o - Waste Isolation Pilot Plant

wipp.energy.gov

o - Waste Isolation Pilot Plant

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PROPERTY OF GSA LIBRARY

EXHAUST SHAFT: PHASE 2

HYDRAULIC ASSESSMENT DATA

REPORT INVOLVING DRILLING,

INSTALLATION, WATER-QUALITY

SAMPLING, AND TESTING OF

PIEZOMETERS 1-12

Prepared for:

Westinghouse

Waste Isolation Division

P.O. Box 2078

Carlsbad, New Mexico 88221

Prepared by:

1012·A Pierce St.

Carlsbad, New Mexico 88220

December 1997

~ I'cl © I'cl D'W I'cl ~

IvlAY - 6 1998

1>P

E/WIPP 97·2278

PROPERTY' OF

SKEE:N·WHITLOC~[ LIBRARY


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TABLE OF CONTENTS

1.0 INTRODUCTION 1

1.1 Background 1

1.2 Objectives of the 1997 Field Investigations 7

1.3 Scope of Work 8

2.0 CONSTRUCTION HISTORY 9

2.1 Shallow Hand Augered Boreholes 9

2.2 Piezometer Construction 9

3.0 DATA PRESENTATION 26

3.1 Stratigraphy 26

3.2 Water-Level Data 26

3.2.1 Water-Level Measurements From Wells C-2505, ..

C-2506, and C-2507 26

3.2.2 Water-Level Measurements From Piezometers 1 to 12 •• 31

3.3 Water-Quality Data 31

3.4 Well Development: Piezometers PZ-1, PZ-2, PZ-4 .

and PZ-9 44

3.5 Hydraulic Testing 44

3.6 Dewey Lake, Rustler, and Salado Formation Behavior in .

the Exhaust Shaft 56

3.7 WIPP Site Precipitation 56

4.0 DISCUSSION 66

4.1 Hydrostratigraphy 66

4.2 Hydrology 66

4.2.1 HydraUlic Gradient 66

4.2.2 Hydraulic Conductivity 66

4.2.3 Santa Rosa Formation Hydrologic Parameters 69

4.2.3.1 The Saturated Area of Investigation 69

4.2.3.2 The Saturated Thickness of the Santa Rosa ..

Formation 69

4.2.3.3 Porosity .a ~70

4.2.3.4 Fluid Volume Calculations ',ro

4.2.4 Water-Level Data ~r1

4.2.5 Preliminary Water-Quality Conductance Measurements ~r1

4.2.6 Nature of the Aquifer ~77

4.3 Dewey Lake and Rustler Formation Pressure Responses. ~r8

5.0 REFERENCES 80

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APPENDIX 1: GEOLOGY OF PIEZOMETER HOLES TO INVESTIGATE

SHALLOW WATER SOURCES UNDER THE WASTE ISOLATION PILOT

PLANT

APPENDIX 2: COMPOSITION AND ORIGIN OF GROUNDWATER AT THE

SANTA ROSA/DEWEY LAKE CONTACT

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LIST OF FIGURES

Figure 1.1 Location of Boreholes C·2505, C·2506, and C·2507 2

Figure 1.2 Well Completion Diagram C·2505 3

Figure 1.3 Well Completion Diagram C·2506 4

Figure 1.4 Well Completion Diagram C·2507 5

Figure 2.1 Location of Shallow Hand Augered Boreholes 10

Figure 2.2 Location of Piezometers PZ·1 Through PZ·12 12

Figure 2.3 PZ·1 Piezometer Completion Diagram 13

Figure 2.4 PZ·2 Piezometer Completion Diagram 14

Figure 2.5 PZ·3 Piezometer Completion Diagram 15

Figure 2.6 PZ·4 Piezometer Completion Diagram 16

Figure 2.7 PZ·5 Piezometer Completion Diagram 17

Figure 2.8 PZ·6 Piezometer Completion Diagram 18

Figure 2.9 PZ·7 Piezometer Completion Diagram 19

Figure 2.10 PZ·8 Piezometer Completion Diagram 20

Figure 2.11 PZ·9 Piezometer Completion Diagram•...........•....•...••..•.....•. 21

Figure 2.12 PZ·10 Piezometer Completion Diagram 22

Figure 2.13 PZ-11 Piezometer Completion Diagram 23

Figure 2.14 PZ·12 Piezometer Completion Diagram 24

Figure 3.1 Water·Level Versus Time for Monitor Well C·2505 ....•.......• 28

Figure 3.2 Water·Level Versus Time for Monitor Well C·2506 29

Figure 3.3 Water·Level Versus Time for MonitorWell C·2507 30

Figure 3.4 Water·Level Versus Time for Piezometer PZ-1 32

Figure 3.5 Water-Level Versus Time for Piezometer PZ-2 33

Figure 3.6 Water-Level Versus Time for Piezometer PZ-3 34

Figure 3.7 Water-Level Versus Time for Piezometer PZ-4 35

Figure 3.8 Water-Level Versus Time for Piezometer PZ-5 36

Figure 3.9 Water·Level Versus Time for Piezometer PZ-6 37

Figure 3.10 Water·Level Versus Time for Piezometer PZ·7 38

Figure 3.11 Water-Level Versus Time for Piezometer PZ·8 39

Figure 3.12 Water-Level Versus Time for Piezometer PZ-9 40

Figure 3.13 Water-Level Versus Time for Piezometer PZ-10 41

Figure 3.14 Water-Level Versus Time for Piezometer PZ·11 42

Figure 3.15 Water·Level Versus Time for Piezometer PZ-12 43

Figure 3.16 Piezometer PZ·1 Pressure Response to Pumping 46

Figure 3.17 Piezometer PZ·2 Pressure Response to Pumping 47

Figure 3.18 Piezometer PZ·4 Pressure Response to Pumping 48

Figure 3.19 Piezometer PZ·5 Pressure Response to Pumping 49

Figure 3.20 Piezometer PZ·6 Pressure Response to Pumping 50

Figure 3.21 Piezometer PZ·7 Pressure Response to Pumping 51

Figure 3.22 Piezometer PZ-10 Pressure Response to Pumping 52

Figure 3.23 Piezometer PZ·11 Pressure Response to Pumping 53

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Figure 3.24 Piezometer PZ·12 Pressure Response to Pumping 54

Figure 3.25 Monitor Well C·2507 Pressure Response to Pumping •.....• 55

Figure 3.26 Exhaust Shaft Instrumentation 57

Figure 3.27 Piezometer Pressures in Dewey Lake Formation , ..

Located in the Exhaust Shaft 58

Figure 3.28 Piezometer Pressures in the Forty·Niner Member , .

of the Rustler Formation Located in the Exhaust Shaft 59

Figure 3.29 Piezometer Pressures in Magenta Dolomite Member ..

of the Rustler Formation Located in the Exhaust Shaft 60

Figure 3.30 Piezometer Pressures in Tamarisk Member of the .

Rustler Formation Located in the Exhaust Shaft 61

Figure 3.31 Piezometer Pressures in Culebra Dolomite Member .

of the Rustler Formation Located in the Exhaust Shaft 62

Figure 3.32 Piezometer Pressures in Unnamed Member of the .

Rustler Formation Located in the Exhaust Shaft 63

Figure 3.33 Piezometer Pressures at the Contact of the Rustlerl .

Salado Formations 84

Figure 3.34 Daily Precipitation at WIPP Site 65

Figure 4.1 3·Dimensional Representation of the Water Bearing .

System 67

Figure 4.2 Equipotential Surface in the Vicinity of the WIPP Site 68

Figure 4.3 Conductance with Respect to Equipotential Surface .

in the Vicinity of the W1PP Site 72

Figure 4.4 CIIBr by Sampling Location 73

Figure 4.5 Potassium (mgll) vs Location 74

Figure 4.6 Moles CI vs Moles Na :. 76

Table 2.1

Table 2.2

Table 3.1

Table 3.2

Table 3.3

Table 4.1

LIST OF TABLES

History of Hand Augered Boreholes 11

Piezometer Completion Information: Piezometers 1·12 25

Summary Stratigraphic Data From PZ Drilling 27

Specific Conductance Measurements for Wells C·2505, "...

C·2506. C2507, and Piezometers 1·12 44

Hydraulic Conductivity Estimates 45

Pressure Measurements for Piezometers Located in "•••

the Exhaust Shaft Monitoring the Dewey Lake Formation .

and Members of the Rustler Formation Converted to "•••

Depth to Water Below Ground Surface 79

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1.0 INTRODUCTION

This report presents data collected during near surface borehole soil

investigations. drilling, fluid sampling for water-quality analysis. water-level

monitoring, and hydrologic-testing activities for the Exhaust Shaft: Hydraulil:

Assessment Program Phase II, at the WIPP site located near Carlsbad in

southeastern New Mexico. Twenty-seven shallow boreholes were hand aU~lered

to determine soli conditions to a depth of about 14 feet. Twelve 2-inch diamf~ter

piezometers were installed to depths of up to 82 feet below ground surface (bgs)

to characterize the areal extent. water-quality. potentiometric surface. and

potential source(s) of fluid at shallow depths in the Santa Rosa Formation.

Drilling. sampling. water-level monitoring and testing activities included in this

report were performed between June 9 and September 24. 1997.

1.1 Background

Surface geophysical investigations mapped possible conductive zones in thl~

shallow soil and bedrock in the vicinity of the Exhaust Shaft and were reported in

Exhaust Shaft: Hydraulic Assessment Program at WIPP (DOE. Jan 1997).

Based on these geophysical investigations. five boreholes were drilled in

September and October 1996 to depths of up to 100 feet bgs to evaluate thEI

near surface formations as potential ground water sources of the fluid seeping

into the Exhaust Shaft (Figure 1.1). Four boreholes (C-2505. C-2506. C-2507,

and ES-001) penetrated water-bearing horizons between 48 and 63 feet bg~;.

located in sandstone's of the lower Santa Rosa Formation and mudstones of the

upper Dewey Lake Formation. Three boreholes (C-2505. C·2506. and C-2507)

were drilled and selectively cored to determine the stratigraphic horizons

producing fluid and were then completed as monitoring wells (Figures 1.2. 1.3.

1.4).

Slug tests were conducted on wells C-2505. C-2506. and C-2507 from Octol)er 1

to October 4. 1996. to characterize the water bearing zones. In addition. a SIIXhour

drawdown pumping test was performed on C-2506 to provide data with

which to estimate the hydraulic conductivity (a measure of formation

permeability). and specific yield of the formation.

Slug-test and pumping-test data indicated a hydraulic condUctivity ranging from

5.48 x e-5 to 1.56 x e-6 mlsec. with storativity values ranging from 1.10x e-2 to

9.38x e-3. Water-level data were used to calculate a hydraulic gradient of

0.0245 ftIft in a south/southeasterly directions. Test data indicated that the ·..,ells

nearest the Exhaust Shaft were capable of sustaining water production in thle

range of 0.3 to 0.6 gallons per minute (gpm) for a period of 24 hours or longler.

In addition. the step-drawdown pumping test in C-2506 indicated that the


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EXHAUST

ES-002


SHAFT

C-2506

~ N 9279.58

(-2505,\

E: 740125

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H: 3412.87

\ N, 926610

E, 7369 78

H, 3413.05

ES-OO 1


C-2507

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N, 9069.04

E 7374.15

H, 3410.01

NOTE,

1. H=COLLAR ELEVATION (TOP OF PIPE)

2. SURVEY DATE 10/03/96

3. FIELD CREW, TPHILLlPS-WESTINGHOUSE

G.AFFOLTER-GARWIN GROUP

4. EOUIPMENT, TC I 600- NA3003 DIGITAL LEVEL

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SCALE

Figure 1,1 Location of Boreholes C-2505. C-2506, and C-2507

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Well Location: C-:2505

Ground Surface

Northing: 9266.10

w Fill, eolian sand 0.0

Eosting: 7369.78

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TOC Elev. (AM5L): 3413.05

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.~ . NOTES:

9.4

IMe,SCOlero l,;aliche

,. I. All dimensions in feet

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unless otherwise specifiE,d.

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12.4

Sandstone and '.,1 2. Tap of casing is locateel

loose sand 2.5 feet above ground s:urface.

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3. Welt Locations: Modified state

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planar coordinates; NAO'-27 NM

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east zone.

:

, 4. Information taken from drilling

logs and geologic core ·:lescriptlon.

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mudstone, dark .1--- Cement Grout from ground surface

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/4-- 7.875-inch Die. Borehole

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Ground Surface ~

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2. Top of casing is located

2.5 feet above ground surface.

Grout from ground surface

00 PVC Casing

',:'')-- 7.875-inch Dia. Borehole

Well Location: C-~

Northing: 9279.58 -- - - I

Eosting: 7401.25 3412.87 I

TOC Elev. (AMSL):~

NOTES:

1, All dimensions in feet

unless otherwise specified .

'rCement

. to 41.5

H-- 4.5-inch

3. Well Locations: Modified stafe

planar coordinates: NAD--27 NM

easl zone.

4. Information taken from drilling

logs and geologic core description.

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First Core Recovered

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Surface

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brown to greenishgray

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/......- 7.875-inch Die. Borehole

Well Location: C-Z5~7

Northing: 9069.04

Eastlng; 7374.15

TOe Elev. (AMSL): 3410.0'

NOTES,

1. All dimensions in feet

unless otherwise specified .

2. Top of casing is located

2.25 feet above ground surface.

3. Well Locations: Modified state

planar coordinates: NAD-27 NM

east zone.

4. Information laken from drilling

logs and geologic core description.

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ẖ j..... Bentonite Clay from 39.0 to 43.0

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flf:I==-,=::fj:·:J.·- Top of Screen 44.0

-'--_~ i= ~ >

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54.0

69,0

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Perforated, slotted cosing-O.01 inch slots

Bottom Cap 69.0

Total Depth 73.0

Figure 1.4 C-2507 Well Completion Diagram

5

.

OA1E:05/97-12/97

REr: J8P/WIPP07 I REV: C

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drawdown cone of depression encountered a no-flow boundary at the end (If the

third pumping period (DOE, Jan 1997).

Water samples were collected from wells C-2505, C2506, and C-2507 a few

days after drilling. The water-quality data from these wells indicated that total

dissolved solids (TDS) were greatest near the Exhaust Shaft, ranging from

11,500 mg/L in C-2506 located east of the Exhaust Shaft to 8500 mg/L to ttle

south of the shaft in G-2505, and to 4000 mg/L in C-2507 located 200 feet

directly south of the shaft.

In February and March 1997, additional water-level monitoring, testing and

water-quality sampling were conducted. Testing consisted of a 72-hour pumping

test in C-2506 and a 24-hour pumping test in C-2505. In addition, water-quality

samples were collected from each well at the completion of testing. The

purposes for conducting longer term hydraulic tests were to:

• determine if the water bearing horizon within the lower Santa Rosa

Formation is limited in areal extent or is part of a sub-regional

groundwater system;

• define local boundary conditions;

• determine if existing wells C-2505 and C-2506 are sufficient to dewater

the area around the Exhaust Shaft;

• determine if additional wells are required to characterize the shallow

groundwater; and

• collect additional water-quality samples to characterize potential

source(s) of groundwater.

Water-level data collected between October 1996 and March 1997 revealed that

water levels had risen linearly in wells C-2505, C-2506, and C-2507 with a I'ange

from 1.6 to 2.6 feet. Water levels in C-2505 and C-2506, located nearest the

shaft had risen at a rate of about 0.012 ftlday, while the water level in C-2507

had risen at a rate of 0.009 ftlday. Fresh-water-head values indicated a 6-foot

difference between well C-2506 located near the Exhaust shaft and well C-:2507

located approximately 200 feet to the south. (DOE, May 1997)

Water-level measurements collected on October 14, 1996, prior to the 6-hour

step-drawdown pumping test indicated a flow direction toward the

south/southeast and a hydraulic gradient of 2.45x e-2 ftIft. Water-level

measurements collected on March 24,1997 also indicated a direction of

south/southeast but a steeper gradient of 3.19x e-2 ftlft.

Comparison of the October 1996 and February 1997 step-drawdown pumping

tests performed in well C-2506 indicated that the hydrologic characteristics of

the system changed during this 5-month period. Both pumping and observation

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well fluid-pressure-data responses indicated:

• a quick pressure recovery response in C-2506; and

• no measurable fluid-pressure response in observation well C-2507 during

the February 1997 pumping test in C-2506.

In the October 1996 test, water levels in both observation and pumping wells

decreased as a function of time during constant-rate withdrawal periods. This

was not the case in the February 1997 test. Also, during the October 1996 test,

there were measurable responses in both of the observation wells in a relatively

short period of time. Again, this was not the case in the 72-hour pumping test

February 1997 test. In the February test, only a minimal response was observed

in well C-2505, and there was no observed response in well C-2507.

During the February 1997, 24-hour C-2505 step-drawdown pumping test,

measurable fluid-pressure responses were observed in both observation wells,

C-2506 and C-2507. However the magnitude of the response in C-2507, 197

feet away from C·2505 was almost twice the magnitude of the response in the

observation well C-2506, 34 feet away from C-2505, suggesting some type of

connection.

Water-quality samples were collected upon the completion ofthe 72-hour

pumping test in well C-2506 and upon completion of the 24·hour pumping test in

well C-2505. In both wells the total dissolved solids (TDS) concentration were

less than observed in October 1996. In C-2506 the TDS decreased from about

11500 to 6000 MG/L, while in C·2505 the TDS decreased from about 8500 to

4500 MG/L.

1.2 Objectives of the 1997 Field Investigations

Following the geophysical site investigations, drilling, hydrologic testing, and

water-quality sampling and water-level monitoring described in Section 1.1 a

second phase of investigation was initiated. The principle objectives of this

second phase were to:

• determine the quantity and areal extent of the fluid present in the lower

Santa Rosa Formation/upper Dewey Lake Formation;

• provide data with which to characterize this fluid in the vicinity of the

Exhaust Shaft; and

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• to obtain data for use in a flow model that could be used to assist in 'the

location further wells if required.

1.3 Scope of Work

Twenty-seven shallow boreholes were hand augered to depths of up to 141'eet

bgs to determine if any water was present in the near surface soil above thEl

Mescalero caliche. Twelve boreholes were drilled to depths of up to 82 feet to

provide potentiometric surface data for determining the hydraulic gradient of the

shallow groundwater in the vicinity of the Exhaust Shaft. These boreholes were

completed as piezometers, and they were also used to collect fluid samples and

to provide water-quality data that will be useful in establishing trends to aid in

characterizing the shallow groundwater. Finally, boreholes were bailed anc!

hydraulic tests were performed to improve conditions for water-quality sampling

and to provide hydraulic information on the piezometers.

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2.0 CONSTRUCTION HISTORY

2.1 Shallow Hand Augured Boreholes

Twenty-seven shallow boreholes (Figure 2.1) were hand augered through the

utility horizon at the WIPP site down to the top of the Mescalero caliche or to a

depth of up to 14 feet below ground surface (bgs). Boreholes were augerod by

hand to comply with site safety regulations related to drilling through the utility

horizon. The objective of the hand-augured boreholes were to:

• determine if any water was present above the Mescalero caliche;

• evaluate general soil-moisture conditions and the quality of the nearsurface

caliche; and to

• provide potential locations for the drilling and installation of

piezometers.

Table 2.1 provides a list of the shallow hand-augered boreholes and their

depths. No water was encountered in any of the twenty-seven boreholes

indicating there are probably no leaks from water or wastewater lines in thla

vicinity of those boreholes.

2.2 Piezometer Construction

Twelve 6~5/8-inch diameter boreholes were hollow-stem augered/cored and/or

air-rotary drilled to depths of up to 82 feet b!!ls through the Santa Rosa

Formation into the Dewey Lake Formation (Figure 2.2) between June 23 and

July 10, 1997. As the boreholes were completed, 2-inch 1.0. piezometers were

installed, packed with sand above the screened intervals, sealed with bentonite,

and grouted to ground surface. The locations and elevations of each piezcmeter

were surveyed immediately upon completion of each installation. Elevation data

were then used with water-level measurement data to determine the locath)n of

succeeding piezometers in order to define the hydraulic gradient, and to

determine the areal extent and vertical extent of fluid within the Santa Ros;E1

Formation. Upon completion of the work, protective well-head covers were

placed on each piezometer in order to maintain security of each location.

Figures 2.3 to 2.14 are completion diagrams for piezometers 1 to 12. Tatlle 2.2

lists the piezometer-completion information for of each piezometer for

comparison.

9

----.--.----------------- --"1- ...


~

~5 >-

g

~ y

SALT WATER

f>-

EVAPORATION

POND

/ A

.24

\/

SALT

STORAGE

AREA

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r---'-------II--Jt----'-------(

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!.! 15 ...J

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TOWER~ )

'--- -- -- -­

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\

WIPP SITE AND VICINITY

WITH HANO AUGlR"£D HOLE LOCATIONS

LEGEND

a

i

TOPSOIL

STOCKPILE

384 SALT HANDLING SHAFT IiOISTHQUSE

411 WASIE HANDLING BUILDING

412 TRUPACT MAINTENANCE BUILDING

413 EXHAUST SHAFT FILTER BUILDING

451 SUPPORT 8UILDING

452 SAFETY & EMERGENCy SERv. FACIUl'r

453 WAREHUUSE/SHOPS BUiLDING

4SS AUXILIARY WAREHOUSE BUILDING

458 GUARD AND SECURITY BUILDING

459 CORE STORAGE BUILDING

486 ENGINEERING BUILDING

950 WORK CONTROL TRAILER

951 PROCUREMENT / PURCHASING

952 TRA.ILER (7-PlEX)

5- SHAlLOW. HAND AuGERED HOLE

I

IIl'

I I

I

THIS DRAWING TAI\tN FROM: 2-4-C-020-W

COMPILED: J B. PALMER, INTERA..

Figure 2.1

Locotion of Shallow Hand

Augered Boreholes


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Table 2.1 Historv of Hand Auaured Boreholes

Borehole:Number Date Mescalero CaliChe Commelilts

i

Too (ft4xls)

Borehole-1 6-10-97 6.0 no water oresent

Borehole-2 6-10-97 9.0 no water oresent

Borehole-3 6-10-97 9.0 no water oresent

Borehole-4 6-9-97 7.0 no water oresent

Borehole-5 6-10-97 11.5 no water present

Borehole-6 6-10-97 ? no water present

Borehole-7 6-9-97 6.5 no water or'esent

Borehole-8 6-10-97 6.5 no water or,esent

Borehele-9 6-9-97 8.0 no water pr,esent

Borehole-10 6-9-97 8.5 no water pr,esent

Borehole-11 6-9-97 9.0 no water or,ssent

Borehole-12 6-9-97 8.0 no water onssent

Borehole-13 6-9-97 8.5 no water orlesent

Borehole-14 6~10-97 5.0 no water orlesent

Borehole-15 6-10-97 5.5 no water pnesent

Borehole-16 6-9-97 9.0 no water onesent

Borehole-17 6-10-97 6.0 no water orlesent

Borehole-18 6-10-97 6.0 no water orasent

Borehole-19 6-10-97 6.0 no water onesent

Borehole-20 6-10-97 12.0 no water pnesent

Borehole-21 7-2-97 ? Auaered to S .0 ft

Borehole-22 7-8-97 ? Auaured to !i .0 ft

Borehole-23 7-7-97 ? Auaered to!i .0 ft

Borehole-24 7-1-97 ? Auaured to 1).0 ft

Borehole-25 7-9-97 ? Auaered to 5 .0 ft

Borehole-26 7-10-97 ? AUQured to 1; .0 ft

Borehole-27 7-10-97 ? Auaered to 1) .0 ft

II


f)

....

1'-

SALT WATER

EVAPORATION

POND

PZ-7 ..

~'r----'----- Y----JHf------L-...

v

\ 1/

'r-

SALT

STORAGE

AREA

II

Y---{/ :~

1--lI--

"Tf-<

II n

II

I-<

II

II

II

II

II

II

-:!J

..

PZ-9

J

•N,

WIPP SITE AND VICINITY

I::

,

..

lECENO

N , .

1I

\

II

PZ-6

\

384

411

412

413

4~1

452

453

4SS

458

459

486

950

951

952

-

II~

140'

SAL T HAN[)l If.C SriAFT HOISTliOUSE

WASTE HANDLING BUILDING

TRUPACT MAINrENANCE BUILDING

Ex.HAUS 1 SHAF r Fil llR BUILDING

supporn tJUILLllNC

SAFETY & EMERGENCY SERVo FACILITY

WAREI10USEjSHOPS BUILDING

AUXIUARi WAREHOUSE BUILDING

GUARD AND ~£CURITY BUILDING

CORE STORAGE BUILDING

ENGINEERING 8UILDINC

WOR~ CONTROL T~lER

PROCUREMENT / PURCHASING

TRAILER (7-PL£X)

PIEZOMETER

LOCATION

SALT S/'-JAFT DRILLING AND

TAILING PIT 1981, DIMENSIONS

ARE APPROXIMATE

Tl-uS ORAWiN" [MEN fROM '.'4-,>020-W

COMI'llEV' J ti PALMER. INJ[RA

1 I Figure 2.2 Location of Piezometers PZ -1 through PZ -12


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w

z

~O

°z

....

z

0.0

NO

67.5

s ..

2 ..

l- "

...

)

:::;

'"

..

0

t.-


oO:

z

::>

I-

00:

c.:>

Ground

,j U1

G:

j.::::.-!------- NO

°

",,,,

... ~ !I!I/

S! U....J

wu

~

Surface

( \

Ie-

H

"

Bottom Cap 62.0

Total Depth 67.5

Piezometer Nome: :]Z-1

Northing: 9554.94

Eosting: 7265.34

TP Elev.(AMSL): 3413.41

NOTES:

1. All dimensions in feet

unless otherwise specified.

2. Top of 2"PVC pipe is IOI:ofed

24" 10 30" above ground surface.

It 3. Well Locations: Modified state

planar coordinates; NAO-'27 NM

, east zone.

: 4. Information taken from drilling

, logs.

5. Not to scale.

.. , TP Top 01 pipe

~

NO ~ Nol determined

11

- - - - }" ... «

- - ...

- - - -c ......


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Ground Surface

W 0.0

z

r

:::>0

Oz

-J(J') .«

'.'

-J

c;: ,

9.0

0

"'w w:r: 12.0 .'

-'u

«-

1/

u-J

(J'):

wu

~ I

'.

f

;

I·····•.

z

0 C,

f= .,

:

:::;;

'"0

l.. ..

: ..

z

:::>

....

:

--Perforoted, slotted screen-O.01 inch slots

f---- . ~~)

- - ~~

- - - - 1==:::::

---- I=~

- _ - _(... i==: = "

w~ -_-_

?='" - - .

w O - - .

Lo_l......L.

Duf..e Engineering Ii Servicu

Bottom Cap 62.0

65.0 .l-;;"'-";-;;"'-"'-'-~",-,"",'-,-'."'.-'-.'-'-'-'"- ..... Total Depth 65.0

Figure 2.4 PZ-2 piezometer completion diagram

14

DATE: 07/97--' 1/97

RrF: JBP/PZ·-2 I RrV: 8


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c

Ground

Surface

0.0

8.0~

r------ I 0.0~

I'

NOTES:

Piezometer Name: :JZ-3

Northing: 9BOB.3B

Easting: 7377.09

TP Elev.(AMSL): 3416.15

1. All dimensions in feet

unless otherwise specified.

2. Top of 2"PVC pipe is located

24" to 30" above ground surface.

3. Well Locations: Modified state

planar coordinates; NAD·~27 NM

east zone.

4. Information taken from drilling

logs.

5. Not to scale.

TP := Top of pipe

Cement Grout from ground sudoc:e

'0 36.0

2-inch fD PVC Pipe

Borehole

Bentonite Clay from 32.0 fa 37.0

1--+------ 3B.0 -e-=",,;\

Gravel Pack-Brody 16-30 Silk'J Sand

from 37.0 to 71.1

o

o

.1:I==~=Ii~-Top of Screen 42.0

==*"/>-- Perforated, slotted screen-O.01 inch slots

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Duke Engineering & Scrvicu

I:!o::==m""f- Bottom Cap 65.0

7I.1 ..l- ......."'-'--'-'-'-'-'-''-'-'--'-'-'-'-- TotaI De pth 71. 1

DATE: 07/97-11/97

figure 2.5 PZ-3 piezometer completion diagram E.='Er":"'Js=p=";;':p'=Z".·'-::3-'-r.:.::: EV 7:-;s:'f

15


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Ground

w

Z

::0 0

°z

~ ° +------

"'w WI

~~

U--'

(I)""

wU

:::0

-

z

o

t-

"" :::0

'"o

"-

Surface

0.0

r .' .

" •...

9.0 -§=:==I•..

12.0~

.(­

f.'­

f--+------ 31.0 -e=..,..f..

:..--+------ 57.0

W z -

"'0

- -

- -

:3;= - -

- -

- -

-

>-""

-

w:::O -

- -

-

- -


)

( ...

.'

'J

. 2.

Piezometer Name: I'Z-4/

Northing: 9444.17

Eosting: 7267.65

TP Elev.(AMSL): 3412.10

NOTES:

1. All dimensions in feet

unless otherwise specifiec.

',~ Borehole

Top of 2"PVC pipe is located

24" to 30" above ground surface.

Well Locations: Modified stote

planar coordinates; NAD-27 NM

east zone.

Information taken from dritling

logs.

Not to scale.

TP = Top of pipe

J--- Cement Grout from ground surface

to 30.0

:4-- 2-inch ID PVC Pipe

~ Bentonite Cloy from 30.0 to 36.0

...~ Gravel Pack-Brady 16-30 Silica Sand

from 36.0 to 65.0

.)

3.

"

: 4.

,

'3:'"

w O - -

...... ~

0"- - -

- -

65.0 .J::._.=.......-'-'-'-'-'-'-'-~.~.~. ",.--Total De pth 65.0

:Y-u!e Engineering & SO'Vicu

I

:-l

.(

s.

Perforated. slotted screen-D.O t inch slots

DATE: 07/97-11/97

Figure 2.6 PZ-4 piezometer completion diagram RE,:JBP/PZ-4 I REV: B

16


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-o:se

~~I/ 0-'

",-0:

rwO

::E

I

Ground

Surface

0.0

7.0

9.0 .'

f .

;

•.. ~

.)

'.,

.:1

NOTES:

1. All dimensions in feet

unless otherwise specified.

2.

3.

4.

5 .

Piezometer Name: PZ-5

Northing: 9810.19

Eostin9: 7196.50

TP Elev.(AMSL): 3415.31

Top of 2" PVC pipe is loc:afed

24" to 30" above ground surface.

Well Locations: Modified state

planar coordinates: NAD-·27 NM

east zone.

Information faken

logs.

Not to scale.

TP :;: Top of pipe

from drilling

D

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z

Q >­

-0:

:::;

'"ọ ...

-0:

z

::>


-0:

....


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--'u

5~v « ....

u--'

U1«

wu

:::l:

"--

z

0

Ground

Surfoce

0.0

7.0 l~~~.

9.0 - .'

E=

>-«

w~

---

_-_-

,'"

p',ozometer Nome: 1'2-61

Northing: 9647.56

Eosting: 6967.02

TP Elev.(AMSL): 3413.49

NOTES:

t. All dimensions in feet

unless otherwise specified.

2.

.(

: ( 3.

.

: 4.

f} :.

II

5.

Top of 2" PVC pipe is located

24" to 30" above ground surface.

Well Locations: Modified state

planar coordinates; NAD- 27 NM

east zone.

Information token from drilling

logs.

Not to scale.

TP ::;: Top of pipe

.J-- Cement Grout from ground surface

to 33.5

~ 2-inch ID PVC Pipe

'~r-- Borehole

_)- Sentonite Cloy from 33.5 to 37.0

>f-- Gravel Pack-Brady 16-30 Silica Sand

.. tram .37.0 to 66,0

'j

=.c:::j.•. )1.E:---=-1l'o.".~ Top of Screen 42.0

--F==="

,-~~~

I-·~··F==

I---.·F=

r" , '~ -: ~ ===Il-~- Perforated. slotted screen-O.Ol inch slots

I-~ r .. F= --->~==

--'~ - - .j== ..

Sottom Cop 62.0

wo:;:e ---- - - - -C·.·J ····>.>.).,

L=:....J 66.0 .J::......;:-"'-'-'-'-'-==~ Totol Depth 66.0

o

o 18

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OAT(, 07/97-·11/97

Duke Englneerlng 4 Services Figure 2.8 PZ-6 piezometer completion diagram REf: JBP/PZ-6 I REV: B


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Piezometer Nome: PZ-7

Ground Surfoce Northing: 10070.34

w

(osting: 6139.11

0.0

z f,

TP Elev.(AMSL): 3413.99

::0 0 ...

Oz ,


--'I/)

':,'

NOT(S:

--'

G: , .~ .

I. All dimensions in feet

7.5 ..

0

unless otherwise specified.

"'w

wI

1/

9.5

'.' 2. Top of t· PVC pipe is located

--'u «- ·..J 24' to 50" above ground surface.

1/)« u--'

..

wu 3. Well Locations: Modified state

::l1 planor coordinates; NAo-27

H

NM

- ,

'. east zone.

: : 4. Information token from drilling

logs.

·

,. 5. Not to scale.

"

z

.

.'

TP ; Top of pipe

;:::

,

°

« ..

::l1

(".

'"

·oJ--- Cement Graut from ground surface

° u.. .,

« to 57.0

z

::0

..... .. ~ 2-lnch 10 PVC Pipe

«

,


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w

Z

::>",

"'z .«

....JI/)

....J

Ie.::

z

0

i= «:::;

'"0 .

... ,

« )

z

..

::>

>-

« ..


u

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o

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u

o

D

Cl

o

°

5~1/

-'u


u

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Ground

Surface

0.0

6.0

9.0

I

c,

( ".

j'

'.

..j

Piezometer Name: PZ-1 0I

Norlhing: 9121.53

Ea,Hng: 6211.37

TP Elev.(AMSL): 3405.80

NOTES:

1. All dimensions in feet

unless otherwise specified.

2. Top of t'PVC pipe is lo[:ated

24" to 30" above grounll surface.

3. Well Locations: Modified state

planar coordinotes; NAD-'27 NM

east zone.

4. Information token from jrilling

logs.

5. Not to scale.

TP = Top of pipe

o

o

o

u

o

o

o

o

o

u

o

~-+------28.0

I

.


y

~ Cement 'Grout from ground surface

to 24.0

~ 2-inch 10 PVC Pipe

'~~ Borehole

• Ie- ~ Sentonite Cloy trom 18.0 to 24.0

" ,")

!-"

:'"1..- Gravel Pock-Brody 16-30 SWe«( Sand

from 24.0 to 57.0

~--c:...: !l::=-=~ol--- Top of Screen 29.0

- . ..., .. ::::::::_:::::::-

- -'- ---c' ::::::::

,-_ ... == = ..

:- _ .....l ::::: :::::

L:_', ~ ====

-:- '-, = =

r-"C'""---=---'


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o

o

o

o

o

o

o

o

o

o

o

z

o

~

::E

'"o

.....

Ground Surface

f--+------ 34,0

~UJ~+------- 71.0

""z

-«0

-'f=

>--«

I

.'

,(

,

.,

..

, :

-_-.c'"

~g ~::=::F

0"'"

_-_::(.::.::.::>

'.

NOTES,

Piezometer Nome: PZ-111

Northing: 106Z4.54

Eastlng: 5735.63

TP Elev.(AMSL): 3418,95

1. All dimensions in feet

unless otherwise specified.

2. Top of 2" PVC pipe Is fo(:oted

24" to 30" above grounc: surface.

"~

' ( 3, Well Locations: Modified state

planar coordinates; NAO-27 NM

, . east zone.

,;.

: 4. Information

, logs.

token from drIlling

.;) 5, Not to scale.

.,' TP ~ Top of pipe

>;.-- Cement Grout from ground surl'oce

., to 37,0

:;.,-- 2-inch 10 PVC Pipe

;

:r-- Borehole

f:

~ Bentonite Clay from 37,0 to 4Z.0

[e

I-" ::/-- Gravel Pack-Brady 16-30 Silica Sand

from 4Z,0 to 8Z.0

L::.-L 82,0 .J...__.>-c..:....:.-'--'--'--'-'-'o.... Total Depth 8Z.0

23

DATE:

07!9i'-11/97

DukeEngIMerl1Ig4Snvlcu Figure 2.13 PZ-l1 piezometer completion diagram REr,JSP!PZ-llI REV,S


u

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

o

Ground Surfoce

w 0,0

z f·

::>0

°z


·C.'

jVl

i: ;

6.0

0

"'w

w:I:

1/

8.0

-.'

-'u «-

Vl« u-'

.'j"

wu

::::!

l- I ';

Z

0

>= «

::::! .,

'"

'-

0

« I> ··

z

::> !' .'

J

~ .' .

'"

.

r

.

-.\;

Piezometer Name: PZ-12!

Northing: 8849,59

Eostln9: 6826,12

TP Elev,(AMSL): 3'·08.99

NOTES:

1. All dimensions in feet

unless otherwise specifh!d.

~".J-- Cement Groul from ground surface

to 32.0

W-2-inch 10

"\"r4- Borehole

2. Top of 2"PVC pipe is located

24" to 30" above ground surface.

l~ 3, Well Locations: Modified state

.. planar coordinates: NAD·-27 NM

I,'

east zone.

"

: 4, Information taken from drIlling

,

logs.

0

5, Not to scale.

'0.

.'

TP = Top of pip•

"

,

pvc Pipe

1:'(

H"3-- Bentonite Clay from 32.0 to 311.0

l;

:.)-- Gravel Pack-Brady 16-30 SllIc" Sand

trom 38.0 to 72.0

.... ::::! _...:....=.:

==

«0 z'" ..::::_,..-...:.:. ='If·;.,l·.-Perforaled, slotted screen-C.Ol

)6~"",,!l"'!- Boltom Cap 64,0

«0 -

- ..

,...« - -

- · ..

w::l!

- ..

~'"

-::-::~

w O ..

0'- -~ - -(

...L.._";",,",-,-,--,-,--,-,,-,-'.= - -

inch slots

DATE: D7/17-11/97

;)ukeEngiMmng 6. Servic... Figure 2,14 PZ-12 piezometer completion diagram R[F, J8P/FZ-12I REV, B

24


u

o

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o

o

o

o

o

o

o

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o

o

o

o

Table 2.2 Piezometer completion information: piezometers 1-12

PIEZOMETERS TOTAL· SCREENED

. '. DEPTH .'. INTERVAL·

.' .. (feet bQ$.~. .. (feet bas)

PZ-1 67.5 42-62

PZ-2 65.0 42-62

PZ-3 71.1 42-65

PZ-4 65 40-60

PZ-5 71.8 42-65

PZ-6 66 42-62

PZ-7 72 46-71

PZ-8 67.7 47.7-67.7

PZ-9 82 45-75

PZ-10 57 29-54

PZ-11 82 42-82

PZ-12 72 38-72

"bgs = below ground surface

25

SAND . BENTClNi:rE

PACKED SEi~H. .

. (feet bQs) .' . (feet ba$l .'

38-67.5 36-:~8

38-65 36-a8

37-71.1 32-:~7

36-65 30·:*3

38.8-71.8 33.5..38

37-66 33.5..37

37-72 37..\0

42-67.7 39-42

51-82 36.5·41

24-57 18-:14

42-82 37·42

38-72 32-,18


u

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o

o

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u

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u

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o

u

3.0 DATA PRESENTATION

3.1 Stratigraphy

Boreholes for piezometers 1-12 were installed using hollow-stem auger and/or

air-rotary drilling methods through the Santa Rosa Formation into the top clf the

Dewey Lake Formation. Where core samples were not collected, air-rotary

cuttings were collected, sampled and described to determine the stratigraphic

horizon exposed in the borehole. Table 3.1 is the stratigraphic description for

piezometers 1-12. These descriptions indicate the stratigraphic depth intervals

for the Mescalero caliche, and the Gatuiia, Santa Rosa and the Dewey Lal(e

Formations. For a complete lithologic description of the core samples and the

stratigraphic nomenclature refer to Appendix 1.

3.2 Water-Level Data

Water-level measurements have been collected from wells C-2505, C-2501>, and

C·2507 since October 1996. In addition, water-level measurements have IIlso

collected from piezometers 1through 12 beginning upon completion of

installation and continuing through September 24, 1997. Water-level

measurements have been collected to provide data with which to evaluate

hydrologic behavior of the Santa Rosa:

3.2.1 Water·Level Measurements From Wells C·2505. e-2506. and C·2507

Water-level monitoring of wells C-2505, C-2506, and C-2507 began in Octl)ber

1996 and extended through September of 1997. Figures 3.1,3.2 and 3.3.lre

linear plots of the water level recorded in feet above mean sea level (arnsl)

verses time in calendar days in wells C-2505, C-2506, and C-2507. respectively.

From October 1996 until mid March 1997 water levels in C·2505 and C-2506

rose approximately 3.0 feet with a 1.6·foot increase in the water level in C..2507

(Figure 3.1-3.3). Since March, water levels in C-2505 and C-2506 have

declined by about 0.5 feet while the fluid level in C-2507 has continued to

increase.

26


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Table 3.1 Summary stratigraphic data from PZ drilling.

o

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D

D

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Depth (tt) Interval for Stratiqraphic Units

Orillhole FiII,Oune Mescalero Gatuiia Santa Rosa Dewey Lake Fm

Sand caliche Formation Formation

PZ-1 nd§ nd nd-40 40--56 -513-67.5 (TO)

PZ-2 0-9 9-12 12-39 39--57 -t;7-65 (TO)

PZ-3 0-8 8-10 10-38 38-63 63-70 (TO)

PZ-4 0-9 9-12 12-31 31-57 51-65 (TO)

PZ-5 0-1 7-9 9-36 36-62.5 62.5-71.5 (TO)

PZ-6 0-7 7-9 9-32 32-55 5~j-66 (TO)

PZ-7 0-7.5 7.5-9.5 9.5-30 30-69 69·71.5 (TO)

PZ-8 0-6.5 6.5-9 9-31 31-60 60-67 (TO)

PZ-9 0-8 8-11 11-36 36-75 75..82.5 (TO)

PZ-10 0-6 6-9 9-28 28-46 41i-57 (TO)

PZ-11 0-10 10-12.5 12.5-34 34-71 71-82 (TO)

PZ-12 0-6 6-6 8-39 39-62 6;~-77 ITO)

§NO = not determined. Oepths are approximate (about ± 1 tt). Some contacts to nearest 0.5 i~ due to

marked contrast. Gatuna-Santa Rosa contact is difficult; the Gatuna incorporated Santa Rosa sediment.

[J

[J

[]

[j

27


,------,

l ..._·

Exhaust Shaft Hydraulic Assessment

C-2505

3350 L-----'---_"----------'--_--'----------'-_--'--L-----'-_---'--------'_---'------'_---'---_L-----'-'---_-'---------'---_-'--------.L__--'----------'

200

300 400 500 600

Time (Calendar Days Starting Janaury 1, 1996)

700

Figure 3.1. Water level versus time for monitor well C-2505


,-------

'----_. c::--J L __J t__~ L_. ! [ j L...--------J' L._ ,..--,

! L '

r---;

,-~ L_.~

,-----.

L- )

,--------,

, l~ L __ J l.__: L_.; L~ !_--~ l_._~

___

Exhaust Shaft Hydraulic Assessment

C-2506

3380 I I , , I ' , I I' I I I' 'I

'"

---.

...J

en

N >

3375 f- -

3370f

-

2

« --

--

_~

¢:: n. ~

-Q) 3365 f-

Q)

...J

....

Q)

+oJ

~

3360 ~-

J:::l

3355 f-

January 1997 July 1997

3350 [ , I ,I I I I I, I

200 300 400 500 600 700

-r:__ ".1"'_1__-1__ r""\._..._ ~"a"":-- 1___ •__ .... -1 nna,

I II lit::: \ vdlt:::IIUdl LJdY::>,;;)L I U11l::I uC:lI1UQI Y I, I aavJ

Figure 3.2. Water-level versus time for monitor well C-2506


-----1 r---'

L -' l-__ ~_~

Exhaust Shaft Hydraulic Assessment

C-2501

3375 -

-.....J

C/)

2

e:(

¢::

3370

l-

-Q) 3365 '- -

w >

Q)

=~

0

..A

.....J

~.

= = .~

=

L..

Q)

[3..,

.... 3360 I- -= -

~

3355 I-

January 1997 July 1997

3350 L----'-----L~L__.---.l'~-'--_l_L_, I_---'----.L~'-----____L_----'-~'-----____L__ILLI ---.J'--_...LI~-'-----'-------L_

200 300 400 500 600 700

Time (Calendar Days Starting January 1, 1996)

Figure 3.3. Water-level versus time for monitor well C-2507


[J

c

o

u

D

[]

D

D

[]

D

L1

[J

D

L1

[]

[]

D

[]

LJ

3.2.2 Water-Level Measurements From Piezometers 1 to 12

Water-level measurements have been collected through September 1997 from

piezometers 1-12 since their completion in June and JUly. As each piezometer

was completed, water-level measurements were used along with geophysical

and other related data to determine the drilling location of subsequent

piezometer boreholes. Depths to water in these piezometers were combined with

their top of casing elevations to provide the water-level elevations in each

piezometer. Figures 3.4-3.15 are linear plots of the water levels recorded ,IS

feet above mean sea leve! (amsl) versus time in calendar days.

3.3 Water-Quality Data

Above drilling and installing the piezometers, Westinghouse implemented ,I

water-quality sampling and analysis program with oversight by Dr. Rich Abitz,

Geochemical Consultant, to collect periodic series of samples from each

piezometer. This program, coupled with the existing water-quality monitoring

program for wells C-2505, C·2506, and C-2507. provided additional information

to improve understanding of the hydrogeology and geochemistry associated with

the groundwater in the Santa Rosa. Suites of samples were collected betwl~en

July 16-22, 1997 and August 25 - September 11, 1997. Samples were colll~cted

using a Grundfous Redi-Flow 111-7/8-inch diameter submersible pump.

Piezometers were pumped for periods ranging from 70 minutes to over 150

minutes depending on the production rate, wellbore volume pumped, and

problems associated with silting and clogging of the pump. Several

piezometers experienced either very low production rates or excessive siltil1g

problems which effected sampling and pumping. These boreholes Included

PZ-1, PZ-2, PZ-4 and PZ-9.

Table 3.2 is a list of field conductance measurements collected during watElrquality

sampling between JUly 16-22, 1997. Groundwater samples were

collected and sent to a certified analytical laboratory for geochemical analysis of

groundwater compositions focusing on major and minor-ion chemistry. FOIr a

complete evaluation and description of the water-quality sampling activities;

performed between July 16-22 and August 25 - September 11, 1997 pleasEl refer

to Appendix 1.

31


L__ J L_J L~L'C=LJC= I i L . L· l_---.J L__ J L j C_J c= c= C:J c= ,....-.., l. ;

Exhaust Shaft Hydraulic Assessment

PZQ1

3380 I I j I I j I I i I I I! ~

3375

........

...J

(f)

~

«

;;=-

3370t

,8Jl800 0000 0 D-£]

1

~

Q) 3365

>Q)

...J

...

~ 3360

~

3355 f- January 1997 July 1997

I

3350

, ,

I

I I

I,

I

200 300 400 500 600 700

Time (Calendar Days Starting January 1, 1996)

Figure 3.4. Water-level versus time for piezometer PZ-1


,--, ,--, ( J ,--, L-J C--1 1 1

,----, ,--, l ! c:::J C'

,----,

L-..--...; ( -1 c:::J c:::J c:::J c:::J

r---'

,-~,

L _

Exhaust Shaft Hydraulic Assessment

PZ-2

3380~, 'I'" I 'I'" I

3375

'"

.-

....J

C/)

:2:

3370

- CI>

>

3365

« r

'_DO DODD c;-B---fJ

¢::

CI>

....J

L0-

....

CI>

~

3360

3355

3350 L-, . ~~,__c, ~~I~::i,:~=:.~~i~-~~_~_~;~_~~l-·~~~_-'-~~--'--'~

January 1997 July 1997

( ( ( I (


I.f I , ( !

200 ' ,I, I

300 400 500 600

Time (Caiendar Days Starting January 1, 1996)

700

Figure 3.5. Water-level versus time for piezometer PZ-2


L__J L~J r--' 1.-- " ,------, L__ : J! L~ L J L : c=J l ! c=J c=J [ J c=J [ : c:::::; r--' c ,

c-::

Exhaust Shaft Hydraulic Assessment

PZ-3

3380, , I I I " I ' I ' I I 'I

3375

-J

(f)

w Q)

"'" -J

2 3370

«

¢:: L

--

Q) 3365

>

....

2 3360

~

3355

January 1997 Ju!y 1997

/;1laatlOO 0000 c;-&-EJ

I, I" I, "

3350 I , ! I I ! I,

200 300 400 500 600 700

Time (Calendar Days Starting January 1, 1996)

Figure 3.6. Water-level versus time for piezometer PZ-3


Exhaust Shaft Hydraulic Assessment

PZ-5

O'l

'"

..-..

...J

(f)

~

«

3375

3370

¢::

'-"

(J) 3365

>

...

(J)

...J

(J)

.....

~

3360

3355

January 1997 JlJly 1997

3350 L_----l.-~_'_____--'-~-"--------'--~__'__(I (

200 300 400 500 600

Time (Ca!endar Days Starting January 1, 1996)

700

Figure 3.8. Water-level versus time for piezometer PZ-5


~

Q)

3360 - -

Exhaust Shaft Hydraulic Assessment

PZ-6

3380 ,---,--,------,-'1,-------,--,----------,-'1--,--,------,-,-- I-----,---,--,------r-I~--,'---,-___,

.......

...J

'" --l >

Q)

...J

3375 I- -

en

:2

«

3370 - -

¢::

-Q) 3365 -

- ~

-

3355 I- -

January 1997 Juiy 1997

3350

, , 1 , I I 1 I, I

200 300 400 500 600 700

Time (Calendar Days Starting Janaury 1, 1996)

Figure 3_9_

Water-level versus time for piezometer PZ-6


,--, ,_.

Exhaust Shaft Hydraulic Assessment

PZ-7

3380 ,----,--.---------.-'1,------,----,------,-'1---,--,--,--,--- 1-----,----,--,----,-1-----,---.------,-'

........

...J

en

::?E

«

¢::

......-

a>

w >

ClO a>

...J

L-

a> ....

~

3375 I-

3370 -

3365 -

3360 t-

-

-

-

3355 r---

January1997 July 1997

-

3350 1------'--_--'--------'-_---l11--'---_-L--l..- 1 -L----.11_---'-_'-------'--_--'-- 1-----'-_.LL--1_'-----_'--1-----'--_--'---------'__

200 300 400 500 600 700

Time (Calendai Days Starting JanuaiY 1, 1996)

Figure 3.10. Water-level versus lime for piezometer PZ-7


Exhaust Shaft Hydraulic Assessment

PZ-8

3380 r------,,---,-----,-'I---,- ,-,-------,- '--,----1-,,----,---,--'1---,--- '-,-----.-~,-I----,-----,-----.-_,_

3375 r----

-

'"

.........

..J

en :2

«

¢::

- a>

>


..J

....

a>-~

3370 r----

r

3365 r----

3360 I-

-

-

-

Dry hole: No water present. Bottom of hole 3350.59 ft AMSL

3355 I-

January 1997

July 1997

-

3350 L---'-----'-_---'--.L_-L..-----LJL-e-----..L------'-_---'----'---_.L-..-----L-------lJ'------'----------'-_...L-_-'---_-'------_"

I I 1 ,I I I

200 300 400 500 600

Time (Calendar Days Starting January 1, 1996)

700

Figure 3.11. Water-level versus time for piezometer PZ-8


,----,

L --'

Exhaust Shaft Hydraulic Assessment

PZ-9

3375

..-..

...J

C/)

:E «

3370

~ '-'

Q) 3365

-I> >

0 Q)

...J

....

Q)

....

~

3360

3355

January 1997 JUly 1997

[!JBB BBBB o--H-8

L-,------l.------'----L---'-----LJ~-----l-------'-- ___'___L____"___~ I.L-!-----'--_---':-----"--_'----'-~

3350200 300 400 500

600 700

"T":__ 1r'_I__....._r n_y~ C ....... r+inn I~nll~r\l 1 10QI=\\

t II I It:: \\JClICIIUCU Vel ~ ""'LC;ULIII~ Ug"""WI, " '---J

Figure 3.12. Water-level versus time for piezometer PZ-9


Exhaust Shaft Hydraulic Assessment

PZ-10

3375

.--..

...J

en

3370 :2

~

... ;;::

~

-Q) 3365

>Q)

...J

....

2 3360

~

3355

January 1997

July 1997

3350 L,--'------'------'--------l-------'-_,c.L!--'--------1----'------'-------'-----1----''--'1"-,_---'-------'----'

200

300 400 500 600

Time (Calendar Days Starting January 1, 1996)

__,_1

700

Fgiure 3.13. Water-level versus time for piezometer PZ-10


--' L_-, C ' r--' L ~ L J c=: L_~ r---: L ; L_ 1 c--: CJ L_~ [ , [ . L , r--1 .---­

' __J L_.

Exhaust Shaft Hydraulic Assessment

PZ-11

3380 I

,

I I

I I

I I

I

I

I

j

r 1

3375

-

~

~ [ ~

C/)

:2E

3370

«

~-

.... a> 3365

!'.)

> a>

...J

....

... a>

~

3360

3355

January 1997 July 1997

3350 I

, I , , I , I I , I,

I

I

200 300 400 500 600 700

Time (Calendar Days Starting January 1, 1996)

Figure 3.14. Water-level versus time for piezometer PZ-11


Exhaust Shaft Hydraulic Assessment

PZ-12

'"

.........

....J

CI)

:2

«

¢::

---

~ >

3375

3370

CD 3365

CD

....J

"-

CD

-~

3360

3355

January 1997

3350 '--_--'---_L___--'-~L----.JI_~L_'_,_~-----L_--'---------'-_~---"-_ ____J_L____'____"__________'___L_______"_____

200 300 400 500 600 700

Time (Calendar Days Starting January 1, 1996)

Figure 3.15. Water-level versus time for piezometer PZ-12·


u

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u

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o

o

u

u

o

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o

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o

Table 3.2 Specific conductance measurements for wells C-2S0S, C-2S(16,

C- 2S07• andI piezometers 1-12

. ...

F DATE ••••

PIEZOMETERS CONDUCTANCE

).lsmhoslClll

7-22-97 PZ-1 122,600

7-17-97 PZ-2 34,132

7-18-97 PZ-3 154,951

7-18-97 PZ-4 50.209

7-16-97 PZ-5 112,916

7-17-97 PZ-6 46484

7-16-97 PZ-7 25720

7/22/97 PZ-8 drv hole

7-22/97 PZ-9 78.500

7-21-97 PZ-10 3700

7-21-97 PZ-11 43093

7-21-97 PZ-12 5,260

7/16/97 C-2505 6,065

7-16-97 C-2506 11,265

7/16/97 C-2507 5,105

3.4 Well Development: Piezometers PZ·1, PZ·2, PZ-4, and PZ·9

Water-quality sampling in July 1997 for piezometers PZ-1, PZ-2, PZ-4 and "Z-9

yielded groundwater samples with an unacceptably high sediment load. Thl~

amount of sediment appeared to be such that water-quality analysis may have

been biased by the dissolution of the sediment during sample-preservation

procedures. In addition, the sediment indicates that the piezometers had limited

productivity at that time due to fine material in the filter pack. Therefore, on

August 11 the four piezometers were bailed to remove sediment and to devolop

the piezometers in order to improve production.

3.S Hydraulic Testing

The addition of piezometers PA-1 to PZ-12 provided an opportunity to expand

the formation hydraulic conductivity data base to an area larger than the

immediate vicinity of the Exhaust Shaft. More widely distributed permeability

data will allow the development of a more representative numerical model to

predict system responses to a variety of stresses. Formation parameter

estimates for PZ-1, PZ-2, PZ-4, PZ-5, PZ-6, PZ-7, PZ-10, PZ-11, and PZ-12

were obtained by conducting pumping tests or slug test between August 21 and

September 12, 1997. In addition, a pumping test was performed on well C·2507

[]

44


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o

o

[J

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o

[J

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o

o

o

o

[]

o

o

o

on September 5, 1997 to complete characterization of the hydrology in the

southeastern portion

of the WIPP site. Estimates of hydraulic conductivity (K) were developed from

drawdown and recovery data from all of these locations. Because estimates of

storage/specific yield are uncertain when derived from single well tests, this

parameter was not reported for any of these tests.

Figures 3.16 through 3.25 present the pressure versus time data from each of

the respective tests conducted during this most recent testing campaign.

Figures representing the testing conducted on monitor wells C-2505 and C-2506

have been presented in Exhaust Shaft Data Report: 72-Hour Pumping Test on

C-2506 and 24-Hour Pumping Test on C-2505 (May 1997). The methodology

used to estimate the hydraulic conductivity for each of the locations has been

previously described in DOE (January 1997) and Exhaust Shaft Data Report: 72­

Hour Pumping Test on C-2506 and 24-Hour Pumping Test on C-2505 (May

1997).

Table 3.3 presents hydraUlic conductivity estimates for each of the monitor

wells/piezometers that have been tested to date.

.

Table 3.3 Hydraulic Conductivity Estimates

~'" -.,....;':' .. ,r~~e·i!i;ii,!ji::i:t:iii.:i'i!:i'iiii;:i:iii ·'iili··· .Gj'·:;~

C-2505 7.80e-6

C-2506 1.9ge-5

C-2507 5.88e-6

PZ-1

5.70e-8

PZ-2

2.64e-8

PZ-3 no value *

PZ-4

2.42e-6

PZ-5

1.3ge-7

PZ-6

3.75e-6

PZ-7

1.73e-6

PZ-8

drv hole

PZ-9 no value *

PZ-10 5. 17e-6

PZ-11

3.28e-6

PZ-12

2.11e-5

..

* Hydraulic conductiVity too low to perform pumpIng test

45


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-'l

Pump On

8

I Pump Off

IPump Off

4

Hydraulic Conductivity = 5.7 e-8 m/s

Pumping Rate = 0.4 gpm

Pump On

0L-..---L~-'-----ffEm--L..~'-----'--~-'---------.l~---'---~'-----'--~-'-------L~---'---_'-----L_-'-------L_---'-----'

247.40

247.36

247.44 247.48

Time (1997 days)

247.52

247.56

Figure 3.16. Piezometer PZ-1 pressure response to pumping


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-2

Pump On

6

I

Pump On

5

Pump On

4

Pump Off

Hydraulic Conductivity = 2.64 e-a m/s

Pumping Rate =Treat as slug test

3

Pump Off

Pump

2L-----"--_--'-------'-_-'-_L------"--_--'-------'-_---'---_L------"--_--'-------'-_---'---_L--~_~~_~~

248.36

248.40

248.44 248.48

Time (1997 days)

248.52

248.56

Figure 3.17. Piezometer PZ-2 pressure response to pumping


--"'

l ..; r--l

L ~·

Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

6

PZ-4

Pump On

Pump Off

5

..-..

0>

"(i)

Q.

'-'

..,. ~ 4

co

::J

fI)

fI)

~

a..

3

I

~

Hydraulic Conductivity = 2.42.e-6 m/s

Pumping Rate = 0.4 gpm

2'------'------'---'-----'------'---'-------'------'---'-------'------'---'-------'------'---'-------'------'---'-------'---~

247.04

247.08

247.12 247.16

Time (1997 days)

247.20

247.24

Figure 3.18. Piezometer PZ-4 pressure response to pumping


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-5

7 ---,------,-----,--'1---.-~-----,--,-~-_r---.-___,--r---,------,-__._---,------,--,---,

Pump On

6

5

4

Hydraulic Conductivity = 1.39 e-7 mls

Pumping Rate = 0.75 gpm

3

2

233.36

233.40 233.44

Time (1997 days)

233.48 233.52

Figure 3.19. Piezometer PZ-5 pressure response to pumping


,---, ,---,

L __~ , L.__~'

Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

7

PZ-6

6

Pump On

I

Pump Off

I

-C)

of/)

0-

---

01 ~ 5

0 ~

f/)

f/)

~

D..

Hydraulic Conductivity =3.75 e-6 m/s

Pumping Rate = 1.6 gpm

4

3'-------'-------'--------'-------'-----'---~-----L-----'---~-~-~--~-~-~-~--

232.44

232.40

232.48

Time (1997 days)

232.52

232.56

Figure 3.20. Piezometer PZ-6 pressure response to pumping


I ! ~ r--r r---; r--: r--, r--l

L.-.......-J L __~· L __ L__ '---J '---J ,---,

L_~·

,----,

L_~ c--J c=J

~

L.~' ~ c=J L; L--i c=J [ j c=J

Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-7

12 I I I I I I I I I I I j I I I I I j 1----,

Pump On

11

01

.....

- 10

.2>

U)

a.

-~ ::;,

9

U)

~

0.. 8

Hydraulic Conductivity = 1.73 e-6 m/s

Pumping Rate = 0.82 gpm

7

Pump Off

6 I ! I ! I I ! ! ! ! I ! I ! I I I I I ! I

249.36

249.38

249.40 249.42 249.44

Time (1997 days)

249.46

249.48

Figure 3.21. Piezometer PZ-7 pressure response to pumping


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-10

....... 6

.0)

rf)

a.

-

~:::::J

rf)

rf)

~

a.. 4

Hydraulic Conductivity = 5.17 e-6 m/s

Pumping Rate = 0.7 gpm

2L---'------_ _'___--'---_-'-_---'---_--'-_---'--_-L_----'-_-i_~_~~_~_~_ _'__~

254.40

254.44

254.48

Time (1997 days)

254.52

254.56

Figure 3.22. Piezometer PZ~10 pressure response to pumping

--~~-_.~~--


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-11


rJ)

a.

-

~::::l

rJ)

rJ)

~

ll. 6

Hydraulic Conductivity = 3.28 e-6 m/s

Pumping Rate = 0.8 gpm

4'-----'-_--'--------'_-"---_.L---L_--'-------'_---L._.L---'-_--'--------'_---L._L------L_--'--------i_---"-----'

254.08

254.04

254.12 254.16

Time (1997 days)

254.20

254.24

Figure 3.23. Piezometer PZ-11 pressure response to pumping


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

PZ-12

3

........

,0)

C/)

a. ........

~ 2

::;,

l1J

C/)

~

0..

Hydraulic Conductivity = 2.11 e-5m/s

Pumping Rate = 0.9 gpm

1

Pump On

Pump Off

o '---_ _'___-L-_--L-_--.L-_--'-_-'-_--'--_---'--_-'-__-----'-_---'_----'__~_~_

24812

248.16

248.20

Time (1997 days)

248.24

_'___

248.28

Figure 3.24. Piezometer PZ-12 pressure response to pumping

---'--'

--'--'--


Exhaust Shaft Hydraulic Assessment (Phase 2)

(Hydraulic Testing of Piezometers)

C-2507

Hydraulic Conductivity = 5.88 e-6 m/s

Pumping Rate = 0.6 gpm

........ 8

.2>

fI)

Q.

-

Pump On

4

Pump Off

o '----------'--_-L-_L------'--_-L-_L------'--_-L-_L------'--__-"-_'--------'--_--'-------''-------L_--'--------.J'----L-----'

247.24

247.28

247.32 247.36

Time (1997 days)

247.40

247.44

Figure 3.25. Monitor well C-2507 pressure response to pumping


3.6 Dewey Lake, Rustler, and Salado Formation Behavior In the

Exhaust Shaft

[J

[]

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fl

U

The Exhaust Shaft was drilled and lined between 1983 and 1985. During that

time, site investigations did not report the presence of groundwater within 195

feet of the surface. During sinking and mapping of the Exhaust Shaft the

shallowest fluid production noted was from the Magenta and the Culebra

dolomites. Both aquifers were instrumented with piezometers to monitor

hydraulic heads. In addition, the Dewey Lake, the Forty-niner, the Tamarisk and

the unnamed member of the Rustler Formation were also instrumented with

piezometers as well as the contact between the Rustler/Salado Formations to

monitor the hydraulic heads in those stratigraphic units. Figure 3.26 provides the

location and depth of the gauges located in the Exhaust Shaft in feet and meters

below the top of the collar.

Figures 3.27 - 3.33 are linear plots of the fluid pressure expressed in poundsper-square

inch (psi) versus time in calendar years (years) for the gauges

monitoring the Dewey Lake Formation, the Forty-niner member, the Magenta

member, the Tamarisk member, the Culebra member, and the unnamed

member of the Rustler Formation and the contact between the Rustler/Salado

Formations.

[1 .J

[]

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o

[]

Figure 3.34 is a plot of precipitation versus time from a climatological monitoring

station located at the WIPP Site for the period extending from August 1 1996 ­

August 31, 1997. Long-term precipitation data may be useful in evaluatin"

infiltration. Figure 3.34 shows that there was significant rainfall between June­

July 1996 and June-August 1997.

3.7 W1PP Site Precipitation

Li

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56


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EXHAUST

SHAFT

o

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Elevalian 3409 II (1039 m)

Surface

Level 1078 ft (329 m)

[1.~

u

[J

[J

[ .J

1

[1 .J

Level

Level

1574 ft (480

2056 it (630

m)

m)

Level 544 ft (t 55 m) DEWEY LAKE

Level 615 ft (t 97 m) MAGENTA

L$~el 673 it (205 m) lAI.4ARASK

Level 721 it (220 m) CULEBRA

Level 768 it (234 m) UNNAMED LOWER

MEMBER

Shait Key

[]

NOTES

1. The term "lever' Is an approximate depth

from the shoft collar at elevation 3409 ft

(1039 m) above MSL,

2. Piezometers and extensometers are orientated

at N7S'E, N45'w and SI5'W.

3, Not to scale.

LEGEND

[::!J Piezometer

~ Extensometer

LJ

u

[!

Duke Engineering d: Services Figure 3,26 Exhaust Shaft Instrumentation

- -------------_.~----------

.--_.._.~

57

DAT(, 12/11/97

REF: JBP/EXSHAFT

REV: A


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4.0 DISCUSSION

4.1 Hydrostratigraphy

Examination of core and drill cuttings from the 12 piezometer boreholes indicate

that there is a water-bearing horizon in the Santa Rosa Formation perched on

top of the less permeable Dewey Lake Formation. Water was found present in

11 of the 12 piezometer boreholes. In addition, the presence of water in the

Santa Rosa is limited in areal extent as indicated by the absence of water in

PZ-8 located 1/4 mile east of the WIPP Site Secured Area. Figure 4.1 is 3-­

dimensional contour plot showing the top of the Dewey Lake Formation. Though

the data is limited. there is clearly an identified structural feature within the

Dewey Lake Formation, which includes a trough dipping to the southwest, and a

semicircular ridge in the southern portion of the site separating a second trough

to the north.

4.2 Hydrology

4.2.1 Hydraulic Gradient

In addition to the 3-dimensional contour plot in Figure 4.1. Figure 4.2 is a 2­

dimensional water-level elevation map based on water-level data collected from

wells C-2505, C-2506, C-2507 and piezometers 1-12. The map indicates that

there is a water-level high located northwest of the WIPP site near PZ-7. There

is also another slight water-level high near PZ-5. The water-level map indicates

that the hydraulic gradient or direction of flow varies across the site. In the

northern portion of the WIPP Site the gradient is west to east. In the southern

portion of the site the gradient is northwest to south and southeast. The

absence of water in PZ-8 maybe due to an apparent saturation front located

somewhere west of PZ-8. The perched water zone indicated that the occurrence

of groundwater in other piezometers may be lensatic in nature (see 4.2.6)

4.2.2 Hydraulic Conductivity

Based on pumping tests and slug tests performed on wells C-2505, C-2506. and

C-2507 and piezometers 1-12, hydraulic conductivity values across the site

range from 2.11 e-5 to 5.7 e-8 mls. Tests indicate that the maximum sustainable

pumping rate is approximately 2.0 gpm at PZ-12. The minimum sustainable

pumping rate is approximately 0.2 gpm at PZ-2. The average sustainable

pumping rate for the wells and piezometers is about 0.6 gpm.

66


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4.2.3 Santa Rosa Formation Hydrologic Parameters

In order to evaluate the hydrology of the Santa Rosa three parameters must be

determined: the saturated area, the saturated thickness, and the porosity of the

Santa Rosa Formation.

4.2.3.1 The Saturated Area of Investigation

Of the twelve piezometers and three wells installed at WIPP between September

1996 and August 1997, only PZ-8 is dry. In every other monitoring well water is

present, indicating that the investigative area bounded by PZ-11 to the north and

west, PZ-12 to the south, and PZ-g to the east appears saturated with water

(Figure 4.1). The area defined by those boundaries is approximately 80 acres in

size. It is also likely that the saturated area is significantly larger than the

present 80-acre investigative area, but in order to clearly define the areal extent

of water within the Santa Rosa Formation additional boreholes would have to be

drilled.

Another important factor is that because piezometer PZ-8 is dry, that there

maybe a wetting front or saturation front moving away from some source

point(s). Typically fluid will move down and through the higher permeable zones

(sandstones) and saturating those horizons, followed by saturating the lesa

permeable zones (siltstones and mUdstones). These siltstones and mudstones

may be discontinuous and/or fractured creating lenses upon which water will

move around rather than through (Iensatic nature). Slight changes in

permeability, fracturing, and other properties will likely create lenses through

which fluid will move preferentially.

4.2.3.2 The Saturated Thickness of the Santa Rosa Formation

During the drilling/coring of the twelve piezometers PZ 1-12 and three wells

C-2505, C-2506 and C-2507 at WIPP, careful attention was paid in identifying

the water bearing horizons within each borehole. In the drilling of C-2505,

C-2506, and C-2507 water-bearing horizons appeared associated with

unconsolidated greenlsh-gray sandstones. These alterated sandstones varied

in thickness ranging from 0.3 to 1.8 feet or more. These sandstones were

sandwiched between relatively dry or less than saturated siltstones and

mudstones indicating that fractures and/or bedding planes may playa role in

transporting fluid from the surface through the Santa Rosa Formation.

In drilling of the piezometer boreholes, delineating the fluid producing horizons

was more difficult as most of the boreholes were drilled with air and no core was

collected. The stratigraphy was based on description of drill cuttings, therefore

once a fluid-producing horizon was intercepted the remaining drill cuttings were

69


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always mixed with fluid making it more difficult to delineate which stratagraphic

units within the Santa Rosa were contributing fluid and which ones were not. In

addition, these stratigraphic units are somewhat variable within the Santa Rosa

Formation across the WIPP site. In other words, flUid may migrate downward

from the surface by the force of gravity around discontinuous lenses of lower

permeability siltstones and mudstones through higher permeability sandstones.

Therefore estimates of the saturated thickness of the Santa Rosa made without

a clearer understanding of the heterogeneity within the Santa Rosa may be

unrealistic and subjective.

4.2.3.3 Porosity

Porosity is the ration of the volume of the void spaces in the soil or rock to the

total volume of the soil or rock, In addition, there are two different types of

porosity. There is primary porosity, which is due to the soil or rock matrix, and

secondary porosity, which may be due to such phenomena as secondary

solution or structurally controlled regional fracturing. The Santa Rosa Formation

appears to have both primary and secondary porosity. There are clearly porous

unconsolidated sandstones within the Santa Rosa that transmit significant

quantities of water. On the other hand, there are also well consolidated lowpermeability

siltstones and mudstones in the Santa Rosa that do not transmit

significant quantities of water. Some core samples contained fractures indicating

that fracturing may be a secondary source for fluid flow within and between more

porous units. Because there are no laboratory analysis of the core samples,

there are no estimates of porosity of the perched horizons beneath the WIPP

site.

4.2.3.4 Fluid Volume Calculations

Estimates of the volume of fluid present in the Santa Rosa can be made to

provide information on what it would take to pump, control or remove the water

from the perching horizons beneath the WIPP site. However, sections indicate

4.2.3.1-4.2.3.3 that there is a great degree of variability in the estimated area

and saturated thickness, the porosity, and the heterogeneity of the Santa Rosa

Formation. Estimated fluid-volume calculations could vary by one-to-two orders

of magnitude. A period of observation monitoring and reevaluation may help

resolve these and provide insight into the best courses of action in the future.

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4.2.4 Water-Level Data

The water-level plots for each of the piezometers reveals that water levels have

risen in piezometers PZ-6 (0.75 ft), PZ-7 (0.5 ft), PZ-10 (1.5 ft), PZ-11 (1.25 ft),

and in PZ-12 (2.5 ft) since July 1997. In addition, water levels in C-2505, and

C-2506 rose by about 2.5 feet between October 1996 and March 1997. And

water levels decreased by as much as a foot between March and June but have

risen by 0.5 feet in July, August and September. The observed fluid-level

responses do not appear to be explainable by local barometric-pressure

variations, a phenomenon indicative of confined aquifers. The pattern of the

fluid-level changes is similar to responses observed to occur as a result of local

recharge. Potential sources of recharge could include features such as local

precipitation captured by the north salt-disposal mound, the retention ponds

located along the south border of the site, the salt-evaporation pond west of the

north-disposal mound, or releases from on-site water or sewage systems.

4.2.5 Preliminary Water-Quality Conductance Measurements

Figure 4.3 is a contour plot of lines of equal fluid specific conductance for water

samples collected in June, 1997. On figure 4.3 the water-quality areal data are

superimposed on a plot of equal water-level elevation measured in the

observation wells and piezometers on September 24, 1997. The pattern of

specific-conductance show that there is an area with high specific conductance

located in the vicinity of PZ-3, and in the north central WIPP-site area in general.

Conductance values from the samples collected in the northern portion of the

site range from 40,000 to over 150,000 lpS/cm. For comparison the specific

conductance of sea water is 50,000 lpS/cm. The high conductance area is also

roughly coincident with the water-level ridge in the central portion of the WIPP

site as shown by the water-level contours on the figure. In contrast, groundwater

downgradient from this saline water has a specific conductance of around

10,000 lpS/cm or less. Plots of CVBr ratio versus location and potassium

concentration versus location (Figures 4.4 and 4.5) indicate that there are

roughly three types of groundwater in the shallow aquifer beneath the WIPP site;

one type in the area around the Exhaust Shaft; one type in the central and northcentral

part of the WIPP site; and a third type in the west and southwest part of

the WIPP site. The data also indicate that potassium-rich groundwater occurs in

the central and north-central WIPP site and was also observed in some early

samples from near the Exhaust Shaft.

In general, groundwater accumulates salinity as it flows downgradient and

freshening occurs only under extra-ordinary circumstances where large

quantities of fresh water enter the flow system. Formation fluids with dissolvedsolids

concentrations greater than sea water are generally found in sediments

71


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beneath evaporating basins such as playa lakes, in groundwater from halite

deposits such as the Salado Formation, in deep sedimentary deposits such as

the Permian Basin, and in water which flows over saline sedimentary deposits

such as exposed salt domes or other salt deposits which either outcrop or are·

found near land surface. The downgradient groundwater in the southeastern

part of the WIPP site not only has a lower salinity than that of the upgradient

water, but also has a different ionic composition and displays characteristics

typical of sedimentary rocks in desert regions with access to calcium sulfate and

nitrogenous soil. Alternatively, water following the groundwater gradient from

the west part of the WIPP site becomes much more saline along flow lines. The

groundwater with high specific conductance is, in general dominated by

dissolved sodium and chloride. However, Figure 4.6 shows that the

concentration data, plotted as moles of sodium and chloride per sample, fall

below a line with a 1:1 ratio of sodium to chloride. The data probably fall below

the line because other chloride salts are present in the material from which the

salt is derived.

Examination of the chloride to bromide (CIIBR) ratios from the results of the

analyses of the water samples from the wells and piezometers also provides

additional insight into the possible origin of these waters. In general, sea water

has a CIIBr ratio between 100 and 300. As halite is precipitated from

evaporating brine, the CUBR ratio decreases as the remaining fluid becomes

relatively enriched in bromide. Alternatively, when the evaporated halite is

subsequently redissolved, the CUBR ratio is greater than 500 because the

precipitation of the halite has selectively removed chloride from the formative

brine. Figure 4.4 shows the.WIPP groundwater with the high dissolved-solids

concentration, as indicated also by the high specific conductance, displays a

CUBr ratio greater than 500, a characteristic of water derived from the

redissolution of halite. The water samples from the central-WIPP-site area also

display relatively high concentration of dissolved potassium as compared to

more dilute groundwater in other parts of the site.

The water-quality data collected at the WIPP site also indicates conductance

has a combination of a Chloride/Bromide ratio characteristic of redissolved halite

and high amounts of potassium.

Given the terrigenous sedimentary composition of the Gatuna, Santa Rosa, and

Dewey lake deposits (See Appendix 1 for a complete lithologic description of the

core samples), it is unlikely that the highly saline water is representative of the

original groundwater in the sedimentary sequence. Given that the shallow

aquifer is unconfined, saline-water recharge is potentially the source of the

saline water in the shallow aquifer. At present, there are two likely sources of

this saline water. The first source is the North Salt Storage Area which contains

material mined from the WIPP repository horizon in the predominantly halite

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Salado Formation. In addition to being highly soluble desegregate salt, the moat

along the south side of the North Salt Storage Area was also the area where

saline construction and sump-collection water was removed from the WIPP

repository horizon was discharged for several years. The North Salt Storage

Area could have and could still serve as a source of recharge to the shallow

perched aquifer beneath the WIPP site.

A second potential source of saline fluid could be attributable to residuum in the

drilling and cuttings pit used during the drilling and excavation of the C&SH (now

Salt) Shaft in 1981. This 150-ft by 120-foot pit was used to settle drill cuttings

from the initial 6-ft-diameter pilot shaft for the Salt Shaft and later served as a

depository for material excavated from the finished shaft. This waste material

could serve as the source of the potassium reported in chemical analysis from

water samples collected from the central WIPP-site area. Because shaft pilothole

drilling and excavation would have encountered the entire Salado formation

including the soluble potassium salts of the McNutt member of the Salado

Formation, and because drilling practice in the 1980's often included the use of

saturated brine from potash operations as drilling fluid in order to mitigate

Salado dissolution, the waste material in the old mud pit could be a source of

both the sodium and potassium chloride content of the shallow saline

groundwater. From personal communication reports (Bob Roland, 1997), upon

completion of drilling of the Salt Shaft in 1982, fluid was pumped from the pit

liner leaving residuum (drill cuttings and non-pumpable fluids) in the pit to dry for

several months before the liner was covered with fill. Approximately a year later,

a series of holes were drilled through the liner to allow any remaining fluid to

drain from the cuttings. The liner and the drill cuttings were later removed and

the pit backfilled with caliche and compacted just prior to the construction of the

engineering bUilding in 1990. Any remnant fluid or cuttings from the Salt Shaft

pit could be a contributing factor to the conductance values observed in the

north-central portion ofthe site near PZ-3 and PZ-5.

4.2.6 Nature of the Aquifer

The combination of the hydraulic-testing, water-level, geologic, and water-quality

data collected during the present investigation appear to indicate that the

shallow groundwater at the WIPP is a variably saturated, perched unconfined

aquifer. Recharge to the system appears to have occurred within the time that

operations have been active at the WIPP site, that is since the early 1980s.

An unconfined aquifer by definition is saturated from a low permeability unit at

the base of the water bearing unit to the water level in the well and the pressure

at the water-table is atmospheric. Perched aquifers are lensatic and may occur

as a series of interconnected lenses depending on local stratigraphic variations

above the water table. Water may directly recharge the water table by moving

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downward from land surface under the influence of gravity. In order for recharge

to occur, fluid must saturate the soil by overcoming the soil-moisture deficit and

achieving sufficient head to overcome soil-moisture tension. Local fractures,

boreholes, and other anthropogenic features may short circuit the normal

recharge routes and thus provide focused recharge to a perched aquifer. The

water levels in wells completed to water-table aquifers generally rise and fall

with seasonally and/or focused recharge. Focused recharge may be due to a

specific event, a soil-moisture condition, or the presence of fractures in rock/soil

overlying the water table, the presence of a continuous water source such as a

body of surface water, or some combination of these (and other) features.

A confined aquifer is bounded above and below by units with lower permeability

that confine flow in the aquifer and allow only limited fluid and pressure

communication with these units. The water level in a confined aquifer generally

is above the level of the upper surface of the aquifer. Recharge areas for

confined aquifers are generally where the units are exposed at land surface or

have access to surface-water recharge. Water levels in wells completed to

confined aquifers are generally very stable unless there is a pointof pressure

disturbance such as a production or injection well. Long-term responses may

occur due to major climatic changes or when some portion of the aquifer is

sUbject of long-term injection or withdrawal.

The water-level changes observed in the shallow wells and piezometers

completed to the Santa Rosa/Dewey Lake aquifer exhibit the short-term fluidlevel

responses typical of unconfined aquifers and the storativities estimated

from pumping tests performed in these boreholes confirm this observation. The

apparent lack of a definite saturation indication in the recovered core samples

collected during well and piezometer installation is probably due in part to the

method of drilling and the thick capillary fringe in the heterogeneous sandy

material encountered during drilling. In addition, some of the short-term

variation in the responses may be due to the effects of a combination of the net

effect of variations in piezometer completion and the periodic water-quality

sampling activities.

4.3 Dewey Lake and Rustler Formation Pressure Responses

Table 4.2 presents pressure head or depth to water measurements for the units

underlying the Santa Rosa Formation. The depth to water in well C-2505,

located approximately 13 feet south of the Exhaust Shaft, is approximately 45.6

feet bgs. As seen in the Table 4.2, the recorded highest water-level

measurement is found in the Magenta dolomite with a depth-to-water

measurement of 296.5 feet bgs, approximately 250 below the fluid level in the

Santa Rosa. The data indicates that there is no communication between the

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Santa Rosa Formation and Dewey Lake Formation or the underlying members of

the Rustler Formation.

Table 4.1 Pressure measurements from piezometers located in the

Exhaust Shaft monitoring the Dewey Lake Formation and members ofthe

Rustler Formation converted to de th to water below round surface.

UN ES ~=--,

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Dewey Lake 544 0 none present

Formation

Fort -Niner 580 85 383.8

Ma enta Dolomite 615 138 296.5

Tamarisk 673 10 649.9

Culebra Dolomite 721 180 305.6

Unnamed Member 768 153.3 615.7

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5.0 REFERENCES

DOEJWIPP 97-2219, January 1997. Exhaust Shaft Hydraulic Assessment Data

Report. Waste Isolation Pilot Plant, Carlsbad, New Mexico.

DOEJWIPP 97-2219, May, 1997. Exhaust Shaft Data Report: 72-Hour Pumping

Test on C-2506 and 24-Hour Pumping Test on C-2505. Waste Isolation Pilot

Plant, Carlsbad, New Mexico.

Freeze, Alan, and Cherry, John, 1979. Groundwater. Prentice-Hall. New Jersey.

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APPENDIX 1:

GEOLOGY OF PIEZOMETER HOLES TO INVESTIGATE SHALLOWWATER

UNDER THE WASTE ISOLATION PILOT PLANT

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APPENDIX 2:

PRELIMINARY DRAFT REPORT ON THE ORIGIN OF PERCHED WATER AT

THE SANTA ROSA/DEWEY LAKE CONTACT

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APPENDIX 1:

Geology of Piezometer Holes to Investigate Shallow

Water Sources Under the Waste Isolation Pilot Plant

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Geology of Piezometer Holes to

Investigate Shallow Water Sources

Under the Waste Isolation Pilot Plant

Dennis W. Powers, Ph.D.

Consulting Geologist

HC 12 Sox 87

Anthony, TX 79821

ABSTRACT

Twelve holes (PZ 1-12) were drilled around the area of the WIPP surface fal~ilities to

determine the lateral and stratigraphic extent of shallow water known to exist in the

lower Santa Rosa Formation around the exhaust shaft. All of the drillholes

encountered surficial eolian sand (and fill), the Mescalero caliche, the Gatufia

Formation, the Santa Rosa Formation, and the upper Dewey Lake Formation. Eleven

drillholes produced water from the lower Santa Rosa.

All units were geologically consistent with previous studies. Across the facility area,

units from Mescalero to Dewey Lake are continuous, exhibit gentle slopes (structure

contours), and reflect broader trends in thickness and structure. Except for drillhole

PZ-8, which was dry, moist zones and water were encountered in the Santa Rosa. The

uppermost Dewey Lake in several of these holes was proven dry; dry dust was blown

from this interval while drilling.

Drilling for design work (1978-79) and mapping in the exhaust shaft (1984) show that

this shallow water did not exist through at least 1984. The air intake shaft (AIS) in 1988

flowed enough water (with dissolved salt) from the Santa Rosa and upper Dewey Lake

to be moist and develop salt efflorescences. Solutes in waters from PZ drillholes and

AIS indicate infiltrating waters contacted WIPP surface salt piles or another nearsurface

source of salt from WIPP activities.

The lower Santa Rosa revealed zones that were much harder drilling due 11:)

silicification. These indurated zones combined with reduced permeability of firle

grained rocks of the uppermost Dewey Lake to perch the water.

Several lines of evidence have been synthesized as possible indicators of site-wide

trends to probable changes in vertical permeability of the Dewey Lake and Santa Rosa.

Data on fluid levels during logging, uppermost reported gypsum, lost circulation zones,

reports of water or moist zones, and site-wide resistivity surveys were gathered from

WIPP sources. These data are less precise than is information from PZ drillholes.

Trends in these data are interpreted as indicators of permeability and are relatl3d to

different perching zones.

As hypothesized, these perching zones are effective at different depths across the

site because of the more recent geological history of the area. There is a strong

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relationship between encounters of water in the Dewey Lake and indicators of perching

zones. At the WIPP site facilities location, the uppermost two effective perching zones

are the lower Santa Rosa (investigated here) and the upper Dewey Lake (as indicated

in the air intake shaft). Southwest across the site, the Santa Rosa is absent bt3Cause of

erosion, and the uppermost effective perching zone is created by cementation changes

(sulfate) in the Dewey Lake.

If the shallow water found in this study under the WIPP facilities has migrated

laterally to the south and west well beyond the present area of investigation, it will

involve Dewey Lake perching zones, as the Santa Rosa pinches out in that direction.

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INTRODUCTION

Project Background

For several years, water has flowed in small volumes into the WIPP exhaust shaft at

shallow depths. The water is clearly not from deeper ground water sources such as the

Rustler Formation, but the extent of the water, its chemistry, and likely sources were

undetermined. Three drillholes very close to the exhaust shaft were drilled during 1996

and prepared for water sampling and water level measurements (Intera, 1996). These

drillholes demonstrated that the water was not restricted to the immediate sha~t area

and that the water occurred in the Santa Rosa Formation (or possibly the uppermost

Dewey Lake Formation). Nevertheless, the areal extent of the water was

undetermined, and the origin(s) poorly bounded.

During June and July, 1997, 12 additional holes were drilled and prepared for water

sampling and water level measurements. The main objectives during this preliminary

phase were to determine the extent of shallow water, obtain head and chemical data to

indicate possible sources of the water, to determine the stratigraphic units in which

water is present, and to provide the basis for any further programs to explore the extent

of water or place dewatering drillholes, if desired. Overall program objectives, drilling

and completion methods, and hydrological data and analysis are included in the main

report by Intera.

Geological descriptions of cores and cuttings, and the interpretation of the geological

data, were the responsibility of Dennis Powers. Field log descriptions are attac:hed to

this report (Appendix A).

Geological Units and Background for PZ Drillholes

Seven identifiable formal and informal artificial and natural units (Figure 1) have

been encountered during drilling for this program, though not all are identifiabh~ or

present in each drillhole. From the surface down, these are: 1) fill - local units

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disturbed by construction or material brought in for construction, 2) Holocene('?) dune

sand, 3) Pleistocene Berino soil, 4) Pleistocene Mescalero caliche, 5) Mioceno ­

Pleistocene Gatufia Formation, 6) Triassic Santa Rosa Formation, and 7) Permian

Dewey Lake Formation. All formations were encountered during the drilling gonerally

as expected,

.~II, construction material

:........... HolOCene (?) dune sand

f=::.:::::::=:j: Pleistocene Berino soil

'--.-=~...,--

=""1,, Pleistocene Mescalero caliche

Miocene-Pleistocene

Gatufia Formation

Triassic Santa Rosa

Formation

. Permian Dewey Lake

Formation

Figure 1

Units Commonly Encountered During

Shallow Drilling at WIPP

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(Geology ofPiezcmeter Holes)

The geology of these

drillholes could be forEicast on

the basis of the mapping of the

exhaust and air intake shafts

(Holt and Powers, 1986, 1990)

as well as nearby drillholes

such as B-25 (Bechtel National,

Inc" 1979) and WIPP:21

(Sandia [National] Laboratories

and US Geological SUI'Vey,

1980). Drilling to inve!;tigate

potash resources revealed the

broader stratigraphic

relationships and presl~nce of

the Santa Rosa over the site

(Jones, 1978). Numemus

shallow holes (B series) were

drilled in 1979 for desi!~n of

surface facilities, and tl1ese

drillholes demonstrated the

lack of very shallow

groundwater as well as; the

distribution of near surface rock units (Sergent, Hauskins & Beckwith, 1979).


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Fill. Constryction Materjals. Around the facilities, significant areas have belln

modified by construction activities, Much of the dune sand has simply been levelled in

place, though some of the upper part has been removed as "soil" for later rehabilitation

following decommissioning of the WIPP facility. Gravel from nearby caliche pits has

been imported to stabilize the surface, and one hole (PZ-1) was drilled through asphalt

SUrfacing. Another drillhole (PZ-7) was located on top of a small berm, constructed of

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around the site. These dunes may be older than Holocene and may represent more

than one episode of dune formation, based on limited examination of aerial

photographs.

Berjno Soil The Berino soil, originally designated by Chugg and others (1971)

during the soil survey of Eddy County, is a dark reddish brown siltstone to argillaceous

sandstone that is partially Iithified, mainly by accumulation of clay minerals. It is a

fossil soil or paleosol. It was examined by Bachman (1980) briefly, who noted its

occurrence overlying the Mescalero caliche and under dune sand. Bachman

interpreted the Berino as probably a remnant B horizon relative to the underlying

Mescalero caliche, and Powers (1993) agreed with that assessment. Powers and

others (1997) reassessed the relationship based on trenches west of WIPP and

concluded that the Berino was distinct from the Mescalero in origin.

In a study ofthe ages of near-surface units, Rosholt and McKinney (1980)

interpreted the age of formation of the Berino as 330,000 ± 75,000 years.

Mescalero Caliche. The Mescalero caliche in the area of WIPP is best known from

the work of George Bachman (e.g., Bachman, 1974, 1976; Bachman and Machette,

1977). The Mescalero is an informal stratigraphic unit originally designated by

Bachman (1976) for the pedogenic carbonate deposits across the Mescalero plains.

The drillhole data for design studies for WIPP was used to prepare a map of the

exshft2. wpd 5

dune sand with caliche surfacing, around an evaporation pond.

Holocene!?) Sand Dynes. The Holocene sand dunes in this area have been little

studied as geological units. While most are stabilized, small areas remain active


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elevation of the top of the caliche in the area where surface facilities now exist

(Sergent, Hauskins & Beckwith, 1979, figure 3). Further away, Powers (1993) studied

the Mescalero in pipeline trenches, finding a range of development from about stage 2

through stage 5 (Bachman and Machette, 1977) across topographic changes. Powers

and others (1997) examined outcrops of the Mescalero exposed in the EI Paso Energy

pipeline trench just west of the WIPP boundaries and found that the caliche is

stratigraphically continuous across the area. The unit is locally variable and was

disrupted by erosion/solution prior to formation of the Berino soil (about 330,000 years

ago). In general, the Mescalero caliche is continuous across the general site area and

provides broad evidence of geomorphic stability.

Rosholt and McKinney (1980) dated carbonate from the Mescalero using urBlniumtrend

methods. The lower part yielded an age of about 570,000 ± 110,000 yeal's, and

the upper part was 420,000 ± 60,000 years.

Miocene-Pleistocene Gatulia Formation. The Gatulia Formation is relatively thin

across most of the WIPP site (Bachman, 1985). In the eastern half ofthe WIPP

withdrawal area, no Gatulia is reported; caliche is developed on the Santa Rosa.

Several caliche quarries at topographic highs east of the WIPP withdrawal are~1 expose

well-Iithified Santa Rosa under caliche. The Gatulia thickens considerably to the west,

especially along Nash Draw and nearer the present day Pecos River (Powers Bind Holt,

1993, 1995a). It was deposited predominantly in a fluvial environment. The base of

the formation is regionally unconformable, and it can fill localized channels caused by

erosion. The thickness of the unit can vary considerably over short distances. The

formation has filled in some areas along the general Pecos River trend where

dissolution caused subsidence (Powers and Holt, 1995a).

Triassic Santa Rosa FOrmation The Santa Rosa is thin near the center of the WIPP

site (e.g., Powers and Holt, 1995b). It thickens rapidly.to the east (Jones, 1978) as a

consequence of eastward dip and eastward rise in the surface topography. The

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formation was deposited in dominantly fluvial environments (McGowen et aI., 1979). It

lies unconformably on the Dewey Lake.

Permian DeweY Lake Formation, The Dewey Lake thickens from west to east across

the site to a regional maximum of about 600 ft east of the WIPP site (Schiel. 1HBB). It

was deposited during ephemeral flooding of shallow streams and rivers. The unit is

characteristically fine-grained, ranging from interbedded fine sandstone to mudstone. It

has a distinctive reddish-brown color with small spots and thin zones that are

greenish-gray.

Unit Distinctions

During this study, some cores were taken using flight augers and retrievable core

barrels. Most holes were drilled using a tricone bit and compressed air to rem()ve

cuttings. The stratigraphy of these drillholes was determined by monitoring thE! cuttings

for composition and color. Because the return time (to the surface) for cuttings at these

shallow depths is very short, distinct changes in composition can commonly be

determined quickly and accurately. Depths to most units are considered accurate to

the nearest foot; a few unit distinctions are taken to the nearest half foot. Over

intervals where cores were not retrieved or cuttings did not return to the surfacl~,

boundaries may be placed on the basis of changes in drilling rates. Most of thl~

following discussion is based on distinctions made on the basis of cuttings.

The fill materiallgraded material is mainly orange to brownish, unconsolidatEld sand

from the stabilized dunes that covered the site prior to construction. Some caliche

gravel or other coarse material is mixed with the upper surface in some locations.

There is little to distinguish the base of graded material at most locations tram 'the

undisturbed dune sand. In some drillholes, the basal dune sand included additional silt

and clay, is more Iithifled. and is a darker reddish brown. This corresponds to 'the

Berino soil (e.g., Chugg et aI., 1971; Bachman, 1980; Powers and others, 1997) that

overlies the Mescalero across most of the site.

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The top of the Mescalero is reliably determined because of the abrupt chan~le in

cuttings to white carbonate and reduced drilling rates. Sergent, Hauskins & Bleckwith

(1979) prepared a contour map of the elevations of the top of Mescalero from the B

series holes, and the data correspond closely to our findings.

The top of Gatuna for this study is placed where brownish to reddish-brown Gatuna

sandstone is observable as part of the cuttings. This corresponds to the contact as it is

observed in outcrops and other cores (Powers and Holt, 1993, 1995; Powers, 11993).

Mescalero caliche infiltrated the upper Gatuna, forming nodules and carbonate crusts.

The alteration decreases with depth. In outcrops, the Mescalero dominates ov,er an

interval that is generally about 3 ft thick (see Powers, 1993; Powers and others, 1997;

Kennedy, 1997). Gatuna character is distinguishable below that and increases: with

depth. Cuttings begin to change color from white to slightly brownish white and are

accompanied by increasing proportions of Gatuna sandstone. The sand graimi are

generally fine to coarse, poorly sorted, and chips show small pores from bioturbation as

well as bluish-black Mn0 2 stains.

The Sergent, Hauskins & Beckwith (1979) study consistently places the Mescalero­

Gatuna boundary much deeper, implying that the Mescalero is 10-15 ft thick across the

WIPP site center. The upper Mescalero, as described in the Sergent, Hauskin:s &

Beckwith report, corresponds to the differentiation of the Mescalero in this repc1rt; they

included much more of the carbonate-cemented sandstone in Mescalero, while I

attribute it to Gatuna that has been altered by Mescalero pedogenic processes.

The Santa Rosa is a common source of the sediment that forms the Gatuna, making

this boundary the most difficult to place in either core or cuttings. The Santa Rosa

includes fine to coarse, highly micaceous sandstones interbedded variably with

claystones or siltstones. Santa Rosa sandstones are generally dark brown, while

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claystones and siltstones can include green. Some beds display whitish reduCition

spots. Outcrops of the Santa Rosa commonly strike the eye as having a purpli:sh cast.

The distinction at the base of Gatuna was commonly made on the basis of higher mica

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concentrations, more intense hues (browns, greens), and induration (slower drilling

rates). Some beds near the base of the Santa Rosa are highly indurated. Cuttings

from these beds are limited, but tests with acid show little carbonate cement. The beds

are probably partially cemented by silica.

The Dewey Lake is most commonly differentiated from the Santa Rosa on the basis

of color (more of a brick red color and chips with greenish-gray reduction spots) and

composition (no coarser sands, decreased mica content). Drilling rates for the Dewey

Lake also increased over the basal Santa Rosa and became more constant.

Origin of Water

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(Geology ofPiezometer Holes)

To understand the origin of this water, we consider both the likely sources as well as

how long the water has been in place. While the current study is designed to

understand the sources of the water in some detail, previous geological studies greatly

constrain the possibilities of how long this zone has been saturated.

Design studies included drilling holes at 54 locations from late 1978 through part of

1979 at the location of proposed WIPP facilities. There were 54 principal drillholes and

6 supplemental or offset drillholes. The drillholes ranged in depth from about 6 to about

902 ft in depth. At 52 locations, the drillholes had total depths of 100 ft or less and

were drilled with air (Bechtel, 1979, p.

10). Two drillholes (B25 and B54) were

901.8 and 210 ft deep, respectively.

Drilling mud was used for B25 (Bechtel,

1979b); I assume drilling fluid was used

for B54, but I found no specific

information in the original reports.

Twelve of the drillholes were drilled with

air and were between 50 and 100 ft deep

(Figure 2) and should have been deep

Figure 2

Depth of B Series Holes

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20-30 40-50 60-70 80-90 100-110

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enough to intercept the water at its current depth. These drillholes cross the ;~rea

where water has currently been found as well as some areas beyond the areal of the PZ

wells; they demonstrate that the water was not present below the site in 1979,

In 1984, the exhaust shaft was constructed and mapped (Holt and Powers, 1986).

No water was found through this shallow interval during the mapping. The water was

not present at the exhaust shaft in 1984.

During the mapping of the air intake shaft (AIS) late in 1988. Holt and Powe,rs (1990)

noted that the shaft walls were wet in the basal sandy siltstones of the Santa I~osa

Formation at a depth of 51.5 ft (33 ft below plenum + 18.5 ft of plenum) (elevation of

3358.5 ft msl). Holt and Powers suggested that water was accumulating in Santa Rosa

sandstones overlying the siltstones. Salt efflorescence accumulated on the surface of

the shaft to a depth of about 63 ft as air flowing into the shaft evaporated the water.

Holt and Powers also found moist zones and salt efflorescence above a cementation

change in the Dewey Lake at a depth of about 182.5 ft (164 + 18.5 ft). They c,oncluded

that the source was infiltration of meteoric water that had come in contact with the halite

muck pile immediately north of the facilities. By 1988, water had infiltrated in the

vicinity of the AIS and charged units at 51.5 ft and 183 ft depth.

These geological investigations show that the shallow water found during this stUdy

(PZ drillholes) did not exist generally across the site in 1979, and was not obsl~rvable

at the exhaust shaft in 1984. It is reasonable to conclude that it did not exist at all at

least as late as 1984. By 1988. the AIS mapping showed that water with dissolved

halite had infiltrated to the Santa Rosa and Dewey Lake at this location. The ~lolutes in

the water in the AIS and also indicated in preliminary testing of water from PZ Iholes

show that the water flow path has to involve a surface source of halite such as tailings

piles from WIPP or brine pits for drilling and is not due. for example. to leaks from pipes

carrying water of drinking quality. Further solute analyses will be significant in

determining what were the sources and flow path of the water.

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SUMMARY STRATIGRAPHIC DATA FROM PZ DRILLING

Basic stratigraphic data for each drillhole in the PZ series is included in a talole for

convenience (Table 1).

TABLE 1

Depth (ft) Interval for Stratiaraphic Units

Drillhole Fill, Dune Mescalero Gatuiia Santa Rosa Dewey ILake Fm

Sand caliche Formation Formation

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PZ-l nd§ nd nd-40 40--56 -56-67.5 (TO)

PZ-2 0-9 9-12 12-39 39--57 -57-65 (TO)

PZ-3 0-8 8-10 10-38 38-63 63-70 (TO)

PZ-4 0-9 9-12 12-31 31-57 57-66 (TO)

PZ-5 0-7 7-9 9-36 36-62.5 62.5-71.5 (TO)

PZ-6 0-7 7-9 9-32 32-55 55-6fi (TO)

PZ-7 0-7.5 7.5-9.5 9.5-30 30-69 69-71.5 (TD)

PZ-8 0-6.5 6.5-9 9-31 31-60 60-61' (TO)

PZ-9 o-a 8-11 11-36 36-75 75-82.5 (TO)

PZ-l0 0-6 6-9 9-28 28-46 46-51' (TO)

PZ-11 0-10 10-12.5 12.5-34 34-71 71-82: (TO)

PZ-12 0-6 6-8 8-39 39-62 62-77' ITO)

§ND = not determined. Depths are approximate (about ± 1 It). Some contacts to nearest 0.5 It due to

marked contrast Gatuila-Santa Rosa contact is difficult; the Gatuila incorporated Santa Rosa sediment

In part because of grading, the fill and dune sand over caliche shows a relatively

uniform depth across the area of investigation. This is also consistent with the findings

of the pre-construction surveys.

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exshft2. wpd

11


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(Powers; Ootober 28. 1997)

(Geology ofPieze'met&r Holes)

The Mescalero is consistently 2 to 3 ft thick in this investigation. This is consistent

with outcrop and trench data in the area, though it contrasts with pre-construction

surveys because of different concepts of the Mescalero-Gatuna contact.

The Gatuna averages 24 ft thick in the 11 drillholes in which both top and base

were picked. Most of the cores and cuttings of the Gatufia display evidence Ol!

bioturbation, Mn staining, and possible mineral precipitation along likely ped [a soil

structurel surfaces that are consistent with pedogenic alteration of the upper part of the

formation as it was accumulating in this area prior to development of the Mescalero.

Most of the formation would be similar to the part called informally the "McDonald

Ranch member" by Powers and Holt (1993, 1995a).

The Santa Rosa averages about 39 ft thick in the PZ series holes. This is

consistent with the broader site relationships, where the site center is near the western

limit of Santa Rosa following erosion prior to Gatufia deposition. The Santa Rosa thins

rapidly to the south and west of this area.

COMPARISON WITH STRATIGRAPHIC DATA

FROM PREVIOUS STUDIES

The main sources of comparable data within the WIPP fenced area and out to a

radius of about 3 miles are drillholes for the design studies (Figure 3) (Sergent,

Hauskins, Beckwith, 1979; Bechtel, 1979), potash exploration for WIPP (Jones, 1978),

and various exploratory and hydrologic drillholes for WIPP (Figure 4) (see, for example,

data summaries of relevant units in Powers and Holt, 1995b). Units down to the upper

Dewey Lake can be compared for the area ofthe facilities; the thickness of the Dewey

Lake for a broader area is based on deeper drillholes that were not a part of this study.

exshft2. wpd 12


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N

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--~-... ~.- -,-

------.-

PZ1~

Figure 3

Basemap of Drillhole Locations Near WIPP Site

,•

.PZ7

• II PZ.2


- .. ----.--

.'!

854..,625

· ..,

PZ~O .,

- •

• PZ9I


• •


• PZ9

.WIPP 21

~PZ3

PZ1

• ePZ2

1'pZ4

•• '"I


I.





• PZ Holes

_ _ _·9jl1_eL[)rilll1..Qt~~ .


• Exhaust Shaft

• Other Shafts '

exshft2. wpd 13


"za


See Appendix B

Figure 3 for deteils

t 1000 ft f

--_..,---.. _--- ~-"~-_._.

(Geology ofPiezometer Holes)

• • ~ •


• • ,

• •

.- N501000

N500000

... -- N499000

..•._.-- +- - .-_. N498000

.1 250m I

--,.,-.---_.-,----_._-.-.

Grid is NM State Plane

N497000


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N

t ,............

P12°

w

w

0 ~

H18

Figure 4

--..._-..._...-...

Drillhole --..._-... ---..,..-..-.-..-.-..-..-.,-

Location Map Around WIPP Site Area

..-..-.~-.-..-_.."I.;. ....-..-.-••-_...... V:f~lf~!':" .....

P13 0 WIPP 34 ~

WIPP33 0

o

P5 ;~\f'f' ~2­

-wasp1..,-- -----0-

o 0

00

---- -,"-- - --------_.+'--

• •

o 0

. !

h22S

, T23S

C') C') • •

0:: 0::

0

Selected Drillholes shown near site center

: :

! I WIPP Withdrawal Area

...........

Hole Location, selected holes identified


:

(Geology ofPiez"meterHoles)

1~.....-••-.-••-.-••-__--'-'"'!"".,

"·I,

1 millL....f

1 1 km 1


• •I

- .~_.-.--

·!••"

•:

I

-_.--:- • ._.. _~--" ...lll-l--­

i

•,

:

••,

•·•

See Appenclix B

Figure 4 for deteils

exshft2. wpd

14


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(Powers; October 28. 1997)

(Geology ofPiezometer Holes)

Dewey Lake Data

From the larger area (Figure 5), Dewey Lake thicknesses reveal three main

features. In the eastern part of the map area, the Dewey Lake is more than 525 ft thick;

this is similar to much of the Dewey Lake to the east, where it thickens to about 600 ft

N

Figure 5

Thickness of Dewey Lake Formation

.........--.-..~"...,.,...--

t

•, ,

,

·

• ..

~ ----.


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325

. --t"-- ·•

, ,"

, -:--

·:

--~---'525

D'

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exshft2. wpd

W

W

0 ~

C"l C"l 4?S

IX: 0::

... ""

'"

contour interval is 25 ft

.......... ,.

15

500

1 mile -l

~

WIPP Withdrawal Area

See Appendix 8

Figure 5 for fietails

approximate western edge of Santa Rosa Frn


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(Powers; October28. 1997)

(Geology ofPiezometerHoles)

(e.g., Schiel, 1988). The southwestern half of the map shows thinning with a persistent

gradient to the southwest. The isopach contours generally parallel the estimated edge

of the Santa Rosa. The northeastern quarter of the map has somewhat thinner Dewey

Lake, about 500 ft thick.

The thickness map also shows two minor features. In the center of the northwest

quadrant, the Dewey Lake appears to be thicker toward the west along a "nost'"

defined by drillholes P12, H18, and WQSP1 (Figure 4). This nose does not dilffer in

thickness greatly from the northwest-southeast trend defined through the site center.

The nose is accentuated by drillholes P13 and WIPP 33, where the Dewey Lake is

significantly thinner. The second minor feature is a narrow thinner zone near tlhe north

center area of the map defined by WIPP12, P5, and WIPP14. This zone trend:s northnortheast.

It is not a significant feature, as it is defined by differences as little as 5 ft

between drillholes WIPP34 and WIPP14, which is generally about the normal

interpretive limits for precision on geophysical logs (e.g., Holt and Powers, 1988).

A map of the elevation of the top of the Dewey Lake (Figure 6) does not reflect

regional structure for these units. The structure of units of the underlying Rustler

Formation show that the regional dip is eastward and is of the order of 100 ftImile. The

general trend of elevation on top of the Dewey Lake is for a relative high or rid~le along

a zone from southeast to northwest with a saddle near the WIPP surface facilities. The

Dewey Lake tends to be slightly higher under the WIPP site. The top of the Dewey

Lake slopes off both to the southwest and northeast from this ridge.

The slope to the southwest corresponds mainly to broader erosional thinning of the

Dewey Lake prior to deposition of the Gatufia. The Santa Rosa is missing over most of

this area, having also been eroded prior to Gatufia deposition.

exshft2. wpd 16


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~ .....

c::: 2

contour interval is 25 ft

.....

• ...o.-.o

The slope to the northeast corresponds to thicker Santa Rosa and slightly thinner

Dewey Lake. I interpret this as due mainly to more localized erosion of the Dewey

Lake prior to Santa Rosa deposition.

Figure 6

Elevation on Top of Dewey Lake Formation


17



(Geology ofPiezometer Holes)

t.-----""1.,..:.-.·-··-··-·1.,.1•..-.•;... ..-•.-..~......-..':' ..-•.-...-•.•-•.-•.-.•-..-...-.'-1~-';>-~-~~'"

exshft2. wpd

.,

1 mile--+

11 km I

WIPP Withdrawal Area

See Appendil( B

Figure 6 for details

approximate western edge of Santa Rosa Fm


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(Powers; October28, 1997)

At the facilities location, concentrated data from the PZ drillholes and B series

permits more detailed reconstruction of the surface of the Dewey Lake that can be

compared to the broader site area information.

The PZ data alone (Figure 7) indicates a northward slope across this limited area.

The exception is the point at drillhole PZ 12 at the south central part of the map with an

elevation of 3344. While a re-examination of the drillhole log data indicates th,e original

N

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exshft2. wpd

Figure 7

Elevation of Top of

Dewe Lake Formation


"",,:::a..',

e "S"' -e.' $

, - ... -'3350

: ",,'·


_.._--.-~ ~- ~~i~---~"-~ .;

~i;j). ,

• •• .! • • 't


.. ; , j

18

(Geology ofPiezometer Holes)

.. __... ~~. __L ..._.... --11N501000


• I .

. ...----1-----"- N499000

!

---+-__~_-_I--_.__._-----:----_.----_._--_.._-~-----

i i PZ D~illhole Data On~

. . See ~ppendix B Figure b& 7

for drqlho/e locations arid detail

. Z I I. I contour interval iSiS It

N498000

i-P Hoes' , 100011 '

-.__.._..;.. :.._Oth~pril!!!Q!$-.------.--• ..__ , N497000

. , , J :t

: ,.Exhaust Sha~ !I 250 m II

• i !- Other Shafts i ! Grid is NM State ,Plane


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• • •




(Geology ofPiezG'meter Holes)

"pick" is consistent with the data, it is also very possible that the contact could be as

high as 3359 ft (depth of 47 ft). Cuttings and core from the claystones and siltstones of

this zone are not always clearly diagnostic (see, for example, AIS mapping; Holt and

Powers, 1990). This datum is not being modified here; no conclusions of this report

have been based on this single point.

N

t

Combining the PZ and B series data (Figure 8) reveals the same pattern aGross the

facilities areas. In addition to the apparent anomalously low value at PZ 12, B 38

-----..-


exshft2. wpd

- •..

Elevation of Top of Dewey Lake Formation


- .

"


••



Figure 8

~..!'~_..!.!.-...........40'__...l'L-__'~ 3350

.,


• PZ Holes ,

.. _.gther DriliholE!s

• Exhaust Shaft

• Other Shafts

19

See AppendiX B

Figure 8 for details

contour Interval 1810 ft

f 1000ft I._

I 250m I

§ 8

00

1B

CD

W

Grid is NM Slate Plane

ffi

.. N501000

- N500000


•. N499000

N498000

. - N497000


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appears to have an anomalously high value of 3386 ft. The broader pattern (Figure 6)

is that the surface of the Dewey Lake is becoming deeper to the east, toward P 2 and

H15. The drill log of B 38 doesn't permit another interpretation of the data.

Santa Rosa Data

(Geology ofPiez""".terHoles)

A map of the thickness of the Santa Rosa (Figure 9) displays a single trend of

thickening to the northeast. The west-southwest half of the map is not known to have

N

Thickness of Santa Rosa Formation

------_..........-....------,----......,

t


.. '.

contour interval is 50 ft

,-..o-

I

1__-1

..... . -...-

Figure 9

____-+:

-~-- :.

, • .

50

~\~ ...

\Ii'>

I 1mile f

~

I WIPP Withdrawal Area

S"" App1'9ndlx B

Figure 9 for Details

approximate western edge of Santa Rosa FrTI

exshft2. wpd 20

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(Geology ofPiezometerHoles)

Santa Rosa, and an erosional edge of the Santa Rosa has been inferred basnd on

drillhole locations and approximate gradient of thickness changes in the Sant;~ Rosa.

Combined with the elevation map on top of the Dewey Lake, the Santa Rosa

thickness indicates modest localized erosion and fill of the deepened area.

Elevations on top ofthe Santa Rosa (Figure 10) do not reflect regional structure

trends. The elevations slope downward to the southwest toward the erosiona I edge of

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Figure 10

Elevation of Top of Santa Rosa Formation

t ~~~:---.

. ~--- .

..

..

: :•·

_._~


• •·• • •:

- _..."

·,•·•• •


r1

LJ


contour interval is 25 ft

..... . .....


WIPP Withdrawal Area

1 mile -I

A

See Appendix B

Figure 10 for delalls

approximate western edge of Santa Rosa Fm

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exshft2. wpd

21


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(Powers; October28, 1997)

(Geology ofPiezometerHoles)

the formation from a high area near the northeast corner of the map. Across the

northern edge of the map, the top of the Santa Rosa drops off more sharply.

Across much of the map area. Gatuiia erosion of the Santa Rosa was fairly uniform

across a planar surface. At the facilities location in the center of the map, a

concentration of data causes some more abrupt contour changes. A modest valley

trends approximately east from the facility areas, mirroring modern surface topography.

Within the facility area, the top of the Santa Rosa can be interpreted in mOff3 detail

by considering the PZ and B series data. Two maps have been constructed, and they

show very similar patterns. One map (Figure 11) uses the PZ and B data that are

explicit; for the second map (Figure 12), I have inferred some Santa Rosa valUllS where

the original report (Sergent. Hauskins & Beckwith, 1979) did not include an

interpretation of the top of Santa Rosa.

These two maps generally show that the top of the Santa Rosa declines to the

southwest. Several drillholes from the area of the exhaust shaft to the southwest

outline a narrow, deeper area of the contact between the Santa Rosa and overlying

Gatuiia. This is interpreted as an erosional channel on top of the Santa Rosa.

The Santa Rosa showed some characteristics that were common to most of the PZ

drillholes. Medium to coarse grained greenish gray sandstones were observed in most

drillholes in the lower part of the Santa Rosa. In addition, a zone of hard drillinl~ was

encountered near the base of the Santa Rosa. Chips from this zone effervescl3d very

little and retained integrity even when treated with strong (muriatic) acid for at 113ast 24

hours. This zone is likely partially silicified.

Gatuna Formation Data

The Gatuiia in general thickens to the south and southwest of the site facilitv area

(Figure 13). North and northeast ofthe facility area, the Gatuiia is not present, and the

Santa Rosa forms the subcrop under surficial sand and the Mescalero caliche.

exshft2. wpd 22


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- -----.-.


exshft2. wpd

--e·

-

Figure 11

~

'--·--·0--"

No inferred data

• PZHoies

°QlhEl f Drillh()les

-Exhaust Shat!

• Other Shafts

23

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(Geology ofPiezometer Holes)

Elevation of Top of Santa Rosa Formation (PZ & B Series Data)

Saa AppanrJix B

. Figura 11 for rJeta/ls

contour interval is 5 It

L 1000 flJ,

I 250 m I

Grid is NM State Plane

'"

N501000

N500000

N498000

_N497000


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October 28, 1997) (Geology ofPieze'meterHoles)

N

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Figure 12

Elevation of Top of Santa Rosa Formation (PZ and Inferred B Series Data)


"";---..:3385


~~1'"

.,,!>1


~"§>


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(Powers; Octobe,28, 1997)

(Geology ofPiez,)mete,Holes)

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t

.....----r--:..:::::o------

,-_...

I I

'-_.J

The Gatufia ranges from 19 to 31 ft thick in drillholes at the location of the surface

facilities (Figure 14).

. ... -..

.'

...."

.'.'.'.'

•........•......•.•..~....

contour interval is 10ft

Figure 13

Thickness of Gatuna Formation

- ;. ---,

...•.. ~

.....•.. :

" "

I I WIPP Withdrawal Area

....,.... approximate erosional edge of Gatuna

The surface of the Santa Rosa was eroded by drainage 'to the

south and southwest before the Gatufia began to accumulate in this area. Thinner

Gatufia under the western area of the surface facilities is likely due to more recent

erosion and erosion before the Mescalero began to form.

exshft2.wpd

25

• I

·0. _

_••~........ _.. -_!•. _,-~--_,L._

°0 j; •

.••... ~

'.

'. ,

'. .

\" i

,,··-----l-

...

!:

: j;

.' .

... .

..··..···~.u. 0 .... :"

.;- ~

, .

_. ,"" L__.! • ,,_. _ "_~.__ :.,,_~ _

I


\. .

'.

\····..:T22S

, ._--._- •. -~._.,,'---


1 mjle -I

~

See Apprenclix B

Figure 13 for details


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Figure 14

Thickness of Gatuna Formation


-

"

• • ••

- --- .

Data from PZ, WIPP 21,

& ERDA 9 Drillholes

• PZHoies

."gth.erDri11holes.

"Exhaust Shaft

" Other Shafts '

J

(Geology ofPiezometerHoles)

See Appmdix 8

Figure 14 for details

contour interval Is 5 ft

1000 ftn.J

'I 250m I

Grid is NM SlalePlane


N501000

N500000

." N499000

..... N498000

.... N497000

It is clear from drilling logs of the B series holes that the contact between G;~tuna

and Mescalero caliche for that work was distinguished differently from the currtlnt study

and from most of the other site drillhole logs. In the B series drillholes, the Me!lcalero

was continued downward through the zone where carbonate dominated or was at least

quite significant. The Mescalero is commonly between 10 and 20 ft thick, as

differentiated by this criterion in the B holes, The Mescalero is about 3 ft thick in other

studies as well as for the PZ holes because the Gatuna is "picked" at about the first

exshft2. wpd 26


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Mescalero Caliche Data


3405

Figure 15

Elevation of Top of Mescalero Caliche


P21

. '\ .


--~.: D~'_Pz&B

~... __ :S~:;:::L

• Exhaust Shaft

,• Other Shafts


j

.~ \


(Geology ofPiezometerHoles)

identifiable Gatutia sandstone, The B hole data are not equivalent to PZ data, they

were not used to construct the map.

The Mescalero is generally present across the site and is noted in basic da'ta

reports for various drillholes. Only the elevation map of the top of Mescalero fClr the

vicinity of the site facilities was constructed (Figure 15). Data from the B holes as well

as current drilling are comparable.

N

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exshft2. wpd 27

See Appendix B '

Figure 15 for demUs

: contour interval Is 5 ft

' 1000 It l

I

.n!

N501000

N500000

..\~.N499000

• '?, '?, ",

~ 'b ~.

'"

. N498000

.......-___ -. L __.~_ N497000

I 250m Ii

Grid Is NM State .Plane


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(Powers: October 28. 1997)

As expected, Mescalero data generally conform to the topography of the area at the

site, rising to the east and north. The most dramatic feature is an elevation low around

3 drillholes of the B series about 200 ft southeast of the exhaust shaft. This

corresponds to a topographic low with more dense vegetation observable on aerial

photos (Figure 16) taken before development of the surface facilities at WIPP.

Figure 16. Aerial photo (10/5/76) of central WIPP site. Scale 1:24000. Arrow Ilear

center points to dense vegetation at location of topographic low and low on Mescalero

caliche (see Figure 16). ERDA 9 drilling pad to left of central arrow.

exshft2. wpd 28

(Geology ofPiezoll1eter Holes}

----"'----"'.:..,-:----"'.::..:..:..:.=..:.=:-----------'------.:....;,,--'-.-_._-----------_._-------,-----,'--'-'--


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(Powers; October28, 1997)

(Geology ofPiez'>meler Holes)

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Surface Sand and Berino Soil

The surficial sediments above the Mescalero were mapped for the design Htudies

prior to construction. The main features of a map of thickness of this sand (BEichtel,

1979, figure 2) is a thick area that corresponds to the low on the Mescalero caliche and

thinner sands to the west and southwest. Because there are very local differe'1ces

associated with dune and interdune areas, no conclusions are based on these sand

distributions.

OTHER DATA RELATED TO PERCHED WATER

In order to better understand the various geological factors that may affect location

and distribution of the water at shallow depths under the facility, I examined re'~ords for

other information that may bear on this problem. While these data are neither as

precise nor as directly relevant as some of the recent drilling data, they are he',pful in

understanding broader patterns. The drilling for the potash tests (Jones, 1978) is used

as the data base because it provides a reasonably consistent data set with respect to

drillhole logging techniques, drilling methods, and descriptions. Some of the other

WIPP drillholes near the WIPP site supplement the data from the potash drilling.

Long study of the WIPP site consistently demonstrates that the rocks abOVEl the

Rustier are not saturated, though apparentlyirregular zones of perched water have

been encountered. As porosity is a necessary factor for perched water, I examined

phenomena that may signify porosity zones in the shallow subsurface. Examples are

reports of cementing minerals, levels of drilling fluids during geophysical logging, loss

of circulation, and resistivity changes.

Presence of Sulfate in Dewey Lake

Sulfate occurs in the Dewey Lake most visibly as fillings of fractures (e.g., Holt and

Powers, 1990). In addition, Holt and Powers (1990) reported a cementation change in

[J

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exshft2. wpd

29


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(Powers; October28, 1997)

(Geology ofPiez.)men.rHoles)

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I plotted the elevation of the uppermost reported sulfate (Figure 17) as an Hstimate

of trend of the cementation/fracture filling across the WIPP site. The map includes an

area along the eastern part of the map where the top of first reported sulfate is high,

above 3200 ft. There are also high areas in the north and western parts. A low area

trends from near the site center to the south-southwest, and there is a low based on

one drillhole at the south central edge of the map.

This map should not be overinterpreted. There is a difference of about 140 ft in the

first reports of gypsum in two adjacent drillholes (P2, H15; Figure 4) in the eas·t-central

part of the map. This is most likely a consequence of a factor such as how the drilling

was returning cuttings to the surface at any particular time. The main features are the

broad high areas and the lows along the northwest corner and south of the facilities,

and they are indicated by several drillholes rather than a single data point.

The top ofthe Dewey Lake is somewhat irregular compared to the general ,~astward

dip on underlying units. To the east and northeast, gypsum is stratigraphically higher

in the Dewey Lake. At P19, gypsum was reported in the lower Santa Rosa. West of

the site center, there are also some drillholes in which the gypsum is stratigraphically

high. To the northwest and in the south central part of the map, gypsum is

progressively lower in the Dewey Lake; at P15, in the southwestern corner of 1228,

R31 E, the Dewey Lake does not appear to have gypsum at all.

As a first approximation, gypsum in the Dewey Lake is believed to signal a vertical

change in porosity due to cementation that can retard further infiltration and rellult in

exshft2. wpd 30

the AIS at a map depth of 164.5 ft (183 ft below surface) that coincided with the

uppermost detectable gypsum fracture fillings. Though not analyzed further, Holt and

Powers (1990) suggested that the cement was probably anhydrite. The Dewl~y Lake

just above this cementation change was moist in the AIS, suggesting that the

cementation change can perch available water if it infiltrates to that depth. For this

analysis, I used reported gypsum, which is almost certainly from fracture fillings, as a

proxy for this cementation change because of the relationship in the AIS.


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(Powers; October 28, 1997)


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T23S

(Geology ofPiezometer Holes)

perched water. This change corresponds generally to a position close to but below

reports of water in the Dewey Lake in the southern part of the site area.

Figure 17

Elevation of Uppermost Reported Sulfate

t ......---......-----......--....,.

""" ..-...-..-..-..-..-.--r'-,ClCl--'

'!j"

N

../

[....(--.p~3~~ .

•·:.


: ........320


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contour interval is 100 ft

r"'--j

! I WIPP Withdrawal Area

I_.._ ......J

exshft2. wpd 31

See Appendix B

Figure 17 for details


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(Geology ofPiezometerHoles)

Fluid Level During Logging

The fluid level during logging is a function of factors such as rock permeability,

drilling techniques (including adding material to reduce loss of drilling fluids), and

adding fluid to the drillhole before logging. While there is no information about the

potash drilling that allows reconstruction of all of these factors, the methods of drilling

were the same, and the logging target was the Salado. It is less likely that. for

example, additional fluid was added to the hole during logging to maintain the level to

near the surface. As in the review of data about gypsum, trends are more likely to be

real, while a single drillhole might be atypical because of a variety of events preceding

and during geophysical logging.

The fluid level was reported explicitly for a few of the potash drillholes (Jonl~s,

1978). The neutron and density log responses for the drillholes indicate depth of water

during logging; the only ambiguous drillhole was P19.

The map pattern of fluid levels during logging (Figure 18) shows high area:3 to the

east and along the west, with a low trough trending northwest-southeast acros!! the

southern part of the site.

Along the eastern side of the map, the logging water remained close to the surface

in a position stratigraphically equivalent to the upper Santa Rosa. The high ehwation

of logging water along the western side and southwestern corner of the map is the top

of the Dewey Lake, also near the ground surface. Along the low trough, the top of the

logging water was commonly 200 to 300 ft below the top of the Dewey Lake.

Loss of Circulation/Reported Water/Resistivity Data

Along with information from the potash drilling, basic data reports for most other

drillholes in the map area were examined, and loss of circulation was indicated: at

relatively shallow depths in several drillholes (Table 2). While loss of circulaticln

indicates zones of relatively greater permeability, it is again only useful as an indicator

exshft2. wpd 32


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..-.".

........... "

'. ..... ··~15 ""

I

..

...,.. ,..."' :. -.__ 1 ••" _ __ ~. _

• • •

.'" ~

.".

"

:•·•


•,·


:

." .

Figure 18

•.........

: .. ~. ".

·'OPt Q&'; •••• _

6 ~ "..

16'& ....



··• PH

."

11· ;

: "'. '.

3tOO

3200

" '.

"T21s,

T23S

(Geology ofPiezemeter Holes)

oftrends. Drilling techniques varied for many holes, and air drilling doesn't respond in

the same manner as drilling with water or brine.

exshft2. wpd

Elevation of Drilling Fluid During Geophysical Logging

o

~

-)

contour interval is 100 ft

1"---"1

II I WIPP Withdrawal Area

33

·.

,


-. '. '.

(I .. ,Area and Type of Resistivity Anomaly (Elliot, 1977)

-..... ".... ..

.P19

"


I1 I.. See Appendix B

Figure 18 for delails

."

---_._-_.._-------~:..,---~,_ .. ,-~-'"


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(Powe",; October28. 1997)

(Geology ofPiezometer Holes)

As a number of the potash holes were drilled with air through the upper section,

encounters of water were more likely to be observed and reported. Water was reported

in the Dewey Lake from three drillholes (P1, P15, P17, noted on Figure 17) dllring

potash exploration, but none of the drillholes was completed as an observation or test

hole for this water. These drillholes are all in the southwestern part of the map. More

recently, WQSP6 (noted on Figure 18) encountered water in the lower part of the

Dewey Lake as well at a location less than a mile from P1 .

A major resistivity survey of the WIPP site was conducted in 1976 and 1977 (Elliot,

1977) as part of site characterization. Three larger areas with anomalously IO'N

resistivity were identified; they were classified as type I and II anomalies (Figure 18).

Elliot (1977) inferred that the type I anomalies, located in the northwest and southwest

corners of the studied area, were associated with a dissolution front and water. The

lobate type II anomaly is oriented northwest to southeast and was believed to reflect an

area of greater porosity. Elliot suggested that this anomaly reflects "an increa:se in

porosity or water-bearing properties of perhaps the upper Salado, definitely th,e Rustler

Formation and maybe even the lower part of the Dewey Lake Formation." AlIl'our of

the drillholes (P1, P15, P17, WQSP6) that encountered water in the Dewey La ke are in

the type I and II resistivity anomalies. [Note that the main differences between ''type I

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In principle, the change in cementation of the Dewey Lake, fluid levels during

logging, loss of circulation, and occurrences of water in the shallow subsurfaCE! should

show some relationship. The three features of cementation, fluid levels, and ICiss of

circulation (Figure 19a,b,c) (Table 2) show little relationship among these varislbles.

The maps (Figures 17, 18) are a better indicator of some trends.

exshft2.wpd 34

and II" anomalies is in the interpretation, not in the geophysical response.]

Discussion of "Other Data"

[


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(POWBrs; October 28, 1997)

c

~ 350

Figure 19

A. Logging Water vs Gypsum

100

200 300 400

Depth (It) to Gypsum

500

B. Gypsum vs Circulation Loss

:; 1===f!j~~ •. ~~-~;;;;..,..~

~'il=j::' ::::/Zl.l=~I-=l-

,~ 300-. ''''(001_. I 1./1' .

~; / , i 1

- ! ./ i-i

0250 '. I i/' ; '-

~200 ,'! I 1/1 -++"i

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S-150 e-..' 1./1

~ /

t 100./1

~ 100 150 200 250 300 350

Depth (It) to Top of Gypsum

C. Log Water vs Loss of Circulation

~ 350 C:c1::::J;~;r;dd;;~;=:X= 'l'=1

.. I ~.......~~~ i r­

aT 300 1-";" j' -r--l~al""""I""""~.v, l-l---b

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5250 1 1 1/1

"" iii 1/1

] 200 ,- '- I-r 1/1/, i

~ , I I 1/ I I 1

'S 150 --H'-+i-f--!+V-:71S.!-.,i,


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(Geology ofPiezometer Holes)

Logging fluid levels indicate that in the east and northeast of the map ama,

there are few porous zones for the fluid to leak into in the shallow subsurface,

The most striking relationship (Figure 18) is between the 3 factors of 10g!Jing

fluid elevations, areas with anomalously low resistivities for the area (Elliot, 1H77),

and occurrences of water within the Dewey Lake. All of the WIPP holes that

encountered Dewey Lake water in the southern area are clearly associated With the

resistivity anomaly. And the outline of anomaly II is very similar to the low area on

drilling fluids. The resistivity anomalies also correspond well with low elevations of

uppermost sulfate in a southeasterly trend as well as at the southwestern comer of

the WIPP site. The very low elevation of sulfate in P3 near the center of the site

doesn't correspond to resistivity anomalies. That point is anomalous with respect to

other sulfate data, and the uppermost sulfate may have been missed.

HYPOTHESIZED PERCHING ZONES ACROSS WIPP

The combination of rock types and observed moisture suggests that them are

four zones (Figure 20) from the top of Rustler that may serve as perching hori,~ons if

water infiltrates to the zones.

The lowermost perching zone (Figure 20) exists across the site because of

the relative impermeability of the uppermost anhydrite of the Rustler. It is likely only

effective around the southern and western margins of the WIPP site (e.g., P15)

where stratigraphically higher horizons are not impeding infiltration.

The next higher perching zone is hypothesized to be a cementation change

within the Dewey Lake, such as Holt and Powers (1990b) observed at the AIS. I

took the uppermost sulfate as an approximation for this cementation change based

on the AIS data. Sulfate is observed progressively higher stratigraphically across

the site from southwest to northeast, with an area corresponding generally to the

resistivity anomaly and water occurrences that roughly parallels dip. From the

exshft2. wpd

36

________________L


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(Powers; October 28. 1997)

sw

Santa Rosa Fm

'" fJl

.....

oil

.....

Mescalero

..... '" 0 ..:

'" '" -...........

caliche ~

,,'

J

Santa Rosa "

~ \' \\\~"g"

silicification

Fm

.... Ci"

.. , ••••• \\01'

.. 1'\8

8 .' a(t\8

C h811Q .'

~atUria

C81l18~18'/ \.8~.~.,"~e\O'"

'11 \ 08 .,.....' 0(\ e

I I I" 1t

\ • I • • I t I , , ~ • • • 1i

,,.. ·ot'l Dewey Lake Fm

Top Rustler

anhydrite

Figure 20

Diagrammatic Representation of Perching Zones

Hypothesized Across the W1PP Site

Rustler Fm

middle of the site to the east. this perching zone may be less involved as overlying

zones reduce infiltration, At the site center. this perching zone appears also to

have affected water infiltrating from surface halite tailings piles. considering thla

report of a second wet zone in the AIS.

Around the WIPP surface facilities, we encountered a hard drilling zone clr

zones in the lower Santa Rosa in association with the shallow water. As the

uppermost Dewey Lake was clearly dry in several PZ drillholes. the finer grain1ad

siltstones and claystones of the Dewey Lake likely combined with indurated lower

Santa Rosa to create a perched zone.

(Geology ofPiezcmeter Holes)

The surface sands above the Mescalero caliche are very commonly damp. as

was noted both during our drilling program for the PZ holes and for the design

studies (B series drillholes). This moisture from surface precipitation ordinarily only

infiltrates to about the level of the Mescalero; this is the source of this particulalr

unit. Well formed Mescalero will impede infiltration locally. but it is unlikely to form

exshft2. wpd

37

NE

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(Powers; Ootober 28, 1997)

(Geolo9Y ofPiezometer Holes)

a strong perching zone. Ifwater ponds frequently in a area, the eventual result will

be to dissolve the carbonate and move it deeper through infiltration. Though I list

the Mescalero as a potential perching zone, it would only be a short term barril~r

from a geological perspective.

CONCLUSIONS

Water encountered during drilling of the PZ holes appears to be restricted to

the lower Santa Rosa. Sandstones in this zone are commonly fine to coarse

grained and quite porous. While some drillholes show thicker greenish-gray

sandstone at about this level, the saturated sandstone.in other drillholes is

generally brown. One characteristic of the lower Santa Rosa is hard drilling zones,

and chips from these units have little carbonate. There is likely some silicification.

The greenish-gray reduction and silicification are undoubtedly ancient features and

are unrelated to the water currently at this level. The water is perched on the upper

Dewey Lake, which was clearly dry in several of the drillholes.

The Santa Rosa also includes interbedded siltstones and claystones that

appear variable in thickness and distribution, though rotary drilling through the

Santa Rosa in most drillholes limits estimates of the thickness and extent of those

less permeable intervals of the Santa Rosa. Cores from some of the drillholes show

relationships and variation consistent with fluvial depositional environments

interpreted for the Santa Rosa. These zones will affect estimates of the saturated

thickness and fluid volume in the saturated zone.

Review of shaft data and facility design drillholes demonstrates that the Santa

Rosa under the site facilities area was not saturated through 1984. The water

encountered here postdates 1984, and the sodium chloride content shows that at

least some infiltrating water contacted surface salt piles or other sources of salt at

exshft2. wpd 38


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(Geology ofPiezometerHoles)

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WIPP. By 1988, the AIS had wet zones with salt effloresence in the Santa Rosa

and also the Dewey Lake.

Less precise data about sulfate cements, fluid levels during logging, loss of

circulation zones, and resistivity anomalies were reviewed as guides to broadllr site

characteristics to explain the shallow water at the site facilities. There are likely

several perching zones (uppermost Rustler anhydrite, cement change in DeWE!y

Lake, silicificationlinduration of lower Santa Rosa, and, temporarily, the MescCllero

caliche) that are involved at different locations and to differing degrees across the

site, depending on the geologic history of erosion and exposure.

To the south and west of the area investigated during this stUdy, the Santa

Rosa pinches out due to erosion prior to Gatufia deposition. If the shallow water in

the Santa Rosa moves in that direction, the Santa Rosa will cease to be a perc:hing

horizon, and the water will seek the next perching horizon, which is most likely the

cementation change in the Dewey Lake.

exshft2. wpd 39


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(Powers; Ootober28, 1997)

Bachman, G.O., 1974, Geologic processes and Cenozoic history related to salt dissolution in

southeastern New Mexico: Open-File Report 74-194, US Geological Survey, Denver, CO.

Bachman, G.O., 1976, Cenozoic deposits of southeastern New Mexico and an outline of the histllry of

evaporite dissolution: Journal of Research, US Geological Survey, v. 4, no. 2, p. 135-149.

Bachman, G.O" 1980, Regional geology and Cenozoic history of Pecos region, southeastern New

Mexico: Open-file Report 80-1 099, US Geological Survey, Denver, CO.

Bachman, G.O., 1985, Assessment of near-surface dissolution at and near the Waste Isolation Pilot

Plant (WIPP), southeastern New Mexico: SAND84-7178, Sandia National Laboratories,

Albuquerque, NM.

Bachman, G.O., and Machette, M.N., 1977, Calcic soils and calcretes in the southwestern United

States: Open-File Report 77-794, US Geological Survey, Denver, CO.

Bechtel National, Inc., 1979a, Soils design report - volume I. Plant sile near-surface structures: Doc.

No. DR-22-V-Ol, Bechtel National, Inc., San Francisco, CA.

Bechtel National, Inc., 1979b, Geologic data for borehole B-25: Doc. No. 22-V-51 0-2, Bechtel Neltional,

Inc., San Francisco, CA.

Chugg, J.C., Anderson, G.W., King, D.L., and Jones, L.H., 1971, Soil survey of Eddy area, New Mexico:

Soil Conservation Service, US Department of Agriculture, Washington, DC.

Elliot, C.L, 1977, Evaluation of the proposed Los Medafios nuclear waste disposal sile by means of

electrical resistivily surveys, Eddy & Lea Counties, New Mexico: Elliot Geophysical Company,

Tucson,AZ.

Holt, R.M., and Powers, D.W., 1986, Geotechnical activilies in the exhaust shaft, Waste Isolation Pilot

Plant: DOE-WIPP 86-008, Department of Energy, Carlsbad, NM 88221.

Holt, R.M., and Powers, OW., 1988, Facies variabilily and post-deposilional alteration wilhin the

Rustler Formation in the vicinily of the Waste Isolation Pilot Plant, southeastern New Mexico:

DOENVIPP 88-004, US Department of Energy, Carlsbad, NM.

Holt, R.M., and Powers, OW., 1990, Geologic mapping of the air intake shaft at the Waste Isolation

Pilot Plant: DOENVIPP 90-051, Department of Energy, Carlsbad, NM 88221,

Intera, 1997, Exhaust shaft hydraUlic assessment data report: DOENVIPP 97-2219, Department (If

Energy, Carlsbad, NM.

Jones, C.L., 1978, Test drilling for potash resources: Waste Isolation Pilot Plant sile, Eddy CounlJr, New

Mexico: Open-file Report 78-592,2 vol., US Geological Survey, Denver, CO.

Kennedy, J.F., 1997, The Pleistocene Mescalero caliche of southeastern New Mexico: M.S. Thesis,

New Mexico State Universily, Las Cruces, NM.

McGowen, J.H., Granata, G.E., and Senl, S.J., 1979, Deposilional framework of the Lower Dockum

Group (Triassic): Report of Investigations #97, Bureau of Economic Geology, Austin, Texas, 60

p.

Powers, OW., 1993, Surficial units and inferences of stabilily, Sand Point Sile, Eddy County, New

Mexico: NMBM-OFR-0418-D, New Mexico Bureau of Miles and Mineral Resounces, Socona, NM

(dated 03/23/93).

Powers, OW., and Holt, R.M., 1993, The upper Cenozoic Gatuna Formation of southeastern New

Mexico: in Geology of the Carlsbad Region, New Mexico and West Texas, John W. Hawtey and

others, eds., 44th NMGS Fall Field Conference Guidebook, New Mexico Geological SocielJr,

Socorro, NM, p. 271-282.

Powers, OW., and Holt, R.M" 1995a, Gatuna Formation (Miocene to Pleistocene) geology and

paleohydrology: IT Corporation report prepared for Westinghouse Electric Corporation, 66 I~. (to

be published as a SAND report)

exshft2.wpd

REFERENCES CITED

40

(Geology ofPiezometerHoles)


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(Geology ofPiez"meterHoles)

Powers, D.W., and Holt, R.M., 1995b, Regional geological processes affecting Rustler hydrogeology:

IT Corporation report prepared for Westinghouse Electric Corporation, 209 p. (to be published as

a SAND report)

Powers, OW., Martin, M.L., and Terrill, L.J., 1997, Geology across Nash Draw as exposed in t"'~ EI

Paso Energy pipeline trench: consultant report prepared for Westinghouse Electric Corpc1ration,

27 p.

Rosholt, J.N., and McKinney, C.R., 1980, Uranium series disequilibrium investigations related to the

WIPP site, New Mexico, part II: Uranium trend dating of surficial deposits and gypsum sprng

deposit near WIPP site, New Mexico: Open-file Report 80-879, US Geological Survey, Denver,

CO..

Sandia [National] Laboratories and US Geological Survey, 1980, Basic data report for drillhole WIPP

21 (Waste Isolation Pilot Plant - WIPP): SAND79-0277, Sandia National Laboratories,

Albuquerque. NM.

Schiel, KA., 1988, The Dewey Lake Formation: end stage deposit of a peripheral foreland basin: MS

thesis. University of Texas at EI Paso, EI Paso, TX.

Sergent, Hauskins & Beckwith, 1979, Volume I. Subsurface exploration & laboratory testing. Plclnt site:

Waste Isolation Pilot Plant: Sergent. Hauskins & Beckwith, Phoenix, />\Z..

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exshft2. wpd 41

_____. . .•. ._. .~-.-,-.C-'","'~_='


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C

0 APPENDIX A

0

Field Geological Logs

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for PZ Series Drillholes

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GEOLOGIC ROCK CORING LOG

HOLEID:

0-/ LOCATION: JI/W'I/."I ;:::, ~ tin$t skff-(J)IPP

DRILLING DATE:

EXCAVATION DATE: NORTHING:

Mn/11

DRILUNG DIRECTION: 1blJ 111 DRILL METHOO: EAsTING:

DRILL MAKE/MODEL:

I COLLAR ELEVATION:

"

HOLE OIAMETER: :l'r,,"lffiv (IN) I HOLE DEPTH: tl1.S- (FT) I DRILLING CREW: (;;,to~.h

..

LOGGED BY: ])11)' YOfll~

...

III

::1: .......

::I ~j;~ 0 I-

..

:>

z 0

0::

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:> .. 0",

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DATE:

&17.:z,1 q=l- SCAI:EUI t~/J ~ J fb SHEET I OFy

0 fj (I: DESCRIPTION REMARKS

5

/1..,;, .1..,; ~"J.

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DRILL MAKE/MODEL

GEOLOGIC ROCK CORING LOG

DRILLING DATE; 617.'JJ ,. DRILL METHOD; EASTIN'i:

I COLLAR ELEVATIOIl:

HOLE DIAMETER: ¥~"f~, (IN) I HOLE DEPTH: 6t S- (FT) I DRILLING CREW: 't!o.o".}t!J~

LOGGED BY: 1'tIJ'JJ ndJ


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GEOLOGIC ROCK CORING LOG

HOLE ID:

Ve. \ LOCATION: j),,; E~/w"dSiu/I

,

DRILLING DATE:

DRILUNG DIRECTION:

DRILL MAKE/MODEL:

1.(141.1:) E XCAVATlON DAlrE: 101z,


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GEOLOGIC ROCK CORING LOG

HOLE 10:

n-/ LOCATION: A), d ;::" /M,j~f

'" ~~~ 0 t- §

gzft

0 a. 0

DESCRIPTION REMARKS

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HOLE 10: Pl-z LOCATION: / ••1-"1 ;:,1. j rL/f i


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HOLE 10: Pe- 2- LOCATION:

E4~/.1 E~It_.I.,J../t

DRILLING DATE:

(;/1.'I!q7 - (PI LS!fr

EXCAVAnON DATE:" NORTHING:

DRILLING DIRECnON: u.u~ DRILL METHOD: 4//,,4'/~ ",,~/S/JN'f EASnNG:

DRILL MAKE/MODEL: v I COLLAR ELEVATIO~I:

HOLE DIAMETER: ;'~Jirn (IN) I HOLE DEPTH: r;;:; (Fl) I DRILLING CREW:

LOGGED BY: OW HJw~~ DATE:

WI.'l/H· iP/l.SI! 'I

w CD '" ""

ll!~_

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~z a DESCRIPTION REMARKS

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