio sandstone, then these two wells should

serve as extraction wells for the removal of the

contamination. See Appendix A and C for a complete

description of well construction procedures and

specifications.

Upon completion of the ^constJUctxpn of the well, the

development process should begin. For a detailed reference

on well development procedures, see Appendix B*

12

Should the water samples indicate contamination in these

zones, aquifer tests using these wells should be implemented.

These aquifer tests should be carried out in conjunction with

previously identified observation wells exhibiting

contamination*

L

Should no indication of contair Inafcion be found from these

new veils, then the extraction system will progress, pssuming-^ - - - „ . - - _ . - , .," • • '•«"*

contamination in Zone 3 only.

»-0 -•^

C " ^

< ^J^&J

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13

SECTION 3:

EAST BORROW PITZONE 1 ~ EXTRACTION ANDAQUIFER TEST DESIGN

14

Water quality data (BAI» 1982) in the area east of the

borrow pits have indicated groundwater contamination in Zone

i. It is proposed that this problem of contamination be

solved by a groundwater extraction system. Previous pumping

( S A I , 1980) in this area has shown that a pump system could

work in the extraction of the contamination. Based on this

previous pumping, two pumping wells with locations shown on

Plate *1 are needed.

Using the transmissivity of 200.5 gal./day/ft, and the

forage coefficient of 0.000105 obtained from Well 304 during

the Well 303 pump test ( S A I , 1 9 8 0 ) , initial discharges/

drawdowns and pumping times were computed for the proposed

Cast Borrow Pit aquifer test. Using a technique for the

solution of the Theis equation, as presented in Section 1 , a

ficwrate of 3 . 3 gal./min. for a minimum pumping time of 10

days was determined. According to the calculation^ this

flowrate will produce a drawdown of 36 feet in the pumping

well (See Figure t 4 ) . The average thckness of Zone 1 as

determined by the geophysical logs is 44 feet. Therefore, a

total of 8 feet is left to accommodate the pump height.

Again, these calculations serve only as guidelines and the

parameters obtained from these calculations will be adjusted/

if necessary? during the field program*

15

'Figure ?4

ZONE 1 " ERST BORROW PIT

TIME « 50 ORYS

(—

1DDO

BILLINGS & RSSOCIRTES,

PROJECT 9 1 2

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The two wells, 603 and 6 0 4 , will be drilled by reaming

Wells 307 and 303, respectively. These wells are being

reamed (redrilled) and reconstructed in order to increase the

efficiency of the well. The diameter obtained by reaming

-(redrilling) will be the same diameter or larger than that of

the original well. The construction and development of Wells

603 and 604 will proceed according to Appendices A and B ,5 '

respectively, except for the reaming process.

iL.

Prior to the initialization of the aquifer test, a step ""

drawdown test will be run in order for a permanent discharge

to be set. See Figure f2 for the pump test layout. Once the

permanent discharge rate has been established, the aquifer

test should proceed in a manner similar to the start-up of

the 400 series extraction system ( S A I , 1 9 8 1 ) *

The first well ( 6 0 3 ) , should begin pumping and when its

radius of influence has reached the halfway mark to the

second well ( 6 0 4 ) , the second well should begin pumping. The

radius of influence for both pumping wells will be determined

by measuring the drawdown occurring at wells 313, 311, 310,

303, 301, 515-A and 516-A. Drawdown in the observation wells

will be measured by a combination of pressure transducers and

watermarkers* A field decision after 10 pumping days will be

ruade as to whether to continue pumping or to begin recovery.

17

The data obtained from the pump wells an^ the observation

wells will be used in analysis techniques to evaluate the

aquifer parameters. These parameters will be used to

ascertain whether or not more wells are needed for the

-permanent extraction system.

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18

APPENDIX A

WELL CONSTRUCTION SPECIFICATIONS

19

Pumping Wglls

The pumping wells ( 6 0 0 , 601, 602, 6 0 3 , and 604) will be

rotary drilled, using Revert as the drillig fluid, to a

diameter of 12 1/4" and to elevation depths of approximately

6857, 6803, 6 9 0 8 , 6871 and 6888 feet above mean sea level,

respectfully. Cuttings will be obtained and recorded at 5

ft. intervals. When the total depth is being approached, the

drilling may be stopped short or deeper than the predicated

final depth, depending upon the cuttings obtained. By doing

this, the possibility of interformational contact due to over

drilling will be greatly lessened* The wells will then be

geophysically logged in order to verify the correct depth of

the target formation. The following parameters will be

obtained from the geophysical log:

• Resistance« Gamma» Spontaneous Potential*

Once the target formations have been identified, the

construction of the wells will proceed according to the

followng procedure (See Figure ( 5 ) :

6 The borehole will, if necessary, be backfilleowith bentonite pellets until a seal isobtained at the bottom of the targetformation.

« The casing \ ill then be lowered into the welluntil the screen is opposite the formation.

• The sand pack will then be placed in theennulys opposite the screen

9 A bentonite seal of approximately 15 feet willthen be placed on top of the sand pack.

20

•\ >^ x' ^~T\"^6" Sch 40

Blank PVC

12 1 /4" Annulus

" Sch 40

PVC Slotted Screen

6 " Sch 40

PVC End Cap

Benfconite Sealr-

20 Sc^nd Pack

Bentonite Seal

(Not to Scale)

Figure <5; Cross-Section of Typical Pumping Well

21

• A bentonite cement slurry will then beinjected into the annul us froni the topbentonite seal up to the ground surface.

Observation Wells:

The observation wells will be rotary drilled, using

Revert as the drilling fluid, to a diameter of 5 inches and

to the elevation depths presented in the following table:

K^JLl, Npx.

521522

Elevation Depth(£t i above miSil.J.

68576859

These elevation depths intersect Zone 2 by apprcxinicitely

2 feet. The wells will then be geophysically logged in order

to verify the depth of the target formation. The parameters

obtained from the geophysical log will be:

• Resistance• Gamma« Spontaneous Potential,

The construction of the observation wells will proceed in

the same manner as the pumping wells except for the size of

the well (See Figure t 6 ) .

22

^ry x' >/2" Sch 40Blank PVC

5" Annulus

»2" Sch 40^VC Slotted Screen

2" Sch 40PVC Fnd Cap

Bentonite-Cement Slurry

Bentonite Sealr '

10-20 Sand Pack

Bentonite Seal

(Not to Scale)

Figure *6: Cross-Section of TypicalObservation Well

23

APPENDIX B

WELL DEVELOPMENT PROCEDURES

24

It is the purpose of well development to clean the well

bore and the immediate area around it of as much drilling mud

and fluid/ fine grained sediment and any other foreignvmaterial as possible. One of the best methods for doing this

is to pump or otherwise produce water from the water bearing, - . - - - - -

zone in order to flush the foreign fluids and sediments.

All of the pumping wells will be developed by: _

1. Circulating for approximately one-half hour with new,clean pit water before setting the casing.

2. Blowing the well dry by sir-lifting, using a drill steminside the well casing* In this procedure? the bottomof the drill stem will be periodically raised at 5 f t .intervals until the entire thickness of the formationhas been blown. If the water is clear, this procedurewill stop. If the water is not clear, the procedurewill begin again.

When the well development process is completed? the water

level in the well will then be allowed to stabilize.

Periodic water levels (approximately every 8 hours) will then

be taken until a decision is reached concerr-ing the static

water level*

The observation wells will be developed by:

1. Circulating for approy-imately one-half hour with usedpit water before setting the casing.

2. Hand bailing the well after the casing is set. Thebailing will discontinue, which terminates thedevelopment of the well when the water becomes clearo

25

The well will then be allowed to stabilize while periodic

water levels are obtained. A decision will be reached as to

when the water level in the well has reached its static

position.

26

APPENDIX C

WELL CONSTRUCTION MATERIALS SPECIFICATIONSSUPPLIED BY UNC

27

Zone 3—- Northeast Corner

Mai.erj.a.l

2" PVC Screen (Sch 40, 0.035 in slot)

2" PVC-Solid (Sch 40, bell end)b-

Bentonite Pellets (1/2" diameter? 50? buckets)

Sand (10-20 grade)

Cement (1 bag & 6 gal. H20 =1 cu. ft.. Type ID

Bentonite (loose bagged)

2" PVC End Caps (Sch 40 solid)

2" PVC slip couplings (Sch 40, long type)

PVC primer (Purple HiEtch)

PVC Glue (Clear Fastset, 1 qt. cans)

6" PVC Screen (Sch 40 , 0 .035 in slot)

6" PVC Slip Couplings (Sch 4 0 r long type)

6" PVC-Soli'd (Sch 40, Bell end)

6" PVC End Caps (Sch 40, Solid)

3 /4 " screws

3/4" Hand Drill

28

100 feet

320 feet

15 buckets

40 cu. ft.

120 bags.

11 cu. ft.

3

15

3 cans

3 nans

50 feet

8

160 feet

2

60

1

ZQJUS.J. and TO^fiviQ - Northeast Corner

Material

3entonite Pellets <1 /2 " diameter, 50fi buckets)

•Quantity12 buckets

Sand (10-20 grade) 40 cu. ft.

Cement (1 bag & 6 gal. H20 = 1 cu. f t . , Type ID 100 bags

Bentonite (loose bagged) 10 cu* ft.

6" PVC Screen (Sch 40, 0 .035 in slot)

6" PVC Slip Couplings (Sch 40, Long Type)

6" PVC-Solid (Sch 40, Bell End)

6" PVC End Caps (Sch 40, Solid)

3 / 4 * 1 Screws

3 /4" Hand Drill

2 li£_l ,-.,.,Eflgt Borrow ,£it£

90 feet

10

310 feet

3

60

1

HfiLL£JLicll

Bentonite Pellets ( 1 / 2 1 1 diameter, 50^ buckets)

Sand (10-20 grade)

Cement (1 bag & 6 gal. H20 = 1 cu. ft.. Type II)

Bentonite (loose bagged)

6" PVC Screen (Sch 40, 0.035 in slot)

6" PVC-Solid (Sch 40, Bell End)

6" PVC End Caps (Sch 40, Solid)

PVC Primer (Purple HiEtch)

PVC Glue (Clear Fa'stset, 1 qt* cans)/

3/4" Screws

3/4" Drill

29

Q ,nfciJ.y

12 buckets

40 cu. ft.

65 bags

10 cu. f t -

90 feet

200 feet

3

2 cans

2 cans

60

1

APPENDIX D

PUMP TEST MATERIALS SUPPLIED BY UNC

30

Ha.terigJ-Submersible Pumps- 1 to 30 ^al/min at 100-250 ft. head

Pressure Transducers- 0-100 p . s . i . , 400 ft. cable on each

Terminal Indicator (with at least 6 ports

Recharger(AC and DC)

Power Source (Generator or Permanent)" 110V and 220V supply

Flexible PEC Tubing and Necessary Couplings

1/4" Stee:. Cable and Reel

Gate Values- 2"

90 degree Elbow" 2"

Kipples- 2" diameter x 6 " length

Flowmeter- 2" Intake and Outake- 1*-50 g . p . m .~ Instantaneous and totalizer

Quick Connect- 2" diameter

Discharge Hose (Quick Connect)- 2" diameter " 1500 feet total length

Barrel" 55 gallon

31

^UAIlUj

3

6

2

1 r ——

1

600 feet

600 feet

9

15

3

3

Support Blocks- approx. 3 feet in height

Watermarker(250 ft.)

'Electrical Conductivity Meter

Sampling Bottles- 1 liter

Duct Tape- 20 foot roll

Hose Clanps

Rubber Gloves- ( p a i r )

Alarm Clock

APPENDIX E

UMC PARTICIPATION

33

UNC Participation;

1. Drill Rig and crew.

2. Technician (Hours 10 p*m. to 6 a . m . " duration oftesting) »

3» Pump setter.

4. Electrician (Start-Up).

5e Geophysical truck and crew.; -,,.^ -^--^ ...*•.-,-iH .- .;. -s|!-'£-—^e..-! i".t"'B13-^^aB

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34

REFERENCES CITED

Desgr.ipti.Qn

Theis, C . V . , 1935, "The Relation Between theLowering of the Piezometric Surface and the Rateand Duration of Discharge of a Well UsingGround-Water Storage:" Am. Geophys. Union Trans.,y*- ML^-P* 519-524.

Science Applications, I n c . , 1981, "Ground WaterDischarge Plan", Submitted to United Nuclear Corp.,Unpublished Report.

Billings & Associates, I n c . , 1982, ^Drilling forSeepage Control System; 500 Series: Church rockM i l l " , Submitted to United Nuclear C o r p . ,Unpublished Report*

"Ground Water and Wells", 1980, Johnson Division/UOP, I n c . , Saint Paul, Minnesota.

Science Applications, I n c . , 1980, "Ground WaterDischarge Plan,' 1 Submitted to United Nuclear C o r p . ,Unpublished Report.

35