UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

REGIO N VII I

9 99 18th STREE T -SUIT E 500 1R<U8? DENVER . COLORAD O 80202-2466 ADMINISTRATIV E

Ref: 8EPR-SR 3^83^> RECORD

ACTIO N MEMORANDUM

DATE: April 7, 1997

SUBJECT: Request for Removal (Response) Action at the California Gulch National Priorities List Site , Leadville , Colorado: ACTION MEMORANDUM for a Time- Critical Removal Action for Removal of Tailing s Pond No. 2 and Tailing s Pond No. 3 of the Apache Tailing s Impoundmen t (Operable Unit 7)

FROM: Mike Holmes , 8EPR-SR

T O: Max H. Dodson Assistan t Regional Administrator Offic e of Ecosystems Protection

and Remediation

Fina l NP L Sit e ID #2 9

CERCLIS ID # COD980717938

Category of Removal: Time-Critical

I . Purpose

Thi s Action Memorandum documents the Agency' s selection an d implementatio n

of the time critical removal (response) action described herein for the Apache Tailing s Impoundments , an area contaminated with metal-laden tailings from

historic minin g an d millin g operations. The Apache Tailing s Impoundmen t area

comprises a smal l portion of the Superfun d RI/FS Stud y Area of the California Gulch Superfun d Site, located in the Leadvill e minin g district of Lake County , Colorado. .

T he Time Critical Removal Action at the Apache Tailing s Impoundment s is

consistent with the remedial activities which wil l be undertaken by EPA at OU 7. Final remedial alternatives for all areas of OU 7 wil l be evaluated in the Feasibilit y Stud y (FS) and Record of Decision (ROD) for OU7. The ROD for OU 7 wil l

ultimatel y specif y those remedial actions beyond those response actions

implemented pursuant to thi s Action Memorandum that are required. The FS will

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evaluate the effectivenes s of a remedy to stabilize the tailings in place or if the main

impoundment will need to be relocated out of the California Gulch flood plain . The

primary goal of thi s Removal Action is to prevent exposure to human population s

from tailing s washed into California Gulch and degradatio n of downstream water

quality. Thi s removal action will also reduce the leachin g and migration of metals

from the tailings into surface and ground waters durin g storm events which occur

prior to implemtatio n of remedial action under thel ROD for OU7. Regardles s of

t he remedy selected by the ROD, the response actions taken under thi s Action Memorandum will allow for the consolidation into a smaller area and the dryin g out

of the tailings .

Remedial action objectives were identified in the Final Screening Feasibilit y Stud y

f or Remediation Alternatives at the California Gulch NPL Site, Leadville , Colorado

(SFS) , (ERA, 1993a). Consisten t with the SFS, removal action objectives for the Apache Tailing s Impoundment s are:

O Control water erosion of tailings material from the source locations

O Control leachin g and migration of metals from tailings into surface

water

O Control leachin g and migration of metal s from tailing s into

groundwater

Removal alternatives to directl y remediate surface water or ground water in the

vicinity of the Apache Tailings Impoundment s have not been evaluated, and will be

addressed under Operable Unit 12.

I I . California Gulch - Sit e Condition s an d Background

T he California Gulch Site was listed on the National Prioritie s Lis t on September 8,

1983. The Site is in a mining area covering 16

 1/£ square miles of a watershed that

drains along California Gulch to the Arkansas River. Startin g in 1859, the area was

mined extensively for gold, lead, silver, copper, zinc, and manganese. California Gulch collect s runof f that drains numerous abandoned mines and wastes from

mining, millin g and smelting. Miners buil t the Yak Tunne l to drain water from the

mine workings and to make mineral exploration and developmen t easier. Thi s

tunnel drains hundreds of miles of mine workings in its 4-mile underground course

a nd discharges approximatel y 210 tons of metals each year into California Gulch. Seventy-five known mill s dumped tailings into 5-6 miles of drainages. Six

impounded tailings dumps surround the City of Leadville . Many smelters , which are

located around the city, processed silver, lead and zinc at various times. Heav y metal residues are present in much of the City. The Arkansas River which receives

water from the California Gulch, has been classified as a recreational resource, and

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is used heavily for irrigation, livestock watering, public water supplie s and fisheries . Approximatel y 4,000 live in nearby Leadvill e and Lake County (Se e Site Location M ap - Figur e 1)

Apache Tailings Impoundment s

A. Background

T he Apache Tailings Impoundmen t consists of a main tailings impoundmen t

a nd two, smaller impoundment s located alon g California Gulch,

approximately 1,500 feet downstream of the Yak Tunnel Water Treatment Plan t Surge Pond, as illustrated on the attached Site Plan . The main

impoundmen t encompasses approximatel y 11.3 acres. The volume of

tailings in the main impoundmen t has been previously estimated at

approximatel y 630,000 cubic yards. The embankment slopes on the north

and east side of the main impoundment range from 1.5:1 (H:V) to 1.75:1 and

reach heights up to 15 feet . The embankment slope on the southwest side

of the main impoundment approaches 1:1 and is up to 50 feet in height. The

t wo smaller impoundments , TP2 and TP3 are located west of the main

impoundment and directly north and adjacent to water flowin g in the gulch. T P2 is located immediatel y west of the main impoundmen t and covers an

area of approximatel y 1.5 acres. TP3 is located immediatel y west of TP2

and covers an area of 0.5 acres. The volume of tailings in TP2 and TP3

have been estimated previously at approximatel y 8,500 and 3,900 cubic

yards, respectively. Impoundmen t berms for both ponds appear to have

been constructed of native soil material from California Gulch. These berms

range from 1:1 to 1.5:1, are approximatel y 10 feet in height and 10 feet wide

across the top.

T he majority of surface water flo w in California Gulch is presentl y conveyed

by the California Gulch channel located on the south side of the gulch in the

vicinity of the Apache Tailing s Impoundment . The channel intersects the

southern edge of the main impoundment where the flow is carried by two 24-

inch diameter clay-tile culverts installed beneath a portion of the main

impoundment . Surface water flo w from the area immediatel y upstream

(approximately 1,000 feet) of the main impoundment and below the elevation

of the constructed California Gulch channel are conveyed under the main

impoundmen t through what appears to be a wooden box culvert. After

exiting these culverts, surface water continues to flo w to the northwest, west

of and adjacent to the southwest embankment of the main impoundment , for

approximatel y 300 feet before turnin g to the west and continuing down the

gulch past the lower impoundment s (TP2 and TP3).

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A field investigation was conducted in November and December 1996 to

supplemen t the existin g data presented in the Remedial Investigatio n and Feasibilit y Stud y for the site. The purpose of thi s investigation was to gather data

to enhance the evaluation of the interaction of surface water and groundwater in the

immediate vicinity of the Apache Tailings Impoundments . As part of thi s

supplemental field investigation , 11 new groundwater monitorin g well s were

installed at the site. Two rounds of groundwater and surface water samplin g were

planned at the site as part of the supplemental investigation ; one samplin g event

was performed in November 1996 to coincide with low-flow condition s at the site

involved the samplin g of 18 groundwater wells , and surface water samplin g at 22

locations. Additional detail s are provided in the Interim Removal Action Plan , Operable Unit 7, Cal Gulch Superfun d Site, dated April 3, 1997 and a letter dated March 13, 1997 which transmits the monitorin g data for the samplin g event

described above. Both these documents are attached to thi s Action Memorandum.

B. Site Characterization - Apache Tailing s Impoundmen t

T he results of previous investigation s related to the Apache Tailings Impoundmen t are presented in various reports includin g the Tailings Disposal Area Remedial Investigation Report, California Gulch Site , Leadville , Colorado, January 1994, the Hydrogeologic Remedial Investigation Report (1995) , and the Surface Water Remedial Investigatio n Report (1995). In Januar y 1996, a Draf t Feasibilit y Stud y (FS) was

submitted for the Apache Tailing s Impoundments . Subsequen t to the

submittal of the draf t FS, additional site investigation activities have been

initiated to supplemen t the previous investigations and to support completio n

oftheFS . T he principal concerns specificall y addressed by thi s Removal Action are:

* Impact s the tailings impoundment s may have on surface water and

groundwater quality in California Gulch; and

* Preparatio n of the tailings material , primaril y through consolidatio n

a nd dewatering, to facilitate the timel y implementatio n of future , final

response actions.

* A letter report dated March 13, 1997 which summarizes groundwater

qualit y data from samplin g events performed in the area of the Apache Tailings Impoundments , durin g November an d December,

1996, is attached.

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C. Other Actions to Date

* A Time Critical Removal Action was performed by EPA on the Apache Energy and Mineral s Property which is included in Operable Unit 7. T he action involved removal of drums and bags of pyrite and

decontamination and demolitio n of buildings and equipment. Thi s Removal Action was addressed in a separate Action Memorandum

dated August 6, 1996.

* During the summer and fall of 1995, ASARCO installed approximatel y

6 horizontal drain pipe s to passivel y drain water from the main

impoundment . The demonstration project proved ineffective in

drainin g the tailings and was abandoned. Over the past several

years ASARCO has monitored water level s on top of the main

impoundment and TPs 2 and 3 and as needed, the ponded water has

been transferred to the Yak Treatment plan t to prevent catastrophic

release of the metal-laden water into California gulch.

D. State and Local Authorities Roles

A cultural resource investigation of the Apache Tailing s Area was conducted

in 1995, and a site with potential archaeological significanc e was identified. Thi s site contains structural remains and artifact scatter and is located

immediatel y south of California Gulch below the culvert outfall s on the

southwest side of the main impoundment . The proposed alignmen t of the

diversion ditch will not impact this area and additional investigation or

research on thi s cultural resource site may be necessary, prior to

implementin g the final actions. The initial focus of thi s removal action is to

avoid any impact s on the area of archaeological significance .

I V. Threat s to Public Health or Welfar e or the Environment

A Final Baseline Aquatic Ecology Risk Assessment (FBAERA) , California Gulch, Leadville , Colorado (Roy F. Weston, Inc.) identifies the Site-wide impact of mine

waste contamination on the terrestrial and aquatic ecosystems at the Site. The FBAERA provides a conceptual model of Site-wide exposure for aquatic receptors.

Thi s Time-Critical Removal Action is necessitated by the threat to publi c health,

welfare and/or the environment posed by the direct contact, inhalation , and

ingestion exposure routes to hazardous substances. The Action wil l also reduce

releases of metals to the surface and groundwater.

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V. Endangerment Determination

Actual and/or threatened releases of hazardous substances from the Apache Tailings Impoundments , if not addressed by implementin g the removal action

selected in this Action Memorandum, presents endangerment to public health, or

welfare, or the environment. The public and environment wil l continued to be

exposed to the release of significan t quantities of contaminated materials.

V I . Proposed Actions/Schedule

A. Proposed Actions

1. The proposed interim actions are described in the Interim Removal Action Plan , Operable Uni t 7, Apache Tailing s Impoundments , California Gulch Superfun d Site, dated April 3, 1997. A copy of this report is attached. The

proposed interim actions include the following:

1.1 Removal of TP 2 and TP3 and consolidation of the material on

t he main impoundment and either divertin g California Gulch

away from the southwest embankment of the main

impoundment below the clay-tile culverts and wooden box

culverts outfalls , or providing erosion protection along the toe

of the tailings embankment area.

The extent of tailings , berms material and native soil to be

removed wil l be determined by visual observation during

excavation. Confirmation samples of the impoundmen t berms

wil l be taken to determine suitability for use as backfil l material. Only material with a lead concentration below 3,500

p pm will be used.

F or thi s removal action, slope stabilit y concerns will be

addressed through the applicatio n of Best Management Practices (BMPs)

1 .2 Surface water that is currently ponded on TP2 and TP3 will be

removed prior to initiatin g excavation by pumpin g the water to

t he existing pond on the main impoundmen t for ultimate

transfer to the Yak Tunnel Water Treatment Pla n (WTP), or by

transportin g it to the WTP using tanker trucks. The base of T P2 and TP3 may currently be below the groundwater table in

this area and, therefore, dewatering durin g excavation may be

required. Water removed during excavation wil l be pumped to

t he existing pond on the main impoundment . Followin g

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excavation, clean fill wil l be placed to restore the area,

promote surface drainage and prevent ponding. Proposed

approximate final contours are shown on the figure entitled

1997 Proposed Interim Action.

1.3 The excavated tailings wil l be transported to the main

impoundment using the temporary road from the west side of

the impoundment near the old foundation s to the new well

installations near the center of the impoundment (AP1TMW12)

and placed on the north side of this road, as indicated on the

1997 Proposed Interim Action Figure, attached. It is

anticipated that placement may be achieved utilizin g low

ground pressure equipment without the use of geotextile or

geosynthetic subgrade suppor* The installatio n of several

settlement plates in the fill placement area is also proposed to

monitor the settlement/consolidation of the underlyin g tailings

as a results of loadin g from the fill.

1.4 Potentiall y contaminated surface run-off from the main

impoundment will be directed through the area between TP2

and the main impoundment to a sediment control structure as

indicated on Figure 4. The sediment control structure wil l

consist of an earthen berm with a hay bale core and a rock or

rip-rap lined discharge notch intended to intercept and retain

sediment in storm water run-off . Thi s structure will be

maintained until the final remedy is implemented. Diversion of

uncontaminated surface run-off along the north side of the

main impoundment wil l also be maintained or upgraded to

minimize potential contact with tailings material or other

potentially contaminated flows.

1.5 The followin g activities involving the protection of the toe of

the main impoundment embankment are proposed. These

activities wil l include excavation of tailings , primaril y at the

knob which extends toward the channel approximately 100 feet

below the clay-tile culvert outfalls , and the placement of clean

fill and/or riprap for erosion protection at the toe of the

embankment.

B. Applicabl e or Relevant and Appropriate Requirements (ARARs)

T he ARARs listed on TABLE F.1 AND F.2 wil l be followed to the extent

practicable. Copies of these Tables are attached.

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C. Performance Standards

T he ARARs were met through compliance with Performance Standards .

1. The designed and constructed response action included provisions to

ensure that there are no visible emissions (dust) durin g removal activities at

t he Apache Tailing s Impoundments . Dust control on the haul route, and

other areas, wil l be maintained through water application , as necessary.

2. During the excavation, on-site transport, and placement of tailings material,

appropriate engineering controls will be maintained to control storm water

runof f and dust generation, silt fences, hay bales and/or other sediment

control devices wil l be used to intercept and retain sediment in storm water

runof f (both from the main impoundment and TP2/TP3). The sediment

control structures wil l be left in place, as necessary followin g the completio n

of excavation. Un-contaminated surface water will be diverted away from

t he tailings to minimize contact with tailings .

3. A long-term maintenance program may be implemented if required by the Final Record of Decision for Operable Unit 7 (Oil 7) to ensure the long-term

effectivenes s of the response action.

D. Project Schedule

April-May 1997 - California Gulch Below the Culverts

June-July 1997 - Removal of Ponded Water from TP@, TP3

a nd Main Impoundmen t

August-September 1997 - Removal of TP2 and TP3

E. Estimated Costs

Thi s response action is being conducted by ASARCO, Inc.

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VII. Expected Change in the Situatio n Should Action Be Delayed or N ot Taken

If this Time-Critical removal action is delayed, or not taken, exposure of the publi c

and environment to heavy metals contained in the mine waste located in the Apache Tailing s Impoundment s wil l continue. Without thi s time-critical response,

release of contaminated tailings into California Gulch and the Arkansas River wil l

continue to contaminate surface water and groundwater in the area around the Apache Tailings Impoundments .

VIII . Outstandin g Policy Issues

A Record of Decision wil l be issued selectin g the final

remedial action for Operable Uni t 7 (OU 7) of this Site .

I X . Enforcement

Thi s Time-Critical Removal Action will be performed by ASARCO, Inc.

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X. Recommendation

Thi s decision document represents the selected Time-Critical removal action for the Apache Tailings Impoundment s portion of OU 7 of the California Gulch Superfun d Site, in the City of Leadville , County of Lake, State of Colorado. It was developed

in accordance with CERCLA, as amended, and is not inconsistent with the NCP. Thi s decision is based on the Administrative Record for the Site .

Condition s at the Apache Tailings Impoundment s meet the NCP Section

300.415(b)(2) criteria for a removal and I recommend approval of the removal

action.

APPROVA L

»-w^ Dodson \ Assistan t Regional Administrator Offic e of Ecosystems Protection

and Remediation

DISAPPROVA L

M ax H. Dodson Assistan t Regional Administrator Offic e of Ecosystems Protection

and Remediation

Q vr

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10
C O L\O R A D O

CALIFORNIA GULCH SUPERFUND SITE

Project No.:

01-283

file: RESWLOC.DWG

Design By: D EVANS Drawn By: T.BOEHLER

( I F SUHOECTIO N MININ G COMPAN Y O N E UNI'E O BAN * CENtC R

iroo LINCOL N STREE T DENVER . COLORADO aQtol

Sco(«. H/A

Date:

JUNE 1995

FIGURE 1

CALIFORNIA GULCH SITE

GENERAL LOCATION
TABLE F.I

SUMMARY OF POTENTIAL FEDERAL AND STATE CHEMICAL-SPECIFIC ARARS

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40 CFR Part 50

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No

No

Not applicable because no community water supply system. Potentially relevant and appropriate for the final Site remedy,

i.e.,OU12. Not applicable or relevant and appropriate for this removal

action. Potentially relevant and appropriate for the final Site

remedy, i.e., OU12.

These standards are applicable. NAAQS are met through the New Source Review Program and the State Implementation Plan. Not applicable because the materials to be managed have

been identified as extraction or beneficiation waste that are

specifically exempted from the definition of a hazardous

waste. Not relevant and appropriate, see Superfun d LDR

Guide #7. ' Not applicable because not a hazardous waste. Potentially

relevant and appropriate for the final Site remedy, i.e., OU12.

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tfSffiSJttiSSr a Colorado Air Quality Control Act 5 CCR 1001-10 Part C (I) &(II) Regulation 8

Y es — Emission standards for lead and hydrogen sulfide. Potentially

applicable, however it is not expected that at Site would ever

violate these standards.

A -l
TABLE F.2 SUMMARY OF POTENTIAL FEDERAL AND STATE LOCATION-SPECIFIC ARARS

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Fish and Wildlife Coordination Act

Wilderness Act

Executive Order No. 1 1988 Floodplai n Management

Executive Order No. 1 1990 Protection of Wetlands

Section 404, Clean Water Act

(CWA)

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50 CFR §§ 200 and 402

16 USC §66 let sea.

40 CFR § 6.302

16 USC 131 1,16 USC 668

50 CFR 53, 50 CFR 27

40 CFR § 6.302 & Appendix A

40 CFR § 6.302(a) and Appendix A

33 USC 125 let seg.

33 CFR Part 330

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Provides protection for threatened and

endangered species and their habitats. Site-specific studies did not document

the presence of threatened or

endangered species.

Requires coordination with federal and

state agencies to provide protection of

fish and wildlife in water resource

development programs; regulates

actions that impound, divert, control,

or modify any body of water.

Limits activities within areas

designated as wilderness areas or National Wildlife Refuge Systems.

Pertains to floodplai n management and

construction and impoundments in

such areas.

Minimizes adverse impacts on areas

designated as wetlands.

Regulates discharge of dredged or fill

materials into waters of the United States. Substantive requirements of

portions of Nationwide Permit No. 38

(General and Specific Conditions) are

applicable to OU7 removal activities

conducted within waters of the United States.

A-2
TABLE F.2 SUMMARY OF POTENTIAL FEDERAL AND STATE LOCATION-SPECIFI C ARARS

The Historic and Archaeological Data Preservation Act of 1 974

16 USC 469

40CFR§6.301(c ) Y es Establishes procedures to preserve

historical and archeological data that

might be destroyed through alteration

of terrain as a result of a federal

construction project or a federally

licensed activity program. A cultural

resource survey was completed in OU7 to identify historic properties

which may be affected by removal

activity.

National Historic Preservation A ct (NHPA)

16USC§470etsea .

40CFR§6.301(b )

36 CFR Part 63, Part 65, Part 800

Y es Expands historic preservation

programs; requires preservation of

resources included in or eligible for

listing on the National Register for Historic Places.

Executive Order 1 1593 Protection and Enhancement of

the Cultural Environment

16 USC § 470 Y es Directs federal agencies to institute

procedures to ensure programs

contribute to the preservation and

enhancement of non-federally owned

historic resources. Consultation with

the Advisory Council on Historic Preservation is required if removal

activities should threaten cultural

resources.

Historic Sites Act of 1 935 16 USC §46 1-467 No No Preserves for public use historic sites,

buildings, and objects of natural

significance.

A-3
TABLE F.2 SUMMARY OF POTENTIAL FEDERAL AND STATE LOCATION-SPECIFIC ARARS

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T he Archeological Resources Protection Act of 1979

16USC§§470aa-47011 No Y es Requires a permit for any excavation

or removal of archeological resources

from public lands or Indian lands. Maybe relevant and appropriate if

archeological resources encountered

during removal activity.

Resource Conservation and Recovery Act (RCRA), Subtitle D

40 CFR Part 257 Y es Provides general classification criteria

f or solid waste disposal facilities

pertaining to floodplain s and safety.

Nongame, Endangered or Threatened Species ActCRS §§ 33-2-101 to 108 No No Standards for regulation of nongame

wildlife and threatened and endangered

species. Site-specific studies did not

document the presence of threatened or

endangered species.

Colorado Register of Historic PlacesCRS SS 24-80.1-101 to 108 Y es (see description). Authorizes the State Historical Society

to nominate properties for inclusion on

the State Register of Historic Places. Applicable only if removal activities

impact an area listed on the Register.

Colorado Historical, Prehistorical, and Archaeological Resources ActCRS §§24-80-401 to 410

1301 to 1305

No Y es Concerns historical, prehistorical, and

archaeological resources; applies only

to areas owned by the State or its

political subdivisions. May be

relevant and appropriate if removal

activities impact an archaeological site.

A-4
TABLE F.2 SUMMARY OF POTENTIAL FEDERAL AND STATE LOCATION-SPECIFIC ARARS

Colorado Species of Special Concern and Species of Undetermined Status

Colorado Division of Wildlife Administrative Directive E-l, 1985, modifiedNo Protects species listed on the Colorado Division of Wildlif e generated list. Urges coordination with the Division

of Wildlif e if wildlife species are to be

impacted. No evidence of species of

special concern have been identified at

this site.

Colorado Natural Areas Colorado Revised Statutes, Title 33 Article 33, Section 104

No Maintains a list of plant species of

"special concern." Although not

protected by State statue, coordination

with Division of Parks and Outdoor Recreation is recommended if

activities will impact listed species.

Colorado Solid Waste Disposal Sites and Facilities Act, Colorado Revised Statutes, Title 30, Article

20, Sections 101-118

6 CCR 1007-2

6 CCR 1007-2, Part I

Y es Establishes regulations for solid waste

management facilities, including

location standards.

Establishes broad siting criteria and

site evaluation procedures for

individual storage and disposal units

(i.e., impoundments, landfills , etc.).

A-5
TABLE F.3

SUMMARY OF POTENTIAL FEDERAL AND STATE ACTION-SPECIFIC ARARS

111

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amended by the Resource

Conservation and Recovery Act

of!976(RCRA )

Hazardous Materials Transportation Act

Occupational Health and Safety A ct (OSHA)

Federal Mine Safety and Health A ct (MSHA)

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Colorado Solid Waste Disposal Sites and Facilities Act

Colorado Water Quality Control Act, Storm Water Discharge Regulations

42 USC §690 1-6987

40 CFR Part 257

49 USC §1801-1813

49 CFR 107, 171-177

29 USC §651-678

30 USC § 800-962

Y es

—

No

No

Y es

No

No

Selected portions of Part 257 establish criteria for

determining which solid waste disposal facilities and

practices pose a reasonable probability of adverse effect s on

health. Applicable to land disposal of non-hazardous solid

waste.

Regulates transportation of hazardous materials. Removal

action within OU7 will not entail off-site transportation of

hazardous materials but may involve use of public roads.

Regulates worker health and safety. Regulations are not

environmental requirements, but will be adhered to as

appropriate.

Establishes requirements to protect worker health and safety

in and around mines. Regulations are not environmental

requirements, but will be adhered to as appropriate.

6 CCR 1007-2

5 CCR 1002-2

Y es

Y es

Establishes standards for licensing, locating, constructing

and operating solid waste facilities. Applicable only if

removal actions will involve establishment of a solid waste

disposal facility.

Establishes requirements for storm water discharges (except

portions relating to Site-wide Surface and Groundwater). Substantive requirements for storm water discharges

associated with construction activities are applicable.

A-6
TABLE F.3

SUMMARY OF POTENTIAL FEDERAL AND STATE ACTION-SPECIFIC ARARS

-•-••••••••••••••••••••••••••••• •

Colorado Mined Land Reclamation Act

CRS 34-32-101 to 125 Rule 3 of Mineral Rules and RegulationsY es Regulates all aspects of land use for mining, including the

location of mining operations and related reclamation

activities and other environmental and socio-economic

impacts. Substantive requirements of selected portions of Rule 3 regarding Reclamation Measures, Water General Requirements (except portions relating to Side-wide Surface

and Ground Water), Wildlife , and Revegetation are

applicable.

Colorado Air Quality Control Act 5 CCR 1001-3; Section III.D.l.a.(i) Sections II.D.2.b. and g. Regulation 1

Yes (see description) Only provisions of Act under Regulation No. 1 concerning

fugitive emissions for construction activities and tailing

ponds are applicable (5 CCR 1001-3; Sections II.D.2.b and

Colorado Noise Abatement Act CRS §§25-12-101 to 108 Y es Established maximum permissible noise levels for particular

time periods and land use related to construction projects.

Regulations on the Collection of Aquatic Life

2 CCR 406-8, Ch. 13, Article III, Sec. 1316No No Requirements governing the collection of wildlife for

scientific purposes. Removal activities within OU6 will not

trigger biological monitoring.

Colorado Hazardous Waste Regulations6 CCR 1007-3 No Y es Certain portions of RCRA Subtitle C requirements may be

relevant and appropriate clean-up standards for conducting

remedial or removal actions at certain portions of the Site if

waste material fail s TCLP, and/or if waste material is

located so that it comes in contact with surface and/or

groundwater.

Colorado Air Quality Control Act 5 CCR 1001-4 Regulation 2 Odors

Y es Applicable if work in tailing impoundments cause odors.

A-7
Colorado Air Quality Control Act

5 CCR 1001-5 Regulation 3 APENs

Y es Substantive provisions of APENs will be met.

A-8
.SPR3

. APACH E TAIUNG S IHPQUNOMEKrS

i - i / jo FOTT KATOUNaunwo C ocooerc vomya DMW tf icz

tnmtM. w n>«

ncuRE 1 SFT E PLAN SHOWIN G MONITORIN G LOCATION S

REV:

; ftBRUARY. 1997 B Y: SCGfCHf-CKED: DlL McCULLEY. FRICK & OILMAN, INC.
FIGURE 2 NOV . '9 6 - PRELIMINAR Y SURFAC E WATER MONITORING DATA PROJECT: 5344.3 I DATE: FEBRUARY. 1997 REV: ——— __ [JY: SCGI CHECKED: Dl McCULLEY, FRICK t t OILMAN, INC. provftffng environmental con*uff**7 Orttf enyftttfing
2/Vt P:\5344V5I4*-12.I>«C Of. PTOt

10150

10100

t,

10050

10000

9950

'AP I TMWl'is"i f 10076^ 'AP1TMK12S 1100B9.9J """" AP1TMW9 (10096.91

P34- - — (10059.5)

N W3 (10062J5) AP1TMW16S < 10060.2)

(10059.3

APPROXIMATE BASE OF TAILINGS

NATNE UATERMLS

N W3

000 100 200 300 400 SOO

NOTES :

1. GROUMDWATER ELEVATON DATA FROM NO^MBER 1S96.

2- NATIVE MATERIALS REFERS TO GLACIAL OUTWASH, RECENT ALLUVIUM AND/OR FIL L MATERIA L

3. NW3 PROJECTED 50 FEET ONTO THE CROSS SECTION; P34 PROJECTED 3O FEET ONTO THE CROSS SECTION. LEVEL

600 700 800

STATION (FEET )

WELL ID (WATER LEVEL ELEVATION)

GROUND SURFACE

SCREEN INTERVAL

TOTAL DEPIH OF BORING

900 1000 1100 1200 13OO 14OO 1500

100

HORIZONTAL SCALE

VERIKM. SCALE

100 FEET

30 0 30 FEET

VERTICAL EXAGGERATION = 3.33

ASARCO ARACHE TMUHGS MPOUMtHOfTS

CROSS SECTION A-A

PRDviECT: 5344 .0 RBft l DATE: UtRCH. 1997 B V: RA3| CHECMEO: gSC McCUtlEY. FFBCK & GiLUAW, IMC

I ' l : '

x •.T.
2/J7

ncune 4

1997 INTERIM REMOVAL ACTION PLAN

PROJECT: 53*4-i I DA.TFj FEBHUMTT. 1997 I McCULLEY, FRICK & GILUAN. INC.

OI ' )

providin g environmental

 484 Pearl East CIrcle

Suite 2OOW consultin g and Boulder. Colorado 8O3O1

engineering services 3O3/447-1823

Fax:447-1836

McCulle y

c. Via U.S. Mail

March 13, 1997 M FC Job No. 5344.2

Ms. Rebecca Thomas Remedial Program Manager U.S. EPA Region VIH

999 18th Street, Suite 500 Denver, CO 80202-2405

R E: TRANSMTTTAL OF MONITORING DATA; OPERABLE UNIT 7 - APACHE TAILINGS

Dear Rebecca:

We are pleased to provide four copies of a draft table summarizing surface water and groundwater

quality data from sampling events performed during November and December 1996 at the Apache Tailings area. The December monitoring included sampling at the inflow and outflow of the wooden box

culvert (APU1 and APD1) during treatment plant shutdown. Flow did not occur at the adjacent California Gulch stations (APUP and APDNl) during the plant shutdown monitoring. Because the data

validation process is not full y complete, the data and associated qualifiers should be considered

preliminary. Also enclosed are a sample site location map and a table which summarizes construction

details for new and pre-existing wells in the vicinity of Apache. After the data validation process is complete, we will distribute a revised version of the data table,

if necessary. If you have any questions, please do not hesitate to call.

Sincerely, MCCULLEY, FRICK & OILMAN, INC.

Bence V. Close, P.E. Senior Engineer/Geohydrologist Associate BVC:sjc

lc: Russ Alien, CDPHE Austin Buckingham, CDPHE '--- '-. Fern Daves, Asarco • Rod Grebb, WESTEC _ Tom Hesemann, RMC Mike Holmes, EPA ~ Paul Rosasco, EMS ^ :

. . Gary Slifka, Asarco ~ ^ ? Sherm Worthington, SMI —

:~ ~ T?

• J:\5344\COMM\RTHOMAS2.LTR £

»~» Albuquerque. NM • Austin. TX • Boston. MA • Boulder, CO • Missoula. MT • Port Lavacq. TX • San Francisco. CA • Seattle, WA • Wallace. ID Si
DRAF T

TABLE 1

OPERABLE UNIT 7 - APACHE TAILING S GROUNDWATER SAMPLIN G RESULT S NOVEMBER 1996

SAMPL E LOCATION L AB NUMBER

SAMPL E NUMBER

SAMPLE DATE Field Parameters

pH (units) Conductivity @25C (umhos/cm) Major Constituents and Inorganics Calcium (mg/L) Chloride (mg/L ) Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L ) Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters

Total Alkalinity (mg/L) Bicarbonate as CaC03 (mg/L) Carbonate as CaC03 (mg/L) Cation-Anion Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaC03 (mg/L) Hydroxide as CaC03 (mg/L) Residue, Filterable (TDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L )

AP1TMW1

L1 1863-20

M-AP1TMWI-01-112498

11/24/96

3.22

5480

530

9

0.1 U

400

0.01 U

0.8 B

0.8 B

20 U

20 B

4400

0.005 U

0.032 J

0.02 U

0.256

0.42

460

0.575

369

217

2U

2U

2 U

12.1

2B

2970

2U

6950

6B

AP1TMW2

L1 181 9-07

M-AP1TMW2-01-111W6

11/19/96

6.41

803

118

3B

0.1 U

49.6

0.01 U

0.62

0.62

1.8

6.6

450

0.008 B

0.005 U

0.005 U

0.002 B

0.01 U

0.02 B

0.001 U

1.53

0.93

47

47

2 U

0.3 U

1 B

499

2U

720

5 U

AP1TMW 7

L1 1808-02

M.AP1TMW7.01-11U96

11/18/96

7.46

736

94.1

9

0.1 U

39.8

0.01 U

2.65

2.65

1.3

4.3

250

0.015 B

0.005 U

0.001 U

0.0002 U

0.01 U

0.01 U

0.0002 U

0.005 U

0.01 U

121

121

2U

0.5

1 U

399

2U

520

5U

AP1TMW9

L1 1863-22

M-APITMW9-01-11249S

11/24/96

6.55

9530

411

11

0.9

2092

0.05

0.02 U

0.02 U

70

6B

9100

0.005 U

0.025 J

0.02 U

0.008 B

0.1 U

28.5

0.004 U

6.51

0.1 U

101

101

2U

0.7

12

9630

2U

12160

8B

AP1TMW11S

L1 1863-1 5

M-AP1TMW11S-OM1249

11/24/96

6.5

6670

443

6

0.3 B

1228

0.08

0.84

0.92

70

24

5600

0.007 B

0.005 U J

0.02 U

0.04

0.04 U

10.1

0.004 U

65.6

65.1

383

383

2U

2.9

4B

6150

2U

7600

52

AP1TMW11D

L11863-17

M-APITMW1 ID-01-1 1248

11/24/96

5.84

1210

134

1 B

0.1 B

67.1

0.01 U

6.3

6.3

2.8

5.7

600

0.005 U

0.005 U J

0.005 U

0.071

0.01 U

4.55

0.086

18.7

30.6

57

57

2U

2.9

2B

611

2U

1000

8B

AP1TMW12S

L1 1863-1 8

M-AP1TMW12S-01-11246

11/24/96

6.17

8430

404

14

0.8

1661

0.08

0.02.U

0.02 B

87

14

7800

0.005 U '

0.005 U J j

0.05 U

0.02 B

0.05 U

132

0.01 U

16.9

2.82

122

122

2U

0.3

6

7840

2U

10460

58

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

U = not detected at the indicated method detection limit (MDL) B = Anaryte concentration detected at a value between the MDL and the practical quantitation limit (PQL) J = estimated value NR = not reported

J:\5344\96SAMP\NOV96DAT.WB 2 Page 1 of 3 McCulley, Frick & Oilman. Inc. Marrh 1? 1P97
DRAFT

TABLE 1

OPERABLE UNIT 7 • APACHE TAILING S GROUNDWATER SAMPLING RESULT S NOVEMBER 1996

SAMPLE LOCATION L AB NUMBER

SAMPL E NUMBER

SAMPL E DAT E Field Parameter*

pH (units) Conductivity @25C (umhos/cm) Major Constituents and Inorganic*

Calcium (mg/L) Chloride (mg/L) Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L ) Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters Total Alkalinity (mg/L) Bicarbonate as CaCO3 (mg/L) Carbonate as CaC03 (mg/L) Cation-Anion Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaCO3 (mg/L) Hydroxide as CaC03 (mg/L) Residue, Filterable (IDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L )

AP1TMW12D

L1 1863-21

M-AP1TMW12D-01-11J48

11/24/96

S.49

1780

196.0

2B

0.1 U

101.0

0.02 B

6.5

6.5

6.6

9.9

1030

0.014 B

0.005 U

0.005 U

0.034

0.04 B

23.7

0.019

37.2

19.0

2U

2U

2 U

2.4

3B

905

2U

1550

54

AP1TMW13S

L1 181 9-02

M.AP1TMW13S-01-111W

11/19/96

6.88

688

82.2

2B

0.1 U

33.5

0.01 U

0.04 B

0.04 B

1.3

2.5

270

0.005 U

0.005 U

0.005 U

0.077

0.01 B

0.01 U

0.023

0.285

11

86

86

2U

0.6 U

1B

343

2U

460

5U

AP1TMW13D

L1 1819-01

M-AP1TMWt3D-01-111M

11/19/96

7.19

938

120

3B

0.1 U

51.3

0.01 U

0.26

0.26

1.5

6.4

370

0.007 B

0.005 U

0.005 U

0.002 B

0.01 U

0.01 B

0.001 U

0.304

0.01 U

123

123

2U

1

1U

511

2U

670

5U

AP1TMW14S

L1 184 5-1 5

M-AP1TMW14S-01-112M

11/20/96

2.17

28190

510

6

0.1 U

510

0.01 U

0.4 U

0.4 U

30 U

30 U

60800

68.8

49

48.9

10.2

47

27167

0.09 B

773

1639

2U

2U

2U

11.7

112

3370

2U

103390

1128

AP1TMW140 L1 1845-16

M-AP1TMW14D-01-1 1206

11/20/96

4.65

2430

216

23

0.4 B

137

0.48

1.79

2.27

eu

28 B

1590

0.022 B

0.005 U

0.005 U

0.3

0.11

47.4

0.004 B

213

45.6

2U

2U

2U

11.1

2B

1100

2U

2550

10 B

AP1TMW1S

L1 1808-01

M-AP1TMW1 5-01-1 1898

11/18/96

6.61

826

126

8

0.1 U

39.8

0.01 U

2.28

2.28

2.4

9.1

360

0.016 B

0.005 U

0.001 U

0.0008 B

0.01 U

0.03 B

0.0002 U

0.523

0.05

90

90

2U

1.6

2B

479

2U

640

28

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

U = not detected at the indicated method detection limit (MDL) B = Analyte concentration detected at a value between the MDL and the practical quantitation limit (PQL) J = estimated value NR = not reported

J:\5344\96SAMP\NOV96DAT.WB2 Page 2 of 3 McCulley, Frick & Oilman, Inc. M~-~h 10 1OO7
DRAF T

TABLE 1

OPERABLE UNIT 7 • APACHE TAILING S GROUNDWATER SAMPLIN G RESULT S

NOVEMBER 1996

SAMPLE LOCATION

L AB NUMBER

SAMPL E NUMBER

SAMPLE DATE Field Parameter*

pH (units) Conductivity @25C (umhos/cm) Major Constituents and Inorganics Calcium (mg/L) Chloride (mg/L) Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L ) Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved

Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters Total Alkalinity (mg/L) Bicarbonate as CaCO3 (mg/L) Carbonate as CaC03 (mg/L) Cation-Anion Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaC03 (mg/L) Hydroxide as CaCO3 (mg/L) Residue, Filterable (IDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L )

AP1TMW16S

L11845-17

M-APITMW16S-01-1120S

11/20/96

6.11

5090

390

7

0.2 B

400

0.02 B

0.02 U

0.02 U

14

19

4280

0.035

0.015 B

0.01 B

0.041

0.03 U

513

0.234

265

197

41

41

2 U

7.7

3B

2620

2U

6220

30

AP1TMW16D

L11845-18

M-AP1TMW16D-OM 1206

11/20/98

6.21

3130

290

5

0.1 U

234

0.02 B

0.02 U

0.02 U

10

12

2130

0.021 B

0.007 B

0.01 1B

0.008

0.02 U

220

0.019

122

92

27

27

2U

12.1

2B

1690

2U

3470

30

NW-16

L1 1819-03

M-NW16-OI-111W 6

11/19/96

6.07

1850

336

13

0.1 U

74.4

0.01 U

1.73

1.73

2.1

41.3

1080

0.009 B

0.006 B

0.005 U

0.002 B

0.01 U

0.01 U

0.003 B

0.024 B

0.08

50

50

2U

1.2

2B

1150

2U

1700

12 B

N WS

L1 1845-22

M-NW3-01-112O99

11/20/96

8.19

264

30

5

0.1 U

11.7

0.01 U

1.78

1.78

1.1

5.5 J

10B

0.024 B

0.007 B

0.001 U

0.0002 U

0.01 U

0.05 U

0.0002 U

0.005 U

0.01 U

105

105

2U

2.9

1B

123

2U

150

12 B

W5A

L1 1766-04

L-W&M11-M1112

11/12/96

6.64

3028

473

0.5 U

0.1 U

285

0.01 U

1.11

1.11

3.02 B

5.76

2780

NR

0.006 B

0.1 U

1.5

0.1 U

0.017 B

0.02 U

1.19

165

25

25

2U

-5.7

1B

2350

2U

3530

198

W SC L1 1766-05

L-WSC-01-M1112

11/12/96

7.61

2102

360

1.2 B

0.1 U

171

0 01 U

0.78

0.78

2.15 B

6.34

1340

NR

0.005 B

20 U

0.008

0.03 B

0.01 U

0.004 U

0.005 U

1.63

105

105

2U

3.3

2B

1600

2U

2110

S B

wso

L1 1766-02

L-W5D-01-M1112

11/12/96

7.50

1060

160

1.7 B

0,1 U

694

0.01 u

0.67

0.67

1.52 B

5.84

495

NR

0.007 B

0.01 U

0.002 U

0.01 B

0.01 U

0.002 U

0.005 U

0.01 U

155

155

2U

14

1 B

685

2U

890

5 U

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

U = not detected at the indicated method detection limit (MDL) B = Analyte concentration detected at a value between the MDL and the practical quanlitatlon limit (POL) J = estimated value NR = not reported

J:\5344\96SAMP\NOV96DAT.WB2 Page 3 of 3 McCulley, Frick & Oilman, Inc.

. 1997
DRAF T

TABLE 2

OPERABLE UNIT 7 • APACHE TAILINGS SURFAC E WATER SAMPLIN G RESULT S NOVEMBER 1996

SAMPLE LOCATION APUP3

L AB NUMBER L11 845-05

SAMPLE NUMBER M-CGAO«-01-1 12298

SAMPLE DATE 11/22/96

Field Ftow(cfs)

pH (units) Conductivity @25C (umhos/cni) Major Constituents and Inorganics Calcium (mg/L) Chloride (mg/L) Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L) Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Metals, Total

Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters Total Alkalinity (mg/L) Bicarbonate as CaCO3 (mg/L) Carbonate as CaC03 (mg/L) Cafon-Anfon Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaC03 (mg/L) Hydroxide as CaCO3 (mg/L) Residue, Filterable (TDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L)

0.96

7.19

1150

19S

1.1 B

0.4 B

48.2

0.01 B

0.27

0.28

2.2

3.8

614

0.007 B

0.005 U

0.005 U

0.009

0.01 U

02

0.002 B

0.496

1.76

0.005 U

0.007

0.01 U

1.03

0.082

0.507

1.8

12

12

2U

3

1 B

686

2U

900

5U

SPR26

L1 1863-03

M-SPR2SO1-112398

11/23/96

0.01

7.51

2610

433

2.9

0.2 B

179

0.01 U

1.3

1.3

2.5

8.1

1600

0.005 U

0.005 U J

0.005 U

0.293

0.02 U

0.11

0.155

1.25

51.5

0.005 U

0.29

0.02 U

0.07 B

0.168

1.17

49.2

141

141

2U

2.5

1B

1820

2U

2460

1 2B

SPR25

L11863-10

M-SPR2W1-1 12396

11/23/96

0.03

7.40

2980

454

2.5

0.1 B

205

0.01 U

0.88

0.88

3.7

7.6

1870

0.01 SB

0.005 U J

0.01 U

0.706

0.03 B

0.16

0.281

5.58

157

0.01 U

0.704

0.02 B

0.94

0.63

4.46

134

110

110

2U

4.2

2B

1980

2U

2930

20

SPR24

L1 1863-06

I*SPR244>1-1 12398

11/23/96

0.11

7.55

1731

242 J

1.7 B

0.2 B

102

0.01 U

0.23

0.23

2.4

7.4

890

0.005 U

0.005 U J

0.002 U

0.115

0.01 U

0.01 U

0.0111

0.083 J

25.4 •

0.002 U

0.114

0.01 U

0.01 B

0.0147

0.088

22.9

160

160

211

0.7 U

1 U

1020

2U

1450

20

APUP 2 L1 1845-03

M-CGAOM1-1 12298

11/22/96

0.93

6.28

1160

195

1.1 B

0.4 B

49.3

0.01 U

0.26

0.26

2.1

3.8

610

0.005 U

0.005 U

0.005 U

0.009

0.01 U

0.21

0.001 B

0.556

1.96

0.005 U

0.008

0.01 U

0.33

0.014

0.543

1.94

12

12

2U

3.7

1B

690

2U

910

5U

SPR24B

L1 1863-09

M-SPR24B-01-1 12396

11/23/96

0.03

7.97

1374

223J

1.1 B

0.3 B

59.8

0.01 U

0.21

0.21

2

4.6

690

0.005 U

0.005 U J

0.01 U

0.049

0.01 B

0.02 B

0.013

0.505

10.6

0.002 U

0.047

0.01 B

0.05

0.017

0.427

9.13

49

49

2U

3.5

1U

803

2U

1110

28

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

cfs = cubic feet per second NM = not measured; flow too low to measure U = not detected at the indicated method detection limit (MDL) B= Anatyte concentration detected at a value between the MDL and the practical quantitation limit (PQL) J= estimated value NR= not reported

J:\5344\96SAMP\NOV96DAT.WB2 Pagel of 4 McCulley, Frick & Oilman, Inc. March 12,1997
DRAFT

•TABLE 2

OPERABLE UNIT 7 • APACHE TAILINGS

SURFAC E WATER SAMPLIN G RESULT S NOVEMBER 1996

SAMPLE LOCATION APUP

L AB NUMBER L1 1845-02 SAMPL E NUMBER HMDUP-OI-IIBM SAMPLE DATE 11/22/96 Field Flow (cfs)

pH (units) Conductivity @25C (umhos/cm) Major Constituent* and Inorganics Calcium (mg/L) Chloride (mg/L) Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L) Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved

Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Metals, Total

Aisenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters

Total Alkalinity (mg/L) Bicarbonate as CaCO3 (mg/L) Carbonate as CaCO3 (mg/L) Cation-Anion Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaC03 (mg/L) Hydroxide as CaCO3 (mg/L) Residue, Filterable (TDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L)

0.20

6.59

1160

196

1B

0.4 B

50.1

0.01 U

0.26

0.26

2.3

4

604

0.009 B

0.005 U

0.005 U

0.009

0.01 U

0.15

0.001 U

0.57 .

1.91

0.005 U

0.008

0.01 U

0.24

0.009

0.551

1.9

12

12

2U

4.6

1 U

696

2U

910

5U

APDN1

L11845-01

IMPON1-01.11229A

11/22/96

1.29

6,77

1150

194

I B

0.4 B

48.9

0.01 U

0.25

0.25

2.2

3.9

630

0.006 B

0.005 U

0.005 U

0.007

0.01 U

0.12

0.001 U

0.4

1.48

0.005 U

0.006

0.01 U

0.83

0.071

0.415

1.54

11

11

2U

1.8

1 B

686

2U

890

6B

SPR23

L1 1863-01

M-SPR23-OM 12398

11/23/96

0.19

7.99

864

106

4.5

0.1 U

49.6

0.01 U

0.46

0.46

1.4

5

263

0.007 B

0.022 B J

0.002 U

0.0004 U

0.01 B

0.01 U

0.0004 U

0.005 U

0.05

0.002 U

0.0004 U

0.01 U

0.01 U

0.0005 B

0.005 B

0.09

163

163

2U

3.7

1B

469

2U

620

5U

APU1

L1 1845-25

iyMPUI-01-1 12198

11/21/96

1.77

6.90

550

67.8

1.48

0.1 U

28.8

0.01 U

0.17

0.17

1.1

2.5

170

0.021 B

0.007 B

0.005 U

0.031

0.01 U

0.01 U

0.005 B

0.199

5.07

0.005 U

0.029

0.01 U

0.17

0.017

0.213

5.4

98

98

2U

4.1

1U

288

2U

360

5U

APD1

L1 1845-23 M-APOi-oi-mise

11/21/96

2.26

7.50

560

69.2

1.7 B

0.1 U

26.5

0.01 U

0.15

0.15

0.9 B

2.6

175

0.017 B

0.005 U

0.001 U

0.0029

0.01 B

0.01 U

0.0048

0.21

5.03

0.002 U

0.0295

0.01 U

0.31

0.0321

0.232

5.4

97

97

2U

2.3

1U

282

2U

370

6B

APDN2

L1 1845-1 3

M4MA044M12198

11/21/96

3.89

7.30

819

127

1.4 B

0.3 B

38.5

0.01 U

0.22

0.22

1.3

3.2

405

0.01 B

0.005 U

0.005 U

0.019

0.01 U

0.07

0.002 B

0.425

3.66

0.005 U

0.017

0.01 U

0.38

0.032

0.411

3.54

52

52

2U

1.1

1 B

476

2U

660

22

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

cfs ~ cubic feet per second NM = not measured; flow too low to measure U = not detected at the indicated method detection limit (MDL) B= Analyte concentration detected at a value between the MDL and the practical quantitation limit (PQL) J= estimated value NR= not reported

J:\5344\96SAMP\NOV96DAT.WB2 Page 2 of 4 McCulley. Frick & Oilman, Inc. March 12,1997
DRAFT

TABLE 2

OPERABLE UNIT 7 - APACHE TAILINGS

SURFAC E WATER SAMPLIN G RESULT S

NOVEMBER 1996

SAMPLE LOCATION SPR9 L AB NUMBER L1 1863-11 SAMPL E NUMBER M-SPRM1-11239S

SAMPLE DATE 11/23/96 Field

Flow (cfs)

pH (units) Conductivity @25C (umhos/cm) Major Constituents and Inorganics Calcium (mg/L) Chloride (mg/L) ' Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sutfate (mg/L) Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Metals, Total Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters Total Alkalinity (mg/L) Bicarbonate as CaC03 (mg/L) Carbonate as CaCO3 (mg/L) Cation-Anion Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaCO3 (mg/L) Hydroxide as CaC03 (mg/L) Residue, Filterable (TDS) (mg/L) Residue. Non-Filterable (TSS) (mg/L)

NM

5.63

2610

274

2.9

0.2 B

206

0.01 B

0.3

0.31

5.1

8.4

1630

0.045

0.012 B J

0.01 U

0.034

0.04 B

43

0.027

55.4

71.5

0.005 U

0.032

0.02 B

43.2

0.074

54

69.8

S B

S B

2U

7

2B

1530

2U

2540

18B

SPR21

L11883-13

M-SPR21-01-1 12396

11/23/96

NM

6.24

2350

194.0

2.5

0.1 U

162.0

0.04 B

0.02 U

0.03 B

7.1

8.5

1520

0.0156

0.006 B J

0.01 U

0.035

0.02 U

105.0

0.057

77.9

70.2

0.005 U

0.032

0.02 U

102.0

0.110

75.3

67.9

15

15

2U

6.8

2B

1150

2U

2170

56

CG03

L1 1845-12

M-CGOM1-1 12198

11/21/96

2.27

7.28

826

131

1.4 B

0.3 B

40.3

0.01 U

0.19

0.19

1.6

3.3

424

0.013 B

0.005 U

0.005 U

0.019

0.01 U

0.61

0.001 U

0.975

4.23

0.005 U

0.018

0.01 U

1

0.027

0.931

4.11

50

50

2U

1.5

1 B

493

2U

640

5U

SPR7

L1 1863-02

M-SPR7-OM123W

11/23/96

0.05

3.24

6360

406

11.6

0.1 U

398

0.01 U

0.03 B

0.03 B

5

13

7140

0.052

0.055 J

0.02 U

0.207

0.28 B

1190

0.776

371

247

0.01 U

0.171

0.1 U

1110

0.718

323

230

2U

2U

2U

0.4

3B

2650

2U

8950

62

SPR8

L1 1863-05

M-SPR8-01-11239S

11/23/96

0.01

3.17

1705

227

3

0.2 B

97.1

0.01 U

0.02 U

0.02 U

2.5

5.4

1350

0.005 U

0.006 BJ

0.005 U

0.058

0.1

56.2

0.394

60.8

46.5

0.005 U

0.056

0.07

53

0.391

52.5

42.8

2U

2U

2U

0.1

28

967

2U

1740

6B

CGA01U

L1 1845-11

M-CGA01U-01-1121S6

11/21/96

3.32

7.33

954

137

1.5 B

0.3 B

45.9

0.01 B

0.21

0.22

1.5

3.4

516

0.011 B

0.005 U

0.005 U

0.02

0.01 U

16.9

0.001 U

6.17

7.74

0.005 U

0.02

0.01 U

17.1

0.053

5.76

7.46

18

18

2U

4.7

18

531

2U

760

36

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

cfs = cubic feet per second NM = not measured; flow too low to measure U = not detected at the indicated method detection limit (MDL) B= Anatyte concentration detected at a value between the MDL and the practical quantitation limit (PQL) J= estimated value NR= not reported

J:\5344\96SAMP\NOV96DAT.WB2 Page 3 of 4 McCulley , Prick & Oilman. Inc. March 12,1997
TABLE 2

OPERABLE UNIT 7 - APACHE TAILING S

SURFAC E WATER SAMPLIN G RESULT S

NOVEMBER 1996

SAMPLE LOCATION CGA01L

L AB NUMBER L1 1845-10

SAMPLE NUMBER IMGAOIL-OI-IIJIW SAMPLE DATE 11/21/96 Field Flow (cfs)

pH (units) Conductivity @25C (umhos/cm) Major Constituents and Inorganics Calcium (mg/L) Chloride (mg/L) Fluoride(mg/L ) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L)

. Phosphorus, dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved

Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Metals, Total

Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters Total Alkalinity (mg/L) Bicarbonate as CaC03 (mg/L) Carbonate as CaC03 (mg/L) Cation-Anion Balance (%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaCO3 (mg/L) Hydroxide as CaC03 (mg/L) Residue, Filterable (TDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L)

3.32

7.02

862

129

1.5 B

0.2 B

43

0.018

0.23

0.24

1.6

3.1

437

0.01S B

0.005 U

O.OOS U

0.024

0.01 U

12.5

0.001 U

5.25

7.79

O.OOS U

0.024

0.01 B

14.4

0.105

5.07

7.89

34

34

2U

7.1

1 B

499

2U

680

44

PD1

L1 1845-06

M-PD1-01-1 12298

11/22/96

1.65

7.52

200

24.7

0.9 B

0.1 B

11.6

0.01 U

0.13

0.13

0.7 B

1.3

14.9

0.005 B

0.006 B

0.005 U

0.002 B

0.01 U

0.01 U

0.001 U

O.OOS U

0.02 B

0.005 U

0.001 U

0.01 U

0.01 B

0.001 u

0.005 U

0.05

89

89

2U

2.9

1 B

109

2U

110

5U

SPR22

L1 1845-07

M^PR22-Ot-1t22»6

11/22/96

NM

6.96

336

42.9

1.5 B

0.1 U

15.6

0.01 U

0.5

0.5

1.7

2.1

61

0.009 B

0.005 U

O.OOS U

0.002 B

0.01 U

0.01 U

0.001 U

• 0.006 B

0.03 B

0.005 U

0.001 U

0.01 U

0.09

0.003 B

0.023 B

0.13

97

97

2U

3.8

1 U

171

2U

200

12 B

CP1

L1 1863-07

VWJP1 -01-1123 9»

11/23/96

NM

8.31

350

40.2

1.8 B

0.1 U

16.7

0.01 U

0.36

0.36

3.5

2.3

64

0.009 B

0.005 U J

0.001 U

0.0003 B

0.01 B

0.01 U

0.0002 U

0.009 B

0.07

0.002 U

0.0004 U

0.01 U

0.17

0.002

0.026 B

0.13

96

96

2U

3.4

1B

169

2U

230

5U

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

cfs = cubic feet per second NM = not measured; flow too low to measure U = not detected at the indicated method detection limit (MDL) B= Analyte concentration detected at a value between the MDL and the practical quantitation limit (POL) J= estimated value NR= not reported

J:\5344\96SAMP\NOV96DAT.WB2 Page 4 of 4 McCulley , Frick & Oilman. Inc. March 12,1997
DRAFT

TABLE 3

OPERABLE UNIT 7 - APACHE TAILING S

SURFAC E WATER AN D GROUNDWATER SAMPLIN G RESULT S

DECEMBER 1996

SAMPLE LOCATION L AB NUMBER

SAMPL E NUMBER

SAMPLE DATE Field Row(cfs)

pH (units) ' Conductivity @25C (umhos/cm) Major Constituents and Inorganics Calcium (mg/L) Chloride (mg/L) Fluoride (mg/L) Magnesium (mg/L) Nitrite as N (mg/L) Nitrate as N (mg/L) Nitrate/Nitrite as N (mg/L) Potassium (mg/L) Sodium (mg/L) Sulfate (mg/L ) Phosphorus dissolved (mg/L) Phosphorus, ortho dissolved (mg/L) Metals, Dissolved Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Metals, Total

Arsenic (mg/L) Cadmium (mg/L) Copper (mg/L) Iron (mg/L) Lead (mg/L) Manganese (mg/L) Zinc (mg/L) Other Water Quality Parameters

Total Alkalinity (mg/L) Bicarbonate as CaCO3 (mg/L)

Carbonate as CaCO3 (mg/L) Cation-Anion Balance(%) Dissolved Organic Carbon (DOC) (mg/L) Hardness as CaCOS (mg/L) Hydroxide as CaCOS (mg/L) Residue, Filterable (IDS) (mg/L) Residue, Non-Filterable (TSS) (mg/L )

APD1 L12135-01

M-APD1-01-121596

12/15/96

0.38

7.67

515

68.5

1.3 B

0.1 U

26.9

0.01 U

0.45 -

0.45

0.6 B

2.3

158

0.01 66

0.005 U

0.002 U

0.0227

0.01 U

0.01 U

0.0039

0.189

4.36

0.002 B

0.0215

0.01 U

0.27

0.0254

0.177

4.02

102

102

2U

4.2

1 U

282

2U

330

10B

APU1 AP1TMW3 L12135-02 L12145-01

M-APU1-01-121596 M-AP1TMW3-01-121796

12/15/96 12/17/96

0.438

7.11

624

63.3

1.3 B

0.1 U

24.2

0.01 U

0.48

0.48

0.7 B

2.1

145

0.005 B

0.005 U

0.002 U

0.0215

0.01 U

0.01 U

0.0052

0.181

3.85

0.002 U

0.0202

0.01 U

0.09

0.0134

0.161

3.65

97

97

2U

3.2

1U

258

2U

310

14 B

NM

5.50

441

58.9

9.4

0.1 U

22.2

0.01 U

2.59

2.59

1.2

4.9

133

0.005 U

0.022 B

0.002 U

0.0004 U

0.01 U

0.01 B

0.0004 U

0.025

0.06

NR

N R

NR

N R

NR

NR

NR

69

69

2U

4.1

1 U

238

2U

300

8B

Data validation not fully complete; data qualifiers may be added, modified or deleted upon completion of the data validation process.

cfs - cubic feet per second NM - not measured NR * not reported U - analyte not detected at the indicated method detection limit (MDL) B B analyte concentration detected at a value between the MDL and practical quantitation limit J = estimated value

J:\5344\96SAMP\DEC96DAT.WB2 Page 1 of 1 McCulley , Frick & Gilman , Inc. March 12,1997
MONITORIN G WEL L CONSTRUCTION SUMMAR Y APACH E TAILING S

Wel l

Identificatio n AP1TMW 1

AP1TMW 2

AP1TMW 3

AP1TMW7

APITMW 8

APITMW 9

AP1TMW1 0

AP1TMW11S

AP1TMW11 D

AP1TMW12S

AP1TMW12 D

AP1TMW13S

AP1TMW13 D

AP1TMW14S

AP1TMW14 D

APITMWI 5

AP1TMW16 S

APITMW16 D

N WS

W 5A

NWS B

W5C

W 5D

N WS

NW16

Date

of Installatio n

09/24/91

09/17/91

09/18/91

10/09/91

10/23/91

10/21/91

10/22/91

10/29/96

10/23/96

10/31/96

10/30/96

1 1/05/96

1 1/07/96

11/12/96

11/11/9 6

11/13/96

11/11/9 6

1 1/14/96

10/25/84

1 1/02/84

11/13/8 4

10/16/90

10/13/90

10/25/84

1 1/07/84

Location

Northin g

513,898.76

513,779.72

513,660.83

513,917.83

513,951.56

513,968.91

513,704.74

513,946.63

513,936.70

513,979.48

513,974.85

513,629.69

513,640.82

514,403.19

514,405.98

514,056.37

513,93513

513,915.00

513,358.50

513,377.06

513,382.80

513,347.82

513,376.86

Easting

1,775,525.87

1,775,709.29

1,775,414.13

1,777,822.94

1,776,525.35

1,776,843.25

1,776,993.72

1,776,544.0!

1,776,555.86

1,776,840.85

1,776,857.18

1,777,199.91

1,777,206.39

1,776,813.39

1,776,803.70

1,777,281.76

1,776,304.13

1,776,304.89

1,777,636.34

1,777,642.07

1,777,655.47

1,777,652.96

1,777,681.41

Elevation T op of PVC

Casing

(ft )

10,044.16

10,041.14

10,029.95

10,146.62

10,117.28

10,114.17

10,114.70

10,117.80

10,118.48

10,116.97

10,116.92

10,099.41

10,099.14

10,116.03

10,115.99

10,118.69

10,065.93

10,065.64

10,113.92

10,114.23

10,114.78

10,115.13

10,117.39

10,067.15

10,124.84

Approximate Ground Surface

(ft )

10,041.80

10,039.69

10,029.10

10,144.95

10,115.45

10,112.83

10,112.70

10,115.80

10,116.48

10,114.97

10,114.92

10,097.41

10,097.14

10,114.03

10,113.99

10,116.69

10,063.93

10,063.64

10,111.92

10,112.23

10,112.78

10,113.13

10,115.39

10,065.65

10,123.96

Casing Diameter

(in)

4

4

4

4

4

4

4

2

2

2

2

2

2

2

2

2

2

2

6

4

4

4

4

6

4

Well Screen Interval

Length

(ft)

10

5

10

10

I S

10

10

10

10

10

10

10

10

10

5

10

10

5

60

20

40

60

40

50

40

Approximate Depth

(ft )

12.0-22.0

9.0-14.0

13.4-23.4

62.2-72.2

20.5-35.5

9.3-19.3

9.0-190

36.3-46.3

54.8-64.8

21.0-31.0

38.8-48.8

4.8-14.8

29.0-39.0

21.5-31.5

47.4 - 52.4

19.0-29.0

4.8-14,8

13.0-18.0

48.0-108.0

15.0-35.0

220.0-260.0

48.0-108.0

221.5-261.5

26.0-76.0

40.0 - 80.0

Approximate

Elevation

(ft)

10,029.8-10,019.8

10,030.7-10,025.7

10,015.7-10,005.7

10,082.8-10,072.8

10,095.0-10,080.0

10,103.5-10,093.5

10,103.7-10,093.7

10,079.5-10,069.5

10,061.7-10,051.7

10,094.0-10,084.0

10,076.1-10,066.1

10,092.6-10,082.6

10,068.1-10,058.1

10,092.5-10,082.5

10,066.6-10,061.6

10,097.7-10,087.7

10,059.1-10,049.1

10,050.6-10,045.6

10,063.9-10,003.9

10,097.2-10,077.2

9,892.8-9,852.8

10,065.1-10,005.1

9,893.9-9,853.9

10,039.7-9,989.7

10,084.0-10,044.0

Sand Pack Interval

Length

(ft)

14.5

9.5

15.5

21.5

21

14

13

14

12.2

12.5

16

11.1

13.1

12.5

8

13

11

9

76

25

150

71.5

55.3

76

48

Approximate Depth

(ft )

9.0-23.5

5.5-15.0

9.5 - 25.0

56.0-77.5

16.0-37.0

6.0-20.0

7.0-20.0

33.0-47.0

52.9-65.1

18.5-31.0

330-49.0

4.0-15.1

27.0-401

19.5-32.0

45.0 - 53.0

16.5-29.5

4.0-15.0

11.0-20.0

32.0-108.0

10.0-35.0

1 10.0 - 260.0

39.6-111.1

208.6 - 263.9

20.0-96.0

32.0-80.0

Approximate

Elevation

(ft )

10,032.8-10,018.3

10,034.2-10,024.7

10,019.6-10,004.1

10,089.0-10,067.5

10,099.5-10,078.5

10,106.8-10,092.8

10,105.7-10,092.7

10,082.8-10,068.8

10,063.6-10,051.4

10,096.5 - 10,084.0

10,081.9- 10,065.9

10,093.4 - 10,082.6

10,070.1-10,057.1

10,094.5-10,082.0

10,069.0-10,061.0

10,100.2-10,087.2

10,059.9-10,048.9

10,052.6-10,043.6

10,079.9-10,003.9

10,102.2-10,077.2

10,002.8-9,852.8

10,073.5-10,002.0

9,906.79-9,851.5

10,045.7 - 9,969.7

10,092.0-10,044.0

Approximate Total Depth of Wel l

Below Top of PVC

(ft)

260

16.3

25.4

77.6

38.1

21.8

21.7

49.1

67.6

33.4

51.0

17.4

416

34.0

55.1

31.1

17.5

20.5

108.0

35.5

260.0

110.5

260.0

92.5

78.8

J:\5344\WELLCNST.WB 2 03/13/97
2/97 D:\5344\5344-1.DWG

PKW OTY. 10 r770»-»1J4

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—«. -f SIT E PLAN SHOWIN G MONITORIN G LOCATION S PROJECT: 5344.0 I DATE: FEBRUARY, 1997 REV: I BY: SCGI CHECKED: DLL McCULLEY. FRICK & OILMAN. INC.
INTERIM REMOVAL ACTION PLAN OPERABLE UNIT 7 - APACHE TAILINGS IMPOUNDMENTS

California Gulch Superfund Site Leadville, Colorado

April 3, 1997

Prepared for:

ASARCO INCORPORATED

495 East 51st Avenue Denver, Colorado 80216-2093

Prepared by:

MCCULLEY, FRICK & OILMAN, INC. providin g environmental consulting and engineering services

4840 Pearl East Circle, Suite 20CW Boulder. Colorado 80301

(303) 447-1823 F AX 447-1836
TABLE OF CONTENTS

LIST OF FIGURES ..................................................... ii

1.0 INTRODUCTION ................................................ 

2.0 BACKGROUND .................................................]

3 .0 CURRENT SITE CONDITIONS

4.0 OBJECTIVES ................................................... 3

5 .0 PROPOSED INTERIM REMOVAL ACTIONS ............................. 3

5.1 REMOVAL OF TAILINGS PONDS 2 AND 3 ........................ 3

5.2 EROSION PROTECTION ...................................... 6

6 .0 TENTATIVE CONSTRUCTION SCHEDUL E ...........................

7.0 REFERENCES ................................................... 8

J;U3«\JJiU-3\RAPLAN DOC McCuIley , Frick & Oilman, Inc. April 3, 1997

xv?;-;-?. >:o:'£.£ A:T
LIST OF FIGURES

PLJLjL*4A_ i Qi ^K *• - * T* 1 H.1 i f 1TM •

1 Site Plan

2 Nov. 1996 - Preliminary Surface Water Monitoring Data

3 Cross Section A-A

4 1997 Interim Removal Action Plan

5 Embankment Protection Details

McCulley , Frick & Oilman. Inc. 11

 April 3, 1997
1.0 INTRODUCTION

Asarco is proposin g to perform interim removal actions at the Apache Tailings Impoundments,

Operable Unit 7 (OU-7) of the California Gulch Superfund Site (the Site) in Leadville, Colorado. In order

to complete these actions in 1997, Asarco is proposing to undertake these actions as a Time-Critical

Removal Action under CERCLA. The proposed interim actions are intended to be consistent with any

proposed remedy evaluated under the revised Feasibility Study to be completed for the Site.

2.0 BACKGROUND

The results of previous investigations related to the Apache Tailings Impoundments are presented

in various reports including the Tailings Disposal Area Remedial Investigation Report (1994), the

Hydrogeologic Remedial Investigation Report (1995), and the Surface Water Remedial Investigation Report

(1995). In January 1996, a draft Feasibility Study (FS) was submitted for the Apache Tailings

Impoundments. Subsequent to the submittal of the draf t FS, additional site investigation activities have

been initiated to supplement the previous investigations and to support completion of the FS.

3 .0 CURRENT SITE CONDITIONS

The Apache Tailings Impoundment consists of a main tailings impoundment and two smaller

impoundments located along California Gulch, approximately 1,500 feet downstream of the Yak Tunnel

Water Treatment Plant surge pond, as illustrated on the Site Plan (Figure 1). The main impoundment

encompasses approximately 11.3 acres within an area zoned for industrial use by the City of Leadville. The volume of tailings in the main impoundment has been previously estimated at approximately 630,000

cubic yards. The embankment slopes on the north and east side of the main impoundment range from

1.5:1 (H:V) to 1.75:1 and reach heights of up to 15 feet. The embankment slope on the southwest side

of the main impoundment approaches 1:1 and is up to 50 feet in height. The two smaller impoundments, Tailings Pond No. 2 (TP2) and Tailings Pond No. 3 (TP3) are located west of the main impoundment and

directly north and adjacent to water flowin g in the gulch, TP2 is located immediately west of the main

impoundment and covers an area of approximately 1.5 acres. TP3 is located immediately west of TP2 and

covers an area of .approximately 0.5 acres. The volume of tailings material in TP2 and TP3 have been

-: j344\sj*».3'.SAWAN.ixx: McCulley , Prick & Oilman. Inc.

1 April 3, 1997

;r.:-:i; L6
estimated previously at approximately 8,500 and 3,800 cubic yards, respectively. Impoundment berms for

both ponds (at the south and west sides of the impoundments) appear to have been constructed of native

soil material from California Gulch. These berms range from 1:1 to 1.5:1, are approximately 10 feet in

height and are approximately 10 feet wide across the top.

T he majority of surface water flow in California Gulch is presently conveyed by the California

Gulch channel located on the south side of the gulch in the vicinity of the Apache Tailings Impoundment. The channel intersects the southern edge of the main impoundment where the flow is carried by two 24-

inch diameter clay-tile culverts installed beneath a portion of the impoundment. Surface water flow from

the area immediately upstream (approximately 1,000 feet) of the main impoundment and below the

elevation of the constructed California Gulch channel are conveyed under the main impoundment through

what appears to be a wooden box culvert. After exiting these culverts, surface water flows continue to the

northwest, west of and adjacent to the southwest embankment of the main impoundment, for approximately

300 feet before turning to the west and continuing down the gulch past the lower impoundments (TP2 and

TP3) .

A field investigation was conducted in November and December 1996 to supplement the existing

data presented in the various Remedial Investigation reports and draft Feasibility S-:dy for the Site. The

purpose of the supplemental investigation was to gather data to enhance the evaluation of the interaction

of surface water and groundwater in the immediate vicinity of the Apache Tailings Impoundments. As part

of this supplemental field investigation, 11 new groundwater monitoring wells were installed at the Site. Two rounds of groundwater and surface water sampling are planned at the Site as part of the supplemental

investigation; one sampling event to coincide with low-flow conditions and one to coincide with high-flow

conditions. The first of these events was performed in November 1996 with the sampling of 18

groundwater wells, and surface water sampling at 22 locations. The locations of the groundwater

monitoring wells and surface water sampling locations are presented on Figure 1. Surface water flow

measurements were obtained at 21 locations. Selected data from this November 1996 event are presented

on the attached Figure 2, entitled Nov. 1996 - Preliminary Surface Water Monitoring Data. Figure 3

presents a cross section (Cross Section A-A indicated on the Site Plan) taken through the lower

impoundments and extending through the main impoundment near the locations of monitoring well clusters

AP1TMW11 an d AP1TMW12 .

McCulley . Frick & Oilman, Inc. April 3. 1997
4.0 OBJECTIVES

The followin g objectives have been established for implementation of interim removal actions at

the site:

* Reduce the potential for impacts the tailings impoundments may have on surface water and

groundwater in California Gulch; and

• Prepare portions of the tailings material, primarily through consolidation and dewatering,

to facilitate the timely implementation of future final remedial actions.

5 .0 PROPOSED INTERIM REMOVAL ACTIONS

The proposed interim actions to meet the objectives presented above include removal of Tailings

Ponds 2 and 3 (TP2 and TP3) and consolidation of this material on the main impoundment, and providing

erosion protection along the toe of the southwest embankment of the main impoundment below the clay-tile

culverts and wooden box culvert outfalls .

5.1 REMOVAL OF TAILINGS PONDS 2 AND 3

The removal of TP2 and TP3 will involve the excavation of the tailings from these impoundments,

placement of the material on the main impoundment, and recontouring the removal area to promote

drainage (adding clean fill as necessary). The proposed interim removal action will eliminate potential

contact with groundwater and eliminate future contact with surface water in California Gulch. Spreading

the excavated material on the main impoundment will promote drainage and drying of the tailings material

and improve their handling characteristics and trafficabiliry , which will facilitate a future final remedy.

The tailings in TP2 and TP3 generally consist of yellow, orange, orangish brown and black silt and

fine-grained sand tailings, and appear to contain abundant pyrite. Three subsurface tailings samples (two

from TP2 and one from TP3), and two samples of the underlying soil (one from beneath each

impoundment) were collected during the Tailings Disposal Areas Remedial Investigation (Asarco, 1994). A summary of the total metals concentrations of these samples is presented in Table 3-10 of the Tailings

RI Report (Asarco, 1994). As indicated in this table, the samples of tailings from TP2 exhibit lead

J:\5344\33u-j\KAPLAN.DOC McCulley, Frick & Oilman. Inc. 3

 April 3.1997
concentrations of 1,930 mg/kg (4 - 5') and 7,410 mg/kg (8.8 - 9.8') and zinc concentrations of 6,700

mg/kg ( 4 - 5') an d 15,400 mg/kg (8.8 - 9.8') . The sample of tailings from TP3 ( 4 - 5') exhibits a lead

concentration of 2,680 mg/kg and a zinc concentration of 4,030 mg/kg. The two samples of underlying

(foundation) soils exhibit lead concentrations of 694 mg/kg (TP3) and 2,060 mg/kg (TP2) and zinc

concentrations of 992 mg/kg (TP2) and 1,600 mg/kg (TP3). The impoundment berms for both TP2 and

TP3 appear to have been constructed of native soil material.

Surface water that currently is ponded on TP2 and TP3 will be removed prior to initiating

excavation by pumping the water to the existing pond on the main impoundment for ultimate transfer to

the Yak Tunnel Water Treatment Plant (WTP), or by transporting it to the WTP using tanker trucks. As

indicated on the cross section, the base of TP2 and TP3 may currently be near or below the groundwater

table in this area and, therefore, dewatering during excavation may be required. Water removed during

excavation will be pumped to the existing pond on the main impoundment.

All tailings and a six- to twelve-inch layer of underlying native soil will be excavated and removed,

the tailing/native soil interface, both vertically and horizontally, will be determined by visual observations

during excavation. Excavation activities will begin at the lower impoundment berm of each impoundment

and proceed toward the northeast. A sump will be created near the berm and any groundwater encountered

during excavation will be pumped from this sump to the main impoundment to maintain water levels below

the bottom of the excavation to the extent practicable. This method of excavation should produce

conditions conducive to a visual determination of tailings removal. Followin g complete removal of all

visually identifiable tailings and impacted subgrade soils, confirmation samples of the native underlying

soil will be obtained. Four grab samples representative of the native soil underlying TP2 and two grab

samples representative of the native soil underlying TP3 will be collected and analyzed for total lead and

zinc, by field X-Ray Fluorescence (XRF) or appropriate wet chemistry methods (e.g., TCP analysis). The

results of these analyses will be used to further document the metals concentrations in the underlying native

soils. The material in the impoundment berms will also be sampled to determine it's suitability for use as

backfill material. Although the interim action levels for lead in soils in a commercial or industrial setting

are in the range of 6,100 to 7,700 mg.kg, only material with lead concentrations below 3,500 mg/kg will

be used to backfill the excavations and recontour the area. Impoundment berm material found to contain

greater than 3,500 mg/kg lead will be placed on the main impoundment. Monitoring well AP2TMW1

c McCulley , Prick & Oilman, Inc. 4

 April 3, 1997
located in TP2, which has been dry and is not being sampled as pan of the supplemental investigation, will

be removed during excavation.

Followin g excavation, regrading and/or limited backfil l placement will be performed in the removal

areas to create a final ground surface above the groundwater table which will promote surface drainage

and prevent ponding. Material from the impoundment berms with lead concentrations less than 3,500

mg/kg will be used as fill material and will be supplemented with import fill, as necessary, from either the

Oregon Gulch or Hecla borrow areas. Regrading/recontouring will be performed to maintain current

surface water flow conditions in California Gulch. The proposed approximate final contours are shown

on Figure 4. Other reclamation activities, such as soil amendment or revegetation, will not be performed

until the final remedy for this area of OU7 is selected.

Potentially contaminated surface water run-off from the main impoundment will be directed

through the area between TP2 and the main impoundment to a sediment control structure as indicated on

Figure 4. The sediment control structure will consist of an earthen berm with a hay bale core and a rock

or riprap lined discharge notch intended to intercept and retain sediment in stormwater runoff. This

structure will be maintained until the final remedy is implemented. Diversion of uncontaminated surface

run-off along the north side of the main impoundment will also be maintained or upgraded to minimize

potential contact with tailings material or other potentially contaminated flows .

During the excavation, on-site transport, and placement of tailings material, appropriate

engineering controls will be maintained to control stormwater runoff and dust generation. Silt fence, or

other temporary sediment control devices, will be installed at the base of the impoundment berms to

intercept and retain sedimen: in stc .nwater runoff from TP2 and TP3 during construction activities. While

dust control will not likely be required in the excavation area, dust control on the haul route will be

maintained through water application , as necessary.

The excavated tailings will be transported to the main impoundment using the temporary road from

the west side of the impoundment near the old foundations to the new well installations near the center of

the impoundment (AP1TMW12) and placed on the north side of this road, as indicated on Figure 4, It is

expected that placement may be achieved utilizing low ground pressure equipment without the use of

J:\5344\5J4t-JVRAftAN.DOC McCulley, Frick & Oilman, Inc.

5 April 3, 1997
geotextiie cr geosynthetic subgrade support. Several settlement plates will be installed in the fill placement

area to monitor the settlement/consolidation of the underlying tailings as a result of loading from the fill.

Water ponded on the main impoundment will be transferred to the Surge Pond at the WTP, Thi s

water will be pumped from the existing sump area near the southwest corner of the existing pond and

conveyed to the Surge Pond via the existing high density polyethylene pipeline. Alternatively, prior to the

initiation of excavation activities at TP2 and TP3, water may be transferred to TP2 and transported to the

treatment plant using tanker trucks. The removal of this water is intended to reduce the potential for

infiltration of ponded water through the main impoundment and to help prepare the tailings for final

remedial actions.

5 .2 EROSION PROTECTION

The California Gulch channel currently follow s the embankment of the main impoundment (flowing

in a northwesterly direction) for approximately 300 feet from the clay-tile culvert outfal l before turning to

the west and flowin g away from the impoundment. Erosion of native soil underlying tailings at the base

of this embankment is evident along this 300-foot reach. Activities involving the protection of the toe of

this embankment are proposed to minimize further erosion, sediment loading and potential surface water

contact with the tailings.

These activities will involve the limited excavation of tailings at the knob which extends toward

the channel approximately 100 feet below the clay-tiie culvert outfalls , and the placement of clean fill

and/or riprap for erosion protection at the toe of the embankment. Currently, the upstream face (south

side) of this knob is nearly vertical. This condition is unstable and there is evidence that, through erosion

and undercutting of the underlying native soil, tailings material has sloughed off of this knob. Excavation

of this knob would be performed to create a more stable surface with a maximum slope of 2H:IV.

Excavated material wil l be placed directly in the erosion channel or slope failure area in the main

impoundment embankment immediately to the north of the knob as shown on Figure 5, and compacted

using non-vibratory compaction equipment. Thi s placement location eliminates the need to haul material

from the area and should provide additional stability to the main impoundment embankment. Erosion

protection of the toe of the embankment from the upstream edge of the knob to the point where the channel

McCullcy . Frick & Oilman, Inc. April 3, 1997
turns away from the main impoundment will be provided through the placement of riprap two to three

vertical feet up the toe of the embankment.

To facilitate these activities and provide access to the work area, flo w in the channel below the

knob will be diverted, or moved, approximately 10 feet to the west of the embankment, and a ramp will

be constructed to provide access for a small track excavator to the top of the knob, as indicated on Figure

5. Silt fence and/or hay-bales will be placed at the base of the knob during excavation to reduce the

potential for excavated material fallin g into the channel, It is anticipated that short-term increases in

sediment loading may be observed during construction activities in and around the channel. Several silt

fence/hay-bale check dams will be installed across the channel in the vicinity of the lower impoundments

to provide sediment control during construction.

A cultural resource investigation of the Apache Tailings Area was conducted in August 1995, and

a site with potential archaeological significance was identified. This site is located immediately west of

California Gulch below the culvert outfall s on the southwest side of the mam impoundment, as outlined

on Figure 5. The site contains structural remains and artifact scatter and was recommended as individually

eligible for nomination to the National Register of Historic Places and contributing to the Leadville Mining District (Asarco, 1995). The site will be protected, as necessary, and avoided during the performance of

work in this area.

6 .0 TENTATIVE CONSTRUCTION SCHEDULE

The proposed schedule for the implementation of interim actions is as follows:

Removal of Ponded Water from TP2 ( TP3

and Main Impoundment

Erosion Protection (SW embankment toe)

Removal of TP2 and TP3

June-Jul y '9 7

April-May '9 7

August-September '9 7

J :\3344VS W*.3\RAPLAN. DOC McCulley, Prick & Oilman, Inc. April 3, 1997
7.0 REFERENCES

Asar=o. 1994. Tailings Disposal Area Remedial Investigation Report, California Gulch Site, Lesdvilie , Colorado. Prepared by Woodward-Clyde Consultants. January.

Asarco, 1995. Cultural Resources Investigations of the Apache Tailings Ares, Operable Unit 7. California Guich Superftin d Site,

Leadvills. Colorado. Prepared by Foothil l Engineering Consultants, Inc., November.

McCulley, Frick & Oilman. Inc. April 3, 1997
UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

REGIO N VII I

9 99 18th STREET-SUIT E 500

DENVER , COLORAD O 80202-24B6

Ref: 8EPR-SR

CONCURRENC E ACTIO N MEMORANDUM

DATE: April? , 1997

SUBJECT: Request for Removal (Response) Action at the California Gulch National Priorities List Site, Leadville, Colorado: ACTION MEMORANDUM for a Time- Critical Removal Action for Removal of Tailings Pond No. 2 and Tailings Pond No. 3 of the Apache Tailings Impoundmen t (Operable Uni t 7)

FROM: Mike Holmes , 8EPR-SR

T O: Max H. Dodson Assistant Regional Administrator Offic e of Ecosystems Protection

and Remediation

Final NPL Site ID # 29

CERCLIS ID # COD980717938

Category of Removal: Time-Critical

I. Purpose / <- Thi s Action Memorandum documents the Agency' s selection an d implementatio n

of the time critical removal (response) action described herein for the Apache Tailing s Impoundments/a n area contaminated with metal-laden tailings from

historic minin g an d millin g operations. The Apache Tailing s Impoundmen t area

comprises a smal l portion of the Superfun d RI/FS Stud y Area of the California Gulch Superfun d Site , located in the Leadville mining district of Lake County, Colorado.

T he Time Critical Removal Action at the Apache Tailings Impoundment s is

consistent with the remedial activities which wil l be undertaken by EPA at OU 7. Final remedial alternatives for all areas of OU 7 wil l be evaluated in the Feasibilit y Stud y (FS) and Record of Decision (ROD) for OU7. The ROD for OU 7 wil l

^ Cultimatel y specif y those remedial actions, beyond those response actions

 ^implemented pursuant to thi s Action Memorandurryiare required. The FS wil l

J/Q-'<H~ 7 p

. , „ ldp

Printed on Recycled Paper
UNITE D STATE S ENVIRONMENTA L PROTECTIO N AGENC Y

REGION VII I

9 99 18th STREE T -SUIT E 500

DENVER , COLORAD O 80202-2466

Ref: 8EPR-SR CONCURRENCE

ACTION MEMORANDUM

DATE: April? , 1997

SUBJECT: Request for Removal (Response) Action at the California Gulch National Priorities List Site, Leadville, Colorado: ACTION MEMORANDUM for a Time- Critical Removal Action for Removal of Tailings Pond No. 2 and Tailings Pond No. 3 of the Apache Tailings Impoundment (Operable Unit 7)

FROM: Mike Holmes , 8EPR-SR

T O: Max H. Dodson Assistant Regional Administrator Office of Ecosystems Protection

and Remediation

Final NPL Site ID # 29.

CERCLIS ID # COD980717938

Category of Removal: Time-Critical

I . Purpose

Thi s Action Memorandum documents the Agency's selection and implementation

of the time critical removal (response) action described herein for the Apache Tailing s Impoundments , an area contaminated with metal-laden tailings from

historic mining and millin g operations. The Apache Tailings Impoundmen t area

comprises a small portion of the Superfun d RI/FS Study Area of the California Gulch Superfun d Site , located in the Leadville mining district of Lake County, Colorado.

T he Time Critical Removal Action at the Apache Tailings Impoundment s is

consistent with the remedial activities which wil l be undertaken by EPA at OU 7. Final remedial alternatives for all areas-of OU 7 will be evaluated in the Feasibilit y Stud y (FS) and Record of Decision (ROD) for OU7. The ROD for OU 7 will

ultimatel y specify those remedial actions beyond those response actions

implemented pursuant to this Action Memorandum that are required. The FS wil l

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evaluate the effectivenes s of a remedy to stabilize the tailings in place or if the main

impoundment will need to be relocated out of the California Gulch flood plain . The

primary goal of thi s Removal Action is to prevent exposure to human population s

from tailings washed into California Gulch and degradation of downstream water

quality. Thi s removal action will also reduce the leachin g and migration of metals

from the tailings into surface and ground waters during storm events which occur

prior to implemtatio n of remedial action under thel ROD for OU7. Regardless of

t he remedy selected by the ROD, the response actions taken under this Action Memorandum will allow for the consolidation into a smaller area and the dryin g out

of the tailings .

Remedial action objectives were identified in the Final Screenin g Feasibilit y Stud y

f or Remediation Alternatives at the California Gulch NPL Site, Leadville , Colorado

(SFS), (EPA, 1993a). Consistent with the SFS, removal action objectives for the Apache Tailings Impoundment s are:

O Control water erosion of tailings material from the source location s

O Control leaching and migration of metals from tailings into surface

water

O Control leachin g and migration of metals from tailings into

groundwater

Removal alternatives to directl y remediate surface water or ground water in the

vicinity of the Apache Tailings Impoundment s have not been evaluated, and wil l be

addressed under Operable Unit 12.

I I . California Gulch - Sit e Condition s an d Background

T he California Gulch Site was listed on the National Priorities List on September 8,

1983. The Site is in a mining area covering 16 Y2 square miles of a watershed that

drains along California Gulch to the Arkansas River. Startin g in 1859, the area was

mined extensively for gold, lead, silver, copper, zinc, and manganese. California Gulch collects runof f that drains numerous abandoned mines and wastes from

mining, millin g and smelting. Miners buil t the Yak Tunne l to drain water from the

mine workings and to make mineral exploration and developmen t easier. This

tunnel drains hundreds of miles of mine workings in its 4-mile underground course

and discharges approximately 210 tons of metals each year into California Gulch. Seventy-five known mill s dumped tailings into 5-6 miles of drainages. Six

impounded tailings dumps surround the City of Leadville. Many smelters, which are

located around the city, processed silver, lead and zinc at various times. Heav y metal residues are present in much of the City. The Arkansas River which receives

water from the California Gulch, has been classified as a recreational resource, and

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is used heavily for irrigation, livestock watering, public water supplie s and fisheries . Approximatel y 4,000 live in nearby Leadville and Lake County (See Site Location Map - Figur e 1 )

Apache Tailings Impoundment s

A. Background

T he Apache Tailings Impoundmen t consists of a main tailings impoundmen t

a n d two, smaller impoundments , located alon g California Gulch,

approximatel y 1,500 feet downstream of the Yak Tunne l Water Treatmen t Plan t Surge Pond, as illustrated on the attached Site Plan . The main

impoundmen t encompasses approximatel y 11.3 acres. The volume of

tailings in the main impoundmen t has been previously estimated at

approximatel y 630,000 cubic yards. The embankment slopes on the north

and east side of the main impoundment range from 1.5:1 (H:V) to 1.75:1 and

reach heights up to 15 feet. The embankment slope on the southwest side

of the main impoundment approaches 1:1 and is up to 50 feet in height. The

t wo smaller impoundments , TP2 and TP3 are located west of the main

impoundment and directly north and adjacent to water flowin g in the gulch. T P2 is located immediatel y west of the main impoundmen t and covers an

area of approximatel y 1.5 acres. TP3 is located immediatel y west of TP2

and covers an area of 0.5 acres. The volume of tailings in TP2 and TP3

have been estimated previously at approximatel y 8,500 and 3,900 cubic

yards, respectively. Impoundmen t berms for both ponds appear to have

been constructed of native soil material from California Gulch. These berms

range from 1:1 to 1.5:1, are approximately 10 feet in height and 10 feet wide

across the top.

T he majority of surface water flo w in California Gulch is presently conveyed

by the California Gulch channel located on the south side of the gulch in the

vicinity of the Apache Tailing s Impoundment . The channel intersects the

southern edge of the main impoundment where the flow is carried by two 24-

inch diameter clay-tile culverts installed beneath a portion of the main

impoundment . Surfac e water flo w from the area immediatel y upstream

(approximately 1,000 feet) of the main impoundment and below the elevation

of the constructed California Gulch channel are conveyed under the main

impoundmen t through what appears to be a wooden box culvert. After

exiting these culverts, surface water continues to flo w to the northwest, west

of and adjacent to the southwest embankment of the main impoundment , for

approximatel y 300 feet before turnin g to the west and continuin g down the

gulch past the lower impoundment s (TP2 and TP3).

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A field investigation was conducted in November and December 1996 to

supplemen t the existin g data presented in the Remedial Investigatio n and Feasibilit y Study for the site. The purpose of this investigation was to gather data

to enhance the evaluation of the interaction of surface water and groundwater in the

immediate vicinity of the Apache Tailings Impoundments . As part of thi s

supplemental field investigation , 11 new groundwater monitorin g well s were

installed at the site. Two rounds of groundwater and surface water samplin g were

planned at the site as part of the supplemental investigation ; one samplin g event

was performed in November 1996 to coincide with low-flow condition s at the site

involved the samplin g of 18 groundwater wells , and surface water samplin g at 22

locations. Additional detail s are provided in the Interim Removal Action Plan , Operable Uni t 7, Cal Gulch Superfun d Site , dated April 3, 1997 and a letter dated March 13, 1997 which transmits the monitorin g data for the samplin g event

described above. Both these documents are attached to this Action Memorandum.

B. Site Characterization - Apache Tailing s Impoundmen t

T he results of previous investigation s related to the Apache Tailings Impoundmen t are presented in various reports includin g the Tailings Disposal Area Remedial Investigatio n Report, California Gulch Site, Leadville , Colorado, Januar y 1994, the Hydrogeologic Remedial Investigation Report (1995) , and the Surface Water Remedial Investigatio n Report (1995). In January 1996, a Draft Feasibilit y Stud y (FS) was

submitted for the Apache Tailings Impoundments . Subsequent to the

submittal of the draf t FS, additional site investigation activities have been

initiated to supplemen t the previous investigations and to support completio n

oftheFS . T he principal concerns specificall y addressed by thi s Removal Action are:

* Impact s the tailings impoundment s may have on surface water and

groundwater quality in California Gulch; and

* Preparation of the tailings material, primaril y through consolidatio n

a nd dewatering, to facilitate the timel y implementatio n of future, final

response actions.

* A letter report dated March 13, 1997 which summarizes groundwater

qualit y data from samplin g events performed in the area of the Apache Tailings Impoundments , durin g November an d December,

1996, is attached.

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C. Other Actions to Date

* A Time Critical Removal Action was performed by EPA on the Apache Energy and Mineral s Property which is included in Operable Unit 7. T he action involved removal of drums and bags of pyrite and

decontamination and demolitio n of buildings and equipment. This Removal Action was addressed in a separate Action Memorandum

dated Augus t 6, 1996.

* During the summer and fall of 1995, ASARCO installed approximatel y

6 horizontal drain pipe s to passivel y drain water from the main

impoundment. The demonstration project proved ineffective in

drainin g the tailings and was abandoned. Over the past several

years ASARCO has monitored water level s on top of the main

impoundment and TPs 2 and 3 and as needed, the ponded water has

been transferred to the Yak Treatment plan t to prevent catastrophic

release of the metal-laden water into California gulch.

D. State and Local Authorities Roles

A cultural resource investigation of the Apache Tailing s Area was conducted

in 1995, and a site with potential archaeological significance was identified. Thi s site contains structural remains and artifact scatter and is located

immediatel y south of California Gulch below the culvert outfall s on the

southwest side of the main impoundment . The proposed alignmen t of the

diversion ditch will not impact this area and additional investigation or

research on thi s cultural resource site may be necessary, prior to

implementin g the final actions. The initial focus of thi s removal action is to

avoid any impacts on the area of archaeological significance.

I V. Threat s to Public Health or Welfare or the Environment

A Final Baseline Aquatic Ecology Risk Assessment (FBAERA), California Gulch, Leadville , Colorado (Roy F. Weston, Inc.) identifie s the Site-wide impact of mine

waste contamination on the terrestrial and aquatic ecosystems at the Site . The FBAERA provides a conceptual model of Site-wide exposure for aquatic receptors.

Thi s Time-Critical Removal Action is necessitated by the threat to public health,

welfare and/or the environment posed by the direct contact, inhalation , and

ingestion exposure routes to hazardous substances. The Action wil l also reduce

releases of metals to the surface and groundwater.

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V. Endangerment Determination

Actual and/or threatened releases of hazardous substances from the Apache Tailings Impoundments , if not addressed by implementin g the removal action

selected in this Action Memorandum, presents endangerment to public health, or

welfare, or the environment. The public and environment will continued to be

exposed to the release of significan t quantities of contaminated materials.

V I . Proposed Actions/Schedule

A. Proposed Actions

1. The proposed interim actions are described in the Interim Removal Action Plan , Operable Uni t 7, Apache Tailings Impoundments , California Gulch Superfun d Site, dated April 3, 1997. A copy of thi s report is attached. The

proposed interim actions include the following:

1.1 Removal of TP 2 and TP3 and consolidation of the material on

t he main impoundmen t and either divertin g California Gulch

away from the southwest embankment of the main

impoundmen t below the clay-tile culverts and wooden box

culverts outfalls , or providin g erosion protection alon g the toe

of the tailings embankment area.

T he extent of tailings , berms material and native soil to be

removed will be determined by visual observation durin g

excavation. Confirmatio n samples of the underlyin g soil s wil l

be collected and soil s exceeding 3,500 ppm lead will be

removed.

F or thi s removal action, slope stabilit y concerns will be

addressed through the applicatio n of Best Management Practices (BMPs)

1 .2 Surface water that is currently ponded on TP2 and TP3 will be

removed prior to initiatin g excavation by pumpin g the water to

t he existing pond on the main impoundmen t for ultimate

transfer to the Yak Tunnel Water Treatment Plan (WTP), or by

transportin g it to the WTP using tanker trucks. The base of T P2 and TP3 may currently be below the groundwater table in

this area and, therefore, dewatering durin g excavation may be

required. Water removed durin g excavation will be pumped to

t he existin g pond on the main impoundment . Followin g

excavation, clean fill will be placed to restore the area,

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promote surface drainage and prevent ponding. Proposed

approximate final contours are shown on the figure entitled

1997 Proposed Interim Action.

1 .3 The excavated tailings will be transported to the main

impoundment using the temporary road from the west side of

t he impoundmen t near the old foundation s to the new well

installation s near the center of the impoundment (AP1TMW12)

and placed on the north side of this road, as indicated on the

1997 Proposed Interim Action Figure , attached. It is

anticipated that placement may be achieved utilizin g low

ground pressure equipment without the use of geotextile or

geosynthetic subgrade support . The installatio n of several

settlement plates in the fill placement area is also proposed to

monitor the settlement/consolidatio n of the underlyin g tailing s

as a results of loadin g from the fill.

1 .4 Potentiall y contaminated surface run-of f from the main

impoundmen t wil l be directed through the area between TP2

and the main impoundmen t to a sediment control structure as

indicated on Figur e 4. The sediment control structure will

consist of an earthen berm with a hay bale core and a rock or

rip-rap lined discharge notch intended to intercept and retain

sediment in storm water run-off . This structure will be

maintained until the final remedy is implemented. Diversion of

uncontaminated surface run-of f along the north side of the

main impoundment wil l also be maintained or upgraded to

minimize potential contact with tailings material or other

potentiall y contaminated flows .

1 .5 The followin g activities involvin g the protection of the toe of

t he main impoundmen t embankment are proposed. These

activities will include excavation of tailings , primaril y at the

knob which extends toward the channel approximately 100 feet

below the clay-tile culvert outfalls , and the placement of clean

fill and/or riprap for erosion protection at the toe of the

embankment.

B. Applicabl e or Relevant and Appropriate Requirements (ARARs)

T he ARARs listed on TABLE F.1 AND F.2 wil l be followed to the extent

practicable. Copies of these Table s are attached.

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C. Performance Standards

T he ARARs were met through compliance with Performance Standards .

1. The designed and constructed response action included provisions to

ensure that there are no visible emissions (dust) durin g removal activities at

t he Apache Tailing s Impoundments . Dust control on the haul route, and

other areas, will be maintained through water application , as necessary.

2. During the excavation, on-site transport, a'nd placement of tailings material ,

appropriate engineering controls wil l be maintained to control storm water

runof f and dust generation, sil t fences, hay bales and/or other sediment

control devices will be used to intercept and retain sediment in storm water

runof f (both from the main impoundment and TP2/TP3). The sediment

control structures will be left in place, as necessary followin g the completio n

of excavation and regrading of the removal area and unti l vegetation is

established and the area is stabilized. Un-contaminated surface water will

be diverted away from the tailings to minimize contact with tailings .

3. A long-term maintenance program may be implemented if required by the Final Record of Decision for Operable Unit 7 (OU 7) to ensure the long-term

effectivenes s of the response action.

D. Project Schedule

April-May 1997 - California Gulch Below the Culvert s

June-July 1997 - Removal of Ponded Water from TP@ , TP3

a nd Main Impoundmen t

August-September 1997 - Removal of TP2 and TP3

E. Estimated Costs

Thi s response action is being conducted by ASARCO, Inc.

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VII. Expected Change in the Situatio n Should Action Be Delayed or N ot Taken

If this Time-Critical removal action is delayed, or not taken, exposure of the public

and environment to heavy metals contained in the mine waste located in the Apache Tailings Impoundment s wil l continue. Without thi s time-critical response,

release of contaminated tailings into California Gulch and the Arkansas River wil l

continue to contaminate surface water and groundwater in the area around the Apache Tailing s Impoundments .

VIII . Outstandin g Polic y Issues

A Record of Decision wil l be issued selecting the final

remedial action for Operable Uni t 7 (OU 7) of thi s Site .

I X. Enforcement

Thi s Time-Critical Removal Action wil l be performed by ASARCO, Inc .

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X. Recommendation

Thi s decision document represents the selected Time-Critical removal action for the Apache Tailings Impoundment s portion of OU 7 of the California Gulch Superfun d Site, in the City of Leadville , County of Lake, State of Colorado. It was developed

in accordance with CERCLA, as amended, and is not inconsistent with the NCR. Thi s decision is based on the Administrative Record for the Site.

Condition s at the Apache Tailings Impoundment s meet the NCR Section

300.415(b)(2) criteria for a removal and I recommend approval of the removal

action.

APPROVAL

M ax H. Dodson Assistant Regional Administrator Offic e of Ecosystems Protection

a nd Remediation

DISAPPROVA L

M ax H. Dodson Assistan t Regional Administrator Offic e of Ecosystems Protection

and Remediation

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ROUTIN G AN D TRANSMITTA L SU P

TO: (Name, office symbol, room number, building, Agen

DO NOT use

7

 this RECOffD of approvals, concurrence's^

clearances, and similar actions \y FROM: fName.org. symbol, Agency/Post)

5041-102

* US. GPO: 1990 - 2G2-080

ML FORM 41 (Rev. 7-76)

..— ,ji by 6SA FPMR (41 CFR) 101-11.206