SDMS Document ID Tin ii i

2000255

IS&R/Car r Fork Remedial Investigation Site Groundwater Conceptual Model

By Order of: United States Environmental Protection Agency Unilateral Administrative Order CERCLA Docket No. 08-2001-12

Prepared by:

ANDERSO N ENGINEERIN G COMPANY , IN C

977 West 2100 South Salt Lake City, UT 84119

(801)972-6222

J BR Consultants Group

1841 East Fort Union Blvd Sandy , Utah 84121

Or. Alan Mayo, Mayo & Associates Brigham Youn g University Provo, Utah

Prepared for:

Atlantic Richfield Company

307 East Park Street, Suite 400 Anaconda, MT 59711

March 12, 2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

TABL E OF CONTENT S [

SECTIO N

1.0 INTRODUCTION.............................................................................................................!

1 .1 General Site Descriptio n ......................................................................................1

1.2 Regulator y ...........................................................................................................2

1.3 Reclamation Histor y ............................................................................................2

1.4 Plannin g Team ....................................................................................................2

2 .0 CURRENT CONCERN S ......:..........................................................................................3

2.1 Problem Statemen t .............................................................................................3

2.2 Previous Groundwater Investigation s ..................................................................4

3 .0 SIT E GROUNDWATER CONCEPTUAL MODEL ...........................................................6

3.1 Geolog y ...............................................................................................................6

3.2 Hydrolog y ............................................................................................................7.

3.2.1 Regional Ground Water Hydrolog y ..........................................................7

3.2.2 Site Subsurfac e Hydrolog y ......................................................................8

3.2.3 Recharge .................................................................................................8

3.3 Groundwater Chemistry .....................................................................................10

3.3.1 IS&R/Carr Fork Area ..............................................................................10

3.3.1.1 Regional Groun d Water Hydrolog y .............................................10

3.3.1.2 Groundwater Chemistr y IS&R Stie & Lincol n ............................. 11

3.3.2 Erda Area ...............................................................................................12

3.4 Potential Chemical Sources and Pathways ........................................................13

3.4.1 IS&R/Car Fork Vicinit y ...........................................................................13

3.4.1.1 Min e De-watering & Pine Canyon Water Settlin g Ponds 13

3.4.1.2 Slag Pile ..........................................................................15

3.4.1.3 Pine Canyon Landfill .......................................................17

3.4.1.4 Elto n Tunne l ....................................................................18

3.4.1.5 Carr Fork Tailings ..........................................................20

3.4.1.6 IS&R Tailing s .................................................................22

3.4.1.7 Waste Isolatio n Cel l ........................................................23

3.4.1.8 Summar y ........................................................................24

3.4.2 Erda Area ..............................................................................................24

4.0 DATA GAPS ................................................................................................................26

4 .1 Existin g Well s and Monitorin g Data ...................................................................26

4.2 Pine Canyon Drainage ......................................................................................28

4.3 Erda Nitrate ........................................................................................................28

5 .0 DECISION RUL E AN D SCHEDULIN G INFORMATION ...............................................29

5.1 Develop a Decision Rule ...................................................................................29

5.2 Specif y Limit s on Decision Errors ......................................................................30

5.3 Optimize Design ................................................................................................30

5.4 Schedul e ...........................................................................................................30

Atlantic Richfield Compan y i March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

6.0 REFERENCE S ............................................................................

LIST OF TABLES Table 1-1 Definition s Table Tabl e 1-4 Plannin g Team Table 3-1 Field Soi l Permeabilities Tabl e 3-2 Laboratory Soi l Permeabilitie s Tabl e 3-3 Groundwater Monitorin g Historical Exceedences Table 3-4 Apex Shaf t Water Qualit y Tabl e 3-5 Settlin g Pond Influen t Water Qualit y Tabl e 3-6 Settlin g Pond Influen t Nitrate 1979-1983 Table 3-7 Sla g Total Metal s Tabl e 3-8 Slag E. P. Toxicit y Tabl e 3-9 Pin e Canyon Landfil l Total Metal s Table 3-10 Pine Canyon Landfill E.P. Toxicity Tabl e 3-11 Assay Result s for Elto n Tunne l Dump Tabl e 3-12 Total Metal s Analyse s for Pine Creek below Elto n Tunne l Tabl e 3-13 Carr Fork Tailings Total Metal s Tabl e 3-14 Carr Fork Tailings E.P. Toxicit y Table 3-15 IS&R Tailing s Total Metal s Table 3-16 IS&R Tailings E.P. Toxicit y Tabl e 3-17 Potential Groundwater Impac t Sources

LIST OF FIGURES

.20

Figur e 1.1 Vicinit y Map Figure 2.1 Past Investigation s - Groundwater: IS&R, Lincoln , Figur e 2.2 Past Investigation s - Groundwater: IS&R, Lincoln , Figur e 2.3 Past Investigation s - Groundwater: IS&R, Lincoln , Figur e 3.1 Groundwater Conceptual Mode l Diagram Figur e 3.2 Geologic Cross Sectio n Figur e 3.3 Tooel e Valle y Geolog y Figur e 4.1 Existin g and Proposed Monitorin g Well s

LIST OF APPENDICES

Appendi x A Groundwater Water Samplin g Data Base

Erda Area Well s - As Erda Area Well s - Pb Erda Area Well s - Nitrate

Atlanti c Richfield Compan y March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

TABLE 1-1 DEFINITION S AECI Anaconda ARA R Atlanti c Richfield BSH W CERCLA C PM

DERR

DOOM

DQO

ERA

F I T

F S F S P

H R S

IS& R

J B R

KUC C L AP

M CL

NRC S

N P L

PA

PARCC

QA

QAPP

QCRARCRA

RD

Rl

ROD

S AP

S CM

SDWP S

SGCM

S I

site S OW

Anderson Engineerin g Co., Inc. Anaconda Copper Compan y Applicabl e or Relevant and Appropriat e Requirements Atlantic Richfield Compan y Bureau of Solid and Hazardous Waste Comprehensive Environmental Response, Compensation , an d Liability Act Critical Path Method Utah Division of Environmental Response and Remediation Division of Oil , Gas, an d Minin g Data Quality Objectives United State s Environmental Protection Agency

EPA' s Field Investigatio n Team

Feasibilit y Stud y ' . Field Samplin g Pla n prepared for the IS&R/Carr Fork site b y AECI Hazard Rankin g System International Smeltin g an d Refinin g Compan y J BR Environmental Consultants , Inc . (Formerl y Known as JBR Consultan t Group ) Kennecot t Utah Copper Corporatio n Laboratory Analytical Protocol Maximum Contaminan t Levels National Resource Conservation Service National Priorities Lis t for Uncontrolled Hazardous Waste Site s Preliminar y Assessment Data Qualit y Indicator s Includin g Precision, Accuracy an d Bias Representativeness , Comparability , an d Completenes s

Qualit y Assurance

Qualit y Assurance Project Pla n Quality Control Remedial Action Resource Conservation and Recovery Act Remedial Design Remedial Investigatio n Record of Decision Samplin g Analysi s Pla n prepared for the IS&R/Carr Fork site by AECI • Site Conceptual Model Secondary Drinkin g Water Protection Standard Site Groundwater Conceptual Mode l Site Inspectio n IS&R/Carr Fork propert y an d adjacen t properties to be investigated. Scope of Work

Atlanti c Richfield Compan y March 12, 2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

TCLP Toxicit y Characteristic Leachate Procedure I D S Total Dissolved Solid s UDEQ Utah Department of Environmental Qualit y UDW R Utah Division of Wildlife Resources USG S United State s Geological Survey U SU Utah State University W IC Waste Isolation Cell: cell where specified wastes were placed in 1986. WP Work Pla n prepared for the IS&R/Carr Fork site b y AECI

Atlantic Richfield Compan y iv March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

1 .0 INTRODUCTION

Thi s Site Groundwater Conceptual Mode l (SGCM) has been prepared as the firs t phase of the

remedial investigatio n concerning the groundwater condition s at the IS&R/Carr Fork project site. T he purpose of thi s document is to provide a framework for understandin g and interpretin g existin g

informatio n and data regardin g groundwater at or near the site. Also, it will facilitat e identifyin g areas of additional study and the need for additional or supplementar y information . Followin g the E RA data qualit y objectives format , it provides projec t background, a summary of previous data

collected an d define s the objectives of the stud y as i t pertain s to the region' s aquifers . It also

outline s samplin g an d data collectio n proposed to be conducted durin g the investigatio n to fil l data

gaps and provide informatio n sufficien t to create alternative remedies, if deemed requisite to meet

reclamatio n objectives .

1 .1 General Site Descriptio n Informatio n

T he site is located in Tooele County , Utah on the west flan k of the Oquirrh Mountain s at the

mouth of Pine Canyon , as shown on Figur e 1.1. The IS&R/Carr Fork site was home to two

separate minin g related operations , the International Smelter (IS&R ) an d Carr Fork

complex, both owned and operated by Anaconda Mineral s Company .

IS&R covered an area of approximatel y 1,200 acres on which copper, lead, and zinc ore

minin g and processin g occurred over a period of about 70 years. The site historicall y

included mine workings, a mill site, a smelter area, a slag pile , tailin g impoundments ,

settlin g ponds , an d landfil l areas. The IS&R operatio n began i n 1909 an d operated

continuousl y unti l 1972.

T he Tooel e Smelter was completel y dismantled, except for a few buildings , includin g the

main offic e building , the chemical laboratory , the general warehouse and various smal l

shops. Mos t of the remainin g smelter features were reclaimed durin g the fall and sprin g of

1986/1987, as described in the reclamation pla n (Anderson , 1986).

T he Carr Fork Milling Operation s were located on 12.5 acres withi n Pine Canyon with the

head structure and mine adit at the head of the canyon. The Carr Fork complex was

completed and began operation in Augus t 1979. It was designed to produce 45,000 to

55,000 metric tons per year of copper concentrates, with an anticipated mine life of 20

years. The flotatio n mill at Carr Fork was located in the narrow middl e part of Pine Canyon. Mill waste consisted of fine s which were disposed of on site in a new tailings pond below

t he old IS&R smelter site. A decision to shut down the mill was made in November 1981. Min e de-watering ceased

in Februar y 1985. Negotiation s for the mine were completed in October of 1985 with the

sale of selected Carr Fork propertie s to Kennecot t Utah Copper Corporation s (KUCC) . The Tooele Valley s portion s of the Carr Fork operation s an d the IS&R disturbances , were not

purchased by KUCC and were reclaimed by Anaconda in 1986. The site was vegetated

durin g the reclamatio n activities in 1986 with grasses, forbes and occasional shrubs. Atlantic Richfield continues to activel y maintai n reclaimed features . In 1994, Atlantic Richfield and the State of Utah entered into a lon g term agreement to establish the site as

a wildlife conservation easement. The Utah Divisio n of Wildlife Resources (UDWR)

Atlantic Richfield Compan y 1 March 12,2002
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IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

provides oversight of the property and has performed wildlife enhancement project s since

1994. The Carr Fork mill was dismantled and shipped off the site in 1986. Reclamation of

t he upper Pine Canyon area was completed by KUCC in 1989.

Pine Canyon is short and narrow with a distance from head to mouth of approximatel y three miles. The canyon is drained by Pine Creek with contribution s from adjacen t Pole Canyon ,

other side canyons, springs and the Carr Fork mine tunnel . The stream flow s west out of Pine Canyon alon g the northern boundary of the former smelter site unti l it infiltrate s the

ground before reaching the Atlantic Richfield propert y line. Historically , Pine Creek also

received water from the Elto n Tunnel . Thi s flo w no longer has a surface expression , as the

tunnel has been collapsed, preventin g future flow s from thi s source. Durin g operation s at

t he site, surface flow s were apparentl y larger as local resident s claim to have used the

water for irrigatio n purposes in the Lincol n area and possibl y as far away as Erda.

1.2 Regulatory

T he Utah Min e Land Reclamation Act of May 1975, required reclamation for the Carr Fork

operations. The IS&R smelter was "pre-law" and did not fall under cleanup requirements

of the Act. However, Atlantic Richfield voluntaril y included both the areas encompassed by

t he IS&R and Carr Fork operations in its reclamation work proposed in the late 1980's.

Followin g preliminar y studies conducted by various agencies, Atlantic Richfield evaluated

t he site in 1986 and prepared a reclamation plan . Upo n approval to proceed from the State

of Utah Division of Oil, Gas and Minin g (DOGM), reclamation actions identified in the pla n

were completed durin g the fall and sprin g of 1986/1987. After several phases of study from the 1980' s through the 1990's , the site was scored in

accordance with the EPA established Hazard Rankin g System (HRS). Based on the HRS

score the site was listed on the national priorit y list under the CERCLA regulations .

1 .3 Reclamation Histor y •

During the years 1986-1987, under the oversite of DOGM, Atlantic Richfield performed an

extensive reclamation at the property . The reclamation work included the removal of

remaining buildings and structures, consolidatio n of waste materials , construction of storm

water control s and placemen t of cover soil over tailin g impoundment s and smelter

operational areas.

Areas of disturbance in Pine Canyon , above the smelter site, were reclaimed by KUCC in

1989.

1 .4 Plannin g Team

T he stud y team is composed of Atlantic Richfield Compan y managers and technical support

professionals . The support personnel are composed of engineers, scientist s and

technicians familiar with the environmental assessments of mine operations , reclamation ,

groundwater, water qualit y and hazardous waste handling. The regulatory agencies

involved include the U.S. Environmental Protection Agency , Region 8 and the State of Utah

Atlantic Richfield Company 2 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

Departmen t of Environmental Quality , Division of Environmental Response and Remediation . Tabl e 1-4 shows the plannin g team by positio n and responsibility .

TABLE 1-4 PLANNIN G TEA M

Organization

E RA

BOR

State of Utah

Atlanti c Richfield Compan y ANDERSON Engineerin g Co., Inc. ANDERSON Engineerin g Co., Inc. J B R

May o & Associates/ Brigham Youn g University

Position Project Manager On Site Coordinator

On Site Coordinator

Project Manager DERR Coordinator

Project Manager

Project Manager

Senior Project Engineer

Project Engineer

Geochemist

Name

Joshua Knight

Richard Thalman n

Michael- Storck

Chuck Stilwell , P.E.

Steven D. Anderson , P.E. Kevin B. Cosper, P.E.

Brian Buck

D r. Alan May o

2 .0 CURRENT CONCERN S

2 .1 Problem Statemen t

T he IS&R smelter operated at the site near Tooele , Utah from 1909 through the mid-1970' s when it was shut down and eventuall y dismantled. Inheren t in the smeltin g process is the

concentratin g of metal s for further refining. Elevated metal s concentrations have been

foun d on the surface at the site by investigation studies since closure of the facilities . In

additio n to surface investigations , water and groundwater studies have also been

completed. The most comprehensive studies of surface and groundwater were completed

in 1984 and 1985 by Anaconda,.the EPA and their contractors.

Investigatio n results have had limited indication s which show limited areas of elevated

constituents of concern. Tabl e 3-3 provides a summary of area monitorin g well results which have historicall y exceeded groundwater MCL's . As part of the IS&R facility and later as part of the Carr Fork operation , minin g activities in

t he Oquirrh range have been conducted. This investigatio n wil l evaluate previous data

from area sampling, regional geologic formation s and area hydrolog y to determine if

samplin g results of concern can be attributed to smelter operation s or if conclusions cannot

be made at thi s time, what data gaps exist so that gaps may be filled, and more conclusive

Atlantic Richfield Company March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

determination s can possibl y be made.

2 .2 Previous Groundwater Investigation s

A number of organization s and agencies have conducted groundwater studies at and near

t he IS&R/Carr Fork site. The followin g paragraphs summarize previous samplin g activities

on the site. A summary of the groundwater analytical result s compared to MCL standards

collected durin g previous investigation s are contained in Appendi x A. Result s of water

qualit y analysi s for As, Pb and Nitrate are presented by well location in Figure s 2.1, 2.2 and

2.3.

Thomas (1946) described the groundwater in Tooele Valley , discussed the geolog y of the

valle y and adjacen t mountains, and studied some aspects of the hydrolog y of the valle y in

detail .

Gates (1965 ) prepared a discussion of the groundwater budget , groundwater usage and

future potential for the groundwater of the Tooele Valley .

T he USGS prepared a publicatio n in 1981 (Razem and Steiger, Technical Publicatio n No.

6 9) which presented the groundwater condition s in the Tooele Valle y from 1976 through

1978. One of the conclusions of the report in regard to water qualit y was that the

groundwater near Pine Canyon tended to have more elevated sulfat e concentrations ,

possibl y due to discharge from the Elton Tunne l or the Carr Fork mine. This report also

discusses the water budget in the Tooele Valle y from 1963 to 1978.

Wahler (1977) presented findings from aquifer testin g performed on the Boys Ranch well

a nd informatio n about the aquifer and groundwater regime at the Site . T he transmissivity of the aquifer was report to be possibl y as high as 844,000 gpd/ft. The

average thickness of the aquifer was reported to be 500 feet . The unsaturated zone

overlyin g the aquifer within the tailings pond area averages 600 feet in thickness. Wahler (1978) presented finding s of a stud y performed in preparatio n for tailings pond management

at the Carr Fork Project . Tailing s and soil s were also tested for geotechnical characteristics.

Ryan et. al. (1981 ) advanced a test boring (Test hole 8) about two miles northeast of Tooele

and about two miles west of Pine Canyon. The test hole was cased to 134 feet and was

drilled and logged to a depth of 1,511 feet . Based on the neutron log, the sediment s did not

appear to be saturated unti l 416 feet below the lan d surface. The resistivity log indicated

water bearing sand and gravel from 416 to 856 feet with only occasional clay zones present. An exceptionall y thick gravel zone occurs from 604 to 760 feet . Fresh water was present

from 426 to 950 feet below which depth water qualit y naturall y deteriorates.

Hebdo n (1984) , working for the Utah Division of Environmental Health , Bureau of Solid and Hazardous Waste (BSHW), now the DERR, presented the finding s of the SI performed at

t he Tooele Smelter and Anaconda - Carr Fork Operation to the EPA. Durin g the site

investigation on Jun e 30, 1984, BSHW personnel collected two groundwater samples ,

includin g a sample of the sprin g emanatin g from under the slag pile , and one from the tap water at Boys Ranch (source was reported to be sprin g water). It was reported that the

Atlantic Richfield Compan y ' 4 March 12,2002
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General Notes

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A DSOEPANCr IN TABLE DATA.

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09/14/99 0.0032

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/ Genera

l Nates

LEGEN D

WELL WELL

J~ NUMBER I— SAMPLE

By-^-xx/xx/xx xjcx

$ f) \ NITRATI ^J I * HTOATt f 1 — COMCCN- [_ WELL SAMPLE TRATION LOCATION (mg/L)

NOTE: WILL NUMBERS CORRESPOND TO TABLE B-l

NOTE: DATA SHOWN ON DRAWMO IN RED INDICATE

S

A DISCREPANCY IN TABLE DATA.

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General Nates

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FIGURE 2.3
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

sample s were collected under the supervision of the BSHW qualit y assurance officer ;

however, detail s of the sample collection were not included in the Site Inspectio n report. T he 1995 DERR site investigatio n report states (see Sectio n 2.5) that the qualit y assurance

data for thi s 1984 site inspectio n analytical results were "absent or very poor." Sample s

were submitted to the Utah State Health Laboratory for analysis . Water sample s were

analyzed for total metals , major cations/anions , an d nutrients. Groundwater sampled from

a sprin g seepin g out from under the slag pile had MCL exceedences for lead and cadmium

concentrations. All tested constituent s withi n the tap.water sampled at the Boys Ranch

. facility (source of water stated as a sprin g to the east in the Oquirrh Mountains ) were below

both the primary and secondary drinkin g water standards .

EPA' s FIT subcontractor Ecology an d Environment , began working at the Site i n 1985. The y collected a groundwater sample from a Pin e Canyon well up gradien t of the site. The

groundwater sample was analyzed for total and dissolved metal s as well as sulfat e and

cyanide concentrations. The FIT report stated that water results were given a QA review

at the EPA Region VIII laboratory prior to being reported. Constituent s tested i n the

groundwater were reported below the primary and secondary drinkin g water protectio n

standards .

J BR conducted a groundwater investigatio n as part of their preparatio n for reclaimin g and

stabilizin g the Site (JBR, 1986). Between Augus t an d December, JBR collected three sets

of samples from the four deeper groundwater well s located north and west of the Site and

a sprin g at the base of the slag pile . The well s sampled by JBR included GW-1 (16-inch Boys Ranch Well), GW-2 (Bruce Sager Well), GW-3 (6-inch Boys Ranch Well), and GW-4 (Tailings Dam Well). At that time the spring, GW-5, was flowin g from the base of the slag

pil e to the northwest of the pile . The sample collected from the existin g sprin g at the base

of the slag pil e was reported to exceed the Primary Drinkin g Water Standard , Maximum Contaminan t Level s (MCL) for cadmium an d lead, an d the SDWPS for sulfat e an d TDS.

Stolp (1994) discusses the increased need for groundwater resources in the Tooele Valle y

as developmen t increases.

Sadik-Macdonald (1997) presented the finding s of a second SI completed at the Site in

1996. The study was conducted by the DERR for the EPA. The study included samplin g

o f four wells; AC-GW-01 ( a USG S Wel l i n Lincoln) , AC-GW-02 (Sagers Well , JBR' s GW-02) , AC-GW-03 (Kennecot t Property Line) , AC-GW-04 (Boys Ranch 6" Well , JBR' s GW-03). A filtered sample and an unfiltered sample were collected from each of the wells . The sample

collected from the 6" Boys Ranch well reported arsenic concentrations above the primary MCL. These result s for the Boys Ranch well were flagged because spike recovery

percentage (69.5%) was below the acceptable range (75% -125%).

T he USGS published another report in 1997 (Steiger and Lowe, Water Resources Investigation s Report 97-4005) which presented the result s of a stud y of recharge and

discharge areas an d qualit y of groundwater in Tooele Valley . The historical analytical

result s for several well s located near the site and in and around Erda were presented. The

report discussed the elevated nitrate concentration s in Erda and although it did not arrive

at definit e conclusions as to the source of the nitrates , it cited the finding s of the UDEQ

study wherein elevated nitrate level s were foun d in the unsaturated zone at the IS&R site.

Atlanti c Richfield Compan y 5 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

A water right s search was conducted withi n a two-mile radius of the site boundary in 2001. T he search included both surface water and undergroun d water rights . The result s of the

research are included in the IS&R/Carr Fork Samplin g an d Analysi s Plan . T he combined groundwater samplin g and analytical results completed by both government

agencies and private consultant s has been assembled into a single data base. Some minor

discrepancies have been identified and will require attentio n as described later in the report.

3 .0 SIT E GROUNDWATE R CONCEPTUA L MODEL

3 .1 Geolog y

Tooele Valle y is in the northeast part of Tooele County , approximatel y 30 miles southwest

of Salt Lake City . See Figur e 1.1. The valle y is bounded by the Great Salt Lake on the

north and by mountains on the three other sides. The valle y floo r and associated mountain

drainages encompass approximatel y 400 square miles . The eastern border of the Tooele Valley , where the former IS&R Smelter resides, i s the north-trendin g Oquirrh Mountain s where the boundary between the valle y fil l an d the mountain s i s usuall y abrupt . The IS&R Smelter site is at an elevation of approximatel y 5400 ft above MSL on the foothill s of Clipper Ridge. Clippe r Peak at the top of Pine Canyon has an elevation of 9207 ft above MSL. The

northerly boundary of the site ranges in elevation from 5000 ft to 5600 ft above MSL.

T he Tooele Valley and the Oquirrh Mountain s to the east are in the Basin and Range Physiographic Provience (Fenneman , 1931). The Oquirrh Mountain s are, for the most part ,

rugged with sharp ridges and deep canyons. Only limited areas of flat meadows or gentle

slopin g hillside s exist withi n the range. Consolidated rock is generall y confined to the Oquirrh Mountai n area. The Oquirrh Mountain s are composed of the Oquirrh group (formation ) of late Mississippian , Pennsylvania n an d early Permian age. The predominan t

litholog y of the consolidated rock is sandstone, quartzite, and limestone with some shale

a n d dolomite (USGS 1994). The consolidated rock has experienced structural deformatio n

by faultin g (Gate s 1963). Solutio n openings may exist in limeston e alon g joints . Large

amounts of unconsolidated material are uncommon and are only foun d in the canyon

bottoms as stream channel deposit s or in the upper canyons as glacial deposits .

T he eastern edge of the valle y is characterized by shore lines and terraces of the Pleistocen e Lake Bonneville up to an elevatio n of about 5100 ft above MSL. Above thi s

elevation , there are remnants of old alluvial fan s that have been dissected by erosion as

base lake level s receded. In profil e the valle y has a concave shape with steep slope s near

t he mountain fron t (broken by terraces) and graduall y becoming flatter near the lake. The

differenc e is elevation from the upper strand lin e near the month of Pine Canyon to the

present lake level is about 1000.ft in distance and approximatel y 10 miles (Wahler 1977). Figur e 3.2 is a geological cross-section of the eastern foothill s of the valley . A map of the

surface geolog y of the valle y is presented as Figur e 3.3.

T he basin valle y i s filled with thick wedges of sediment from long-term erosion of the uplifted

mountain range. The sediment s consist of alluvial , colluvial , lacustrin e an d volcanic material s of Tertiar y and Quaternary age. These sediment s were deposited as

interfingerin g layers of clay , sand, an d gravel (USDA 1992). Some volcanic material s exist

Atlantic Richfield Compan y . 6 March 12,2002
OQUIRRH MOUNTAIN S

CONSOLIDATED ROCK '

t al depoalta mbitura of

day. sand, gravel, cobfatas

lynlcal In all borings. ANDERSO •NOINKBRtNO COMOANVN.

TOOELE VALLEY

GEOLOGY

CROSS SECTION

ERDA, LINCOLN, I TOOELE, l/TAH

-.»-

tux»a

""iWWCHJCIK

AS5H7/M

M. *

FIGUR E 3?
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

in the southeastern area of the valley . Deposit s are more coarsely grained near the surface

a nd become more dense and fin e with depth. Above the 5100-foot elevation , the old alluvia l

fan s are coarse grained with layers of clayey zones resultin g from weathering and mixin g with colluvial soil s from the steep slope s of the adjacen t mountain sides.

T he alluvia l fil l of the valle y thicken s rapidly due to normal fault s alon g the base of the

mountain front . Wahler (1977) indicates a 1800 ft depth of alluvial material s over

consolidated rock at the mouth of Elto n Tunnel . Alon g the Railroad right of way, between Lincol n and Erda, the depth of alluvial material s over bedrock is 2600 feet . Bedrock near

t he lake, at the northern end of the valley , ranges from 3500 to 7100 feet below ground

surface.

T he Occidental faul t has been mapped alon g the eastern boundary of the valle y and passes

jus t east of the smelter an d Erda area. Thi s faul t has displaced the alluvia l fil l alon g the

foothills . Geologic reports indicate that the Occidental faul t has a normal displacemen t with

upthrown side to the east. It is speculated that thi s faul t may have some influenc e on

groundwater movement but apparentl y does not act as a barrier to groundwater movement

in the area.

T wo streams which traverse the site discharge snow melt water and rainfall from Pine Canyon and Dry Creek Canyon. Pine Canyon's creek has perennial flo w due to springs

located withi n the canyon and drainage from the West Dip Tunnel . West Dip water is piped

from the tunnel in Pole Canyon into the Pine Canyon Creek.

3 .2 Hydrolog y

3.2.1 Regional Ground Water Hydrolog y

Logs compiled durin g installatio n of area well s generall y indicate that the valley - margin deposits , as described above,.are comprised of sand and gravel with varyin g

amounts of silt and clay while the deposit s toward the center of the valle y are

predominantl y silt and clay with sand interbeds. Smalle r stream channel and

colluvial deposit s locall y interfinger with the alluvial an d lacustrin e deposits . The

stream channel deposit s are typicall y well sorted and very permeable whereas the

colluvial deposit s are poorl y sorted and have low permeability . Alon g the bench areas, where the IS&R Smelter site resides, ground water occurs

under watertable condition s in the valle y margin deposit s which consist mostl y of

alluvial fan and beach material . These deposit s thicken rapidl y and are very

permeable, with transmissivities of 60,000 gpd/ft not uncommon. The ground water

in the valle y margin areas is recharged largel y by seepage of stream water and

irrigatio n water and predominantl y by subsurface flo w from the bedrock of the

mountain fronts . Recharge from direct precipitatio n alon g the valle y margins was

estimated by Razem and Steiger to be 3 percent of the annual precipitatio n falling

at these elevations . The valle y margin unconfined ground water is generall y quite

deep (+400 feet ) and moves down dip toward the center of the valle y and the Great Salt Lake. As the ground water moves into the valley , it becomes confined by the

clay-rich lacustrin e deposits , resultin g in artesian condition s throughout most of the

Atlantic Richfield Compan y 7 March 12,2002
GREAT SALT LAKE

IS4R/CAR R FORK SMELTER SIT E

ANDERSON

Between 0 and 500 feet (150 meters) of valley

fill saturated with water containing less tnan 1000 iH mg/l of dlsorved solids. Between 500 and 1000 laet (150 and 300 meters) rr-T at valley ffll saturated with water containing loss _ than 1000 mg/l of dlsotved soOds. Valle y fill saturated with water containing more

than 1000 mg/l of disotvod solids or water quality

unknown.

TOOELE VALLEY GEOLOGY

Groundwater Area Boundary as denned In USGS, Tech Pub No. 69EHOA. LINCOLN. » TOOELE. UTAH

97-06WH

4-MARO43002

A6 SHOWN

FIGUR E 33
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

valle y floo r includin g the Erda area.

3.2.2 Site Subsurfac e Hydrolog y

T he Carr Fork property is located in the east Tooele Valley ground water district . T he tw o major facilities , the IS&R Smelter site an d the IS&R/Carr Fork tailings , were located on alluvial-fa n and lacustrin e deposits . Bechtel (1977 ) described the

bulk of the unconsolidated material underlyin g the tailings area as alluvia l fan

detritus which consists of crudely stratified, poorl y to partl y sorted clay , silt , sand

a nd gravel layers. The alluvial material was estimated by Bechtel (1977) to be more

than 700 feet thick in the vicinity of the tailings . Wahler (1977 ) presented gravity

data which indicated that the thickness of unconsolidated material under the EIton Tunne l portal was approximatel y 1,800 feet . Wahler (1977 ) also estimated the

thickness of alluvium under the smelter site to be approximatel y 1,400 feet . This is

due, in part , to the location of the propert y on the down dropped sides of two major

fault systems which intersect southeast of the smelter. The surficial deposits , in the

area of the tailings , are comprised of lacustrin e fin e grained sand with interbeds of

silt and gravel. The edge of the beach deposi t is located at the base of the bluffs

about 2,000 feet to the northwest of the smelter. At thi s locatio n the lacustrin e

deposit s have a thi n edge and thicken to a depth of about 50 feet under the tailing

dam. The alluvial and lacustrin e deposit s are traversed by the stream deposit s of D ry and Pine Creeks. Much is known about the geohydrolog y of the propert y through the soil testin g and

ground water monitorin g well s drilled by Anaconda durin g operations. The 1977 Wahler reports includes data from pum p tests of the 16-inch Boys Ranch well usin g

t he 6-inch Boys Ranch well as the observation well . Thi s test indicated that the

static water level was at a depth of 575 feet and that the transmissivit y was 844,000

gpd/ft . Wahler (1977 ) estimated that approximatel y 12,000 acre-feet per year was

recharged to the watertable aquifer in the vicinit y of Pine Canyon. Potentiometric

contours calculated by Razem (Razem 1981) indicate, in general , water beneath the IS&R flow s in a northwesterly direction towards the Great Sal t Lake. Flow s

originatin g in the Oquirrhs in thi s northeast part of the valle y are bounded by the

bedrock Oquirrh mountain interface on the east and on the west by a ground water

mound formed by the much greater annual recharge (26,000 acre-feet) at the mouths of Settlemen t an d Middle Canyons .

Similar to Middle Canyon , the mouth of Pine Canyon may also have a ground water

mound created by the surface water flowin g in the canyon. Under native conditions , without the artificial flo w created by mine de-watering, the stream recedes into the

ground before the west Atlantic Richfield property line. During mine de-watering,

flo w was discharged down Pine Canyon with excess water historicall y being used

f or irrigatio n in the Lincol n and Erda area.

3.2.3 Recharge

Recharge to the aquifers is primaril y by flo w from the Oquirrh range consolidated

rock with a smaller amount by surface flo w infiltration . The potential for surface

Atlanti c Richfield Compan y 8 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

water recharge of the aquifer in the interfluvial portion s of the site was investigated

by Wahler (1977 ) who presented data from other workers (Freeze and Banner,

1970) and Isaacson et al. , 1974) to show that direct recharge via infiltration of

precipitatio n was unlikely . The y based thi s conclusion on data from soil sample s

obtained on the propert y that had average moisture contents of approximatel y 8

percent at a depth of 5 feet and field capacities of approximatel y 17 percent. This

moisture deficienc y was based on the net negative precipitatio n regime caused by

evapotranspiratio n exceeding precipitatio n by 23 inches annually . The y also

calculated that the unsaturated zone underlyin g the propert y had the retention

capacity of an average of 60 acre-feet per acre.

Another possible source of recharge was historic mine water discharge from past

mine and smelter operations . The Elto n Tunne l discharged water at an average

rate of about 5 cfs from 1941 through 1958 after which the tunnel was plugged by

caving ground. The Pine Canyon Tunne l began dischargin g mine water in 1972 and

averaged 5 cfs from 1977 to 1978 while water in the old mine workings open to the Apex Shaft were pumped out. A pumped flo w of approximatel y 3-4 cfs was

maintained durin g operation of the Carr Fork Min e unti l the pumps were shut off in

1984. Althoug h Anaconda stopped minin g activities earlier than 1984, the water

continued to be pumped in the event that metal prices recovered enough to once

again start operations . In 1984 the pumpin g was discontinued and the shaf t was

allowed to flood. Most of thi s mine water was utilized for irrigatin g and agricultural

lan d in the Lincoln-Erda area. Bechtel (1977) conducted field and laboratory

permeabilit y tests on the IS&R tailing, alluvial materials , an d lacustrin e deposit s that

covered the property . The result s of thi s test work are shown in Tabl e 3-1 and Tabl e

3-2. This data indicates that the alluvial deposit s and the wel l sorted lacustrin e

sands are moderatel y to highl y permeable, and the IS&R tailing s have a low

permeability .

Atlantic Richfield Compan y 9 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

Tabl e 3-1 Field Soi l Permeabilitie s (from Bechtel , 1977

Field Horizontal K Value s (ft/yr) Material Tailing s Lacustrin e Deposit s

Alluvia l Deposit s

N o. of Test s

2

15

11

Max.

600

11,000+

13,300+

.Min .

400

100

250

Media n

500

1,800

4,600

Avg.

500

3,350

4,870

Field Vertical K Value s (ft/yr) Material Tailing s Lacustrin e

, Deposit s

Alluvial Deposit s

N o. of Test s

2

14

11

Max.

120

5,500

2,650

Min .

80

20

50

Media n

100

700

770

Avg.

100

1,300

950

'Note: 1 ft/y r equals 1.0 xlO"6 cm/sec. Tailing s data refer to in-place IS&R tails .

Tabl e 3-2 Laboratory Soi l Permeabilitie s (from Bechtel, 1977) Material

Gravell y Sands Silt s Silt y Sands IS& R Tail s

Vertical K (ft/yr)

2 ;000lb/ft 2

surcharae

1,200

20

1,100

5

Vertical K (ft/yr)

4,000-6,000 Ib/ft 2

surcharae

300

1

550

no data

3 .3 Groundwater Chemistr y

3.3.1 IS&R/Carr Fork Site Area

3.3.1.1 Regional Groundwater Chemistry

Groundwater in the basin fil l aquifer in the Tooel e Valle y generall y ranges

between calcium magnesium bicarbonate type and sodium chloride type. In addition , some areas contain water which represents a mixture of the two

type s with sulfat e being one of the major ions. In general , water in the

southwestern part of the valle y is of the calcium bicarbonate type , and water

in the northern and middl e part s of the valle y is of the sodium chloride type. Usuall y the bicarbonate type water is representative of recharge areas,

which may be indicative of the predominatel y carbonate bedrock in the

area. The water qualit y in the recharge zone is generall y good with TDS

Atlanti c Richfield Compan y 10 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

values of 1,000 ppm or less. As water moves through the valle y fill, it tends

to pick up additional dissolved solids and become more sodium chloride rich. Water produced in the middle of the valley is of lower quality with IDS values of 1,000 to 3,000 ppm.

3.3.1.2 Groundwater Chemistry - IS&R Site an d Lincol n

Historical data collected to date, by a multitude of organizations , from

existin g well s indicate that there is minimal evidence of impact from smelter

operation s on local or regional groundwater. Well s used to monitor the

smelter operation s impact durin g operation s and since are listed below. Also listed is the number of sample records for each well which exceed MCL

standards. Tabl e 3-3 Groundwater Monitorin g Historical Exceedances

Current Nam e

6" Boys Ranch Wel l (AE-GW-1 )

16" Boys Ranch Well

(AE-GW-1 B)

Sagers Wel l (AE-GW-2)

Tailing s Dam Wel l (AE-GW-4)

USG S Wel l (AE-GW-USGS )

USG S Designation

3-4-1 2dcc-1

3-4-1 3abb-1

3-4-14abd-1

3-4-1 3cdb-1

3-4-1 Oddd-1

Prior Designation s

GW-3(JBR1985 ) AC-GW-4(DER R 1995)

GW-1 (JBR 1985)

GW-2(JB R 1985) AC-GW-2(DER R 1995)

GW-4 (JBR 1985)

AC-GW-1 (DER R 1995)

Drinkin g Water

Exceedances

( 4) As 1982 170pp b

1995 150pp b

2001 139pp b Pb 1982 220 ppb

(11 ) As 1973 210 ppb

1973 350 ppb

1974 82 ppb

2001 180 ppb Pb 1973 45 ppb

1973 33 ppb

1975 20 ppb

1977 28 ppb

N 03 1973 16.7 ppm

1973 16. 6 ppm

1974 17.5 ppm

( 3) Pb 1973 30 ppb

N O3 1974 15.6 ppm

1977 10. 5 ppm

( 0)

( 0)

Atlantic Richfield Compan y 11 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

As shown in Tabl e 3-3, there is limited historic evidence that the

groundwater in the vicinit y of the Site has been impacted. All but one of the

elevated lead level s were from sample s collected in the 1970s. The last

elevated lead level was a concentration of 220 ppb in the 6-inch Boys Ranch

well in 1982. The five elevated nitrate concentrations were also encountered

in sample s collected from 1973 through 1977. Elevated level s of arsenic

have been encountered in the two Boys Ranch well s (6-inch and 16-inch) off

a nd on from the 1970's through the present recent samplin g conducted in December 2001.

Groundwater in the area of the site and in the town of Lincol n have also

exhibited elevated level s of sulfat e (150 to 380 mg/L ) and TDS (480 to 625 mg/L) in the past. Recent sample s collected in December 2001 generall y

indicate sulfat e level s between 100 and 200 mg/L and TDS level s of 400 to

500 mg/L . •

T he source of the sulfate s in groundwater has been the subject of past

studies . Gates (1965) and Razem and Steiger (1981 ) suggested that the

elevated sulfate s in the groundwater near Pine Canyon could be the result

of mine de-watering from the ISR/Carr Fork minin g operations. A study

conducted by W.A. Wahler and Associates (1977) foun d that the dewatering could be an explanation , however suggest s alternative cause may

^ be a link between the well s containin g elevated sulfat e level s with the

j proximit y of known faults . It i s suggested that perhaps groundwater flow s

j from mineralized zones upward alon g fault s and related structures result s

 in elevated sulfate s in groundwater. Well s containin g elevated sulfat e level s

a re foun d in close proximit y to the faults .

3.3.2 Erda Area

Groundwater in the Erda area is a mixture of bicarbonate and sodium chloride

types , with some well s exhibitin g higher sodium chloride , probabl y due to heavy

local pumpin g for agricultural use, an d high sulfat e level s (greater than the

secondary drinkin g water level of 250 mg/L and up to 1,200 mg/L). There is a

general correlation between elevated chloride concentrations and elevated nitrate

level s in the same samples , which may indicate a lin k to domestic sewage sources. Conversely , when sulfat e levels are below the secondary level of 250 mg/L , nitrates

a re also below the drinkin g water standard of 10 mg/L . Level s of total dissolved

solids (TDS) have been foun d to be above the secondary drinkin g water standard

of 500 mg/L . Metalli c element s in well s in the Edra Area have always been below the MCL with

t he exception of Arsenic hits (>200 ppjft) at the Price well in 2001. Steiger and Lowe (1997) reported that seven wells , located east of Erda, had nitrate plus nitrite

concentrations greater than the MCL . Two of these well s were sampled for Nitroge n

15 isotope. The USGS foun d that the isotopic nitrogen contents were consistent

with contamination from septic systems an d cultivated, irrigated field s that have

natural organic material in the soil . However, they admittedl y did not know what the

Atlanti c Richfield Compan y 12 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

isotopic character of minin g related nitrogen was and could not definitel y determin e

i f their isotopic data rejected the possibilit y that the nitrate contaminatio n could have

come from the Carr Fork site. The Carr Fork site was mentioned as a concern

because they had been told by Hele n Sadik-MacDonald (DERR) that there were

elevated nitrate concentrations in lysimeter, non-saturated zone water sample s

obtained from the Carr Fork site.

3.4 Potential Chemical Sources and Pathways

Thi s section describes the relative potential for site and non-site sources to contribute to the

limited groundwater impact s as described in Sectio n 3.3. The Groundwater Source/Mechanism Diagram, Figur e 3.1, illustrate s the possible sources of the potential

impact to groundwater associated with the IS&R/Carr Fork operation . Also shown are the

release mechanisms by which an impact could occur. The sources and mechanisms shown

a re further described and discussed throughout the text of thi s report startin g in Sectio n

3.4.1. These sections provide an interpretatio n of the relative potential for sources and

pathway s to contribute to the limited groundwater concerns at or near the site.

3.4.1 IS&R/Carr Fork Vicinit y

3.4.1.1 Min e De-watering and Pine Canyon Water Settling Ponds

During de-watering operations of the Carr Fork Mine , water pumped from

underground workings was transported down the canyon in a concrete

flum e which discharged into the Pine Canyon Creek channel above the slag

pile . The water flowed past the slag pile to a stream diversion below the

slag where the flo w in the stream was directed into a series of settlin g ponds

northeast of the Carr Fork tailings . The settled solids were retained in the

ponds and the clarified water was discharged back to the stream channel

where it could be used for irrigatio n purposes. Pumpin g began in 1971 and

averaged 5 cfs from 1975 to 1978. Pumpin g continued at a rate of about 3

to 4 cfs unti l all pumpin g ceased in February 1985.

Anaconda records indicated that initial pumpin g and a follo w up monitorin g

sample two months later from the Apex Shaf t in 1971 produced water with

t he followin g characteristics: , "~

^_ Tabl e 3-4

Apex Shaf t Water Qualit y Parameter Arsenic Cadmium Lead Nitrate Sulfat e Zin c

pH

6 /1 2/71 (mg/l )

0.35 , N D

42.9

55.0

3,598

96.2

5.6

•8/4/71 (mg/l )

2.88

0.05

N D

2.42

3,520!

112.0

5.8

Atlanti c Richfield Compan y 13 March 12,2002
,

^

in

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0

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ac UJ

ujXI /I

POTENTIA L SOURCES

HISTORI C

CAR R FORK MIN E DISCHARG E

HISTORI C SMELTE R OPERATION WATE R DISCHARG E

TAILIN G POND S

SIT E SOI L

SLAG PIL E

LANDFILL S

SPECIA L WAST E CEL L

AGRICULTURA L FERTILIZE R

SHALLOW SEPTI C SYSTEM S

NATURA L MINERALIZATION / BACKGROUN D IN SOI L

—— I

— |

FIGUR E 3.1. GROUNDWATE R SOURCE/MECHANIS M DIAGRA M

NOTE : THI S DIAGRAM ILLUSTRATE S TH E RANG E O F POSSIBL E SOURCES . PATHWAYS . AN D EXPOSUR E MECHANISM S T O POTENTLA L GROUNDWATE R CONCERNS . RECEPT

HUMA N

RELEAS E SECONDAR Y ^EASE* ' PATHWA Y EXPOSUR E AREA SIT E SIT E UECHANK U SOURC E UFf-HAKIIS U fAIHWA T ROUT£

 RESIDENT S VISITOR S WORKER S

OR

ECOLOGICA L

TERRESTRIA L AQUATI C

I

u f LmJTP ETO

 F piMr l . PIN E

 u INFILTRATION/1 '

 u

 [GROUND] INGESTION • ' ' " I" CRTEEKmi:J

 CREEK

 [ PERCOLATION J , [jtfATERj

 DIRECT CONTACT •

INFILTRATION/1 or,,, INFILTRATION/1 t [GROUND ^ INGESTION • ' 1 { PERCOLATION J " 0 L

 [ PERCOLATION J ^WATER j D.RECT CONTACT •

LEGEN D

i = Incomple l O = Exposure

9 = Exposure

(Inciden t

• = Exposure (Direct 1

INFILTRATION/1 „. . flNFILTRATION/ l (GROUND ] INGESTION • ' ' [PERCOLATION ] -

O I L

 [PERCOLATION ] ^WATER J DI REC T CONTAC T •

f DESORPTION/1 fOROUNDl INGESTION • ' '

[ PERCOLATION J 1

WATER J DIRECT CONTACT •

1 i

1 I

I i

1 i

> or virtuall y Incomplet e

potential relatively low

potential Intermediate

il Ingestlon/Contact )

potential relatively high

igestlon/Contoct )

i i

i i

i i

i ,

Central Notes ~"

No. RBvtaton/lssue Date ,

IS&R/CAR R FORK

SMELTER SrT E TOOELE, UTA H

ATLANTI C RICHFIEL D COMPAN Y MONTAN A

ANDERSO CNOINEEniN O COMPANYN, INC .

177 ww tin teat* SALT LAKE OTT. UTAH 64MB (801) m-«m

^ J

r >

FIGURE 3.1

GROUNDWATE R CONCEPTUA L

SIT E DIAGRAM

r

 DRAWN BT: CNF ^

CHECKED BY: SOA

APPROVED; SDA

RLE: GmnDMItr CtraiAal Mafeldvig

"*" 97-06M4 "*""

04-Marcn-20(12 SO 1 H

NoScah ^

\

\

/
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

Water qualit y in the Carr Fork mine de-watering program apparentl y

improved over time likely due to dilutio n of the stagnan t water in the old mine

workings from inflo w through the host rock durin g de-watering.

T he water qualit y of the influen t an d effluen t from the settlin g ponds was

monitored by Anaconda durin g operation s and some of these data were

presented in the reclamation pla n for the site (JBR, 1986). The

concentrations for the influen t water qualit y are shown in Tabl e 3-5.

Tabl e 3-5 •Settlin g Pond Influen t Water Qualit y Cone,

(mg/l ) Average

Maximum

Minimum

Std. Dev. M CL

Arsenic

0.0038

0.016

0.001

0.003

0.05

Lead

0.0571

0.146

0.008

0.039

0.015

Zin c

0.0708

0.385

0.006

0.078

N S

Copper

0.0252

0.096

0.007

0.017

1.3

Cadmium

0.0123

0.032

0.001

0.008

0.005

PH

8.1

10.2

7.5

0.58

6.0-9.0

These data indicate that the average and maximum influen t water

concentrations into the settlin g ponds were above the MCL s for lead and

cadmium but below MCL' s for arsenic, copper, an d zinc. Review of data for

nitrate influen t concentrations to the ponds for the period from 1979 to 1983

produces the result s in Tabl e 3-6

Tabl e 3-6 Settlin g Pond Influen t Nitrate 1979-1983

Concentration s (mg/l )

Average

Maximum

Minimum

Standard Deviation

M CL

Nitrate

3.65

9.73

0.03

2.45

10

Data from 70 measurements from 1/79 to 2/83

These data indicate that the nitrate concentrations fluctuated widel y durin g

operation s of the Carr Fork mine in 1979 to 1983 but the average

concentration was less than 4 mg/l . Water chemistry data for the beginnin g of the Apex shaf t de-watering

process showed a nitrate value of 55 mg/ l on 6/12/71 when pumpin g

initiated. However, within two months the nitrate value on 8/4/71 had

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IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

dropped to 2.42 mg/l.

T he settlin g ponds were not lined and seepage from these ponds could have

been a potential source of ground water impact s in the past , though the

constituen t concentration s of the influen t water do not indicate thi s water is

a concern. Razem and Steiger (1981 ) attributed a general increase in

groundwater level s in the Lincoln-Erda area to Carr Fork mine de-waterin g water.

T he precipitated sludge in the bottoms of these ponds was sampled by JBR (1986). Saturated paste extract data showed that soluble metal s

concentrations were low for all the metal s of concern. In particular, arsenic

concentrations were at or below 0.01 mg/l, cadmium 0.07 mg/l, and lead

0.11 mg/l. These sludge s do not appear to present a source of groundwater

impact .

T he settlin g ponds handled a very large quantit y of water which slightly

exceeded MCLs for lead and cadmium but did not exceed MCLs for arsenic

a nd nitrates . The water seepin g from these ponds , and seepin g into the

ground in the irrigated field s north of the Site, could have possibl y

contributed lead, cadmium, arsenic and nitrate into the local groundwater but

thi s likely did not result in exceedances of MCLs for arsenic or nitrate

because their concentrations were too low in the pond water. The ponds

have not been used since de-watering was discontinued for the Carr Fork Min e in 1985 and they have been reclaimed so any impact to groundwater

from these ponds is in the past.

T he settlin g ponds are not likely a source of nitrate or arsenic contamination

recently observed in the Boys Ranch well s and do not have the potential for

being an ongoin g source of thi s contamination . Water from these ponds that

w as discharged to the irrigated field s was not likely the source of the nitrate

groundwater contamination currently observed in the Erda area because the

nitrate concentrations in the water discharged from the ponds was lower

than the groundwater contamination observed in Erda, and the duratio n of

time of the relativel y large discharge was short and over 30 years ago.

3.4.1.2 Slag Pile

T he slag pil e was deposited in the Pine Canyon drainage over the

operational life of the IS&R Smelter complex. The pil e consists of slag from

t he reverb and blast furnaces , which was dumped in molten form at the slag

pile . There \s also fin e granularmaterial mixed in with the slag, which may

be fly ash and/o r flue dust. The slag material is a basalt-like to glass y material that is elevated in total metal s but these metal s were foun d nonleachable from the slag (JBR, 1986). The higher leachable concentration s

were foun d to occur in the fin e granular material within the slag and thi s

material also had a net acid generatin g potential (see Table s 3-7 and 3-8 ).

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Table 3-7 Slag Total Metal s (JB R 1986) Cone, (mg/kg )

Average

Minimum

Maximum

Arsenic

280

110

380

Cadmium

30

11

40

Copper

3,026

1,730

3,780

Mercury

0.15

0.11

0.2

Lead

10,883

8,900

13,100

Tabl e 3-8 Slag E.P. Toxicit y (JB R 1986) Cone,

(mg/l ) Average

Minimum

Maximum

Arsenic

0.1

<0.1

0.23

Cadmium

0.12

0.1

0.15

Chromium

0.01

<0.01

0.02

Mercury

O.0001

<0.0001

O.0001

Lead

1.3

0.5

2.6

T he slag pil e was apparentl y buil t out over the original Pin e Creek stream

channel which resulted in pushin g the creek to the north. The old channel

deposit s were buried by the slag and a remainin g expression of thi s historic

flo w regime was a sprin g that flowed from the west toe of the slag pil e in the

approximate positio n of the old creek channel. This sprin g was sampled as SW-7 in 1985 before and durin g the 1986 reclamation of the Site . The

8/22/85 sample of SW-7 showed elevated arsenic (0.032 mg/l), cadmium

(0.26 mg/l) , nickel (0.102 mg/l) , an d zinc (8.4 mg/l ) concentrations (JBR,

1986). Later sample s of thi s same sprin g in 1987 showed lower arsenic,

cadmium, nickel and zinc concentrations compared to before the 1986

reclamation . The sprin g dried up in Augus t 1987 and has not flowed since

that time (JBR, 1990). It is believed that this is the result of the 1986

reclamation where the slag pile was capped, resultin g in most meteoric

water being discharged by evapotranspiration .

T he presence of the elevated metal s in the 1985 sample for SW-7, and the

presence of the slag waste in the historic Pine Creek channel indicates the

slag pil e may be a potential source of surface water and groundwater

impact .

T he slag pil e contains material s with relativel y elevated concentrations of

total metals and the fin e granular material in the pile has soluble metal

content, yet the arsenic concentrations in the slag material is relativel y low. T he slag was known in the past to be in contact with shallo w groundwater

at its west side (SW-7). The shallow water table has apparentl y dropped as SW-7 has now dried up. Slag pil e impact s would most likely be limited to

cations and anions attributable to metallic compounds and would not likely

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IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

include sources of nitrate or arsenic.

Surfac e water samplin g above and below the slag pil e as outlined in the Field Samplin g Pla n will provide informatio n on whether or not the slag is

impactin g Pine Creek.

3.4.1.3 Pine Canyon Landfil l

T he Pine Canyon Landfill consists of a wide variety of debri s and granular

material that may include flu e dust , furnace brick, laboratory waste, cinders,

slag (JBR, 1986). The waste material in the landfill has been shown to have

high level s of total metal s with elevated level s of soluble metal s (see Table s

3 -9 and 3-10). Acid Base Potential testin g of the landfill wastes, in 1985,

showed that they were acid generating. The soil s under the wastes were

shown to have net neutralizin g capacit y and assays of the foundatio n soil s

indicated that metal concentrations decreased significantl y from the wastes

down into the foundatio n soils. The lower portion s of the waste were

saturated in 1985. During reclamation, the lower portion of the waste was

drained with a french drain and the drained waste was excavated and

relocated up the hill away from the stream channel.

Tabl e 3-9 Pine Canyon Landfil l Total Metal s (JBR 1986)

Cone, (mg/kg ) Average

Minimum

Maximum

Arsenic

3,370

25

10,200

Cadmium

651

20

3,250

Copper

9,403

125

28,600

Mercury

1.99

0.02

14.7

Lead

48,550

300

96,800

Tabl e 3-10 Pine Canyon Landfil l E.P. Toxicit y Cone, (mg/l ) Average

Minimum

Maximum

Arsenic

0.141

0.1

0.428

Cadmium

1.05

0.1

3.49

Chromium

0.012

0.01

0.018

Mercury

0.0005

0.0001

0.0021

Lead

3.82

0.5

14.9

Seeps and springs alon g the toe of the landfill-historically formed a smal l

stream that flowed into Pine Canyon Creek. The sample SW-13 was taken

from thi s stream in 1985. Sampl e SW-13 showed a lead concentration

above the MCL (0.075 mg/l) and elevated TDS. Similar to the seeps below

t he slag pile , seeps from the landfil l ceased to flo w shortl y followin g cappin g

of the landfill durin g site reclamation in 1986.

T he presence of high concentrations in SW-13 of metalliferous and acid

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IS&R / Carr Fork Remedial Investigatio n Sit e Groundwater Conceptual Mode l

generatin g material s in the landfill waste, and the fact that the waste was at

o ne time in contact with shallo w subsurface water in the old Pine Canyon Creek channel makes the Pine Canyon Landfill a potential source of past

groundwater impact . During the 1986 reclamation the landfill waste that was

in the Pine Canyon drainage was excavated and relocated toward the south

so that it was permanentl y above the water table. Thi s mitigation , and the

vegetated soil cover that was placed over the landfill can be reasonably

assumed to have eliminated or greatl y reduced ongoin g release of leachate

from the landfil l waste.

Wahler (1978) estimated that the local recharge to the aquifer in the Pine Canyon area was approximatel y 12,000 acre feet per year. Wahler also

estimated the groundwater flo w velocities in the area of the mouth of Pine Canyon to be 2.5 to 5 ft/day. Thi s flo w rate would be sufficien t to have

allowed metallic impact s to move from the vicinit y of the Pine Canyon Landfill to areas down gradien t of the site by now.

3.4.1.4 Elto n Tunne l

T he Elto n Tunne l was started in 1937 and completed in 1941. The tunnel

w as about 23,000 feet lon g and was driven to intercept the Apex Min e

undergroun d mine workings for mine access and to drain water from the

lower workings of the old Apex mine. Anaconda records show that the

range fron t faul t was crossed by the tunnel about 9,000 feet from the portal . T he firs t 8,000 feet of tunnel were reportedl y driven though unconsolidated material . The firs t 5,000 feet of tunnel made no water and the firs t 9,000 feet

of tunnel made a total of 297 gpm. After crossing the range fron t fault, the

tunnel made water throughout most of its length to its end. Prior to

connecting with the Apex Min e workings, at times the tunnel made over 8 c fs of water. Seven drill holes were advanced from the tunnel to the old Apex Min e in June , 1941. When these dril l holes were completed, they

flowed 4.5 cfs. The total flo w from the tunnel portal at thi s time was about

12.5 cfs. The water flowed out of the tunnel by gravity . The Elto n Tunne l

discharged water at an average rate of 5 cfs from 1941 through 1950 when

parts of the tunnel began to cave. The discharge ceased in about 1958

when the tunnel was completel y plugged by caving ground.

T he water discharged from the Elton Tunne l was used by the local ranchers

f or irrigation . Accordin g to Utah State Engineer records (Gates , 1965) the

water level s in the Erda area, where the Elto n Tunne l water was used for

irrigation , showed an increase in average water level s of about 12 feet from

about 1939 unti l about 1950 after-which it declined-to even lower than what

it was in 1939. This corresponds to the annual flo w from the tunnel which

stayed at over 3,700 acre-feet unti l 1950 after which it rapidl y decreased to

less than 1,000 acre-feet in 1953, and then to less than 100 acre-feet in

1955 with all flo w endin g in 1958.

Anaconda records noted that the water flowin g from the tunnel was generall y

good enough for irrigatio n purposes but occasional pumpin g of mine water

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IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

from the Rood Shaf t workings that were deeper than the Elto n Tunne l

apparentl y produced water of poor qualit y which was not suitable for

irrigation . Durin g these periods of poor water, the Elto n discharge was

diverted from the irrigation systems that normall y used the water (McArthur

a nd Botz, 1971) . Thi s report also states that mine water was released into

t he Elto n Tunne l infrequently . A partial water analysi s for the Elto n Tunne l

flo w on Jun e 20 1941 (after connecting with the Apex Mine ) showed a TDS

of 3,780 mg/ l and sulfat e of 1,970 mg/ l whereas the water in April, 1941

(before connectin g with the Apex Mine ) showed a TDS of 329 mg/ l and

sulfat e of 77.4 mg/l . Data for arsenic, nitrate or other analyses of Elto n Tunne l water discharge have not been located to date.

It i s possible that water flowed from :the old mine workings into the Elto n Tunne l void from 1958 unti l the workings were de-watered in the early

1970' s for the Carr Fork mine operations. Thi s water did not flo w from the

tunnel portal because of the caving conditio n but it is possible that the tunnel

water was discharged to the subsurface in the portion of the tunnel driven

through unconsolidated material that was apparentl y above the water table. Thi s water could have recharged the alluvial fan deposit s near the mouth of Pine Canyon. In September 1971, Anaconda installed Dril l Hol e No.4 down

into the Elto n Tunne l to see if there was water in the tunnel . The y did

intercept water in the tunnel and a water sample obtained on 10/5/71

showed arsenic, cadmium, and lead concentrations below detection limit s

a nd nitrate at 0.32 mg/l . This would indicate that the water in the tunnel

between where it is plugged and the Apex Min e workings was good qualit y water and therefore is not likel y to be a source for groundwater impact . The

location of thi s drill hole has not been determined at thi s time, however to

better interpret the water chemistry data research wil l continue to fin d the

exact location .

T he mapped alignmen t of the Elto n Tunne l takes i t directl y under the settlin g

ponds so it is possible that migration of seepage from these ponds was

influenced by the tunnel alignmen t which may have had higher permeabilit y

tha n the surroundin g ground. If thi s happened, lateral migratio n of the

seepage from the ponds could have been preferentiall y directed alon g the

tunnel toward its portal location .

Durin g the tunnel excavation waste rock was stockpiled in the Pin e Creek

drainage bottom moving the creek flo w out of its original channel to the

northerl y side of the drainage. The DERR (1996 ) obtained one sample from

t he waste rock at the Elto n Tunne l and the total metal s analyses are shown

in Tabl e 3-11. The assay result s for the DERR sample of Elto n Tunne l

waste rock does not indicate that the waste rock is a potential significan t

source of groundwater impact .

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IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

Tabl e 3-11 Assay Result s for Elto n Tunne l Dump Parameter

Arsenic

Cadmium

Chromium

Copper

Lead

Manganese

Mercury Zin c

Concentration (mg/kg )

56.5

9

4.5

239

700

387

0.79

1,360

Water samples have been taken from the creek above and below the mine

dump. The ERA contractor sampled the creek below the Elto n Tunne l in

1985 (TS-SW-02). JBR established a monitorin g locatio n on the Pine Creek

below the dum p (SW-10) . These , sample results are shown in Tabl e 3-12.

Tabl e 3-12 Total Metal s Analyse s for Pine Creek below Elto n Tunne l

Parameter

Arsenic

Cadmium

Chromium

Copper

Lead

Zin c

TS-SW-02 (mg/l )

0.012

O.005

O.005

0.009

<0.03

0.049

SW-10 8/85 (mg/l )

0.01

0.007

<0.005

0.01

<0.01

0.055

Historic samplin g data shows that the Elto n Tunne l discharge water has not

been a likely source of metal s or nitrate to the groundwater aquifers . The

most recently available data collected by Anaconda in 1971, as described

above, shows that water which may be stored in the tunnel is of good

quality , so it further indicates Elto n Tunne l is not currently impactin g area

aquifers .

3.4.1.5 Carr Fork Tailings

T he Carr Fork tailing s were produced from the Anaconda Carr Fork Project mill and have been shown to have low total and soluble metal concentrations

a nd a high net neutralizin g capacit y due to their carbonate mineral content

(JBR, 1986) (see Tabl e 3-13. an d 3-14). The Carr Fork tailing s were

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. IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

deposited in the northern portion of the Carr Fork tailings pond durin g the

short operational history of the Carr Fork project . The y are impounded

behind the Carr Fork tailing s dam.

Tabl e 3-13 Carr Fork Tailin g Total Metal s

Cone,

(mg/kg ) Average

Minimum

Maximum

Arsenic

82.5

60

100

Cadmium

5

3

8

Copper

926

735

1040

Mercury

0.05

0.02

0.12

Lead

127

20

345

Tabl e 3-14 Carr Fork Tailings E.P. Toxicit y Cone,

(mg/l ) Average

Minimum

Maximum

Arsenic

<0.1

<0.1

<0.1

Cadmium

<0.1

<0.1

<0.1

Chromium

0.02

0.01

0.03

Mercury

<0.0001

<0.0001

<0.0001

Lead

<0.05

<0.05

<0.05

T he tailings solids analyses indicate that the Carr Fork tailing s contain

arsenic, cadmium, copper, mercury and lead but the average concentrations

a re not high. The leachable metal s content is low. This would indicate the Carr Fork tailings solids do not represent a significan t source of metal s

impact for the groundwater.

A sample of Carr Fork tailings (TS-T-02) taken by the ERA (1985 ) showed

total metal s assays for arsenic (124 mg/kg ) an d lead (173 mg/kg) . Anaconda records showed that durin g millin g operation s the tailing s water

contained in the Carr Fork tailings slurry had the followin g chemistry: sulfate (650 mg/l) , TDS (1,160 mg/l) , arsenic "(0.001 mg/l) , lead (0.05 mg/l) ,

cadmium (0.01 mg/l) and zinc (0.02 mg/l). These concentrations are low

a nd indicate that the original tailings water deposited with the Carr Fork

tailings did not represent a significan t source of impact for the groundwater.

T he DERR (1996 ) installed a lysimeter (AC-LY-03) in the Carr Fork tailing s

a nd obtained a water sample that represents near surface water contained

in the uhsaturated Carr Fork tailings at that time. Non e of the water qualit y

parameters from thi s sample exceeded MCLs . Wahler (1978) estimated that the depth to the water table in the area is

about 400 to 600 feet . The y measured the porosity , specifi c yield, field

capacity , moisture content , and moisture deficienc y in the deposit s

underlyin g the Carr Fork tailings pond. The y concluded that seepage from

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IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

t he Carr Fork tailings pond would take approximatel y 240 years to reach the

water table through vertical flo w in the unsaturated zone.

J BR (1986 ) used data an d calculation s developed by Wahler (1978 ) to

estimate the groundwater impact attributable to the Carr Fork tailings . These calculation s showed .that the concentrations of metal s in the

groundwater under the tailings pond were not expected to exceed any

groundwater protection standards . This appears to be verified by the tailing s

pond monitorin g well (GW-4) located immediatel y west of the Carr Fork

tailing s dam. The monitorin g data presented by JBR (1986) showed that

sample s from thi s well taken in 1985 did not indicate any impact of the

groundwater above MCLs . T he Carr Fork tailing s were completel y covered with topsoi l an d vegetated

as part of the 1986 reclamation . Thi s vegetation cover greatl y reduces the

n et infiltration of meteoric water into the tailings by evapotranspiration . Eliminatin g most of the infiltration and the depth to groundwater under the

site in all likelihood precludes any contribution of ongoin g leachate from the

tailing s solids into the groundwater.

Based on the above characterization of the Carr Fork tailings , they do not

appear to present a significan t source of past , present or potential futur e

impact to the groundwater qualit y at the site.

3.4.1.6 IS& R Tailing s

T he IS&R tailings were produced from the historic IS&R concentrator

operation s before the Anaconda Carr Fork mine operation s and are present

beneath the Carr Fork tailings and to the south and east of the Carr Fork

tailings . Analyse s of the IS&R tailing s showed them to have relativel y higher

total and soluble metal concentrations than the Carr Fork tailing s and

generall y have a net acid generatin g potential (JBR, 1986) (Table 3-15 and Tabl e 3-16).

Tabl e 3-15 IS& R Tailing s Total Metal s

Cone, (mg/kg ) Average

Minimum

Maximum

Arsenic

2082

75

10430

Cadmium

21

3

85

Copper

639

105

2640 .

Mercury

0.99

0.22

6.7

Lead

8453

110

33100

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Tabl e 3-16 IS& R Tailing s E.P. Toxicit y Cone,

(mg/l ) Average

Minimum

Maximum

Arsenic

0.86

0.1

8.4

Cadmium

0.1

0.02

0.23

Chromium

0.016

0.01

0.63

Mercury

0.0003

0.0001

0.01

Lead

0.72

0.50

2.2

A sample of IS&R tailings (TS-T-03) taken by the ERA (1985) showed total metal s assays for arsenic (1,320 mg/kg ) an d lead (3,760 mg/kg) . A sample of tailing s (AC-SC-02) , probabl y IS&R tailings , taken by the DERR (1996 ) showed total metal s assays for arsenic (646 mg/kg ) and lead (5,150 mg/kg) . No water qualit y informatio n has been foun d to date for the IS&R tailing s

slurry when it was deposited. The DERR (1996) installed a lysimeter (AC- LY-04) in the IS&R tailing s deposit . A water sample obtained from the tailin g

solids was analyzed and foun d to compl y with all MCL s except nickel where

t he sample concentration of 0.151 exceeded the nickel MCL (0.1 mg/l).

T he greater age, relativel y high metal s content, and the net acid generatin g

capacit y of the IS&R tailing s compared to the Carr Fork tailing s make them

a more likely potential source of ground water impact than the Carr Fork

tailings . However, monitoring of the groundwater at Sagers well (GW-2) and

t he Carr Fork tailings dam well (GW-4) down gradien t of the IS&R tailing s

have not produced minimum result s exceeding MCL s (Se e Tabl e 3-3). The

investigation s of the Site for the desig n of the Carr Fork tailing s dam

(Bechtel , 1977) included a number of borings and test pit s installed in IS&R tailings and these showed that the IS&R tailing s were not saturated, which

greatl y reduces their potential for releasing seepage.

During the 1986 reclamation the IS&R tailings were completel y covered with

topsoi l and revegetated. This vegetation cover and the correspondin g

evapotranspiratio n greatl y reduces the net infiltration of meteoric water into

t he tailings . The lack of infiltration and the depth to groundwater under the

site likel y precludes an y contribution of ongoin g leachate from the IS&R tailing s solids into the groundwater.

Based on the above characterization of the IS&R tailings , they do not appear

to present a significan t source of past, present or potential future impact to

groundwater qualit y at the site.

3.4.1.7 Waste Isolatio n Cell

 :

T he Waste Isolation Cell was constructed durin g the 1986 reclamatio n of the

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IS&R / Carr Fork Remedial Investigatio n Sit e Groundwater Conceptual Mode l

IS&R site and contains smelter solid wastes that had high total and soluble metal s concentrations and net acid generatin g potential s which were

relocated durin g cleanup of the smelter site (JBR, 1986). The cel l was

purposel y constructed over the thickest part of the modern Carr Fork tailing s which were shown to be unsaturated in 1986 before the cell was

constructed. The low permeabilit y an d high capacit y of the Carr Fork tailing s

were expected to retard and neutralize any acid leachate produced from the

wastes contained in the cell . The DERR and ERA have expressed concern

over the potential for the waste cell to be contributin g source of impact to

groundwater.

T he available field data for the waste cel l site indicates that the underlyin g

tailing s have the neutralizin g capacity to neutralize and stabilize any acid

leachate that might migrate from the cell . The construction of the cel l bottom

. and slopin g cover made up of low permeabilit y material and a vegetated

surface cap are designed so that net recharge of meteoric water or seepage

from adjacen t tailings into the cell is eliminated or very minor. The lack of

seepage from the cell , its recent age, and the depth to groundwater indicate

that any seepage from the cell is not likel y to have entered the groundwater. T he waste isolatio n cell is not likely a source of existin g groundwater impact

a nd is not likel y a potential future impact source. The field investigation s

alread y proposed as part of the Remedial Investigatio n to investigate the

water content and chemistry of the material s in and under the waste cel l

should be sufficien t to confirm thi s assumption .

3.4.1.8 Summar y

In general the samplin g at and near the site has not shown impact s to

groundwater related to facility operations , either metalliferous or nitrate. The

o ne possible exception is elevated arsenic in the Boys Ranch wells . Availabl e informatio n does not indicate a obvious source of arsenic

originatin g on the site.

Based on the foregoin g description , Tabl e 3-17 contains a prioritized

summary of potential sources for the groundwater impact issues related to

water qualit y immediatel y down gradien t of the site. Sectio n 4 proposes

specific actions to confirm there is not a general groundwater concern at or

down gradien t of the site and furthermore whether there is a connection

between the site and the arsenic concern in the Boys Ranch wells .

3.4.2 Erda Area

T he USGS has monitored well s in Erda for several years and at certain location s

produced sample s with high concentrations of nitrate+nitrite expressed as nitrogen . As stated previously , at times durin g the de-watering of the mines associated with

t he IS&R/Carr Fork facilities , the excess water was used for irrigatio n purposes in Erda. Some have theorized that the concentration level of nitrogen foun d in the Erda well s may have an origin at the IS&R/Carr Fork facility.

Atlantic Richfield Compan y 24 March 12,2002
Tabl e 3-17 Potential Groundwater Impac t Sources I n IS&R/Car r Fork Area Source Prioritized as

to Likelihood

of Potential Impac t on Boys Ranch Well s

Sla g Pine Canyon

Elto n Tunne l

Settlin g Hx^j IS&R^S *

Carr Fork Tailing s

Waste Cel l

1 Total Metal s Content

Hig h

Hig h

Low

Low

Hig h

Low

Hig h

Acid/Base Potential

Acid

Acid

Acid (3)

Alkalin e

Acid

Alkalin e

Acid

Solubl e Metal s Content

High (2 )

Hig h

L ow (4)

Hig h (6 )

Hig h

Low

Hig h

Arsenic Content

Low

Hig h

Low

Low

Moderate

Low

Hig h

Nitrate Content

Negligibl e

Negligibl e

L ow (5)

Low

Low

Low

Negligibl e

Known Contact w/Groundwater

in the Past?

Y es

Y es

Likel y Likel y N ot Likel y

N o t Likel y

N o

Ongoin g Source of Groundwater Impact? (1 )

Possible

Possible

N ot Likel y N ot Likel y N ot Likel y

N ot Likel y

N ot Likel y

Proximity to Boy' s Ranch Well s (ft )

5,600

5,500

2,000

3,600

2,500

2,900

3,800

1) Thi s relative quantitative ratin g is based on the current condition of the potential sources, includin g source potential (constituen t concentrations, relative

solubility ) and pathway potential (connection to groundwater).

2) Though total metal s concentrations in slag are relativel y high, arsenic and nitrate concentrations are low.

3) pH of the tunnel'discharg e was reported to generally be between 5 and 7 with occasional lower values.

4) No historical data, but water qualit y in the tunnel in 1971 had low concentrations of metals .

5) No historic quantitative data, but water qualit y in the tunnel in 1971 had low nitrate.

6) Only a concern for lead and cadmium
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

Nitroge n occurs in several forms in groundwater including: ammonium, ammonia,

nitrite , nitrate, nitrogen gas, nitrous oxide, and organic nitrogen . Groundwater

commonly acquires nitrate from several sources including: precipitation ,

decompositio n of plan t residue in soil , mineral fertilizer , and sewage. Because

nitrate is very soluble in oxidizin g condition s (i.e. shallow unconfined groundwater) ,

it moves in the water with little retardation and is not readil y transformed to less mobile species. When groundwater systems become confined and the available

oxygen is consumed, nitrate is reduced to the non-harmful form of nitrous oxide.

. The USGS has completed conceptual groundwater model of^the potential fate an d

transport of site impact sources being transported to the Erda area in the

groundwater. Particle trackin g analysi s was performed with MODPATH software

in conjunctio n with the existing, steady-state numerical groundwater module alread y

developed for the Tooele Valley (Lambert an d Stolp, 1999). Based on thi s modeling, they concluded that groundwater movement from the Site is not a likely

source of nitrate contamination in the Erda area. The y left open the hypothesi s that

t he Erda contamination could have occurred from surface transport of the nitrate in

irrigatio n water originatin g from the Site. However, surface water monitorin g result s

as discussed above indicate that there has not been a significan t source of nitrate

emanatin g from the IS&R/Carr Fork operation .

There are several indicators in the Erda area that the nitrate level s foun d in the local well s are much more likel y to be from local sources. Initial research has foun d that

the Erda area has historicall y been and continues to be an agriculture area where

nitrogen based amendments have been added to the soil s for many years. In

additio n the area formall y had many chicken farms which local residents claim were

heavily laden with chicken organic waste. High chloride level s isolated to the Erda

area also could suggest an organic source. The only known organic source at the

smelter site are septic tanks , however, thi s source would not onl y be small , the USGS model has shown that subsurface migration is not a likel y source of impact

to groundwater in Erda.

4 .0 DATA GAP S AND STUD Y PROPOSED

4 .1 Existin g Well s and Monitorin g Data

T he followin g existin g well s wil l be sampled durin g Rl field samplin g activities , (see Figur e

4.1)

AE-GW-1B: (JBR GW-1, 16" Boys Ranch Well) Thi s is a 16-inch diameter, 660 foot deep

well reported to be a former Boys Ranch well . There are two well s in the same vicinity , one

on west side of the current fence and one on the east side. Since the two well s are in close

proximit y of each other and recent samplin g confirms that the well s produce similar result s Atlantic Richfield proposes to onl y sample the 16" Boys Ranch Well. Video of the two well s

also shows that the 16" well is in much better conditio n and is perforated whereas the 6"

well is not and has significan t crystallizatio n from stagnated water. The Boys Ranch well s

a re onl y used for monitorin g and no water right is currently attached to it. The static water

level durin g the first quarter samplin g was sounded at 591 feet below ground surface.

Atlantic Richfield Compan y 26 March 12,2002
Colo r Chart(s )

T he followin g pages

contain color that does

n ot appear in the scanned

images.

To view the actual images ,

please contact the Superfun d Records Center

at (303 ) 312-6473.
LEGEN D

New / Restored Wel l

Existing Well

G IWUSGSR14201

ANDERSON

EXISTING & PROPOSED GROUNDWATE R MONITORIN G WELLS
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

A E- GW-2: (JBR GW-2, Sagers Well) Thi s is an 8-inch diameter, 650-foot deep well referred

to in past samplin g events as the Bruce Sagers well , however, the water right for thi s well

belongs to Rodney Mecham. The well is reportedl y used for domestic purposes . The static

water level durin g the firs t quarter samplin g was sounded at 540 feet below ground surface. AE-GW-3A: This well is also located on Atlantic Richfield property , in the extreme northwest

corner, detail s about the well are unknown. The USGS has indicated that they have not

sampled it in the past , and no water right is attached to it. The well has a collapsed casing

at approximatel y 210ft . below the surface. There was no evidence of water at 210ft . This well will be restored to 750 ft. and cased for the purpose, of future monitoring. AE-GW-4: (JBR GW-4, Carr Fork Tailings Dam Well) Thi s well was installed jus t west of the

tailing s impoundmen t dike, reportedl y by the USGS. this is a 6" diameter well , 654 ft deep. Well video of thi s well shows evidence of abandonmen t and no water at a depth of

approximatel y 650 ft. below the surface. Thi s well wil l be restored or replaced to a depth

of 750 ft and cased for the purpose of future monitoring.

. AE-GW-6: Thi s well is upgradien t from the site, on Kennecot t property . The well is an 8-

inch diameter well that is 200 ft. deep. The static water level in December 2001 was 103

feet below ground surface.

GW-USGS: Thi s USGS well is located west of the town of Lincoln . Thi s is a 4-inch diameter

well which is 543 feet deep. The static water level in December 2001 was sounded at 420

feet below ground surface.

To better understand the conditio n of the wells , AE-GW-1 A, AE-GW-1 B, AE-GW-3a and AE- GW-4 were videoed. Result s of the videoin g have been taken into consideratio n in

developin g thi s samplin g plan . A copy of the video logs has been submitted to EPA under

separate cover. The existin g well s discussed above (except the 6" Boys Ranch Well) will

be analyzed quarterly for the parameters listed in Tabl e 6-1 of the SAP. In additio n to the

existin g wells , the installatio n of a limited number of new monitorin g well s will be drilled as

described below.

Additional research will identif y the apparen t discrepancies in existin g data and will be

clarified before the historic data are utilized to identify long-term water qualityitrends near

t he Site . In addition , the historic data wil l be checked for inferior qualit y compared to current

expectation s and reviewed for qualit y with basic QA checks such as cation/anio n balances

before it is used in the RI/FS. Atlantic Richfield wil l also continue to research publi c an d private records for historic data

on the Anaconda groundwater monitorin g effort s at the Site before and after de-watering

a n d millin g operation s began for the Carr Fork mine. In additio n Anaconda may have

collected data from additional well s at site and at well s near Erda. Data from these

location s may have been collected as early as 1971 and 1972.

 : Finally , al l available data related to the qualit y of the de-watering water from the Pine Canyon Tunne l and the settlin g ponds will be gathered and reviewed to determin e the

qualit y of the water that was routed through the settlin g ponds and applied to the irrigation

field s between the Site and Erda.

Atlantic Richfield Compan y 27 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

4 .2 Pin e Canyon Drainage

T he water table under the Pine Canyon Creek drainage bottom may be more shallo w than

the regional water depth of 400 to 600 feet as indicated by depth to water at AE-GW-6 and

t he abundant riparian vegetation growing within the drainage. The drainage basin consists

of an alluvial wash material which is being recharged from surficial flow s from Pin e Creek

which may create a groundwater mound which has a steeper hydraulic gradien t as it flow s

toward the valle y unti l it eventuall y intersects the regional aquifer. The Boys Ranch wells , which have historical evidence of metalli c level s above MCLs , are located withi n the

drainage. Though no obvious connection exists between the arsenic concentration s in the Boys Ranch well s and site sources, one additional well between the site and the Boys Ranch well could provide valuable informatio n in determinin g if the aquifer contains elevated

constituents . If it does not, there is a strong likelihood that the elevated arsenic foun d down

gradien t is not connected with the site. This well will allow for the obtainin g of water table

elevation and water chemistry data for the uppermos t aquifer down gradien t of the slag pil e

a nd landfill. This new data will assist in determinin g if the slag or landfill have impact s to

t he uppermos t aquifer immediatel y down gradien t of the facilities . T he Kennecot t well (AE-GW-6 ) will be sampled as an up gradien t well to the slag and other

site features . Thi s well will provide the up gradien t groundwater elevatio n and water

chemistry.

4 .3 Erda Nitrate

T he nitrate concentrations, observed by the DERR (1996) in lysimeter samples on site, are

within the range of naturall y occurring soil nitrate and do not indicate a man made source

of nitrate impact significan t enough to effec t the Erda area. Literature will be searched to

provide additional informatio n definin g thi s condition .

Literature will also be searched for informatio n related to the nitrogen isotopic signature of

groundwater nitrate originatin g from use of minin g explosives . The nitrogen isotopic

character of groundwater nitrate originatin g from chemical explosives i s likely differen t than

domestic and agricultural sources of nitrate. To addres s the hypothesi s that the Erda nitrate level s are due to transport of high nitrate

concentrations in irrigatio n water originatin g from the Carr Fork site, a thorough review will

be conducted of Anaconda monitorin g records to obtain all available water qualit y data for

t he mine de-watering system. The nitrate concentrations indicated in these data will be

compared to the concentration s in the Erda area. As described above nitrate

concentrations in the de-watering water researched to date is not high enough to have

resulted in the observed elevated level s at Erda.

T he Anaconda records will be searched for informatio n on where the irrigatio n water

originatin g at the Carr Fork site was applied . This could be used in conjunctio n with the

existin g USGS modelin g to see if it would be possible for the nitrate from these irrigated

areas to be transported to the well s in Erda since the time thi s irrigation occurred.

Nitroge n and oxygen isotopes can provide a powerful tool for identifyin g sources of nitrogen

in groundwater. The isotopic composition s (i.e. the ratio of heavy to light isotopes ) of

Atlanti c Richfield Compan y 28 March 12, 2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

nitrogen and oxygen in nitrogen species are dependen t on the original source of the

nitrogen. Fertilizer, soil organic matter, manure, septic system leachate, industrial

chemicals , and nitrogen compounds derived from use of explosives each have their own

distinctive isotopic composition . Isotopi c composition s are determined by measuring the

ratio of heavy to light isotopes in a water sample related to a standard.

In addition , the high nitrate content in the Erda well s are accompanied by chloride s above

t he secondary drinkin g water standards . Thi s conditio n occurs in a vast number of well s

sampled in Erda. High nitrate together with high chloride level s is a more positive indicatio n

of sewage seepage or barnyard pollutio n than nitrate alone (Driscoll,1987) . Atlanti c Richfield proposes obtainin g samples of water from key location s in the Carr Fork

a nd the Erda area and analyzin g them for Nitroge n 15 and Oxygen 18 isotopes to provide

their isotopic characterization. These data would then be compared agains t the standards

identified in the literature an d against each other for interpretation . Atlanti c Richfield wil l

also sample these same sources for stable water isotopes (Oxygen 18 and Hydroge n 2)

which wil l allow discrimination of the differen t waters themselves.

Atlantic Richfield proposes that isotopic sample s be obtained from impacted and nonimpacted well s i n Erda, monitorin g well s at the Site, an d water obtained from KUCC' s

current pumpin g of the Carr Fork mine workings to compare isotopic signatures of the

various water sources.

5 .0 DECISIO N RUL E AN D SCHEDULIN G INFORMATIO N

5 .1 Develop a Decision Rule

This portion of the investigatio n is broken down into two distinct areas for samplin g and data

evaluation . The vicinit y of the site, specificall y lower Pin e Canyon/Lincol n area and the Erda areas. The determinatio n of whether an area is considered impacted wil l be made

by comparison of the finalized historical data with newly collected data and the Primary Drinkin g Water Standards(MCL). Further determination s can be made by performin g

exposure and risk calculation s in accordance with standard approaches and methods

acceptable to the USEPA. The second component of thi s determinatio n wil l be confirmatio n

of the source or sources. As the stud y progresses, Atlantic Richfield will continue to work

with the EPA to insure that the methods and samplin g provide the needed data to fully

generate accurate site specific informatio n for the groundwater investigations/

5 .2 Specif y Limit s on Decision Errors

Collectio n of the new and supplementar y groundwater data in thi s proposal will be in

accordance with the IS&R/Carr Fork Remedial Investigatio n Samplin g an d Analysi s Plan . T he Data Qualit y Assurance Pla n , which is a part of the SAP, will be complied with for

sample collection , handling, analytical procedures, data reduction , validatio n an d reporting. Atlanti c Richfield has prepared the SAP in cooperation with the EPA, Region 8 to provide

sufficien t sample result s to result in consistent and applicabl e estimates of the mean for

calculatin g UCL's .

Atlantic Richfield Compan y 29 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

5 .3 Optimize Design

Thi s Site Groundwater Conceptual Mode l has been developed to addres s specificall y the

data gaps related to groundwater qualit y concerns in the vicinit y of the Site and at Erda. As the work progresses with installatio n of new wells , sampling, data collection , research

a nd clarificatio n of data discrepancies the model will be re-evaluated to insure that the

collected data wil l provide the informatio n essential to solvin g health and environmental

concerns associated with the former IS&R/Carr Fork facility .

5 .4 Schedul e

Upo n approval of thi s Site Groundwater Conceptual Mode l an d proposed data collectio n

actions well drilling activities will begin. Research and evaluation of old process and

operational activities will be initiated upon the same approval . Also , clarificatio n of data

descripencies andfinalizatio n of the comprehensive Site database wil l be completed durin g

t he drillin g an d samplin g period. It i s Atlantic Richfield' s intention to attempt to instal l the

proposed well s to meet the next quarter samplin g event period.

6 .0 REFERENCE S

Anderso n Engineerin g Co., Inc., 1986. As-built Drawings - IS&R Site.

Bechtel Corporation . 1977. Design Report Tailing Embankment: report prepared for the Anaconda Company , Carr Fork Project , Utah. Division of Environmental Response and Remediation . 1996. Analytical Result s Report , Anaconda Copper - Carr Fork, Tooele County , Utah UTD093120921: Utah Dept . of Environmental Quality .

Driscoll , FletcherG . 1995. Groundwater an d Wells , Groundwater Chemistry , U.S. Filter/Johnso n Screen.

Environmental Protection Agency. 1985. Analytical Result s for Tooele Smelter, Tooele , Utah T DD R8-8508-09. ,

Fenneman , N.M.,1931 , Physiograph y of the Western United States , New York, McGraw-Hil l

Gates,J . S. , 1963, Hydrolog y of Middle Canyon , Oquirrh Mountains , Tooele County , Utah, USG S Water Suppl y Paper 1619K. Gates , J. S. 1965. Reevaluation of the Ground Water Resources of Tooele Valley , Utah: U.S. Geological Survey an d Utah State Engineer/Technical Publicatio n No . 12 . ••••-•• •

t Hebdon , J. 1984, Site Inspectio n of the Toole Smelter an d Anaconda- Carr Fork Operation , Toole , UT, Submitted to EPA, Reg.8, Utah State Division Of Environmental Health, Bureau of Solid

a nd Hazardous Waste.

J BR Consultant s Group. 1986. Reclamation/Stabilizatio n Plan , Anaconda Mineral Company , Carr Fork an d IS&R Tooele Smelter, Tooele Valley , Utah: report prepared for the Anaconda

Atlantic Richfield Compan y 30 March 12,2002
IS&R / Carr Fork Remedial Investigatio n Site Groundwater Conceptual Mode l

Mineral s Company .

J BR Consultant s Group. 1990. Carr Fork Reclamation Project , Water Quality , Waterfal l Erosion, Revegetation , Photo Plots: report prepared for Anaconda Mineral s Company .

Lambert , P.M. , an d Stolp, B.J. 1999. Hydrolog y an d Simulatio n of the Groundwater Flo w System i n Tooel e Valley , Utah: U.S. Geological Survey , Water Resources Investigatio n Report

99-4014.

McArthur, G.M. , an d Botz, M.K. , 1971, Dewatering the Carr Fork Min e an d Disposin g of Water into

t he Tooele Valley : report prepared for the Anaconda Company .

Razem, A.C. , an d Steiger, J.I. 1981. Ground Water Condition s i n Tooele Valley , Utah 1976-78: U.S. Geological Survey an d Utah State Engineer, Technical Publicatio n No.69. Ryan, K. H., B. W. Nance , and A.C. Razem, 1981, Tes t Drilling for fresh Water in the Tooel e Valley , Utah 1976-78, State of Utah, Division of Natural Resources, Technical Publicatio n No.

69.

Sadik-Macdonald , Hele n L, 1997, Anaconda Copper - Carr Fork, Utah State Department of Environmental Quality .

Steiger, J.I., and Lowe, M. 1997. Recharge and Discharge Areas and Qualit y of Groundwater in Tooele Valley , Tooele County , Utah: U.S. Geological Survey , Water Resources Investigatio n Report 97-4005.

Stolp, B.J. , 1994, Hydrolog y an d Potential of Groundwater Developmen t in Southeaster n Tooele Valle y an d Adjacen t Areas in the Oquirrh Mountains , Tooele County , Utah, State of Utah Dept .

of Natural Resources, Technical Publicatio n No. 107.

Thomas , H. E. , 1946. Groundwater in Tooele Valley , Tooele County , Utah, Utah State Engineer, Technical Report No. 4, Utah State Engineerin g 25 Bienn. Rept.

Tooele Count y Historical Societ y 1986. Minin g Smeltin g an d Railroadin g i n Tooel e County . Claude F . Atkin . USDA, 1998, Soi l Survey of Tooel e Area, Utah

Wahler, W. A. an d Associates , 1977, Groundwater Studies: Min e Water Managemen t Plan , Prepared for the Anaconda Company . .

Wahler an d Associates . 1978. Tailings Pond Managemen t Plan , Carr Fork Project , Tooele , Utah ,

report prepared for Anaconda Company .

Atlantic Richfield Compan y 31 March 12, 2002
TARGE T SHEE T E RA REGION VII I SUPERFUN D DOCUMEN T MANAGEMEN T SYSTEM

DOCUMEN T NUMBER : 2000255_______

SIT E NAME : ____International Smeltin g & Refinin g

DOCUMENT DATE: March 12, 2002_____________

DOCUMEN T NO T SCANNE D Due to one of the followin g reasons:

D PHOTOGRAPHS

D 3-DIMENSIONAL

D OVERSIZED

D AUDIO/VISUA L

D PERMANENTL Y BOUN D DOCUMENT S

D POOR LEGIBILIT Y

D OTHER

D NOT AVAILABL E

0 TYPES OF DOCUMENTS NOT TO BE SCANNED

(Data Packages, Data Validation , Samplin g Data, CBI, Chai n of Custody )

DOCUMEN T DESCRIPTION :

Appendi x A - Groundwater Samplin g Database______________

Contact the Superfun d Records Center to view available document.

(303)312-6473
9 77 Wes t 2100 South

Sal t Lake City , Utah 84119

(801)972-6222

(801 (972-6235 FAX

www.andersoneng.cpm ANDERSO ENGINEERIN G COMPANY INC N .

Grants , Ne w Mexico

(505 ) 285-6484

March 14, 2002 00

rn :.

Joshua Knight |r International Smeltin g & Refinin g Remedial Project Manager ^ > Superfun d Remedial Section , 8EPR-SR g' i . r US Environmental Protection Agency , Region VIII -^ \._ \ -

9 99 18

th

 Street , Suite 300 ~ '"' - Denver, CO 80202-2466 *

R e: Site Groundwater Conceptual Model

Dear Joshua:

Please fin d enclosed your hard copy of the Site Groundwater Conceptual Model . Also

included in this packet is video taken of the inside of the well s located at or near the site.

CO

Sincerely , ANDERSON Engineering Co., Inc . K

Paulin e Barney (^\ Administrative Assistan t

cc. Michael Storck Chuck Stilwel l

Reviewed by,

Steven D. Anderson IS&R/Carr Fork Project Manager

CIVI L ENGINEER S A CONSTRUCTION MANAGER S A LAN D SURVEYOR S