SDMS Document ID

479625

RECORD OF DECISION

OPERABLE UNIT 5 EGWA SITE S

CALIFORNL 4 GULCH SUPERFUN D SIT E LEADVILLE , COLORADO

OCTOBER 2000

U.S. Environmental Protectio n Agency

9 99 18th Street , Suit e 500 Denver, Colorado 80202
RECORD OF DECISION

OPERABLE UNIT 5 EGWA SITES

CALIFORNIA GULCH SUPERFUN D SIT E LEADVILLE , COLORADO

T he U.S. Environmental Protection Agency (EPA) present s thi s Record of Decision (ROD) for Operable Unit 5 (OU5) of the California Gulch Superfun d Site in Leadville , Colorado. 1

 Thi s

includes slag and non-residential and residential area soils for Elgin Smelter, Grant/Union Smelter, Western Zinc Smelter an d Arkansas Valle y South Hillside Slag Pile sites (collectivel y known as

t he "EGWA" sites). The ROD is based on the Administrative Record for OU5 EGWA sites,

including the Remedial Investigation/Feasibilit y Stud y (RI/FS), the Proposed Plan, the! public

comments received, and EPA responses. The ROD present s a brief summary of the RI/FS, actual

and potential risks to human health and the environment, and the selected remedy. EPA followed

t he Comprehensive Environmental Response, Compensation , and Liabilit y Act, as amended, the National Contingency Plan (NCP), and EPA guidance (EPA, 1999) in preparatio n of the ROD. T he three purposes of the ROD are to:

1. Certif y that the remedy selection process was carried out in accordance with the

requirements of the Comprehensive Environmental Response, Compensation , and Liabilit y Act, 42 U.S.C . 9601 et seq., as amended by the Superfun d Amendments

a nd Reauthorization Act (collectively , CERCLA) , and, to the extent practicable,

t he NCP;

 :

2. Outline the engineering components and remediation requirements of the Selected Remedy; and

3. Provide the public with a consolidated source of information about the history,

characteristics, and risk posed by the condition s of OU5 EGWA sites, as well as a

summary of the cleanup alternatives considered, their evaluation, the rationale

behind the Selected Remedy, and the agencies consideration of, and responses to

the comments received. :

T he ROD is organized into three distinct sections: I

1. The Declaration section function s as an abstract for the key information contained

in the ROD and is the section of the ROD signed by the EPA Regional • Administrator.

2. The Decision Summary section provides an overview of the OU5 EGWA

characteristics, the alternatives evaluated, and the analysi s of those options . The Decision Summary also identifie s the Selected Remedy and explain s how the

remedy fulfills statutory requirements; and

3. The Responsivenes s Summar y section addresses publi c comments received on

t he Proposed Plan , the RI/FS, and other informatio n in the Administrative Record.
DECLARATION
DECLARATION

SIT E NAM E AN D LOCATION

Operable Unit 5 EGWA Site s ; California Gulch Superfun d Site Leadville , Colorado CERCLIS2COD98071793 8

STATEMENT OF BASI S AND PURPOSE

Thi s decision document presents the Selected Remedy for Operable Unit (OU) 5 Elgi n Smelter, Grant/Union Smelter, Western Zinc Smelter an d Arkansas Valle y South Hillside Slag Pile sites

(collectivel y known as the "EGWA" sites) within the California Gulch Superfun d Site : ("the Site" )

in Leadville , Colorado. The Environmental Protection Agency (EPA) selected the remedy in

accordance with Comprehensive Environmental Response, Compensation , and Liabilit y Act, 42 U.S.C . 9601 et seq., as amended by the Superfun d Amendments and Reauthorization Act

(collectively , CERCLA) , and to the extent practicable, the Comprehensive Environmental Response, Compensation , and Liabilit y Act , as amended, the National Contingency Plan (NCP)

i

i Thi s decision is based on the Administrative Record for OU5 EGWA sites within the California Gulch Superfun d Site. The Administrative Record (on microfilm) and copies of key documents

a re available for review at the Lake County Public Library, located at 1115 Harrison Avenue in Leadville , Colorado, and at the Colorado Mountain College Library, in Leadville , Colorado. The

complete Administrative Record may also be reviewed at the EPA Superfun d Record Center,

located at 999 18th Street , 5th Floor , North Terrace in Denver, Colorado.

T he State of Colorado has been consulted throughout the preparation of thi s Record of Decision

(ROD). The State is aware of EPA's selected remedy and has chosen to make no further

comment.

 :

ASSESSMEN T OF TH E SIT E

T he response action selected in this ROD is necessary to protect public health or welfare or the

environment from actual or threatened releases of contaminants from the OU5 EGWA sites,

which may present an imminent and substantial endangerment to public health or welfare.

DESCRIPTION OF THE SELECTE D REMEDY

Thi s ROD specificall y addresses the portion of OU5 that includes slag, non-residential'an d

residential area soil s at the EGWA sites. The OU5 EGWA sites are one of 11 OUs within the Site identified as source areas. The remaining portion s of OU5 (the "AV7CZL " sites) will be

addressed separately . The OU5 EGWA sites include slag, non-residential and residential area

soil s from former smelter sites. Pursuant to the Augus t 26, 1994 Consent Decree at the California Gulch Superfun d Site, it was agreed that the decision on remediation of Site-wide Surfac e Water

D -l
a nd Groundwater (i.e. , OU12 ) would be made only after records of decision for source

remediation were selected and implemented at each OU. Remedial actions selected for the OU5

EGWA sites are consistent with the ASARCO , Inc. work area management pla n (WAMP).

T he Selected Remedy is the Institutional Control s Alternative, which was presented in the Final

Focused Feasibilit y Stud y Report (FFS ) (McCulley , Frick & Gilman , Inc.[MFG] , 1999). The FF S

evaluated and screened remedial alternatives retained in the site-wide Screenin g Feasibilit y Stud y (EPA, 1993) for slag and non-residential area soils. Non-residential area soil s are defined as soil

in areas currently zoned agricultural/forest , recreational, highway/business , retail core,

commercial, and industrial mining. For the purpose of the FFS and ROD, non-residential area

soil s were evaluated instead of both non-residential and residential area soil s because no

residences are located within the OU5 EGWA sites. However, it is reasonably anticipated that

some of the sites may be occupied as residential land use in the future based on the current

residential zoning.

T he FFS used a comparative analysis to evaluate four alternatives and identif y the advantages and

disadvantages of each. Selectio n of the Institutional Control s Alternative was based on thi s

analysis. The Selected Remedy consists of measures to provide information to current and/or

future land owners regarding the environmental condition s at the site through a zoning ''overlay

district." and to ensure that if the site is developed any necessary special precaution s or

requirements are followed. Any samplin g or response actions will be conducted or funded by ASARCO Inc. , consistent with the developmen t plans . The Selected Remedy i s protective of

human health and the environment, and is considered effective because (1) slag in its existin g

conditio n does not present a significan t risk to human health or the environment, (2) no significan t

pathway s for transport of contaminants of concern (COC ) from soil or other environmental media

have been identified, (3) the EGWA sites are currently vacant; however, the sites may

intermittentl y be used for recreation. One sample locatio n at the Elgi n Smelter site has been

identified as having lead and arsenic concentrations in soil that exceed the action level for

recreational use. The Elgi n Smelter site is private propert y and wil l be evaluated in 2001 as part

of the five-year site review, and (4) as the land use changes, the institutional control s wil l ensure

that waste left in place will be addressed to prevent exposure to human health.

STATUTOR Y DETERMINATION S

T he Selected Remedy is protective of human health and the environment, complie s with Federal

a nd Stat e requirements that are legall y applicabl e or relevant and appropriat e to the remedial

action, is cost effective , and utilizes permanent solution s to the maximum extent practicable. The

remedy for the OU5 EGWA sites does not satisf y the statutor y preferenc e for treatmen t as a

principal element of the remedy because various treatment option s considered early in the

feasibilit y study process for slag, non-residential area soils , and residential area soil s were

determined to be either technicall y impracticable and/or not cost effective . Because thi s remedy

wil l result in hazardous substances, pollutants , or contaminant s remaining on site above healthbased level s that wil l allow for unlimited use and unrestricted exposure, a statutor y review wil l be

conducted within five years after initiatio n of remedial action to ensure that the remedy is, or wil l

b e. protective of human health and the environment. Thi s remedy is acceptabl e to the community

of Leadville .

D-2
R OD DATA CERTIFICATION CHECKLIST

T he followin g information is included in the Decision Summary section of this ROD. Additional

information can be found in the Administrative Record for this site.

• COCs and their respective concentrations.

• . Baseline risk represented by the COCs.

• Cleanup level s established for COCs and the basis for these levels.

• How source materials constitutin g principal threats are addressed.

• Current and reasonably anticipated future land use assumptions used in the baseline

risk assessments and ROD.

• Potential land use that will be available at the site as a result of the Selected Remedy.

• Estimated capital costs, annual operation and maintenance costs, and total present

worth costs, discount, rate, and the number of years over which the remedy cost

estimates are projected.

• Key factors that led to selecting the remedy.

M ax H. Dodson Date Assistant Regional Administrator

Ecosystems Protection and Remediation U.S . Environmental Protection Agency, Region VIII

D-3
DECISION SUMMAR Y
TABL E OF CONTENTS

SECTION PAG E

1 .0 Site Name, Location, an d Description .................................. . DS-1

2 .0 Operable Unit Histor y and Enforcement Activities .................... . .

:

... . DS-4

3 .0 Highlight s of Community Participation .................................. . DS-6

4 .0 Scope and Role of Operable Unit ...................................... . DS-8

5 .0 Summary of Sit e Characteristics ....................................... . DS-9

5 .1 Physical Characteristics ...................................... . DS-9

5.1.1 Summary of Soil and Smelter Waste Material Samplin g - Elgin Smelter ........................................ . DS-9

5.1.2 Summary of Soil and Smelter Waste Material Samplin g - Grant/Union Smelter ................................... . DS-9

5.1.3 Summary of Soil and Smelter Waste Material Samplin g - Western Zinc ........................................ . DS-9

5.1.4 Summary of Samplin g - Arkansas Valle y South Hillsid e Slag Pile . DS-10

5 .2 Ground-water and Surfac e Water Quality ........................ . DS-10

5.2.1 Elgi n Smelter ....................................... . DS-10

5.2.2 Grant/union Smelter .................................. . DS-11

5.2.3 Western Zinc Smelter ................................. . DS-11

5.2.4 Arkansas Valle y South Hillside Slag Pile ................... . DS-11

5 .3 Historic and Cultural Resources ............................... . DS-12

6 .0 Current an d Potential Future Land Use .....................'........... . DS-13

7 .0 Summary of Site Risks ............................................. . DS-14

7 .1 Human Health Risks ..................................... . i. .. DS-14

7.1.1 Media an d Contaminants of Concern ....................!.. . DS-15

7.1.2 Exposure Assessment .............................. . |. .. DS-15

7.1.3 Risk Characterization ...............................;.. . DS-15

7 .2 Ecological Risks .........................................

;

. .. DS-17

7.2.1 Media and Contaminant s of Concern .................. . .

;

. . . DS-18

7.2. 2 Exposure Assessment ...............................'.. . DS-1 8

7.2.3 Risk Characterization .................................. . DS-18

7 .3 Summary of Risks/Basi s of Actio n ...........................;.. . DS-19

8 . 0 Remedial Action Objectives ...................... . ................'.. . DS-20

9 .0 Descriptio n of Alternative s ......................................... . DS-21

DS-i
TABL E OF CONTENT S (continued )

SECTION PAG E

10.0 Summary of Comparative Analysi s of Alternatives ....................... . DS-24

10.1 NCP Evaluation an d Comparison Criteria ....................... . DS-24

10.1.1 Threshold Criteria ................................... . DS-24

10.1.2 Primary Balancing Criteria ............................. . DS-24

10.1.3 Modifyin g Criteria .................................... . DS-25

10.2 Evaluatin g the Alternatives with the NCP Criteria .................. . DS-25

10.2.1 Overall Protection of Human Health and the Environment ...... . DS-25

10.2.2 Complianc e with Applicabl e or Relevant and Appropriat e Requirements ....................................... . DS-26

10.2.3 Long-term Effectivenes s an d Permanence ................. . DS-26

10.2.4 Reduction of Toxicity , Mobility , or Volume Through Treatmen t . . DS-26

10.2.5 Short-term Effectivenes s ............................... . DS-26

10.2.6 Implementabilit y ..................................... . DS-26

10.2.7 Cost .............................................. . DS-27

10.2.8 Stat e Acceptance .................................... . DS-27

10.2.9 Community Acceptanc e ............................... . DS-27

11.0 Principal Threat Wastes ........................................... . DS-28

12.0 Selected Remedy ............................................... . DS-29

12.1 Rationale for Selected Remedy ................................ . DS-29

12.2 Description of Selected Remedy ............................... . DS-30

12.3 Estimated Remedy Cost s .................................... . DS-3 1

12.4 Expected Outcome of the Selected Remedy ...................... . DS-3 1

13.0 Statutor y Determinations ...................... . .................. . DS-32

13.1 Protection of Human Health an d the Environment ................ . DS-32

13.2 Complianc e with ARARs .................................. . DS-32

13.3 Cost Effectivenes s ......................................... . DS-33

13.4 Utilizatio n of Permanent Solution s and Alternative Treatmen t Technologie s

( Or Resource Recovery Technologies ) to the Maximum Extent Possibl e . DS-33

13.5 Preference for Treatmen t as a Principal Element ............. . .... . DS-33

13.6 Five-Year Review Requirements . . .............. . ............ . DS-33

14.0 Documentation of Significan t Changes ................................ . DS-34

15.0 References ..... . ......... . ..... . ........ . .. . ........... . . . DS-35

APPENDI X

A Responsiveness Summary

DS-i i
LIST OF FIGURES

FIGUR E

1 General Location Map, California Gulch Superfun d Site, Leadville, Colorado

2 California Gulch Superfun d Site an d Operable Units , Leadville , Colorado

3 OU5 EGWA Sites , California Gulch Superrund Site, Leadville , Colorado

4 Elgi n Smelter Location and Site Features , Operable Unit 5, California Gulch Superrun d Site , Leadville, Colorado

5 Grant/Unio n Smelter Location and Sit e Features , Operable Unit 5, California Gulch Superrun d Site , Leadville , Colorado

6 Western Zin c Smelter Location and Site Features , Operable Unit 5, California Gulch Superfun d Site , Leadville , Colorado

7 Arkansas Valle y South Hillside Slag Pile Location an d Site Features , Operable Uni t 5, California Gulch Superfun d Site , Leadville , Colorado

8 Results of Investigation s at the Elgi n Smelter Site, Operable Unit 5, California Gulch Superrun d Site , Leadville , Colorado

9 Results of Investigation s at the Grant/union Smelter Site, Operable Unit 5, California Gulch Superfun d Site , Leadville , Colorado

10 Result s of Investigation s at the Western Zinc Smelter Site, Operable Unit 5, California Gulch Superfun d Site , Leadville , Colorado

11 Result s of Investigation s at the Arkansas Valle y Smelter South Hillside Slag Pile Site, Operable Unit 5, California Gulch Superrund Site , Leadville , Colorado

12 Human Health Site Conceptual Model - Leadville and Stringtow n Residents, Minin g and O re Processin g Waters , California Gulch Superfun d Site, Leadville , Colorado

13 Conceptual Site Mode l for Residential Exposure, California Gulch Superfun d Site , Leadville , Colorado

14 Conceptual Model for California Gulch Ecological Assessment for the Terrestrial

Ecosystem, California Gulch Superfun d Site , Leadville , Colorado

DS-ii i
LIST OF TABLE S

TABL E

1 Results of Surfac e Water Analyses for Georgia Gulch and Evans Gulch, OU5 EGWA Sites , California Gulch Superfun d Site

2 Summary of Comparative Analysi s of Remedial Alternatives , OU5 EGWA Sites, California Gulch Superfun d Site

3 Summary of Potential Chemical-Specific ARARs, OU5 EGWA Sites , California Gulch Superfun d Sit e

4 Summary of Potential Location-Specifi c ARARs, OU5 EGWA Sites , California Gulch Superfun d Sit e

5 Summary of Potential Action-Specifi c ARARs, OU5 EGWA Sites , California Gulch Superfun d Sit e

6 Detailed Cost Estimate: Alternative 2 - Institutional Controls , OU5 EGWA Sites , California Gulch Superfun d Site

7 Present Worth Analysis: Alternative 2 - Institutional Controls , OU5 EGWA Sites, California Gulch Superfun d Site

DS-iv
LIST OF ACRONYM S AND ABBREVIATIONS

AOC ARAR Asarco AWQ C BARA CD

COM CDPHE CERCLA C FR

COC

C ZL

EGWA

E PA ERA F EC F S F F S

Colder

f f l

HQ LCCH P M FC

mg/kg mg/L MK

mmN CP N PL NRHP

O &M OU

PCPRP RARIRiVff i ROD

S F S SPLP T BV TCLP

Administrative Order on Consent

Applicabl e or Relevant and Appropriat e Requirements ASARCO Incorporated ; Ambient Water Quality Criteria Baseline Aquatic Ecological Risk Assessment Consent Decree

Camp Dresser & McKee Inc. Colorado Department of Public Health and Environment Comprehensive Environmental Response, Compensatio n and Liabilit y Act Code of Federal Regulations Contaminants of Concern Colorado Zinc-Lead Elgin Smelter, Grant/Unio n Smelter, Western Zinc Smelter, an d Arkansas

Valle y South Hillsid e Slag Pile U. S. Environmental Protectio n Agency

Ecological Risk Assessment Foothil l Engineering Group Feasibilit y Stud y Focused Feasibilit y Stud y Golder and Associates

Hazard Index Hazard Quotient Lake County Community Health Program McCulley , Frick & Gilman , Inc. Milligrams per kilogram

Milligrams per liter

Morrison Knudse n Corporatio n Millimeter

National Oil and Hazardous Substances Pollutio n Contingency Plan National Priorities Lis t National Register of Historic Places Operation and Maintenance Operable Unit Primary grid Potentiall y Responsible Party Risk Assessment Remedial Investigatio n . Reasonable Maximum Exposure Record of Decision Screenin g Feasibilit y Stud y Synthetic Precipitatio n Leachin g Procedure Toxicit y Benchmark Value s

Toxicitv Characteristic Leachin a Procedure

DS-v
LIST OF ACRONYM S AN D ABBREVIATION S (continued )

I D S Total Dissolved Solid s T S S Total Suspended Solid s U AO Unilateral Administrative Order U CL Upper confidence limit of the arithmetic mean USD C U. S. District Court W CC Woodward-Clyde Consultant s

\iS/L Micrograms per liter

|im Micron

umhos/cm Micromhos per centimeter

DS-vi
1 .0 SIT E NAME , LOCATION , AN D DESCRIPTION

Operable Unit 5 EGWA Site s California Gulch Superfun d Site Leadville , Colorado CERCLIS # COD980717938

T he California Gulch Superfun d Site ("the Site") is located in Lake County , Colorado, in the

upper Arkansas River basin, approximatel y 100 miles southwest of Denver (see Figure 1). The

study area at the Site encompasses approximatel y 16.5 square miles and includes the towns of Leadville and Stringtown , a portion of the Leadville Historic Mining District, and the portion of

t he Arkansas River from its confluence with California Gulch downstream to the Lake Fork Creek

confluence.

T he California Gulch Superfun d Site has been organized into 12 operable units (OU). Figur e 2

shows the Site study area boundaries and the locatio n of the 12 OUs within the California Gulch Superfun d Site. The U.S. Environmental Protection Agency (EPA) i s the lead agency for

activities at the California Gulch Superfun d Site and is supported by the Stat e of Colorado

through the Colorado Department of Public Health an d Environment (CDPHE). ASARCO Incorporated (ASARCO), a potentiall y responsible party (PRP), is financin g the remedial actions

at OU5.

O US includes four smelter sites (Elgin Smelter, Grant/Unio n Smelter, Western Zinc Smelter an d Arkansas Valle y South Hillside Slag Pile) as shown in Figure 3. Thi s Record of Decision (ROD)

specificall y addresses the slag, non-residential and residential area soil s for Elgi n Smelter, Grant/Unio n Smelter, Western Zin c Smelter an d Arkansas Valle y South Hillside Slag Pile sites,

collectivel y known as the "EGWA" sites. The remaining portion of OU5, which includes the Arkansas Valle y Smelter and Colorado Zinc-Lead Mill sites, will be addressed separately .

T he Elgi n Smelter site is located in north-central Leadville on the south bank of Big E\>ans Gulch

near the intersection of U.S. Highway 24 and State Highway 91. The Elgi n Smelter site operated

intermittently from 1879 until 1903. Material s at this site consist primarily of slag pile s and slag

veneer, and minor amounts of smelter debris and coke/coal . The Elgin Smelter features are

shown in Figur e 4. The estimated total volume of slag and slag veneer is approximatel y 1,000

cubic yards. The volume of smelter debris has not been estimated. Currentl y the Elgi n Smelter

site is vacant. The site is located within the Business zoning district (i.e., commercial/industrial)

established by the Lake County Board of County Commissioners (Lake County , 1997)!

T he Grant/Unio n Smelter site, which was actuall y two separate smelters , is located near the

confluence of Georgia Gulch and California Gulch and northeast of the Colorado Mountain College campus. The Grant Smelter operated from 1878 to 1882 and the Union Smelter operated

intermittentl y from 1892 to 1900. Currently , smelter waste material identified at the site consists

of a small slag pil e located to the northwest of the former smelter, a relativel y larger slag pil e

apparentl y placed fo construct a railroad grade that crosses the site, scattered areas of slag veneer,

a nd coke and/or coal located to the northeast of the former smelter. The Grant/Unio n Smelter

DS-1
features are shown in Figur e 5. The volume of the slag pil e located to the northwest of the former

smelter is estimated at 5,200 cubic yards. Based on aerial photography , the volume of the slag at

the abandoned railroad grade is estimated to be 63,500 cubic yards, and the volume of the veneer

slag layer is 1,500 cubic yards. The land is vacant at this time. Part of thi s site is located within

Urban Residential zoning district established by the Lake County Board of County Commissioners

(Lake County , 1997) and the remaining portion is located within the Traditional Residential/Commercial zoning district established by the Cit y of Leadville . Current land use

surrounding the site consists of both residential and recreational use.

T he Western Zin c Smelter site is located in the western part of Leadville , approximatel y 75 feet

west of McWeth y Drive and approximatel y 100 feet south of the Lake County Fairgrounds . The

Western Zinc Smelter began operation s in 1914 and continued operatin g unti l 1926. The smelter

processed zinc ore to a zinc oxide product for use as pigment . Material s identified in 1992

(WCC , 1992a) include slag piles , slag veneer, smelter debris (includin g old foundatio n footprint s

a nd bricks possibl y used in the furnaces), and solidified bag-house/flue dust. The Wester n Zin c Smelter features are shown in Figur e 6. The volume of the slag pile s is estimated to be

approximatel y 23,000 cubic yards. The volume of bag-house/flue dust and smelter debris are

estimated at less than 5 and 600 cubic yards, respectively . The lan d is vacant at thi s time. The

site is located within an Urban Residential zoning district established by the Lake Count y Board

of County Commissioners (Lake County, 1997).

T he Arkansas Valle y South Hillsid e Slag Pile i s located south of U.S . Highwa y 24 on the hillside

across from the Arkansas Valle y Smelter site and extends approximatel y 2,000 feet , roughly

parallelin g California Gulch and U.S. Highway 24. Thi s slag pil e is also referred to in the Lead Slag Remedial Investigatio n (RI) report as the "Tramway" Slag Pile (MK, 1992a). The history of

this slag pil e is unknown; it is possible that either the Arkansas Valle y or Grant/Unio n Smelter s

supplied the slag at thi s site. Usin g current aerial photographs the volume is estimated to be

approximatel y 16,000 cubic yards from the two elongated pile s of slag. The larger slag pil e exist s

as a wedge-shaped mound, formin g what appears to have been a roadbed up to 50 feet wide at

t he base. The smaller slag pile extends southeast about 400 feet . The site feature s of the Arkansas Valle y South Hillside Slag Pile are shown in Figur e 7. Much of the slag consists of aircooled, whole "slag buttons" measuring up to three feet across. There are no smelter remains,

buildin g debris, or other waste materials except slag. The land at thi s site is vacant at thi s time. T he site is located within the Industrial and Minin g zoning district established by the Lake County Board of County Commissioners (Lake County , 1997).

Lake County is relativel y small (380 square miles) and is predominatel y rural, with a 1990

populatio n of 6,007 (U.S. Department of Commerce, 1990). About hal f of thi s populatio n resides

within the Cit y of Leadville . The populatio n of Lake Count y has fluctuated with the minin g

industry . The populatio n increased to about 9,000 between 1960 and 1981 and then declined

throughout the 1980s. About two-thirds of the land in Lake Count y is federall y owned and is

either pan of San Isabe l National Fores t or managed by the Bureau of Land Management .

T he climate of Lake Count y is semi-arid continental , characterized by long, cold winters and

short, cool summers. The Cit y of Leadvill e is at an elevation near 10,000 fee t above mean sea

level . The average annual maximum temperature in the Leadvill e area is 50.5 degrees Fahrenheit ,

DS-2
and the average annual minimum temperature is 21.9 degrees Fahrenheit , with an annual mean

temperature of 37.3 degrees Fahrenheit. Average annual precipitatio n is approximatel y 16 inches,

which represents 59 years of record from the Colorado Climate Center (1997) . Prevailin g winds

in the Leadville area are largely from the west-northwest and to a lesser extent from the northeast

(ESI, 1986), with winds typicall y ranging from 0 to 20 miles per hour (WCC, 1992b).

DS-3
2 .0 OPERABLE UNI T HISTOR Y AN D ENFORCEMEN T ACTIVITIES

T he California Gulch Superfun d Site is located in the highly mineralized Colorado Mineral Belt of

t he Rocky Mountains. Mining, mineral processing, and smeltin g activities have produced gold,

silver, lead, and zinc for more than 130 years in the Leadville area. The Leadville Historic Minin g District includes an extensive network of underground mine workings in a mineralized area of

approximatel y eight square miles located around Breece Hill. Mining in the District began in

1860, when placer gold was discovered in California Gulch. As the placer deposit s were

exhausted, underground workings became the principal method for removing gold, silver, lead,

and zinc ore. As these mines were developed, waste rock was excavated alon g with the ore and

placed near the mine entrances. Many mines were operated in the area as evidenced by more than

2,000 mine waste rock piles identified at the California Gulch Superfiin d Site. Mined ore was

transported to nearby mill s where it was crushed and separated into metallic'concentrate s and

waste (mil l tailing) . The high grade ores and mill concentrates were refined and processed at

smelters. Slag and other waste product s were produced from the smelters .

Approximatel y 17 smelter facilitie s are reported to have once operated within the Site! Most

operation s ceased by about 1900, although some facilitie s once continued to operate into the

1960s. At present, nearly all the mines within the site boundaries are inactive. All of the mill s and

smelters that operated on the Site are inactive and/or demolished.

D ue to historic mining, milling, and smeltin g operations, the Site contains many tailing,

impoundments, fluvial deposits , slag piles , waste rock piles , and mine water drainage tunnels. Slag on the Sit e is the waste byproduct of smeltin g and results from the processin g of ore in high

temperature furnaces.

T he California Gulch Site was placed on the National Priorities List (NPL) in 1983 under the

authority of the Comprehensive Environmental Response, Compensation , and Liabilit y Act

(CERCLA ) of 1980. The Site was placed on the NPL because of concerns about the impact of

mine drainage on surface waters in the California Gulch and the impact of heavy metals loadin g in

the Arkansas River.

In September 1990, EPA and the PRPs entered into an Administrative Order on Consent (AOC)

f or the performance of soil s samplin g and air monitoring. EPA issued a Unilateral Administrative Order (UAO) in 1991 that required ASARCO to conduct studies and complete RIs. :

Several subsequent investigation s have been conducted within the California Gulch Superfun d Site that have addressed the smelter/slag/mil l sites (i.e. , OU5) . A Smelter Site Reconnaissance

(WCC , 1992a) was conducted in 1991 as part of the Smelter RJ and a Slag Pile Reconnaissance

as part of the Slag Pile RIs. '

I

In 1991 through 1992, a Smelter RI was conducted and primaril y focused on smelter impacted

soil s but also included samplin g of discrete location s where smelter bag houses, dust chambers, or

roasting furnaces may have been located (Walsh, 1993). This study was initiated by ASARCO

a n d included the Elgi n Smelter, Grant/Unio n Smelter, Wester n Zin c Smelter , an d Arkansas Valley - Smelter sites.

DS-4
A surface water RI (Surfac e Water RI) of the California Gulch Site was conducted in 1991 and

1992. The final Surfac e Water RI report was issued in 1996 describing the result s of the surface

water investigation (Golder, 1996a). The study included surface water and sediment samplin g in

t he Arkansas River and its tributaries, includin g California Gulch.

A groundwater RI (Hydrogeologic RI) at the California Gulch Site was conducted in 1991

through 1992. The study included installatio n of monitoring well s and piezometers , water level

measurements, and groundwater samplin g and analysis. The final Hydrogeologi c RI Report

describin g the result s of the investigation was issued in 1996 (Golder , 1996b). Objectives of the

study were to investigate groundwater quality and flo w directions , evaluate potential impact s to

surface water receptors, and characterize background groundwater quality .

Denver and Rio Grande Western Railroad, another PRP at the Site, undertook RJs of seven major

lead slag pile s (MK, 1992a) includin g the Elgi n Smelter and Grant/Unio n Smelter sites and one

zinc slag pil e (MK, 1992b), Western Zinc slag pile , within the California Gulch Site. The Zin c Slag RI was performed concurrent with the Lead Slag Pile RI. Investigatio n activities durin g

these two RIs focused mainly on the slag material that may have the potential to leach metal s to

t he environment.

In 1993, the EPA conducted a Screenin g Feasibilit y Stud y (SFS) (EPA, 1993) to initiate the

overall CERCLA feasibilit y study (FS) process at the California Gulch Site. The purpose of the S FS was to develop general response actions and identif y an appropriate range of alternatives

applicabl e to the various contaminant sources to be considered during feasibilit y studies for the California Gulch Site . Remedial alternatives retained in the SFS for slag an d non-residential area

soil s in OU5 for the EGWA sites were further evaluated and screened durin g the focused

feasibilit y study (FFS ) (MFG , 1999).

ASARCO entered into a Consent Decree (CD) (USDC, 1994) with the United States , the Stat e of Colorado (State), and other PRPs at the California Gulch Sit e on May 4, 1994 In the CD, ASARCO agreed to perform certain remediation work in three operable units (OU5, OU7, and OU9). The Work Area Management Plan , included as Appendix B to the CD (USDC, 1994),

define s the scope of work to be performed by ASARCO.

In February of 1999, ASARCO submitted the Focused Feasibility Study for Operable Unit 5 EGWA Sites (MFG, 1999), according to the terms of the CD. The FFS provided a detailed

analysi s of the two retained alternatives from the SFS as applied to slag and four alternatives from

t he SFS for non-residential area soils . Non-residential area soil s are defined as soil in areas

currently zoned agricultural/forest , recreational , highway/business , retai l core, commercial, and

industrial mining. For the purpose of the FFS an d ROD, non-residential area soil s were evaluated

instead of both non-residential and residential area soil s because no residences are located within

t he OU5 EGWA sites. However, it is reasonably anticipated the some of the sites may be

occupied as residential land use based on the current residential zoning. Institutional control s wil l

ensure future protectiveness .

A Proposed Pla n describin g the EPA' s preferred alternative was issued on July 21, 2000. The

preferred alternative was .Alternative 2. Institutiona l Controls .

DS-5
3 .0 HIGHLIGHT S OF COMMUNIT Y PARTICIPATION

Public participatio n is required by CERCLA Section s 113 and 117. These sections require that

before adoptio n of any pla n for remedial action to be undertaken by EPA, the State, or an

individual (e.g., PRP), the lead agency shall:

1. Publish a- notice and make the Proposed Plan available to the public , and

2. Provide a reasonable opportunit y for submission of written and oral comments and

an opportunit y for a public meeting at or near the site regardin g the Proposed Pla n

a nd any proposed findings relatin g to cleanup standards . The lead agency shall

keep-a. transcript of the meeting and make such transcript available to the public. T he notice and analysis published under item #1 above shal l include sufficien t

information to provide a reasonable explanatio n of the Proposed Plan and

alternative proposal s considered.

Additionally , notice of the final remedial action pla n set forth in the ROD must be published, and

t he pla n must be made available to the public before commencing any remedial action. Such a

final pla n must be accompanied by a discussion of any significan t changes to the preferred remedy

presented in the Proposed Plan alon g with the reasons for the changes. A response

(Responsiveness Summary) to each of the significan t comments, criticisms, and new data

submitted in written or oral presentation s during the public comment period must be included with

the ROD.

E PA has conducted the required community participatio n activities through the presentation of

t he RI/FS and the Proposed Plan , a 30-day public comment period, a formal public hearing, and

t he presentation of the Selected Remedy in this ROD. Writte n comments were received from CDPHE . EPA' s response to written comments received during the public comment period i s

included in the Responsiveness Summary, which is Appendix A.

T he Proposed Plan for OLJ5 EGWA sites was released for public comment on July 27, 2000. The RI/FS and the Proposed Plan were made available to the public in the Administrative Record

located at the EPA Superfun d Records Center in Denver and the Lake County Public Library in Leadville. A formal public comment period was designated from July 27 through August 28,

2000. ;

On Augus t 1, 2000, the EPA hosted a public meeting to present the Proposed Plan for EGWA Site s OU5 of the California Gulch Superfun d Site. The meeting was held at 7:00 p.m. in the

Minin g Hal l of Fame an d Museum in Leadville , Colorado. Representatives from ASARC O

presented the Proposed Plan , which discussed the followin g four alternatives:

Alternative 1: No Action

Alternative 2: Institutional Control s Alternative 3: No Actio n for Slag, Containmen t for Non-Residential .Area Soil s

a nd Residential Area Soils , and Institutional Control s

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Alternative 4: No Action for Slag, Removal/Transport/Disposal of Non - Residential Area Soils and Residential Area Soils to an On-Site Repository , and Institutional Control s

Institutional Controls , Alternative 2, was presented as EPA' s preferred alternative. A portion of

t he public meeting was dedicated to answering questions and acceptin g formal oral comments

from the public . Community acceptance of the Selected Remedy is discussed in Sectio n 10.0, | Summary of Comparative Analysi s of Alternatives , of this Decision Summary. j

DS-7
4 .0 SCOP E AND ROLE OF OPERABLE UNIT

T he California Gulch Superfun d Site covers a wide area (Figure 2). As with many Super-fun d

sites, the problems at the California Gulch Superfun d Site are complex. As a result , EPA

established the followin g OUs for the division of liabilit y in geographically - or media-based areas

within the Site. The OUs are designated as:

O U1 Yak Tunnel/Water Treatment Plan t O U 2 Malta Gulch Fluvial Tailing/Leadvill e Corporatio n Mill/Malta Gulch Tailin g Impoundmen t O U3 D&RGW Slag Piles/Railroad Easement/Railroad Yard an d Stockpiled Fin e Slag O U4 Upper California Gulch O U S ASARCO Smelter/Slag/Mil l Site s O U6 Starr Ditch/Penrose Dump/Stra y Horse Gulch/Evan s Gulch O U7 Apache Tailin g Impoundment s O US Lower California Gulch O U9 Residential Populated Areas OU10 Oregon Gulch OU11 Arkansas River Valle y Floodplai n OU12 Site-Wid e Water Quality

Remedial actions undertaken within OUS EGWA sites are intended to be consistent with the

remedial action objectives and goals identified for the entire California Gulch Superfun d Site and

other OU investigations.

Thi s decision document makes no determination on whether surface water or groundwater within O US EGWA sites requires remediation. Pursuant to the August 26, 1994, CD at thi s Site,

(USDC, 1994) it was agreed that the decision on remediation of Site-wide Surfac e Water and Groundwater (OU12 ) would be made only after remedies for source remediation were selected

a nd implemented at each OU. As a result , specifi c water quality goals for Surfac e Water and Groundwater have not been established at this time.

DS-8
5 .0 SUMMAR Y OF SITE CHARACTERISTICS

Numerous investigations have been conducted at the California Gulch Superiun d Site'for the

purpose of: (1) characterizing site-wide environmental conditions; (2) identifyin g an d

characterizing historic smelter activities and associated waste materials, and (3) characterizing

lead and zinc slag. Site characterization to assess the general condition s of the OU5 EGWA sites

and to evaluate the nature and extent of contamination within these sites is based on information

presented in the FFS (MFG, 1999), Lead Slag RI (MK, 1992a), Zin c Slag RI (MX , 1992b), Soil s

Investigatio n (CDM, 1994), Smelter RI (Walsh, 1993) and Smelter Supplementa l RI (WESTEC,

1997a).

5 .1 PHYSICAL CHARACTERISTICS

T he physical characteristics of each of the four sites are discussed below.

5.1.1 Summar y of Soi l an d Smelter Waste Material Samplin g - Elgi n Smelter

Soil and smelter waste material samples were obtained at the Elgi n Smelter site. Sampl e LES101 ,

a composite slag sample, was obtained during the Lead Slag RJ (MK, 1992a). Sample s collected

during the Smelter RI included one discrete sample, S09-003, and three primary grid (PG)

samples , PG-620, PG-621, an d PG-643 (Walsh, 1993). Three samples , SEL01, SEL02, SELr03,

were collected during the Smelter Supplemental RI (WESTEC, 1997a). Analytical results and the

locations for these samples are shown on Figure 8.

T he average concentrations of lead and arsenic in soil from the 0 to 6 inch depth interval at the

Elgin Smelter site are 2,790 and 113 mg/kg, respectively .

5.1.2 Summar y of Soi l an d Smelter Wast e Material Samplin g - Grant/Unio n Smelter

Soi l and smelter waste material samples were obtained at the Grant/Unio n Smelter site. One

sample, GGS101 , was obtained during the Lead Slag RI (MK, 1992a). Five samples obtained

during the Smelter RI include PG-215, PG-216, PG-232, PG-252, and PG-0275 (Walsh, 1993). Sampl e SGU01 was collected during the Smelter Supplemental RI (WESTEC, 1997a). Analytical

results and the locations for these samples are shown on Figure 9.

T he average concentrations of lead and arsenic in soil from the 0 to 6 inch depth interval at the Grant/Unio n Smelter site are 2,286 and 50 mg/kg, respectively .

5.1.3 Summar y of Soi l an d Smelter Wast e Material Samplin g - Wester n Zin c

Soil and smelter waste material sample s were obtained at the Wester n Zin c Smelter site. Four

samples , HSS101, HSS102, HSS103, an d HSS104, were obtained during the Zin c Slag R I (MF ,

1992b). As reported in the Smelter RI, four primary grid samples (PG-208, PG-222, PG-223,

a nd PG-238 ) and two discrete samples (S22-001 and S22-002) were obtained (Walsh, 1993) .

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O n e sample, SWZ01 , was obtained for suspected bag-house/flue dust durin g the Supplementa l Smelter RI (WESTEC, 1997a).

Analytical result s and the locations for all the samples are shown on Figur e 10 In addition , Toxicit y Characteristic Leaching Procedure (TCLP) analysis of sample SWZ0 1 (suspected baahouse/flue dust material) shows that the metals in this material are not readil y leachable and the

material is relativel y inert chemically. Concentration s of arsenic, cadmium and lead in the TCLP

effluen t were all below the respective limit s of detection for these metals. Zin c was detected in

t he TCLP effluen t at a concentration of 0.01 milligrams per liter (mg/L) .

T he average concentrations of arsenic and lead in soil from the 0 to 6 inch depth interval at the Western Zinc Smelter site are 100 and 803 mg/kg, respectively .

5.1.4 Summar y of Samplin g - Arkansas Valle y South Hillsid e Sla g Pile

There has been no samplin g or analysi s of slag material at the Arkansas Valle y South Hillside Slag Pile site. As part of the site-wide Soil s Investigatio n (CDM, 1994) and Smelter RI (Walsh , 1993) ,

soil surrounding the site was sampled and analyzed. Analytical result s and the location s for these

samplin g effort s are shown on Figur e 11.

Sample s obtained as part of the site-wide Soil s Investigatio n included PG-046, PG-065, and PG076. Sample s obtained as part of the Smelter RI included SME-147 and SME-152 . The result s

indicated that soils at the site may have been impacted by emissions from the Arkansas Valle y Smelter , rather than b y metal s released from the Arkansas Valle y South Hillside Slag Pil e (CDM,

1994).

T he average arsenic an d lead concentrations in soil for the Arkansas Valle y South Hillsid e Slag Pile site are 140 and 1,161 mg/kg, respectively .

5 .2 GROUNDW ATE R AN D SURFAC E WATE R QUALIT Y

Synthetic Precipitatio n Leaching Procedure (SPLP, EPA Method 13 12) an d column leachin g test s

conducted on samples of lead and zinc slag indicate that metal concentrations in slag leachate is

not a significant contaminant migration pathway (MK, 1992a and 1992b).

5.2.1 Elgi n Smelter

Result s of the Surfac e Water RI (Golder , 1996b) indicate that surface water qualit y in Big Evans Gulch is not being adversely affected by waste material s at the Elgi n Smelte r site. Surfac e water

samplin g station EG-1 is located on Big Evans Gulch upstream of the confluenc e with Littl e Evans Gulch an d approximatel y 2,500 feet upstream from the former Elgi n Smelter site. Surfac e

water samplin g statio n EG-2 i s located approximatel y 1,000 feet downstream of the Elgi n Smelter

site. Result s of the Surfac e Water RI for the four EGWA samplin g station s are presented in

Tabl e 1. Water chemistry data for upgradien t (EG-1 ) an d downgradien t (EG-2 ) station s are

virtually identical indicatin a that the smelter material s were not a sianifican t source of metal s to

DS-I O
Evans Gulch during thi s samplin g period. Any impact to Surfac e Water and Groundwater will be

addressed in OU12.

5.2.2 Grant/Unio n Smelter

There are no surface water features at the site and no obvious runof f channels or erosion features

that would indicate a potential migration pathway to Georgia Gulch or California Gulch. Samplin g conducted at Georgia Gulch (surface water monitoring station GG-1) indicates that

water quality in this drainage does not appear to be adversely affected by slag or other material s at

t he Grant/Unio n Smelter site (Golder , 1996b). Surfac e water monitoring station GG-1 is located

immediatel y west of the former Grant/Unio n Smelter site, jus t upstream from the confluence with California Gulch. Table 1 does show impact to surface water, however, the impact does not

come from the Grant/Union Smelter site. Any impact to Surfac e Water and Groundwater wil l be

addressed inOU12.

5.2.3 Wester n Zin c Smelter

There are two groundwater monitoring point s in the vicinity of the Western Zin c Smelter site. Wel l BMW-1 is screened in bedrock at a depth of approximatel y 1,229 to 1,244 feet below

ground surface. Piezometer PZ-4 is screened in alluvium at a depth of approximatel y 125 to 137

feet below ground surface. Groundwater quality in these two well s is consistent with other

background .monitoring wells , which suggests that smelter waste materials have not adversely

affected groundwater at these depths . Thi s is consistent with the SPLP and column leaching test s

conducted by MK (1992b ) on samples of zinc slag. Tes t result s indicate that metal concentrations

in slag leachate do not create a significan t contaminant migration pathway at this site.

T he Surfac e Water RI (Golder, 1996b) did not identif y any surface water bodies at the Western Zin c Smelter site and no samplin g was conducted. Because of the absence of surface water

features, it is not expected that smelter-related materials at this site could adversely impact surface

water quality in the area. Any impact to Surfac e Water and Groundwater will be addressed in OU12. :

5.2.4 Arkansas Valle y South Hillsid e Sla g Pile

T he Surfac e Water RI (Golder, 1996b) did not identif y any surface water bodies at the. Arkansas

Valle y South Hillside Slag Pile site and no samplin g was conducted. Because of the absence of

surface water features , waste at this site is not expected to impact surface water qualit y in the

area. There are no groundwater monitoring well s in the vicinity of the site. Any impact to Surfac e Water and Groundwater wil l be addressed in OU12. Although several erosion features

that have "cut through" sections of the main slag pil e are evident, a review of aerial photographs

datin g back to 1944 indicate that transport of slag does not appear to be an ongoin g condition .

DS-l l
5 .3 HISTORI C AND CULTURA L RESOURCES

T he cultural resources of OU5 were surveyed in August and September 1995 for Elgi n Smelter

site and Grant/Unio n Smelter site (FEC , 1996a) and in Jun e 1996 for Wester n Zin c Smelter site

with the result s included as an addendum (FEC, 1996b). The Arkansas Valle y South Hillside Slag Pile was not surveyed or evaluated; however, since thi s site consists solel y of slag piles , it is very

unlikely that the site contains any features of historical or cultural significance. The Elgi n Smelter

(5LK893) , Grant/Unio n Smelter (5LK894) , an d Western Zin c Smelter (5LK924 ) sites were

recommended as not being eligible for National Register of Historic Places (NRHP) and are not

contributin g features to the Leadville Historic Minin g District under NRHP criteria.

DS-1 2
6 .0 CURRENT AND POTENTIAL FUTUR E LAND US E

Land surrounding and within the California Gulch Superfun d Site is predominatel y dedicated to

mining, commercial/industrial , and residential uses. The OU5 EGWA sites are located within

areas zoned residential , commercial, and industrial. The EGWA sites are currently vacant and

m ay have intermittent recreational visitors. The Grant/Union and Western Zinc Smelter sites are

currently zoned residential . It is reasonably anticipated that these two sites may be used for

residential . The Elgin Smelter an d Arkansas Valle y South Hillside Slag Pile sites are currently

zoned Business and are not likel y to be re-zoned for residential use. Potential future land use is

reasonably anticipated to be consistent with the local Business zoning.

T he effectivenes s of the "overlay district," as well as land use changes, and plans/proposal s for

future land use at each site, would be monitored and evaluated as part of the five-year review

process.

DS-I :
7 .0 SUMMAR Y OF SITE RISKS

Baseline risk assessments (RA) characterize potential human health and ecological risks at a site

based on current condition s (i.e. , no action taken at the site). Remedial action is driven by the

potential for human health or ecological risk; the RA indicates the media and exposure pathway s

to be addressed. Contaminants, receptors , exposure pathways, and baseline risks at OU5 are

described below.

7 .1 HUMAN HEALTH RISKS

T he followin g human health RAs are pertinen t to OU5:

• Weston . 1991. Preliminary Human Health Baseline Risk Assessment for the California Gulch NPL Site, Leadville , Colorado. Prepared by Roy. F. Weston , Inc. for the EPA. December. (Preliminary RA).

• Weston . 1996a. Baseline Human Health Risk Assessment for the California Gulch Superfun d Site, Risk to Resident s from Lead (Part A). Prepared by Roy. F. Weston , Inc .

f or the EPA. January .

• Weston . 1996b. Baseline Human Health Risk Assessment for the California Gulch Superfun d Site, Risk to Residents from Contaminants Other Than Lead (Part B). Prepared by Roy. F. Weston , Inc. for the EPA. January.

• Weston. 1995a. Baseline Human Health Risk Assessment for the California Gulch Superfun d Site, Part C: Evaluation of Worker Scenario and Evaluation of Recreational Scenarios. Prepared by Roy. F. Weston , Inc. for the EPA. April.

T he preliminary RA (Weston , 1991 ) evaluated residential risks from exposure to contaminated

media (i.e. , soil , waste rock, tailing, etc). The preliminary RA also evaluated potential risks to

workers from future exposure to slag, even though the exposure pathway for lead is incomplete. Since the completio n of the preliminary RA, several studies were completed that provided

additional data on contaminant concentrations and on human and ecological exposures. Additionally , Leadville official s and business leaders expressed concern over possible risks and

liabilitie s associated with commercial and recreational uses within the Site. The final baseline RA (Weston , 1995a, 1996a, and 1996b) was composed of the followin g three parts:

• Pan A Risk to Residents from Lead - evaluated residential risk from exposure to

lead,

• Pan B Risk to Residents from Contaminant s Other than Lead - evaluated risk to

resident s from exposure to contaminants other than lead; and

• Pan C Evaluation of Recreational Scenarios and Evaluation of Worker Scenario -

developed in response to community concerns, presented risk-based action level s

to determine whether chemical concentrations presented a risk at location s used

f or commercial, industrial , or recreational purposes .

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T he followin g sections summarize the result s of these RAs, includin g media and contaminant s of

concern (COC) , exposure assessment, and risk characterization , as they relate to OU5.

7.1.1 Media and Contaminant s of Concern

Potential media of concern in OU5 includes of slag, non-residential soils , and residential area soil s

of the EGWA sites. Result s of the preliminary RA (Weston , 1991 ) and the final RA (Weston ,

1995a) indicate that human receptors are expected to have minimal exposure to slag. Both the

preliminary and final RA indicate that soil is the medium of concern for human exposure. Arsenic

a nd lead were used as indicator contaminants for risk in the final RA (Weston , 1995a). These

chemicals were selected based on the result s of the preliminary RA (Weston , 1991) , which

indicate that lead and arsenic are responsible for the majorit y of human health risks at the California Gulch Superfun d Site .

7.1.2 Exposure Assessmen t

T he EGWA sites are currently vacant. The Elgi n Smelter an d Arkansas Valle y South Hillside Slag Pile sites are currently zoned Business and are not likel y to be re-zoned for residential use. Human receptors of concern at the Elgi n Smelter an d Arkansas Valle y South Hillside Slag Pile

sites consist of commercial and industrial workers and recreational visitors . The Grant/Unio n and

Wester n Zin c Smelter sites are currently zoned residential . Human receptors of concern at the Grant/Unio n and Western Zin c Smelter sites are recreational visitors , and potential future

residents .

T he preliminary RA identified potential primary sources of metal s of concern, the mechanisms of

releases to the environment, and receptors in a conceptual site model as shown in Figur e 12. A

conceptual site model was also created for residential use (specifically , exposure to children ) and

is shown in Figur e 13. The final RA identified soil ingestion as the exposure pathway of concern

f or recreational visitors; ingestion of soil and dust was identified as the exposure pathwa y of

concern for commercial/industrial workers; and ingestion of soil/dus t and waste pile s as the

exposed pathway of concern for residents . Exposure to other media (e.g. , slag piles ) and

exposure to soil/dus t through other pathways (e.g., dermal) are considered of insignifican t

concern for workers, recreational users and resident s (Weston , 1991) .

7.1.3 Risk Characterization

T he final RA (Weston , 1995a) developed risk-based action level s for lead and other metals . As

described above, arsenic and lead are responsible for the majorit y of human health risk at the California Gulch Superfun d Site. The action level s developed in the final RA represen t risk-based

chemical concentrations , which are protective of human health and can be compared to

contaminant concentrations in soil to identif y areas of potential concern to commercial/industrial

workers, recreational visitors , or residents . The action levels , presented as a range, represen t the

l ow and high values calculated based on the uncertainties and variation s of the exposure

parameters.

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F or commercial/industrial exposure, the soil action level for lead ranged from as low as 2,200

mg/kg to as high as 19,100 mg/kg, which is based on the widel y varying exposure parameters ,

with central tendency values in the 6,100 to 7,700 mg/kg range. Soil action level s for arsenic

based on commercial/industrial exposure ranged from 330 to 1,300 mg/kg, which is based on the

widely varying exposure parameters, with central tendency values in the 610 to 690 mg/kg range.

F or recreational exposure, the soil action level for lead ranged from as low as 5,000 mg/kg to as

high as 85,000 mg/kg, dependin g on the input parameters. The lead concentration for

recreational exposure was 16,000 mg/kg, which is the action level calculated in the RA (Western ,

1995a). For arsenic, soil action level s for recreational exposure ranged from 1,400 to 3,200

mg/kg based on carcinogenic and systemic effects , respectively . The most appropriate arsenic

concentration for use as a recreational action level was 1,400 mg/kg, based on the potential for

carcinogenic effects .

F or residential exposure, the soil action level s are 3,500 mg/kg for.lead and 120 to 340 mg/kg for

arsenic. The arsenic level is presented as a low and high range because of a number of uncertain

parameters (e.g. , ingestion rate for soil , ingestion rate for dust , the contribution of soil to dust , the

uptake of metal s into vegetables , and the ingestion rate of home-grown vegetables).

T he action level s are summarized below:

coc

Lead

Arsenic

Soi l Action Levels , mg/kg

Residential

3,500

120 - 340

Commercial/Industrial

6,100-7,700

610-690

Recreational

16,000

1,400-3,200

Soil samplin g data for the EGWA sites are reported for several depth intervals includin g 0 to 1

inch, 1 to 2 inches, 2 to 6 inches, and 12 to 18 inches. The metals concentrations from the depth

intervals less than 6 inches and the weighted average concentrations for the 0 to 6 inch depth

interval were compared to the established action level s for various land use scenarios.

At each of the four OU5 EGWA sites, the average concentration of lead and arsenic for all

samples at each site (in the 0 to 6 inch depth interval) are below the risk-based action level s

established by the EPA for residential use scenario at the California Gulch Superfim d Site. However, metals concentrations in soil at several individual sample locations exceed the action

level s associated with their current zoning, as described below. ]

At the Elgi n Smelter site (currently zoned commercial/industrial) concentrations of lead and

arsenic at one sample location , S09-003 (in the 0 to 6 inch depth interval) in an area within the

footprin t of the historic slag pil e and near the stream channel in Big Evans Gulch have been

measured above the site action levels* established for the commercial/industrial worker and

recreational exposure scenarios.

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At the Grant/Unio n Smelter site (currently zoned residential ) concentration s of lead at two sample

location s - SGU0 1 and PG-232 - (in the 0 to 6 inch depth interval) in an area near the existin g

slag pil e and within the footprin t of the historic slag pil e have been measured above the risk-based

site action level s established for residential use scenarios.

At the Western Zin c Smelter site (currently zoned residential ) and the Arkansas Valle y Smelter South Hillside Slag Pile site (currently zoned commercial/industrial) , measured concentration s of

lead and arsenic at all sample locations (in the 0 to 6 inch depth interval) are below the risk-based

action level s established by the EPA for residential and commercial/industrial use scenarios,

respectively . However, one sample (S22-001 ) at the Wester n Zin c site exhibits arsenic

concentrations, in the 0 to 1 inch depth interval, that exceeds the residential action level .

Because these sites are vacant and the average soil concentration s across each site are well below

t he risk-based site action level s for a recreational use scenario, which is consistent with current

uses, condition s at these sites do not pose current unacceptable risks. One sample locatio n at the

Elgi n Smelter site has been identified as having lead and arsenic concentration s in soil that exceed

t he action level for recreational use. The Elgi n Smelter site is private propert y and will be

evaluated in 2001 as part of the five-year site review. Under potential future use scenarios, the

relativel y small areas of soil with lead or arsenic concentration s exceedin g their risk-based action

level s may present a potential human health risk, dependin g on the actual developmen t of the site

7 .2 ECOLOGICA L RISKS

Baseline RAs characterizing ecological risks at OU5 consist of:

• Weston . 1995b Final Baseline Aquatic Ecological Risk Assessment , California Gulch

N PL Site . (BARA) .

• Weston . 1997. Ecological Risk Assessment for the Terrestrial Ecosystem, California Gulch NPL Site . Leadville , Colorado. (ERA).

T he BARA (Weston , 1995b ) characterizes the impact s of mine waste contamination on the

aquatic ecosystem of the California Gulch Superfun d Site. There are no surface water bodies at

OU5, and surface water run=off is minimal. The BARA does not evaluate risks associated with OU5. Based on this information , aquatic risks are not discussed further in this document.

Potential risks to the terrestrial ecosystem from mine waste contamination are characterized in the

E RA (Weston , 1997). The ERA provides a conceptual site model for terrestrial receptors at the California Gulch Superiun d Site and is shown in Figur e 14. In the ERA, the potential for adverse

effect s was evaluated on a station-by-station basis and on an OU basis.

Result s of the ERA relatin g to OU5, includin g media and contaminant s of concern, exposure

assessment, and risk characterization, are summarized below.

DS-1 7
7.2.1 Media and Contaminant s of Concern

T he primary COCs identified in the ERA were arsenic, cadmium, copper, lead, and zinc. Metal s

concentrations were measured in tailin g piles , mine waste piles , slag piles , surface soils , surface

waters, and fluvial sediments. These media were considered likel y pathway s of exposure to

biological receptors that would or could occur in the uplan d and/or the wetland areas present in

t he Leadville area.

O U5 was subdivided into five subunits (A through E) in the ERA as follows: Arkansas Valle y Smelter/Colorado Zinc-Lead Mil l (OU5A) , Arkansas Valle y South Hillside Slag Pile (OU5B) , Wester n Zinc Smelter (OU5C) , Grant/Unio n Smelter (OU5D) , an d the Elgi n Smelter (OU5E) . Risks to ecological receptors were calculated from exposure to metal s in slag and soil in the ERA.

7.2.2 Exposure Assessmen t

Uplan d species included mountain bluebird, least chipmunk, blue grouse, American kestrel , and

soil fauna. Wetlan d species included red winged blackbird, long-tailed vole, belted kingfisher, and

spotted sandpiper. Specie s evaluated that would be potential receptors in both habitat s included

bald eagles, mule deer, red-tailed hawk, and plants .

T he exposure pathways evaluated in the ERA consisted of direct exposure to contaminated

media, incidental ingestion of contaminated media, and indirect exposure through the food chain. Contaminant intakes for the receptors evaluated were based on exposure assumption s such as

food ingestion rates and body weight.

T he ERA used the 95 percent upper confidence limit of the arithmetic mean (UCL) of

contaminant concentrations in media to evaluate exposure and risks for each OU. If the maximum

contaminant concentration was less than the 95 percent UCL, the maximum was used as the

exposure point concentration.

7.2.3 Risk Characterizatio n

T he ERA reviewed lexicological literature to derive acceptable contaminant intake values for

birds and mammals. Resultin g benchmark values, referred to as Toxicit y Benchmark Values

(TBV), were compared to calculated contaminant intakes for ecological receptors. To estimate

risks, the ERA divided estimated intake by the TBV to derive a hazard quotient (HQ). Contaminant intakes greater than TBVs (HQ greater than 1) indicated the potential for toxicit y to

t he receptor. Result s of the ERA indicated that terrestrial receptors in OU5 could have

contaminant intake greater than TBVs. Soils within the OU5 EGWA sites may contribute to

potential risks to terrestrial receptors (e.g. , the mountain bluebird) . However, risks to terrestrial

receptors from exposure to metal s in soil s at the OU5 EGWA sites are considered moderate to

low, and remediation of source area across the California Gulch Superfun d Site will reduce

exposure to terrestrial receptors.

DS-1 S
7 .3 SUMMAR Y OF RISKS/BASIS OF ACTION

T he response action selected in this ROD for OU5 EGWA is warranted to protect the public

health or welfare or the environment from actual or threatened releases of pollutant s or

contaminants that may present an imminent and substantial endangerment for potential future use

of the sites. Because the OU5 EGWA sites are vacant and the average soil concentrations across

each site are well below the risk-based site action level s for a recreational use scenario, which is

consistent with current uses, condition s at these sites do not pose current unacceptable risks. One

sample location at the Elgi n Smelter site has been identified as having lead and arsenic

concentration s in soil that exceed the action level for recreational use. The Elgi n Smelter site is

private propert y and will be evaluated in 2001 as pan of the five-year site review Under potential

future use scenarios, the relatively small areas of soil with lead or arsenic concentration s

exceedin g their risk-based action level s may present a potential human health risk, dependin g on

t he actual developmen t of the site.

DS-1 9
8 .0 REMEDIAL ACTION OBJECTIVES

Thi s ROD was prepared according to EPA guidance (EPA, 1999). The remedy outlined in thi s R OD is intended to be the final remedial action for OU5 EGWA sites. The primary objectives of

the remedy presented in this ROD are:

Sla g

Control of leaching of metals of concern in concentrations that would have an

adverse impact on soils , surface water, or groundwater;

Control airborne transport of contaminated materials, and

Control erosion of contaminated material s to prevent depositio n into local surface

water courses.

Non-residential Area Soil s

• Control airborne transport of contaminated materials;

• Control erosion of contaminated materials and depositio n into local water courses;

• Control leaching and migration of metals from soil into surface water;

• Control leaching and migration of metals from soil into groundwater; and

• Control contaminant exposure to animals and aquatic life.

Residential Area Soil s

"• Prevent direct exposure of the populatio n to elevated concentrations of

contaminants in the surface soil .

T he effectivenes s of the remedial action alternatives were evaluated with respect to these RAOs. Remedial actions undertaken within the OU5 EGWA sites are consistent with the remedial action

objectives an d goal s identified for the entire California Gulch Superfun d Site.

DS-20
9 .0 DESCRIPTION OF ALTERNATIVES

A wide range of cleanup option s were considered in the SFS (EPA, 1993). Some of the

alternatives were eliminated during preliminary screening because they would not effectivel y

address contamination, could not be implemented, or would have had excessive costs. Remedial

action alternatives for OU5 for slag and non-residential area soil s that were retained after

screening alternatives from the SFS were evaluated in the FFS (MFG, 1999). Al l of the

alternatives were evaluated using the nine criteria required by the NCP as described in the next

section, and then compared with each of the other options .

A brief descriptio n of the four clean up alternatives that were considered for the slag, nonresidential area soils , and residential area soil at the OU5 EGWA sites as presented in the FFS

(MFG, 1999) and the Proposed Plan (EPA, 2000) is provided below.

Alternative 1: No Actio n

Estimated capital and operatin g cost: SO

Implementatio n time: Immediate

Thi s alternative leaves the slag, non-residential area soils, and residential area soil s in plac e with

no remediation, engineering or institutional controls , or long-term maintenance. Generally , the No Action Alternative is provided for consideration as a baseline against which other technologies

can be compared in accordance with the NCP. No Action is not protective of human health and

t he environment. A site-wide surface and groundwater monitoring program wil l be developed

once all source areas have been addressed. ASARCO would conduct any required monitoring at

t he slag piles , non-residential area soils , and residential area soils . Thi s alternative is technicall y

feasible and cost-effective since it does not rely on any technology and has no cost.

Alternative 2: Institutional Control s

Estimated capital and operatin g cost: $85,496

Implementatio n time: Immediate

Institutional Control s consists of legal restrictions applied to the sites to restrict accessor

activities and includes measures to provide information to current and/or future land owners

regardin g environmental condition s at the site, and to ensure that if these sites are developed any

necessary special precautions or requirements are followed. Lake County and/or Cit y of Leadville

zoning ordinances would be modified to create a zoning "overlay district" to provide alscreenin g

process to identif y properties where special precaution s or requirements may be necessary and a

mechanism to notif y owners and/or developers of these requirements. The requirements would

include condition s that must be met to ensure protectivenes s and may require additional samplin g

or response actions, to be conducted or funded by Asarco, consistent with the developmen t plans .

At the Wester n Zin c Smelter site (currently zoned Urban Residential ) an d the Arkansas Valle y Hillside Slag Pile site (currently zoned Business), there is no evidence that soil contaminatio n

exist s in exceedance of established risk-based action level s associated with land use scenarios

DS-21
consistent with the current zoning of these two site. At the Grant/Unio n (currentl y zoned Residential) and the Elgi n (currentl y zoned Business) Smelter sites , soil samplin g data indicate

that while average concentrations of metals in soil (in the 0 to 6 inch depth interval) are below the

established risk-based action level s for a residential land use scenario, several small isolated areas

exhibit lead and/or arsenic concentrations that exceed the risk-based action level s for residential

a nd commercial/industrial use scenarios, respectively . As stated previously , all of the OU5

EGWA sites are vacant.

If and when future remediation occurs, ASARCO would conduct or fun d the response activities

consistent with the procedures and requirements of the Lake County Community Health Program

(LCCHP). These activities would be funded by ASARCO separate from the LCCHP trust fund. As the EGWA sites are developed or zoning changes are implemented, the areas with the elevated

metal s concentrations would be addressed under the procedures and requirements of the "overlay

district." The cost for potential future remediatio n was not included in the cost estimate for

Alternative 2 because of the many uncertainties and unknowns associated with potential future

remediation effort . The effectivenes s of the "overlay district/ as well as land use changes, and

plans/proposal s for future land use at each site, would be monitored and evaluated as pan of the

five-year review process.

Alternative 3: No Actio n for Slag; Containmen t (Sourc e Surfac e Control ) for Non - Residential Area Soil s an d Residential Area Soils; an d Institutiona l Control s

Estimated capital and operatin g cost: 5151,714

Implementatio n time: Immediate

Thi s alternative entail s leaving slag in place. Soil covers (fo r containment) would be placed over

those areas that have elevated lead or arsenic concentrations in non-residential and residential area

soil s exceedin g the risk-based action levels . Soil covers would be required at the Elgi n and Grant/Unio n Smelter sites. For the purpose of the FFS and ROD, the areas where soil would be

covered are each 100 feet lon g by 100 feet wide. A simple cover of 12 inches of clean borrow

soil , compacted in place , would prevent exposure to the soil by reducin g the potential for direct

contact and reduce surface water contact and infiltration . Revegetation of the cap would reduce

erosion due to surface water runoff , prevent the entrainment and transport of dust/particle s by

wind, and further reduce infiltration .

Institutional controls , as described in Alternative 2, would be implemented in the cover areas to

prohibit activities that might compromise the remedy. Control s would include: (1) land use

restriction s and requirements for the soil cover areas and (2) prohibitio n of activities that would

compromise the integrit y of the soil cover. The effectivenes s of the "overlay district," as wel l as

land use changes, and plans/proposal s for future land use at each site, would be monitored and

evaluated as part of the five-year review process.

DS-22
Alternative 4: No Actio n for Slag ; Removal/Transport/Disposal of Non-Residential Area Soil s and Residential Area Soil s to an On-Site Repository ; and Institutional Control s

Estimated capital and operatin g cost: 5181,668 Implementatio n time: Immediate

Thi s alternative entail s leaving slag in place. The elevated lead or arsenic concentrations in nonresidential area and residential area soil s that may pose a potential human health concern at the

Elgi n and Grant/Unio n Smelter sites would be removed (to a depth of 2 feet) , transported and

disposed at an on-site repository . The removal action level s for the Elgi n and Grant/Unio n Smelter sites would be based on future land use, which would be residential and

commercial/industrial, respectively. Because of the volume of materials is not well quantified, for

t he purpose of the FFS and ROD, it is estimated that the extent of excavations at the Elgi n and Grant/Unio n Smelter sites would each be 100 feet lon g by 100 feet wide by 2 feet deep (i.e. ,

approximatel y 740 cubic yards). Disposal would be at the Arkansas Valle y Smelter site, Apache Tailin g Impoundment s (which is part of OUT) , or an on-site repository to be developed for OU9

residential soils . The excavated areas would be backfilled with clean soil.

Soil s above action level s may still remain because the extent of removal is limited to a 2 foot

depth. Institutional controls , such as the proposed "overlay district" would appl y to all areas of

t he EGWA sites. Additional soil samplin g or other activities may be required, which would be

conducted or funded by Asarco, in order to be consistent with the development plans . The cost

f or potential future remediation was not included in the cost estimate for Alternative 4 because of

t he many uncertainties and unknowns associated with potential future remediation effort . The

effectivenes s of the "overlay district," as well as land use changes, and plans/proposal s for future

land use at each site, would be monitored and evaluated as part of the five-year review process.

DS-Z :
10.0 SUMMAR Y OF COMPARATIV E ANALYSI S OF ALTERNATIVES

Sectio n 300.430(e)(9) of the NCP requires that the EPA evaluate and compare the remedial

cleanup alternatives based on the nine criteria listed below. The firs t two criteria, (1) overal l

protectio n of human health and the environment and (2) complianc e with applicabl e or relevant

a nd appropriate requirements (ARAR), are threshold criteria that must be met for the Selected Remedy. The Selected Remedy must then represent the best balance of the remaining primary

balancin g and modifyin g criteria.

10.1 NCP EVALUATION AND COMPARISON CRITERIA

10.1.1 Threshold Criteria

1. Overall protectio n of human health and the environment addresses whether each

alternative provides adequate protectio n of human health and the environment and

describes how risks posed through each exposure pathwa y are eliminated, reduced, or

controlledjjhrough treatment, engineering controls , and/or Institutional Controls .

2. Complianc e with ARARs addresses whether or not a remedy wil l compl y with identified

federal and state environmental and citin g laws and regulations .

10.1.2 Primary Balancin g Criteria

3. Long-term effectivenes s and permanence refers to expected residual risk and the abilit y of

a remedy to maintain reliable protectio n of human health and the environment over time,

once clean-up level s have been met. Thi s criterion includes the consideration of residual

risk that will remain on site followin g remediation and the adequacy and reliabilit y of

controls .

4. Reduction of toxicitv. mobility , and volume through treatment refers to anticipated

performance of the treatment technologies that may be included as part of a remedy.

5. Short-term effectivenes s addresses the period of time needed to complete the remedy and

any adverse impact on human health and the environment that may be posed during the

construction and implementatio n period until cleanup goals are achieved.

6. Implementabilitv refers to the technical and administrative feasibilitie s of a remedy,

includin g the availabilit y of materials and services needed to carry out a particular option .

7. Cos t evaluates the estimated capital costs, operatio n and maintenance (O&M ) costs, and

presen t worth costs of each alternative.

DS-24
10.1.3 Modifyi n Criteria

8. Stat e acceptance indicates whether the Stat e (CDPHE), based on its review of the

information , concurs with, opposes , or has no comment on the preferred alternative.

9. Community acceptance is based on whether community concerns are addressed by the Selected Remedy and whether or not the community has a preference for a remedy.

10.2 EVALUATIN G TH E ALTERNATIVES WITH TH E NCP CRITERIA

T he section summarizes the evaluation and comparison of the OU5 EGA alternatives against the

nine NCP criteria. The followin g subsections are a brief summary of the evaluation and

comparison and comparison of the OU5 EGWA alternatives against each criteria. Additional

detail s evaluating the alternatives are presented in the FFS. Tabl e 2 provides a comparison of the

nine remedial action alternatives and the nine NCP criteria. Informatio n for this section was

obtained from the Final FFS OU5 EGWA Site s (MFG, 1999) an d the Proposed Plan for OU5

EGWA site (EPA, 2000).

10.2.1 Overall Protectio n of Huma n Health and the Environment

Thi s criterion is based on the level of protection of human health and the environment afforded by

each alternative. As shown in Tabl e 2, Alternatives 2, 3, and 4 would meet the RAOs. All of the

alternatives would control airborne transport , erosion, and metals leaching from contaminated

materials because no significan t pathway for transport of constituents from slag or soil to other

environmental media have been identified (MFG, 1999). Alternatives 3 and 4 would provide

additio n benefi t by eliminatin g the potential for airborne transport , erosion, and metal s leaching

from contaminated materials.

A ll of the alternatives would control contaminant exposure to animals and aquatic life because the

potential risks to the terrestrial receptors through direct contact of certain sources at OU5 are

considered low. Alternatives 3 and 4 would provide incremental reduction in risk through

elimination of direct contact of limited sources.

Since the EGWA sites are currently vacant and may have only intermittent recreational use, Alternatives 1 and 2 would prevent any significan t direct exposure of the populatio n to elevated

concentration of contaminants in the surface soil because the average metals concentrations in soil

do not exceed risk-based action level for recreational use. One sample location at the Elgi n Smelter site has been identified as having lead and arsenic concentrations in soil that exceed the

action level for recreational use. The Elgi n Smelter site is private propert y and will be evaluated

in 2001 as part of the five-year site review. Alternatives 3 and 4 would provide additional

protectio n under current land use by reducing the potential risk associated with the isolated areas

of soil with elevated metal s concentrations. Under future land use, Alternative 1 (no action) may

result in unacceptable exposure. The institutional control s in Alternatives 2, 3, and 4 would

maintain protectivenes s under future land use.

DS-25
Alternative 1 would not provide overall protectio n of publi c health and the environment because

though slag, non-residential area soils , and residential area soil s in their existin g conditio n are not

considered a source of environmental or human health risk, this alternative would not ensure

protectio n under potential future land use. All of the alternatives, except Alternative 1 (No Action) , would provide adequate protectio n of human health and the environment. Alternative 2

would provide additional protectio n because institutional control s would help ensure protectio n

under future land use. Alternatives 3 and 4 would provide minimal additional benefi t under

current site condition s and land uses by isolatin g and removing areas of soil with elevated metal s

concentrations, respectively .

10.2.2 Complianc e with Applicabl e or Relevant and Appropriat e Requirements

Thi s criterion is based on compliance with chemical-, location-, and action-specific ARARs. ARARs are presented in Table s 3 through 5. Alternatives 2, 3, and 4 would compl y with all ARARs.

10.2.3 Long-Term Effectivenes s and Permanence

Under future use scenarios, Alternative 2 would provide long-term protectio n and permanence

using the institutional controls , which would rely on the success of the "overlay district" and

would require some administrative maintenance and review. Alternative 3 would provide

additional long-term protectio n through isolatio n at the Elgi n and Grant/Unio n Smelter sites. Alternative 4 would provide the greatest long-term protectio n through removal at the Elgi n and Grant/Unio n Smelter sites. Institutional control s would still be required in .Alternative 3 to protect

t he containment barrier (i.e. , soil cover) and in Alternative 4 because the removal activities would

be limited. If the response activities for Alternative 3 and 4 were performed in advance of

development , these activities may not correspond to the ultimate use or configuratio n of the land

under developed site conditions . Alternative 3 and 4 would require some level of inspectio n and

maintenance to achieve permanence.

10.2.4 Reduction of Toxicity , Mobility , or Volum e Through Treatmen t

No treatment processes are being considered to reduce toxicity , mobility , or volume of slag, nonresidential area soils, or residential area soils .

10.2.5 Short-Term Effectivenes s

T he short-term effectiveness , based on disturbance during implementation , would be good for

Alternative s 3 and 4, but Alternative 4 would pose a greater short-term risk durin g the

transportatio n of contaminated materials. Alternative s 1 and 2 would not have any disturbance.

10.2.6 Implementabilit y

A ll alternative s would be relativel y easy to implement . Lake Count y and the Cit y of Leadvill e

have agreed to implement the institutional controls in the form of the '"overlay district/ as

described in .Alternative s 2. 3, and 4. In addition , institutional control s for .Alternative s 2. 3. and 4

DS-26
would be easy to implement because Asarco would help fun d the "overlay district" and fun d any

potential screening (e.g., soil sampling ) and remediation. Alternatives 3 and 4 would require

more time and effort to implemen t compared to Alternative 2 because the areas with elevated

metals concentrations have not been specificall y quantified. However, Alternatives 3 and 4 could

probabl y stil l be performed in one construction season with conventional construction equipment.

10.2.7 Cost

Thi s criterion evaluates the estimated capital , O&M, and present worth costs of each alternative. Present worth costs range from zero (Alternative 1) to $181,668 (Alternative 4). The present

worth of post-removal site control costs for a 30-year period were calculated assuming a 5

percent discount rate.

10.2.8 Stat e Acceptanc e

T he Stat e has been consulted throughout this process. The Stat e i s aware of EPA' s selected

remedy and has chosen to make no further comment.

10.2.9 Communit y Acceptanc e

Public comment on the RI/FS and Proposed Plan was solicited during a formal public comment

period extending from July 27 to August 28, 1999. No comments from the community were

received during the formal public comment period.

DS-27
11.0 PRINCIPAL THREAT WASTES

T he NCP establishes an expectatio n that EPA will use treatment to address the principal threat s

posed by the site wherever practicable (NCP §300.430(a)(l)(iii)(A)). Identifyin g principal threat

wastes combines concept s of both hazard and risk. In general, principal threat wastes are those

source materials considered to be highly toxic or highly mobile that generally cannot be contained

in a reliable manner or would present a significant risk to human health or the environment should

exposure occur. Conversely , non-principal threat wastes are those source materials that generall y

can be reliabl y contained and that would present only a low risk in the event of exposure. The

manner in which principal threat s are addressed generally will determine whether the statutory

preference for treatment as a principal element is satisfied.

T he source materials identified at the OU5 EGWA site include slag, non-residential area soils , and

residential area soil. These source materials do not constitute principal threat wastes; hence, they

are considered non-principal threat wastes.

DS-28
12.0 SELECTE D REMEDY

Based upon consideration of CERCLA requirements, the detailed analysi s of alternatives , and

public comments, EPA has determined that the Institutional Control s alternative presented in the Proposed Plan , with no modifications , is the appropriate remedy for the slag, non-residential area

soils , and residential area soil s at the OU5 EGWA sites within the California Gulch Superfiin d Site. Lake County and/or City of Leadville zoning ordinances will be modified to create a zoning

"overlay district" to provide a screening process to identif y properties where special precaution s

or requirements may be necessary and a mechanism to notif y owners and/or developers of these

requirements. Any samplin g or response actions will be conducted or funded by Asarco,

consistent with the developmen t plans .

T he Institutional Control s alternative is protective of human health and the environment and is

considered effective because slag in its existing condition does not present a significan t risk to

human health or the environment. In addition , no significan t pathway s for transport of COCs

from non-residential and residential area soil s or other environmental media have been identified

and average metals concentrations in soil at each site are well .below the risk-based site action

level s for recreation use scenario, which is consistent with current uses. The "overlay district,"

under potential future use scenarios, wil l ensure that any necessary precautions or requirements

a re followed for those relativel y small areas of soil with lead or arsenic concentrations exceeding

their risk-based action levels , which may present a potential human health risk.

12.1 RATIONALE FOR SELECTE D REMEDY

Based upon consideration of the requirements of CERCLA and the NCP, the detailed analysi s of

alternatives , and public comments, EPA has determined that Alternative 2 - Institutional Control s

presented in the Proposed Plan is the appropriate remedy for the slag, non-residential area soils ,

a nd residential area soil s within the OU5 EGWA sites. Alternative 2 either meets or exceeds

benefit s associated with the selectin g criteria compared to the majority of the other alternatives. T he approach for waste left in place as described in Alternative 2 is consistent with the.approach

used in the LCCH P and other areas within the California Gulch Superrun d Site where waste was

left in place. Institutional control s would still be required for Alternatives 3 and 4 because

Alternative 3 involves a soil cover barrier and the removal activities for Alternative 4 would be

limited. Alternative 2 is less expensive than Alternatives 3 and 4. Thi s selected remedy will

reduce risk to human health and the environment through the following:

• As required, Alternative 2 meets the threshold cleanup evaluation criteria (overal l

protectio n of human health and the environment and compliance with ARARs).

• Under Alternative 2, potential risks to human health and the environment would be

controlled through implementatio n of samplin g or appropriat e response'action s

consistent with the developmen t of a site.

• Alternative 2 would be permanent and provide long-term effectivenes s consisten t

with future post-developmen t site condition s and land use.

DS-29
T he Selected Remedy best meets the entire range of selectio n criteria an d achieves, in EPA' s

determination , the appropriat e balance considerin g site-specifi c condition s an d criteria identified in CERCLA and the NCP, as provided in Section 13.0, Statutor y Determinations.

12.2 DESCRIPTION OF SELECTE D REMEDY

Institutional Control s will be established as the Selected Remedy to warn of potential hazards and

to maintain the effectivenes s of the remedy by limitin g access to or use of the propert y (current

a nd potential future land use scenarios), includin g temporary and permanent measures.

Institutional Control s involve restricting access or activities that could result in human contact

with the slag, non-residential area soil s and residential area soil s or increase the potential for

leachin g from the slag piles , non-residential area soils , and residential area soils . Thi s alternative

includes measures to provide information to current and/or future land owners regardin g

environmental condition s at the site, and to ensure that if these sites are developed any necessary

special precaution s or requirements are followed. Lake Count y and/or Cit y of Leadvill e zoning

ordinances will be modified to create a zoning "overlay district" to provide a screening proces s to

identif y propertie s where special precaution s or requirements may be necessary and a mechanism

to notif y owners and/or developers of these requirements. The requirements will include

conditions that must be met to ensure protectiveness and may require additional samplin g or

response actions, to be conducted or funded by Asarco, consistent with the developmen t plans . A ny samplin g or response actions will be conducted or funded by Asarco, consistent with the

developmen t plans . As the EGWA sites are developed or zoning changes are implemented, the

areas with the elevated metals concentrations will be addressed under the procedures and

requirements of the "overlay district." The effectivenes s of the "overlay district," as well as land

u se changes, and plans/proposal s for future land use at each site, wil l be monitored and evaluated

as part of the five-year review process. EPA, upon consultatio n with CDPHE , wil l review and

approve proposed response activities.

At the Western Zin c Smelter site (currently zoned Urban Residential ) and the Arkansas Valle y Hillside Slag Pile site (currently zoned Business), there is no evidence that soil contamination

exists in exceedance of established risk-based action level s associated with land use scenarios

consistent with the current zoning of these two site. At the Grant/Unio n (currentl y zoned Residential) and the Elgi n (currently zoned Business) Smelter sites, soil samplin g data indicate

that while average concentrations of metals in soil (in the 0 to 6 inch depth interval ) are below the

established risk-based action level s for a residential land use scenario, several small isolated areas

exhibit lead and/or arsenic concentrations that exceed the risk-based action level s for residential

a nd commercial/industrial use scenarios, respectively . As stated previously , all of the OU5

EGWA sites are currently vacant.

Proposed control s for the Grant/Unio n and Wester n Zin c Smelter sites, which are currently zoned

residential and essentiall y surrounded by OU9, will involve includin g these sites in the overlay

district . If and when future remediation occurs, Asarco wil l conduct or fun d the response

activities , consistent with the procedures an d requirements of the LCCHP . Thes e activitie s would

be funded by Asarco separate from the LCCHP trust fund.
T he Elgi n Smelter an d Arkansas Valle y South Hillside Slag Pile sites are located in the Lake County business zoning district (commercial/industrial use) and are not likel y to be re-zoned for

residential use. If the Elgi n Smelter site, in the future, was included in an area of proposed

development , incidental construction activities may adequatel y contain/cover impacted soil or

reduce constituent concentrations in the upper soil layer, thereby reducing risks associated with

incidental soil ingestion. A deed notice or formal notificatio n to the propert y owner will be

considered for the Elgi n Smelter site to provide available site characterization information to the

owner for consideration in plannin g future development .

An O&M program will be developed. O&M activities will involve creation and maintenance of

t he "overlay district" for the institutional control.

12.3 ESTIMATED REMEDY COST S

T he detailed cost estimate and present worth analysis for Alternative 2, the Selected Remedy, are

presented in Table s 6 and 7, respectively . The net present value of the estimated capital and

operatin g cost for a 30-year period is approximatel y $85,496. The cost for a response action of

this nature would include administrative expenses to obtain zoning and/or deed restrictions. Cost s

f or future response actions, if any, are not included in thi s estimate because of the many

uncertainties. These future response actions, if any, wil l be funded by Asarco. The Selected Remedy is anticipated to be implementable immediately upon finalizatio n of the overlay district . T he informatio n in this cost estimate table is based on the best available informatio n regardin g the

anticipated scope of the remedial alternative. Changes in the cost elements are likel y to occur as a

result of new information and data collected during the engineering design of the remedial

alternative. Major changes may be documented in the form of a memorandum in the Administrative Record file, an Explanatio n of Significan t Difference , or a ROD amendment. Thi s

is an order-of-magnitude engineering cost estimate that is expected to be within +50 to -30

percent of the actual project cost.

12.4 EXPECTE D OUTCOME OF THE SELECTE D REMEDY

Sinc e the EGWA sites are currently vacant with only intermitten t recreation use, institutional

controls will be relied upon for future developmen t and land use to maintain the protection of

human health and the environment. As the EGWA sites are developed or zoning changes are

implemented, the .areas with the elevated metals concentrations will be addressed under the

procedures and requirements of the "overlay district.'1 If and when future remediation occurs at

t he Grant/Unio n and Western Zinc Smelter sites, which are currently zoned residential , Asarco

will conduct or fun d the response activities consistent with the procedures and requirements of

t he LCCHP. These activities will be funded by Asarco separate from the LCCHP trust fund.

DS-3 1
13.0 STATUTOR Y DETERMINATIONS

Under CERCLA Sectio n 121, EPA must select a remedy that is protective of human health and

t he environment, that complies with ARARs, is cost effective , and utilizes permanent solutions

and alternative treatment technologies or resource recovery technologies to the maximum extent

practicable. In addition , CERCLA includes a preference for remedies that include treatment

which permanently and significantl y reduces the volume, toxicity , or mobility of hazardous wastes

as a principal element.

T he followin g sections discuss how the Selected Remedy meets statutory requirements.

13.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

T he Selected Remedy is protective of human health and the environment, and is considered

effective because (1) slag in its existing conditio n does not present a significan t risk to human

health or the environment, (2) no significan t pathways for transport of COCs from soil or other

environmental media have been identified, and (3) the EGWA sites are currently vacant; however,

t he sites may be intermittentl y used for recreation. One sample location at the Elgi n Smelter site

has been identified as having lead and arsenic concentrations in soil that exceed the action level

f or recreational use. The Elgin Smelter site is private propert y and will be evaluated in 2001 as

part of the five-year site review, and (4) as the land use changes, the institutional control s wil l

ensure that waste left in place will be addressed to prevent exposure to human health.

T he Selected Remedy would control airborne transport , erosion, and metals leachin g from

contaminated materials because no significan t pathway for transport of constituent s from slag or

soil to other environmental media have been identified (MFG, 1999). In addition , the Selected Remedy would control contaminant exposure to animals and aquatic life because the potential

risks to the terrestrial receptors through direct contact of certain sources at OU5 are considered

low. Under current land use, The Selected Remedy would prevent direct exposure of the

populatio n to elevated concentration of contaminants in the surface soil because the average

metals concentrations in soil do not exceed risk-based action level for recreational use. The Selected Remedy would maintain protectiveness under future land use.

13.2 COMPLIANC E WITH ARARs

T he Selected Remedy will compl y with all ARARs identified in Table s 3, 4, and 5. No waiver of ARARs will be necessary. Final performance standards wil l not include ARARs for Site-wide Surfac e Water and Groundwater or require a specified decrease in point or non-point source

loadings of COCs to Site-wide Surfac e Water and Groundwater (USCD, 1994). It was agreed

that the decision on remediation of Site-wide Water Quality (OU12 ) would be made between the

E PA and the PRPs and memorialized in the CD only after remedies for source remediation were

selected and implemented at each OU. As a result , specific water quality goal s for surface

streams and ground-water have not been established at thi s time.

DS-32
13.3 COST EFFECTIVENES S

E PA has determined that the Selected Remedy is cost effective in mitigatin g the principal risks

posed by slag, non-residential area soils , and residential area soils. Sectio n 300.430(f)(ii)(D) of

t he NCP requires evaluation of cost effectiveness . Overall effectivenes s is determined by the

followin g three balancing criteria: long-term effectivenes s and permanence, reduction of toxicity ,

mobility , and volume through treatment; and short-term effectiveness . Overall effectivenes s is

then compared to cost to ensure that the remedy is cost effective . The Selected Remedy meets

t he criteria and provides for overall effectivenes s in proportio n to its cost. The estimated cost for

t he Selected Remedy is $85,496.

13.4 UTILIZATION O F PERMANEN T SOLUTION S AN D ALTERNATIV E TREATMENT TECHNOLOGIE S (OR RESOURCE RECOVERY TECHNOLOGIES ) T O TH E MAXIMUM EXTEN T POSSIBL E

No remedial action is necessary to ensure protectio n of human health and the environment. Institutional control s allow for management of the site if the land use changes. Moreover, since

the slag, non-residential area soils, and residential area soils will remain on site with no treatment,

t he Selected Remedy will require a five-year review under Sectio n 121(c ) of CERCLA and Sectio n 300.430(f)(4)(ii ) of the NCP.

13.5 PREFERENC E FOR TREATMENT AS A PRLNCIPAL ELEMEN T

Various treatment option s for slag, non-residential area soils , and residential area soil s were

considered in the FS process; however, due to the nature and size of the slag, non-residential area

soils , and residential area soils, these option s were determined to be either technicall y

impracticable and/or not cost effective (EPA, 1993).

13.6 FIVE-YEA R REVIEW REQUIREMENT S

Because the slag, non-residential area soils , and residential area soil s wil l remain on site, the Selected Remedy will require a five-year review under Sectio n 121(c ) of CERCLA and Sectio n

300.430(f)(4)(ii ) of the NCP. The five-year review includes a review of all monitorin g data and

an evaluation as to how well the Selected Remedy is achieving the RAOs and ARARs that it was

desisned to meet.

DS-:
14.0 DOCUMENTATION OF SIGNIFICANT CHANGES

T he Proposed Plan for slag, non-residential area soils , and residential area soil s at the OU5

EGWA sites was released for public comment in July 2000. The Proposed Plan identified

Alternative 2, Institutional Controls , as the preferred alternative. Comments were received

during the public comment period. EPA determined that no significan t changes to the remedy, as

it was originally identified in the Proposed Plan , were necessary or appropriate .

DS-34
15.0 REFERENCES

Camp Dresser & McKe e Inc. (CDM) . 1994. Final Soils Investigation Data Report, California Gulch CERCLA Site, Leadville, Colorado. Prepared by CDM for Resurrection Minin g Company . July .

Colorado Climate Center. 1997. Colorado State University , Department of Atmospheric Sciences , http://ulysses.atmos.colostate.edu/access.html .

Engineering-Science, Inc. (ESI). 1986. Final Yak Tunnel/California Gulch Remedial Investigation. Prepared for State of Colorado, Department of Law.

Foothil l Engineering Consultants , Inc. (FEC). 1996a. Cultural Resources Investigations of Selected Smelter Sites, Operable Unit 5, California Gulch Superfund Site, Lake County, Colorado. March.

FEC. 1996b. Addendum to Cultural Resources Investigations of Selected Smelter Sites, Operable Unit 5, California Gulch Superfund Site, Lake County, Colorado. July.

Golder and Associates (Golder) . 1996a. Final Surface Water Remedial Investigation Report, California Gulch Site, Leadville, Colorado. May.

Golder. 1996b. Final Hydrogeologic Remedial Investigation Report, California Gulch Site, Leadville, Colorado. May.

Lake County. 1997. Lake County Zoning Districts Map. Lake County Board of County Commissioners.

McCulley , Frick & Gilman , Inc. (MFG). 1999. Final Focused Feasibility Study for Operable Unit 5 EGWA Sites, California Gulch Superfund Site. Prepared for Asarco Inc. Apri l 6.

Morrison Knudsen Corporatio n (MK). 1992a. Report for Lead Slag Pile Remedial Investigation

at the California Gulch Site, Leadville, Colorado. Prepared for Denver & Rio Grande Western Railroad. December.

MK. 1992b. Report for Zinc Slag Pile Remedial Investigation at the California Gulch Site, Leadville, Colorado. Prepared for Denver & Rio Grande Western Railroads December.

U.S. Department of Commerce. 1990. Selected Population and Housing Characteristics. Bureau of the Census.

U.S. District Court (USDC) , District of Colorado. 1994. Civi l Actio n No. 83-C-2388, Consent Decree with Asarco, Inc. , Resurrection Minin g Company , Newmont Minin g Corporation ,

a nd the Res-Asarco Joint Venture, Appendix B: Work Area Management Pla n for Asarco Incorporated at the California Gulch Superfun d Site, Leadville , Colorado. May.

DS-35
U .S Environmental Protectio n Agency (EPA). 2000. Proposed Plan for Oregon Gulch Operable Unit 5 EG WA Sites, California Gulch Superfund Site, Leadville. Colorado. March.

EPA. 1999. A Guide to Preparing Superfund Proposed Plans, Records of Decision, and other Remedy Selection Decision Documents. EPA 540-R-98-03 1. July.

EPA. 1993. Final Screening Feasibility Study for Remediation Alternatives at the California Gulch NPL Site, Leadville, Colorado. September.

EPA. 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA. EPA/540/G-89/004. Offic e of Emergency and Remedial Response, Washingto n D.C. October.

Walsh and Associates , Inc. (Walsh) . 1993. Smelter Remedial Investigation, California Gulch Superfund Site, Leadville, Colorado. Prepared for ASARCO , Inc. April.

WESTEC . 1997a. Smelter Supplemental Remedial Investigation Work Plan, California Gulch CERCL4 Site. Prepared for ASARCO , Incorporated. October.

WESTEC . I997b . Final Draft Smelter Feasibility Study, California Gulch CERCLA Site. Prepared for ASARCO, Incorporated. January 17.

Weston , Inc. and Terra Technologies . 1997. Ecological Risk Assessment for the Terrestrial Ecosystem. California Gulch NPL Site. Leadville, Colorado. January 1997.

Weston , Roy F., Inc. (Weston ) 1996a. Baseline Human Health Risk Assessment for the California Gulch Superfund Site, Risk to Residents from Lead (Part A). Prepared by Roy. F. Weston , Inc. for the EPA. January 2.

Weston . 1996b. Baseline Human Health Risk Assessment for the California Gulch Superfund Site, Risk to Residents from Contaminants Other Than Lead (Part B). Prepared by Roy. F. Weston , Inc. for the EPA. January 2.

Weston . 1995a. Baseline Human Health Risk Assessment for the California Gulch Superfund Site, Part C Evaluation of Worker Scenario and Evaluation of Recreational Scenarios Prepared by Roy . F. Weston , Inc. for the EPA. April .

Weston . 1995b. Final Baseline Aquatic Ecological Risk Assessment (BARA), California Gulch, N PL Site. Prepared by Roy F. Weston , Inc. for EPA. September.

Weston . 1991. Preliminary Human Health Baseline Risk Assessment for the California Gulch N PL Site, Leadville, Colorado. Prepared by Roy F. Weston , Inc. for the EPA. December.

DS-36
Woodward-Clyde Consultant s (WCC) . 1992a. Smelter Site Reconnaissance Report, California Gulch Site, Leadville, Colorado.

WCC . 1992b. Final - Air Quality Monitoring Report, California Gulch Site, Leadville. Colorado.

DS-37
FIGURES
DENVER AND RIO GRANDE • WESTERN

CANTERBUR Y TUNNE L

J

Turquoise Lake

LEADVILL E DRAINAG E TUNNE L

Evens

CALIFORNI A GULC H SUPERFUN D SIT E BOUNDAR Y

0 .5 1.0

Y AK TUNNE L

CALIFORNI A GULC H

SCAL E IN MILES

Figure 1

GENERA L SIT E LOCATION MAP

California Gulch Superfun d Site Leadvllle, Colorado
Operabl e Unit

s

O U1 - Yak Tunnel/Water Treatment Plant

O U2 • Malta<Gulch Fluvial Tailing/Laadvill e Corp. Mill/Malta Gulch Tailin g Impoundment s

O U3 - D&RG Slag Piles/Railroad Easement/ Railroad Yard

O U4 - Upper California Gulch

O U5 - Asarco Smelters/Slag Mil l Site s

O U6 - Star Ditch/Panrose Dump/ Stray Horse <3u!ch/Evans Gulc

h

O U7 - Apache Tailing Impoundment

O U8 - Lower California Gulch

O U9 • Residential Populated Areas

OU10- Oregon Gulch

OU11 -.Arkansas River Valley Roodplain

OU12 - Site Water Quality

_ __ Operable Unit Boundary

Figure 2

California Gulch Superfun d Sit e

a nd Operabl e Unit s Leadville , Colorad o

Date: 25-SEP-2000 M a p Fil e Mama: nassma

o oubndrvjvi A' l v8:0.l
LEGEN D

APPROXIMAT E OU 5 EGWA SIT E BOUNDARIE S

FORME R SMELTE R SIT E

STREAM/DRAINAG E

DIR T ROA D

GRANT/UNIO N SMELTE R SIT E

WESTER N ZIN C SMELTE R SIT E

-ARKANSA S VALLE Y SOUTH HILLSID E SLA G PIL E SCAL E

2000 2000 FEET

RgureS

SIT E MAP OPERABLE UNIT 5 EGWA SITES

California Gulch Superfun d Site Leadville, Colorado
C OM PATH P;V5280-015\OU5\ROO\ECWA\ng4.d«g 08/09/00

2000 UPSTREAM

EG-1

LEGEN D

SIT E FEATURE S

SLA G PIL E

SLA G VENEE R

COK E AND/OR COA L

APPROXIMAT E FORME R ELGI N SMELTE R LOCATION

B I G EVAN S GULCH

APPROXIMAT E LOCATION O F SURFAC E WATE R SAMPLIN G STATIO N

SCAL E

200 2 00 FEET

• SOURCE : MK, 1992a.

Rgure 4

ELGIN SMELTER LOCATION A N D SIT E FEATURES OPERABLE UNIT S

California Gulch Superfun d Site LsacMIle, Colorado
C OM PATH P:\3280-015\OU5\ROO\EGWA\Flg3.dwg 08/09/00

I ll

GG-1 A

LEGEN D

SIT E FEATURE S

SLA G PIL E

SLA G VENEE R

COK E AND/O R COAL

FORME R GRANT/UNIO N SMELTE R LOCATIO N

CALIFORNI A GULC H

O U 9 - RESIDENTIA L POPULATE D AREA S

APPROXIMAT E LOCATION O F SURFAC E WATE R SAMPLIN G STATIO N

SCAL E

300 300 FEET

* SOURCE : MK, 1992a.

Figure s

GRANT/UNION SMELTE R LOCATION AND SIT E FEATURES OPERABLE UNIT 5

California Gulch Superfun d Site Leadvilte, Colorado
C OM PATH P:\3280-015\OU5\ROD\ECWA\Fig6.dng 08/09/00
C DM PATH P:\3208-015\OU5\ROD\ECWA\FTg7.dwg M\09\00

LEADVILL E WATE R TREATMEN T

PLANT .

LEGEN D

SIT E FEATURE S

SLA G PIL E

ARKANSAS VALLEY SOUTH HILLSID E SLA G PIL E LOCATION AND SIT E FEATURES OPERABLE UNIT 5

CALIFORNI A GULC H

California Gulch Superfun d Site Leadvllle, Colorado
C OM PATH P:\3280-015\OU5\ROO\ECWA\Flg8.d«q 08/09/00

L

SEL01

0-1"

1-2"

2-6

6-12"

As

25

25

13

24

Pb

155

101 ,

17 "

17

LES101 *

0-3FT

As

235

Cd

7.6

Pb

10,000

Zn

26,800 ———— —

* COMPOSIT E SLAG SAMPLE .

S09-003

0-1"

1-2"

2-6"

6-12"

As

<250jim

2552

2118

1976

1177

<2mm

540

508

367

578

Cd

<250^m

58

71

79

48

<2mm

39

36

30

47

Pb

<250Mm

26.153

22.788

21.897

24.047

<2mm

16,090

11.521

10,432

1 6.226

<250M<|

1 2.38C

10,86^

11.722

Zn j n

\

1 1 ,03C/

<2mm J

7.510

5.607

5,792

8.039 ,

PG-621

o-r

1-2

2-6"

6-12"

12-18"

As

NO

90.5

NO

3.1

N D

Cd

12.8

10.4

7.1

5.2

2.9

P b (

2,334

1.353

908

252

59

Zn

2.381 i

1.683 |

) 862 )

H

266

X

r

321.500

SIT E FEATURE S

SLA G PIL E

SLA G VENEE R

COK E AND/O R COA L

APPROXIMAT E FORME R ELGI N SMELTE R LOCATIO N

B I G EVAN S GULC H

A LES10 1

SAMPL E LOCATION S

LEA D SLA G R l (MK , 1992a ) SAMPL E LOCATIO N

• SOILS/SMELTE R R l PRIMAR Y GRI D PG-621 (COM , 1994; WALSH . 1993 )

• SOILS/SMELTE R R l DISCRET E S09-003 (COM, 1994; WALSH , 1993 )

X SMELTER SUPPLEMENTA L R l SEL0 1 (WESTEC , 1997b )

SEL02

, o-r

 1-2"

2-6"

6-12"

As

64

38

26

23

Pb

719

209

57

24

,PG-643 I, o-r

| 1-2"

I 2-6"

j 6-12"

I 12-18"

As

NO

20.1

24.5

14.6

3.7

Cd

ND

1.8

ND

ND

ND

Pb

353.6

154.9

173

37.4

61.4

Zn

410

202

163

76.4

149

.SEL03

0-1

1-2"

2-6

6-12"

As

48

57

104

105

Pb

715

921

1.490

1,570

PG-620

o-r

1-2"

2-6"

6-12"

12-18"

As

<250/an

186

272

15.1

7.7

17

<2mm

202

107

9.5

5

9

Cd

<250Mm

25.7

39.3

7.3

5.9

7.7

<2mm

59.6

26.7

5.9

4.7

6

Pb

<250/im

5,080

7,450

383

95.3

429

<2mm

6,660

3,930

293

67.4

2 12

Zn

<250/im

2,390

4,950

693

636

939

<2mm

7,090

2,310

585

450

709

200

NOTES : AL L CONCENTRATION S AR E IN mg/kg SOLI D MATERIA L UNLES S IDENTIFIE D OTHERWISE , AL L SAMPLE S AR E SOIL . ND = NOT DETECTED .

SCAL E

2 00 FEET

Figure 8

RESULTS OF INVESTIGATIONS AT T H E ELGIN SMELTER SIT E OPERABLE UNIT 5

California Gulch Superfund Site Leadvilte, Colorado
C OM PATH P:\3280-015\Oy5\ROO\ECWA\Rg0.dwg 08/08/00

SGU0 1

o-r

1-2"

2-6

6-12"

As

130

136

1 15

1 16

Cd

NA

N A

NA

N A

Pb

4,910

4,340

4,500

4,470

Zn

NA

NA

NA

NA

PG-232

o-r

1-2"

2-6

6-12"

12-18"

As

N D

N D

N D

N D

N D

Cd

35.3

40.4

35.8

6.4

2.7

Pb

5.173.6

5.575.6

5,370.1

6.318.7

6.451.0

, Zn

'6,224. 7

|6,31 1 .8

6,908.2

J 1 1,366

, 1 1 ,665 I

PG-217

o-r

1-2"

2-6"

6-12"

12-18"

As

27.4

42.2

79.3

50

6.3

Cd

N D

. 5.9

N D

8.8

4.9

Pb

1,360.3

1,334.5

1.377.0

1,680.0

1.322.0

Zn

500.7

538.2

626.2

634.1

521.4

PG-216

o-r

1-2" -

2-6"

6-12"

12-18"

As

ND

ND

ND

6.2

24.1

Cd

6.5

4.6

1.4

N D

0.5

Pb

642.7

419.4

162.0

69.2

32.7

Zn

370.2

232.9

132.3

79.7

63.2

. . .'SGUf-01,

f PG-/23 G S1

GGS10 T

0-3 FT

As

272

,Cd Pb

<0.4 16,000 18,300

Zn

* COMPOSIT E SLAG SAMPLE .

PG-275

o-r

1-2"

2-6"

6-12"

12-18"

As

N D

ND

ND

ND

ND

Cd

N D

13.1

N D

6.2

N D

Pb

2J274.0

t

2.'061.7

i

1 ,943.9

.1

5J869.1

981.1

Zn

1 .650.2

1,113.7

923.6

861.7

639.0

PG-252

o-r

1-2"

2-6"

6-12"

12-18"

As

ND

N D

23.3

N D

7.5

Cd

15.4

12.3

9.8

N D

N D

j P b

1.322

971

1,135.0

556.0 i

J12 5

Zn

2.424

1,797

1094

551

205

PG-215

o-r

1-2"

2-6"

6-12"

12-18"

As

<250/im

88.5

44.2

18.2

11.4

7

<2mm

43

31.1

11.7

5.6

5.3

I Cd

<250iun

'13. 3

12

i4.4

1.3

0.6

<2mm

12.8

10.1

3.3

1.2

0.6

Pb

<250/tm

2.120

1 .290

355

148

85.6

<2mm

1.900

997

228

87

67.4

Zn

<250Mm

505

492

283

156

109

<2mm

491

433

233

130

102

§

SCAL E

[ ..... |

SIT E FEATURE S

SLA G PIL E

SLA G VENEE R

COKE AND/O R COA L

FORME R GRANT/UNIO N SMELTE R LOCATIO N

CALIFORNI A GULC H

O U 9 - RESIDENTIA L POPULATE D AREA S

SAMPL E LOCATION S

A LEA D SLA G R l (MK , 1992a ) GGS10 1 SAMPL E LOCATIO N

• SOILS/SMELTE R R l PRIMAR Y GRI D PG-217 (COM , 1994; WALSH , 1993 )

SWELTE R SUPPLEMENTA L R l (WESTEC , 1997b )

300 3 00 FEET NOTES : AL L CONCENTRATION S AR E I N mg/k g SOLI D MATERIAL . UNLES S IDENTIFIE D OTHERWISE , AL L SAMPLE S AR E SOIL . ND = NOT DETECTED . NA = NOT ANALYZED .

* SOURCE : MK , 1992a.

Figure 9

RESULTS OF INVESTIGATIONS AT T H E GRANT/UNION SMELTE R SIT E OPERABLE UNIT 5

California Gulch Superiund Site Leadville, Colorado
C OM PATH P:\3280-015\QU5\RQD\EGWA\Fig1Q.dw g 08/09/00

HSS104 *

0-3 FT

As

1 12

Cd

18.9

Pb

793

Zn

67.800

* COMPOSIT E SLAG SAMPLE .

HSSIO f

0-3 FT

As

414

Cd

29.5

Pb

739

Zn

63,200

* COMPOSIT E SLAG SAMPLE .

HSS102 *

0-3 FT

As

277

Cd

28.6

Pb

925

Zn

63.300

• COMPOSITE SLAG SAMPLE.

PG-223

o-r

1-2

2-6"

6-12"

12-18"

As

130.2

25.9

31.9

8.4

4.9

Cd

ND

20.5

22.6

ND

4.14

Pb

794.2

600

717.2

121.4

23.5

Zn

8,366.6

4.911.8

4.706.7

873.4

426.7

HSS103 *

0-3 FT

As

154

Cd

25

Pb

192

Zn

70.000

• COMPOSIT E SLAG SAMPLE .

PG-208

0-1"

1-2"

2-6"

6-12"

12-18"

As

N D

N D

N D

N D

N D

Cd

19.6

15.7

N D

13.6

13.5

Pb

1.461.0

1.423.7

1.529.5

1.435.3

1.342.7

Zn

2,116.0

2.024.5

2,016.9

2.126.5

1,742.5

LAK E COUNT Y FAI R GROUND S

APPROXIMA T OF SOI/IDIFIED B A G HOUSE/ F DUST/MATER I

SIT E FEATURE S

£ g ] SLA G PIL E [TIT J SMELTER DEBRI S AREA

$ 8 & COK E AND/OR COAL

SAMPL E LOCATION S

A ZIN C SLA G R l (MK , 1992b ) HSS10 1 SAMPL E LOCATIO N

• SOILS/SMELTE R R l PRIMAR Y GRI D PG-222 (COM , 1994; WALSH , 1993)

• SOILS/SMELTE R R l DISCRET E S22-022 (COM , 1994; WALSH , 1993 )

SMELTE R SUPPLEMENTA L R l (WESTEC . 1997b ) X SWZ0 1

S22-002

0-1"

1-2"

2-6"

6-12"

As

<250/im

71

58

75

72

<2mm

1 12

83

54

83

Cd

<250fim

30

31

12

6

<2mm

20

19

7

4

Pb

<250jtim

410

214

135

319

<2mm

295

139

29

139

Z n

<250jim

6.765

7,005

3,606

2,158

<2mm

5.483

4,444

2.257

4,444

PG-238

o-r

1-2"

2-6"

6-12"

12-18"

As

627

125.7

N D

14.5

1.9

Cd

4.8

1'5. 1

6.6n

^

D

N D

Pb

2,271.3

1.481.2

489.8

213

186

Zn

14,342.6

5,637.5

1,572.7

245.1

222.3

swzor

GRAB

As

60

j C d

41

Pb

260

Zn

5,100

SAMPL E OF POTENTIA L FLU E DUST MATERIAL .

522-001

0-1"

1-2"

2-6"

6-12"

As

<250(im

261

245

136

122

<2mm

107

142

164

108

Cd

<250Mm

287

333

229

44

<2mm

146

207

175

37

Pb

<250Mm

2,415

1.923

1.112

536

<2mm

941

923

929

276

Z n

<250yum

53,493

63,350

37.966

1 1 .749

<2mm

30,213

40,629

32,758

8,795

PG-222

o-r

1-2"

2-6"

6-12"

12-18"

As

ND

3.3

5.65

11.6

ND

J G d

J N D

.1; N O

•1.9

U.4

\

N D

Pb

251.5

82.9

105.6

415.6

296.3

Zn

740.1

166.1

164.5

839.4

471.1

SCAL E NOTES : AL L CONCENTRATION S AR E IN mg/kg SOLI D MATERIAL . UNLES S IDENTIFIE D OTHERWISE , AL L SAMPLE S AR E SOI L ND = NOT DETECTED . 200 2 00 FEET

RgurelO

RESULTS OF INVESTIGATIONS AT T H E WESTERN ZIN C SMELTER SIT E OPERABLE UNIT 5

California Gulcti Superfund Site Leadvilte, Colorado
C OM PATH P:\3280-015\OU5\ROD\EGWA\Fig11 .dwg 08/09/00

SME-14 7

o-r

1-2"

2-6"

6-12"

SME-14 7

o-r

1-2"

2-6"

6-12"

As

<250/im

194

181

247

189

<2mm

142

123

1 65

99

Pb

<250/im

1.494

1.170

1,593

1.299

<2mm

1.632

1,114

1,497

900

Cd

<250/im N D

15

N D

23

<2mm N D

N D

N D

N D

Zn .

<250jim

261

179

192

200

<2mm

162

N D

133

133

SIT E FEATURE S

SLA G PIL E

— •• — CALIFORNI A GULC H

« SMELTE R R l (WASH, 1993) SME-U 7 SAMPL E LOCATIO N

• SOIL S INVESTIGATIO N PG-621 PRIMAR Y GRI D (COM , 1994)

NOTES : AL L CONCENTRATION S AR E I N mg/k g SOLI D MATERIA L UNLES S IDENTIFIE D OTHERWISE , AL L SAMPLE S AR E SOIL . ND = NOT DETECTE D

PG-046

o-r

1-2"

2-6"

6-12"

12-18"

As

397.5

179.1

34.6

10.9

4.9

Cd

14.1

3.0

7.2

N D

0.24

Pb

2.404.7

1,323.1

249

37.8

35.5

Zn

318.1

177.0

112.8

225.0

82.0

LEADVILL E WATE R TREATMEN T PLAN T

PG-076

o-r

1-2"

2-6"

6-12"

12-18"

As

15

82.9

39.3

91.3

237.9

Cd

4.1

3.5

7.6

15.5

8.3

Pb

359.6

1,315.6

886.9

1,479.3

1,850.1

Zn

392.9

768.8

719.2

723.3

431.4

PG-065

o-r

1-2"

2-6"

6-12"

12-18"

As

357.2

274.2

33.3

22.2

1.3

Cd

16.5

18.4

0.24

12.9

10.0

Pb

2,865

1.703

490.8

103.3

40.7

Zn

488.1

378.1

315.1

213.6

157.6

SME-15 2

0-1"

1-2"

2-6"

6-12

SME-15 2

0-1"

1-2"

2-6"

6-12"

As

<250Mm

226

129

44

39

<2mm

1 21

82

48

47

Pb

<250>tm

2.863

1,254

282

27

<2mm

963

467

144

42

Cd

<250/im

27

22

NO

15

<2mm N D

21

N D

N D

Zn

<250>im

1.572

576

259

163

<2mm

644

244

221

166

SCAL E

400 400 FEET

Figure 11

RESULTS OF INVESTIGATIONS AT T H E ARKANSA S VALLEY SMELTER SOUTH HILLSID E SLA G PIL E SIT E OPERABLE UNIT 5

California Gulch Superfund Site Leadville, Colorado
PRIMAR Y RRI.BASB SOURC E MKCIIANISM- I

SMELTE R (OTHER THAN — * PARTICIPATE )

8LAQ —— »

MIN E TAILING S

1 —————————— — I

WEATHERE D WASTE — — f

1 —————————— ROCK— 1

—— » WIND .

— — » UtACIDNQ

•

„ HUMAN ACTIVITIE S

— » RUNOFF

* —

—— (

RESIDEN T SECONDAR Y RBI.BAS E TERTIAR Y BXPOSURB EXPOSUR R SOURCK MBCIIANlSM-1 SOURCB ROUT E POTENTIAL *

C

———————————————————————————————————— — ; ———————————————— — fc .

— — * 0«

m O°«A' » ————— — » .NFILTBATIO 1 ————— — I 1 ————— N —— — ^— ^ INDOO R AIH J

————————————————————————— — A ————

NIIALATIO N O

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INGESTION

DERMAL

N A » N \«

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6

— — — * GROUND WATBf t — — ' | HUMAN IIAIIC INQESTION B niiM- _

DERMA L

•

O

•

o

— — t «OIL ——— — ————————— — ' ————————————— — . — : ———————— — • »

— J Biorir —— ^ VKOKTABIXB; UPTAK E PLANT S

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•

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-I 1 ——— »^ aioTir ^ »vrv ^ UPTAK E CATTL E

— * SEDIMENT*1 -t — '• ——————————————————— ——————^———— —— »

1 —— _ —— » BIOTIC ——— ^ ———————— » UrrAK E "3

"

O BXPOSIJRB OR DOJB POTENTIAL R81.ATIVBI.Y LOW

• BXP03UKUURIXUH POTENTIA L RBLATTVBL Y HUH

N A NOT AIT I ICABI.B 5INCH BXPOSURB PATHWA Y U NOT " CURHUNTI.Y INVESTIGATIONS ARE UNDERWAY TO D IJJAOB IN 11IBLBAUVILLB ARBA * KUHIHS TO wvv SBIMMBNTJ. DHY SBDVMBHT* WOOL I'O k SOU .

SOURCE : Preliminar y Huma n Health Baselin e Risk Assessment (V

•

INOESTION

DERMA L

•

O

•

o

INQE4TION • •

INGESTIO N

DERMAL

INUESTIU N

O

O

N A

o

o

•

INOESTION

DERMA L

O

O

•

o

o

•

INflESTIO N

DERMA L

•

O

•

o

COMPIJTB F-KI mill H H«B Figur e 12 llHRMlNHANVPRIUHNTnRnilHIlWATR R '- r U IUB B 1/3 U ^^^^^ a

DBBSIMII.A « T O TUB PATHWAY S SHOWN HUMAN HEALTH SIT E CONCEPTUA L MODEL - LEADVILL E AN D STRINGTOW N RESIDENTS , MININ G AN D OR E PROCESSIN G WASTE S

VESTON , 1991 ) California Gulch Superfun d Site , Leadville , Colorado
HISTORI C SOURC E

MININ G & SMELTING — OPERATION S

LEGEND.

. . ..... PATHWAY 1 Y////////A HOWEVER. LAt*KlrVu» ' KXXXXXXXX a ANOUA Y OUAMTITAT I

SOURCE : Baselin e Huma n Hea

PRIMAR Y TRANSPOR T CONTAMINATE D SOURC E PATHWAY S MEDI A

STACK INDOOR DUST - ULKJSIIIU N IWO.FWX A EMISSIONS ,. I "TM"

MAiinwr. KRAniufi r— •• OUTDOOR SOIL

RUNOF F WIN D

EXPOSUR E ROUT E

ORAL —

L

 DERMAL — ORAL — DERMAL —

--•••"•- ^riVEGETABLESl —— | ORAL 1 ——

DISCRET E — —

" WASTE PILES

S OR MAY BE COMPLETE; RISK IS LOW OR DATA ARE

3UAUTATIVC EVALUATION ONLY. S OR MAY BE COMPLETE. BE SIGNF1CANT: VC EVALUATION.

th Risk Assessment (WESTON, 1<

_ ZJ FODDER

} H BEEF fLEACHING . INFILTRATION H cnou| ,OWAT,R

 - •1 VmUUNUnnltr t

t »

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EXPOSE D POPULATION

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Figur e 13

CONCEPTUA L SIT E MODEL FO R

RESIDENTIA L EXPOSUR E

Californi a Gulch Superfun d Site , Leadville , Colorado
PRIMAR Y SOURC E PRIMAR Y RELEASE PRIMAR Y TRANSPOR T

SECONDAR Y SECONDAR Y EXPOSUR E SOURCE RELEAS E MEDIA

Sol BdM SpotUd Vountdn *>}«1 9u« *TMriOT TdUd Odd Ueri TdM Hub R«l OUM Cn^Ur Sampciv Bkj^rt Btoctt-d Groat laird Hnrk Co^> fhlpmrt Vote D«v FIECEND

[ | INCOUPLCTI

POrtKtWLLY COMPLOE

SOURCE : Ecological Risk Assessmen t for Terrestrial Ecosystem (WESTON, 1997)

Figur e 14

CONCEPTUA L SIT E MODEL

ECOLOGICA L RISK ASSESSMEN T FO R TH E TERRESTRIA L ECOSYSTE M

California Gulch Superfun d Site , Leadville , Colorado
TABLES
TABL E 1 RESULT S OF SURFAC E WATE R ANALYSES FOR GEORGIA GULCH AND EVANS GULCH O U 5 EGWA SITES

CALIFORNIA GULCH SUPERFUN D SIT E

Total Metal s

Aluminum Antimon y Arsenic Barium Cadmium Chromium Copper Iro n Lead Manganese Mercury Nicke l Selenium Silve r Zin c

Unit s

ug/ L

ug/ L

ug/ L

ug/ L

ug/L

ug/L

ug/ L

ug/L

ug/ L

ug/L

ug/L

ug/L

ug/ L

ug/L

ug/ L

GG-1

(Ice-Off . 1991)

2790U

40.6

109

4.6U

80.8

4000

932

325U

U

U

2.3

1180

EG-1

(Sprin g 1991)

80.7U

1.3

50.6

0.80U

7.5

94.2

8.6U

U

U

U

U

1 13

EG-1

(Fal l 1991) UU

U

75.5

0.48U

U

U

U

U

U

U

U

U

60.9

EG-2

(Sprin g 1991)

58.6U

2.7

52.1

0.87U

8.1

86.1

8.2

13.8U

U

U

U

101 Dissolved Metal s

Aluminum Antimon y Arsenic Barium Cadmium Chromium Copper

Iro n Lead

Manganese

Mercury Nicke l Selenium Silver Zin c

ug/ L

ug/ L

ug/L

ug/ L

ug/L

ug/L

u.g/L

ug/L

ug/L

ug/L

ug/L

ug/L

ug/L

ug/ L

ug/ L

85.8U

11.2U

1.9U

9.7

61

15.5U

U

U

U

U

34

UU

U

50.8

0.54

U

4.0

U

U

U

U

U

U

U

U

U

4.1

U

69.3

0.32

U

U

U

U

U

U

U

U

UU

U

U

U

49.6

0.46

U

3.6U

U

U

U

U

U

U

U

Major Constituent s

pH (field ) Alkalinit y Calcium Chloride Cyanide DOC Fluoride

Magnesium Nitrat e -t- nitrite as N Potassium Silica Sodium

Specifi c Conductance Sulfat e T D S T S S Total Phosphorus as P

S.U . mg/L

mg/ L

mg/L

mg/L

mg/L

mg/L

mg/L

mg/ L

mg/L

mg/ L

mg/ L

umhos/cm

mg/ L

mg/L

mg/L

mg/ L

8.46

19

5U

U

U

U

U

0.02

U

3U

35U

50

138

0.26

7.76

58

17U

U

15

U

8

0.04

U

3U

137

54

96

4

U

8.46

98

24

U

N A

2

0.1

12U

U

1U

189U

96UU

8.32

56

16U

U

16U

8

0.05

U

3U

136

35

82

4

U

Source: Colder , 1996b.

EG-1 an d EG-2: Evan Gulch surface water monitorin g locations . GG-1: Georgia Gulch surface water monitorin g location . N A : No t analyzed

U : No t detected

ug/L : micrograms per liter mg/L : milligram s per liter TDS : total dissolved solids TSS : total suspended solids

umhos/cm: micromhos per centimeter
TABL E 2 SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S O U 5 EGWA SITE S

CALIFORNI A GULC H SUPERFUN D SIT E

Evaluatio n Criteria Alternativ e 1 No Actio n Alternative 2 Institutiona l Control s

Alternativ e 3 No Actio n for Slag ; Containmen t for Non-Residential Area Soil s an d Residential Area Soils; an d Institutiona l Control s

Alternative 4 No Actio n fo r Slag ; Rcmuval/Transport/Disposa l of Non - Residential Area Soil s an d Residential Area Soil s to an On-Site Repository ;

a n d Institutiona l Control s

OVERAL L PROTECTIVENES S

Huma n Health Protectio n

Airborne transport

of contaminated

material s

Erosion of

contaminated

material s into local

water courses

Metal s leachin g an d

migratio n from soil

into surface water

Metal s leachin g an d

migratio n from soil

into groundwaler

Contaminan t

exposure to animal s

a n d aquatic life

No significan t pathways for

transport of constituent s from

slag or soil to other

environmental media have

been identified . No significan t pathway s for

transport of constituent s from

slag or soil to other

environmental media have

been identified . No significan t pathway s for

transport of constituent s from

slag or soil to other

environmental media have

been identified

No significan t pathways for

transport of constituent s from

slag or soil to other

environmental media have

been identified .

Potential risk to the terrestrial

receptors through direct

contact of certain sources at O U5 are considered low.

No significan t pathways for

transport of constituent s from slag

or soil to other environmental

media have been identified.

No significan t pathways for

transport of constituent s from slag

or soil to other environmental

media have been identified.

No significan t pathway s for

transport of constituent s from slag

or soil to other environmental

media have been identified.

No significan t pathways for

transport of constituent s from slag

or soil to other environmental

media have been identified .

Potential risk to the terrestrial

receptors through direct contact of

certain sources at OU5 are

considered low.

Containment would virtually eliminate

potential for airborne transport of

particles from the isolated areas of soil

with elevated metal s concentration.

Containment would virtuall y eliminate

potential for erosion of material s into

surface or groundwater from the isolated

areas of soil with elevated metal s

concentration.

Conlaiiunen t would virtuall y eliminate

potential for metal s leachin g into surface

water from the isolated areas of soil with

elevated metal s concentration.

Containment would virtuall y eliminate

potential for metal s leachin g into

groundwater from the isolated areas of

soil with elevated metal s concentration.

Incremental reduction of risk through

eliminatio n of direct contact of limited

sources.

Removal would virtually eliminate

potential for airborne transport of

particle s from the isolated areas of soil

with elevated metal s concentration.

Removal would virtuall y eliminate

potential for erosion of material s into

surface or groundwater from the isolated

areas of soil with elevated metal s

concentration.

Removal would virtuall y eliminat e

potential for metal s leachin g into surface

water from the isolated areas of soil with

elevated metal s concentration.

Removal would virtuall y eliminate

potential for metal s leachin g into

groundwater from the isolated areas of

soil with elevated metal s concentration.

Incremental reduction of risk through

eliminatio n of direct contact of limited

sources.

Page 1 of 6
TABL E 2 (continued ) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S O U 5 EGWA SITE S

CALIFORNI A GULC H SUPERFUN D SIT E

Evaluatio n Criteria

Prevent direct

exposure of the

populatio n to

elevated

concentration of

contaminant s in the

surface soil

Environmental Protectio n

Alternative 1 No Actio n

Under current land use,

average metal s concentrations

in soil do not exceed riskbased action level for a

recreational use. Under future

land use, no action may result

in unacceptable exposure.

No significan t risk associated

with exposure to source

materials .

Alternative 2 Institutiona l Control s

Under current land use, average

metal s concentrations in soil do not

exceed risk-based action level for a

recreational use. Under future land

use, Institutional Control s would

maintain prolectiveness.

Similar to Alternative 1 , except

institutional control s help ensure

protection under future land use.

Alternative 3 No Actio n for Slag; Containmen t for Non-Residential Area Soil s an d Residential Area Soils; an d Institutiona l Control s

Containmen t would reduce potential risk

associated with the isolated areas of soil

with elevated metals concentration if a

site were developed. Under future land

use, Institutional Control s would

maintain protectiveness.

Simila r to Alternative 1, except

institutional controls help ensure

protection under future land use. Containment and maintenance would

virtuall y eliminate potential for risk to

environment.

Alternative 4 No Actio n fo r Slag; Removal/Transport/Disposa l of Non - Residential Area Soil s an d Residential Area Soil s to an On-Site Repository ;

a n d Institutiona l Control s

Removal would reduce potential risk

associated with the isolated areas of soil

with elevated metals concentration if a

site were developed. Under future land

use, Institutional Control s would

maintain protectiveness .

Simila r to Alternative 1, except

institutional control s help ensure

protection under future land use. Disposal would virtuall y eliminate

potential for risk to environment.

COMPLIANC E WIT H ARARs

Chemical-Specifi c ARAR s

Location-Specific ARAR s

Action-Specifi c ARAR s

Other Criteria and Guidanc e

Chemical-specifi c ARARs are met.

Location-specific ARARs are met. Action-Specifi c ARARs are met. Non e identified .

Chemical-specific ARARs are met.

Location-specific ARAR s are met.

Action-Specifi c ARARs are met.

None identified.

Chemical-specific ARARs are met.

Location-specific ARARs are mel.

Action-Specifi c ARAR s are met

Non e identified.

Chemical-specific ARARs are met.

Location-specific ARARs are met

Action-Specifi c ARAR s are met.

Non e identified.

Page 2 of 6
TABL E 2 (continued ) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVES

O U 5 EGWA SITE S

CALIFORNI A GULC H SUPERFUN D SIT E

Evaluatio n Criteria Alternative 1 No Actio n Alternative 2 Institutiona l Control s

Alternative 3 No Actio n for Slag ; Containmen t for Non-Residential Area Soil s an d Residential Area Soils; an d Institutiona l Control s

Alternative 4 No Actio n fo r Slag ; Removal/Transport/Disposal of Non - Residential Area Soil s an d Residential Area Soil s to an On-Sitc Repository ;

a n d Institutiona l Control s

LONG-TERM EFFECTIVENES S AN D PERMANENC E

Airborne transport

of particles

llrosio n ot" material s

into surface water

or groundwaler

Metal s leachin g into

surface water

Metal s leachin g into

groundwaler

Contaminan t

exposure to animal s

a n d aquatic life

Adequac y and Reliabilit y of Control s

No change in long-term

effectiveness .

No change in long-term

effectiveness .

No change in long-term

effectiveness . Minimal

leachin g potential .

No change in long-term

effectiveness . Minimal

leachin g potential .

No change in long-term

effectiveness .

No control s over remaining

contamination . No reliability .

Similar to Alternative 1, except that

institutional controls help ensure

protection under future land use.

Similar to Alternative 1, except that

institutional controls help ensure

protection under future land use.

Simila r to Alternative 1, except that

institutional controls help ensure

protection under future laud use.

Similar to Alternative 1, except that

institutional controls help ensure

protection under future land use.

Simila r to Alternative 1, except Institutional control s help ensure

protection under future land use.

Simila r to Alternative 1 , except Institutiona l control s help ensure

protectio n under future land use.

Containment would provide good longterm effectivenes s and permanence if maintained.

Containment would provide good longterm effectivenes s and permanence if maintained..

Containmen t would provide good longterm effectivenes s and permanence if maintained. Minimal leachin g potential .

Containment would provide good longterm effectivenes s and permanence if maintained. Minimal leachin g potential .

Containment and institutional controls

would provide good long-term

effectivenes s and permanence.

Containmen t would provide good control

of source materials . Reliabilit y can be

high i f maintained. Failur e to maintain

cover can increase potential for airborne

transport , erosion, and leaching. Institutiona l control s are limited in

effectivenes s due to enforceability .

Disposal would provide good long-term

effectivenes s and permanence.

Disposal repository would have to be

erosion resistant. Long-term

maintenance required.

Disposal repository would provide good

long-term effectivenes s and permanence. Long-term maintenance required. Minimal leachin g potential .

Disposal repository would provide good

long-term effectivenes s and permanence. Long-term maintenance required. Minimal leachin g potential .

Disposal and institutional control s

would provide good long-term

effectivenes s and permanence.

Disposal would provide good control of

source materials . Reliabilit y can be high

i f maintained. Failur e to maintai n

repository can increase potential for

airborne transport , erosion, and

leaching. Institutiona l control s are

limited in effectivenes s due to

enforceabililv.

Page 3 of 6
TABL E 2 (continued ) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S O U 5 EGWA SITE S

CALIFORNI A GULC H SUPERFUN D SIT E

Evaluatio n Criteria Alternative 1 No Actio n Alternative 2 Institutional Control s

Alternative 3 No Actio n for Slag; Containmen t for Non-Residential Area Soil s an d Residential Area Soils; an d Institutional Control s

Alternative 4 No Actio n fo r Slag; Rcrnoval/Transport/Disposal of Non - Residential Area Soil s an d Residential Area Soil s to an On-Site Repository ;

a nd Institutional Controls

REDUCTION OF TOXICITY , MOBILITY , OR VOLUME THROUGH TREATMEN T

Reduction of Toxicily , Mobility ,

or Volume

Does not include treatment. Does not include treatment. Does not include treatment. Does not include treatment.

SHORT-TERM EFFECTIVENES S

Communit y Prelectio n No disturbance to the

community.

Under current land use, no

disturbance to the community. Under future land use, potential

minor risk to community due to

increase in dust emissions and

exposure of contaminants. Controllabl e through standard

construction practices.

Minor risk to community due to increase

in dust emissions and exposure of

contaminants. Controllabl e through

standard construction practices. Road

traffic would increase over the shortterm.

Minor risk to community due to increase

in dust emissions and exposure of

contaminants . Controllabl e through

standard construction practices. Road

traffic would increase over the shortterm.

Worker Protectio n No risk to workers. Under current land use, no risk to

workers. Under future land use,

potential for inhalatio n of airborne

particle s and contact with

contaminated material s durin g

response activities .

Potential for inhalatio n of airborne

particles and contact with contaminated

material s durin g remedial activities .

Potential for inhalatio n of airborne

particles and contact with contaminated

material s durin g remedial activities .

Environmental

Impact s

No change in short-term risk

to the environment.

Under current land use, no change

in short-term risk to the

environment. Under future land

use, potential minor risk to

community due to increase in dust

emissions and exposure of

contaminants . Controllabl e tlirough

standard construction practices .

Minor risk to community due to increase

in dust emissions and exposure of

contaminants . Controllabl e through

standard constructio n practices . Road

traffic would increase over the shortterm.

Minor risk to communit y due to increase

in dust emissions and exposure of

contaminants . Controllabl e through

standard construction practices . Road

traffic would increase over the shortterm.

Page 4 of 6
TABL E 2 (continued) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S

O U 5 EGWA SITE S

CALIFORNI A GULC H SUPERFUN D SIT E

Evaluatio n Criteria

Tim e Unti l Actio n

is Complet e

Alternativ e 1 No Action N ot applicable .

Alternativ e 2 Institutional Controls

Immediate .

Alternativ e 3 No Actio n fo r Slag; Containmen t fo r Non-Residential Area Soil s an d Residential Area Soils ; an d Institutional Control s

Immediate.

Alternativ e 4 No Actio n fo r Slag; Rcmoval/Transport/Disposa l of Non - Residential Area Soil s an d Residential Area Soil s to an On-Site Repository ;

a nd Institutional Control s

Immediate .

IMPLEMENTABIL1T Y

Ability to Construct

and Operate

Ease of Doing More Actio n i f Needed

Abilit y to Monitor

Effectivenes s

Abilit y to Obtain Approval s and Coordinate with Other Agencies

Availabilit y o f Equipment , Specialists , an d

Material s

Availabilit y o f Technologie s

No construction or operation.

May require ROD amendment

if future action is taken.

No monitoring.

No approval necessary.

Non e required.

Non e required

Under current land use, no

construction or operation. Under

future lan d use, relativel y standard

construction, i f needed.

Institutiona l controls allows for

future response actions, if needed.

Land use plans/proposal s for future

land use would be monitored as

part of the five-year review process.

Coordination and cooperation with

property owners and local agencies

would be necessary.

Non e required for current land use.

Standard equipment is readil y

available for future action as

required.

Non e required for current land use. Technolog y for screening and

response actions is readil y

available .

Relativel y standard construction.

Institutiona l control s allow s for future

response actions , i f needed.

Monitorin g and maintenance inspection s

would give notice of failure before

significan t exposure occurs.

Coordination and cooperation with

property owners and local agencies

would be necessary.

Standard equipmen t i s readil y available.

Containmen t technolog y i s readil y

available .

Relativel y standard construction.

Institutiona l controls allow s for future

response actions, if needed.

Land use plans/proposal s for future land

use would be monitored as part of the

five-year review process.

Coordinatio n and cooperation with

properl y owners and local agencies

would be necessary. Same as Alternative

2.

Standard equipment i s readil y available

Removal , transport , an d disposal

tecluiolog y i s readil y available .

Page 5 of 6
TABL E 2 (continued) SUMMAR Y O F COMPARATIV E ANALYSI S O F REMEDIA L ALTERNATIVE S

O U 5 EGWA SITES

CALIFORNI A GULC H SUPERFUN D SIT E

Evaluatio n Criteria Alternative 1 No Actio n Alternative 2 Institutiona l Control s

Alternativ e 3 No Actio n for Slag; Containmen t for Non-Residential Area Soil s an d Residential Area Soils; an d Institutiona l Control s

Alternative 4 No Actio n fo r Slag ; Removal/Transport/Disposa l of Non - Residential Area Soil s an d Residential Area Soil s to an On-Site Repository ;

a n d Institutiona l Control s

COST

Capital Cost

Annual O&M Cost

Present Worth Cost

(5% Rale of Return, 30

year period )

$0

$0

$0

$33,600

$2,500

$85,496

$83,445

$3,500

$150,714

$129,875

$3,000

$181,668

STAT E ACCEPTANC E

Stat e Acceptance Alternative not preferred by

t he State . T he Slat e i s aware of EPA' sselected remedy and has chosen to

make no further comment.

T he Stat e i s aware of EPA' s selected

remedy and has chosen to make no

further comment.

T he Stat e i s aware of IZPA' s selected

remedy and has chosen to make no

further comment.

COMMUNIT Y ACCEPTANC E

Community Acceptance Alternative not preferred by

t he community

Alternative preferred by the

community. Alternative not preferred by the

community

Alternative not preferred by the

community

Page 6 of 6
TABLE 3 SUMMAR Y OF POTENTIA L CHEMICAL-SPECIFI C ARAR S O U S EGWA SITES

CALIFORNI A GULCH SUPERFUN D SIT E

Standard, Requirement , Criteria,

or Limitatio n

Citatio n

Potentiall y Applicabl e

Potentiall y Relevant and

Appropriat e

Description

FEDERA L

RCRA Subtitl e C 40 CFR Part

261.4(b)(7)an d Sectio n 3001 (b)

(Bevil l

Amendment )

No Y es T he sources of contamination at the OUS EGWA Sites are various combination s of

t he following : tailing , waste rock, slag, and baghouse flue dust from processin g of

primary lead ore. Based on 40 CFR 261.4(b)(7 ) and Sectio n 3001 (b) (Bevil l Amendments) , tailing , waste rock, and slag waste are excluded from RCRA Subtitl e C. However, bag house/flue dust identified at the Western Zin c Smelter

site i s potentiall y subject to RCRA i f these material s fai l TCLP are disposed. Consolidatio n or on-site management of flue dust within area of contamination

would not constitut e disposal and, therefore , RCRA subtitl e C would not be

applicable . However, provision s of RCRA are potentiall y relevant and appropriate

to flue dust . (See action-specific ARAR s below).

Clean Air Act , Nationa l Primary and Secondar y Ambien t Air Qualit y Standard s

40 CFR Part 50 No No National ambient air qualit y standards (NAAQS) are implemented through the N ew Source Review Program an d Slate Implementatio n Plan s (SIP) . The federal N ew Source Review Program addresses only major sources. Emission s associated

with proposed remedial action at the OU5 EGWA Site s wil l be limited to fugitiv e

dust emissions associated with earth moving activitie s durin g construction. These

activitie s wil l not constitute a major source. Therefore , attainmen t and

maintenance of NAAQS pursuant to the New Source Review Program are not ARARs . See Colorado Air Pollutio n Prevention an d Control Act concerning

applicabilit y of requirements implemented through the SIP .

Page 1 of 2
TABL E 3 (continued) SUMMAR Y O F POTENTIA L CHEMICAL-SPECIFI C ARAR S O U 5 EGWA SITES

CALIFORNI A GULC H SUPERFUN D SIT E

Standard, Requirement, Criteria,

or Limitatio n

Citatio n

Potentiall y Applicabl e

Potentiall y Relevant and Appropriat e

Description

STATE OF COLORADO

Colorado Air Pollutio n Preventio n and Control A c t5CC R 1001-14;

5CC R 1001-10 Part C (I ) Regulatio n 8

Y es Pursuant to the Colorado Air Pollutio n Prevention an d Control Act , applicant s for

construction permit s are required to evaluate whether the proposed source wil l

exceed NAAQS. Applicant s are also required to evaluate whether the proposed

activitie s would cause an exceedance of the Colorado ambient standard for

paniculate 10 microns or less in aerodynamic diameter (PM10) . Constructio n

activitie s associated with proposed remedial action at the OU5 EGWA Site s wil l be

limited to generation of fugitiv e dust emissions. Colorado regulates fugitiv e

emissions through Regulatio n No. 1. Complianc e with applicabl e provision s of

t he Colorado air qualit y requirements wil l be achieved by adhering to a fugitiv e

emissions dus t control pla n prepared in accordance with Regulatio n No. 1. Thi s

pla n wil l discuss monitorin g requirements, if any, necessary to achieve these

standards .

Regulatio n No. 8 sets emission limit s for lead. Applicant s are required to evaluate

whether the proposed activitie s would result in an exceedance of these standards . T he proposed remedial action at the OU5 EGWA Site s is not expected to exceed

t he emission level s for lead, although some lead emissions may occur.

Complianc e with Regulatio n No. 8 wil l be achieved by adherin g to a fugitiv e

emissions dus t control pla n prepared in accordance with Regulatio n No. 1. Thi s

pla n wil l discus s monitorin g requirements, i f any, necessary to achieve these

standards .

Page 2 of 2
TABL E 4 SUMMAR Y OF POTENTIAL LOCATION-SPECIFI C ARAR S O U 5 EGWA SITES

CALIFORNIA GULCH SUPERFUN D SIT E

Standard , Requirement,

Criteria, or Limitatio n Citatio n

Potentiall y Applicabl e

Potentiall y Relevant and Appropriat e

Description

FEDERA L

Nationa l Histori c Preservation Ac t (NHPA )

Executive Order 11593 Protectio n and

Enhancement of the Cultural Environment

T he Histori c an d

Archaeological Data Preservation Act of 1974

Histori c Site s Act of 1935

T he Archeological Resources Protectio n Act

of 1979

Executive Order No.

11990 Protectio n of Wetland s

Executive Order No.

11988 Floodplai n

Managemen t

16USC§470e t

sea..; 40 CFR § 6.301(b);36CF R

Part 63, Part 65, Part

800

16 USC § 470

16 USC 469

40 CFR §6.301(c )

16 USC §461-467

16 USC §§470aa47011

40 CFR § 6.302(a)

a nd Appendi x A

40 CFR § 6.302 & Appendi x A

Y es

N o

No

No

No

Y es

Y es

—

N o

Y e s

Expands historic preservation programs; requires preservation of resources

included in or eligibl e for listin g on the National Register for Histori c Places

(NRHP). The OU5 EGWA Site s have been recommended as not eligibl e for

listin g on the NRHP and are not considered contributin g to the Leadvill e Histori c Minin g District .

Direct s federal agencies to institut e procedures to ensure that programs contribute

to the preservation and enhancement of non-federall y owned historic resources.

Consultatio n with ihe Advisor y Council on Histori c Preservation is required if

removal activitie s should threaten cultural resources.

Establishe s procedures to preserve historical and archeological data that might be

destroyed through alteratio n of terrain as a result of a federal construction project

or a federall y licensed activit y program.

Preserves for publi c use historic sites , buildings , and object s of natural

significance.

Requires a permi t for any excavation or removal of archeological resources from

public lands or Indian lands. May be relevant and appropriat e if archeological

resources are encountered durin g remedial activities . Minimizes adverse impact s on areas designated as wetlands .

Pertain s to floodplai n management and constructio n of impoundment s in such

areas.

Page 1 of 3
TABL E 4 (continued) SUMMAR Y OF POTENTIA L LOCATION-SPECIFI C ARAR S

O U 5 EGWA SITES

CALIFORNI A GULCH SUPERFUN D SIT E

Standard, Requirement,

Criteria, or Limitatio n Citatio n

Potentiall y Applicabl e

Potentiall y Relevant and Appropriat e

Description

Sectio n 404, Clea n Water

A c t (CWA )

33 USC 1251 et seq..

33 CFR Part 330

Y es Regulates discharge of dredged or fil l material s into waters of the United States . Portion s of the OU5 EGWA Site s are adjacen t to waters of the U.S. Substantive

requirements of portion s of Nationwide Permit No. 38 (General and Specifi c Conditions ) are applicabl e to OU5 EGWA Sites remedial activitie s conducted

withi n waters of the United States , although none are anticipated.

Fish an d Wildlif e Coordinatio n Act

16 USC §661 et

seq.;

40 CFR § 6.302

No No Requires coordinatio n with federal and state agencies to provide protectio n of fish

a nd wildlife in water resource developmen t programs; regulates actions that

impound, divert , control , or modif y any body of water. However, proposed

remedial action activitie s at the OU5 EGWA Site s wil l not affec t fish or wildlife . If i t appears that remedial activities may impact wildlif e resources, EPA wil l

coordinate with both the U.S. Fish an d Wildlife Service an d the Colorado Departmen t of Natural Resources.

Endangered Specie s Act 16 USC § 1531 et

seq..;50CF R §§200

and 402

N o No Provides protectio n for threatened and endangered species and their habitats . However, site-specifi c studies did not document the presence of threatened or

endangered species. If threatened or endangered species are encountered durin g

remedial activitie s at the OU5 EGWA Sites , then requirements of thi s Act would

be applicable . Wildernes s Ac t 16US C 1311 ; 16 U SC 668; 50 CFR

53; 50 CFR 27

N o No Limit s activitie s withi n areas designated as wildernes s areas or National Wildlife Refuge Systems . Remedial activitie s planned for OU 5 EGWA Site s wil l not

impact any designated areas. The Act is, therefore, not a potential ARAR.

Resource Conservatio n

a nd Recovery Act

(RCRA) , Subtitl e D

40 CFR Part 257, Subpart A, §257.3-1 Floodplains ,

paragraph (a)

N o N o Provides general classificatio n criteria for solid waste disposal facilitie s pertainin g

to floodplains . Remedial activitie s planned for OU 5 EGWA Site s wil l not

involve establishmen t of a solid waste disposal facility .

STATE OF COLORADO

Colorado Historical , Prehistorical , and

Archaeological Resources

A c t

C RS §§24-80-401 to

410

1301 to 1305

N o Y e s Concerns historical , prehisiorical , an d archaeological resources; applie s onl y to

areas owned by the State or its politica l subdivisions . May be relevant and

appropriat e i f removal action impact s an archaeological site.

Page 2 of 3
TABL E 4 (continued) SUMMAR Y OF POTENTIA L LOCATION-SPECIFI C ARAR S

O U 5 EGWA SITES

CALIFORNI A GULC H SUPERFUN D SIT E

Standard, Requirement,

Criteria, or Limitatio n Citatio n

Potentiall y Applicabl e

Potentiall y Relevant and Appropriat e

Description

Colorado Register of Histori c PlacesCRS§ § 24-80.1-101

to 108

No No Authorize s the State Historical Societ y to nominate propertie s for inclusio n on the State Register of Histori c Places . Applicabl e only i f removal action activitie s

impact an area listed on the Register. Nongame , Endangered or

Threatened Specie s Ac t

CRS§ § 33-2-101 to

108

No No Standards for regulatio n of nongame wildlif e and threatened and endangered

species. Site-specifi c studies did not document the presence of threatened or

endangered species. If threatened or endangered species are encountered durin g

remedial activities at the OU5 EGWA Sites , then requirements of the Act wil l be

applicable .

Colorado Specie s of Specia l Concern and Specie s of Undetermined Statu sColorado Divisio n of Wildlif e Administrative Directive E-l , 1985, modified

No No Protect s species listed o n the Colorado Divisio n of Wildlife generated list . Urges

coordination with the Divisio n of Wildlife i f wildlif e species are to be impacted. No evidence of species of special concern have been identified at the OU5 EGWA Sites .

Colorado Natural Areas Colorado Revised Statutes , Title 33 Articl e 33, § 104

N o No Maintain s a lis t of plan t species of special concern. Althoug h not protected by State statue , coordination with Divisio n of Parks and Outdoor Recreation is

recommended i f activitie s wil l impact listed species.

Colorado Solid Waste Disposal Site s an d Facilitie s Ac t

6 CCR 1007-2

6 CCR 1007-2, Part 1

Y es No Establishe s regulation s for solid waste management facilities , includin g locatio n

standards . Non e of the proposed remedial actions in OU5 wil l establish a solid

waste management facility . Selected portion s potentiall y applicabl e i f future

activitie s establish a solid waste management facility .

Colorado Nois e Abatemen t

A c t

C RS §§25-12-101 to

108

Y es Establishe s maximum permissible noise level s for particular time periods an d land

use related to construction projects._________________________

Page 3 of 3
TABL E 5 SUMMAR Y OF POTENTIA L ACTION-SPECIFI C ARAR S

O U S EGWA SITES

CALIFORNIA GULCH SUPERFUN D SIT E

Standard, Requirement,

Criteria, or Limitatio n Citatio n

Potentiall y Applicabl e

Potentiall y Relevant and

Appropriat e

Description

FEDERA L

Solid Waste Disposal Ac t

as amended by the Resource Conservation

a nd Recovery Act of 1976

(RCRA )

Hazardous Material s Transportatio n Ac t

40 CFR Part 257, Subpar t A: § 257.3-

1 Floodplains ,

paragraph (a); §

257.3-7 Air,

paragraph (b)

49 USC § 1801-1813

49 CFR 107, 171-

177

Y es

Y es No

Selected portion s of Part 257 pertainin g to floodplain s and air are applicable . These provision s establish criteria for classificatio n of solid waste disposal

facilitie s and practices.

Regulates transportatio n of hazardous materials . Would be applicabl e i f future

remedial action at the OU5 EGWA Sites involved the of f site disposal of flue

dust .

STATE OF COLORADO

Colorado Air Qualit y Control Act

Colorado Air Qualit y Control Act

Colorado Air Quality . Control Act

Colorado Solid Wast e Disposal Site s an d

Facilitie s Ac t

5CC R 1001-4 Regulatio n No. 2, Odors

5 CCR 1001-5 Regulatio n No. 3, APEN s

5 CCR 1001-3;

§ lll.D.l.b.c.d .

§ III.D.2.a,b,c,e,f,g . Regulatio n No. 1

6 CCR 1007-2

Y es

Y es

Y es

N o

—

—

Y es

Applicabl e only i f remedial action activitie s cause objectionable odors. Remedial

action at ihe OU5 EGWA Site s is not expected to produce odors.

Substantive provision s of APENS wil l be met. Establishe s emissions control

regulation s for construction or modificatio n of stationar y sources. An APEN wil l

be filed i f future remedial actions disturb contaminated soils .

Regulatio n No. 1 provision s concerning fugitiv e emissions for construction

activities , storage and stockpilin g activities , haul roads, haul trucks, and tailin g

ponds are applicabl e (5 CCR 1001-3; Section s III.D.2.a,b,c,e,f,g.). Constructio n

activitie s at the OUS EGWA Sites , if any, wil l be conducted in accordance with a

fugitiv e emission s dus t control plan .

Establishe s standards for licensing, locating, constructin g an d operatin g solid

waste disposal facilities . Futur e remedial activitie s planned fo r OU S EGWA Site s

m ay involve the disposal of solid waste.

Page 1 of 2
TABL E 5 (continued ) SUMMAR Y OF POTENTIA L ACTION-SPECIFI C ARAR S O U 5 EGWA SITES

CALIFORNI A GULC H SUPERFUN D SIT E

Standard , Requirement,

Criteria, or Limitatio n

Colorado Water Qualit y Control Act , Storm Water Discharge Regulation s

Colorado Mined Land Reclamatio n Ac t

Colorado Nois e Abatemen t Act

Regulation s on the Collectio n o f Aquatic Life

Citatio n

5 CCR 1002-2

C RS 34-32-101 to

125; Rule 3 of Mineral Rules and Regulation s

C RS §§25-12-101

to 108

2 CCR 406-8, Ch.

1 3 , Articl e III , §

1316

Potentiall y Applicabl e

Y es

N o

Y es

N o

Potentiall y Relevant and Appropriat e

—

Y es

—

No

Description

Establishes requirements for storm water discharges (except portion s relatin g to Site-wide Surfac e an d Groundwater) . Substantive requirements for storm water

discharges associated with construction activitie s are applicable .

Regulates all aspect s of land use for mining, includin g the locatio n of mining

operation s and related reclamation activitie s and other environmental and socioeconomic impacts . Substantive requirements of portion s of Rule 3 regardin g Reclamation Measures, Water - General Requirements (except portion s relatin g to Site-wide Surfac e an d Ground Water) , Wildlife, an d Revegetation are potentiall y

relevant and appropriate . .

Establishe s maximum permissible noise level s for particular time periods and land

u se related to construction projects .

Requirements governing the collectio n of aquatic life samples for scientifi c

purposes. Remedial action activitie s withi n the OU5 EGWA Site s wil l not

include biological monitoring.

Page 2 of 2
TABL E 6

DETAILED COST ESTIMATE : ALTERNATIV E 2 - INSTITUTIONAL CONTROLS

O U 5 EGWA SITES

CALIFORNIA GULCH SUPERFUND SIT E

Item/Descriptio n

DIRECT CAPITA L COST S

Institutional Control s

Program Developmen t

Program Implementatio n

Quantity

80

200

Uni t

hr

hr

Uni t Cost

80

80

SUBTOTA L DIRECT CAPITA L COST S

INDIREC T CAPITA L COST S

Indirec t Capital Costs

Administratio n Costs

Constructio n Managemen t Cost s

Permit Cost s

15%

0%

0%

SUBTOTA L INDIREC T CAPITA L COST S

Capital Cost Contingenc y (Applied to both Direct an d Indirec t Costs ) 20%

TOTA L ESTIMATE D CAPITA L COST S

ANNUA L OPERATION & MAINTENANC E COST S Administrative Cost s 1 I s 2,500

Total Cost

$6.400

$16,000

$22,400

$3.360

$0

$0

$3,360

S7.840

$33,600

$2,500

TOTAL ANNUAL O&M COSTS || $2,500

FIV E YEAR REVIEW COST S

Labor - 1 Engineers ($100/hr) & 1 Technicians ($70/hr) - 1 week @ 40 hrs/wk

Travel

Per diem

Laboratory Cost s

Office/Administrative

40

2

2

0

20

mh

each

mndy

each

mh

80.00

100.00

50.00

0.00

45.00

SUBTOTA L FIV E YEAR REVIEW COST S

Five Year Review Contingency 0.10

TOTA L FIV E YEAR REVIEW COST S

$3,200

$200

$100

$0

$900

S4.400

$440

$4,840

TOTAL PRESENT WORTH $85,496

( 5% rate of return. 30 vear period )
TABLE ? PRESENT WORTH ANALYSIS : ALTERNATIV E 2 - INSTITUTIONAL CONTROLS O U 5 EGWA SITES

CALIFORNI A GULCH SLPERFUN D SIT E

Year

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

Capital Costs

533,600

O &MCosts

52.500

52,500

52.500

$2,500

57,340

52.500

52.500

52,500

52.500

57,340

52,500

52.500

52,500

52,500

57,340

52.500

52.500

52.500

52.500

57,340

52.500 S2.500

52.500

52.500

57.340

52.500

52,500

52,500

52,500

57,340

Total Annual

Expenditure

S33.600 S2.500

$2.500

$2.500

$2,500

57,340

$2.500

$2.500

52.500

52,500

57.340

52,500

$2,500

$2,500

$2,500

$7,340

$2,500

$2,500

52.500

52.500

$7,340

$2.500

$2,500

$2,500

52,500

57,340

52,500

$2.500

$2,500

$2,500

$7,340

TOTA L PRESEN T WORTH

Rate of Return = 3% Discount Factor

1.0000

0.9709

0.9426

0.9151

0.8885

0.8626

0.8375

0.8131

0.7894

0.7664

0.7441

0.7224

0.7014

0.6810

0.6611

0.6419

0.6232

0.6050

0.5874

0.5703

0.5537

0.5375

0.5219

0.5067

0.4919

0.4776

0.4637

0.4502

0.4371

0.4243

0.4120

Present Worth

$33.600

52,427

$2,356

$2,288

$2,221

$6,332 S2.094

$2,033

$1,974

$1,916

$5,462

$1,806

$1,753

$1,702

$1,653

$4,711

$1,558

$1,513

$1,468

$1,426

$4,064

51.344

$1.305

$1,267

$1.230 i

$3,506

$1,159

$1,125

$1,093 !

$1.061

$3,024

@3%

$100,470

Rate of Return = 5% Discount Factor

1.0000

0.9524

0.9070

0.8638

0.8227

0.7835

0.7462

0.7107

0.6768

0.6446

0.6139

0.5847

0.5568

0.5303

0.5051

0.4810

0.4581

0.4363

0.4155

0.3957

0.3769

0.3589

0.3418

0.3256

0.3101

0.2953

0.2812

0.2678

0.2551

0:2429

0.2314

Present Worth

S33,600

$2.381

$2.268

$2.160

52,057

$5,751

51,866

$1,777

$1,692

$1.612

$4.506

51,462

$1,392

$1,326

$1,263

$3,531

$1,145

$1.091

$1.039

$989

$2,766 S897

$855

$814

$775

$2,168

$703

$670

$638

$607

$1,698

©5%

$85,496

Rate of Return = 10% Discount Factor

1.0000

0.9091

0.8264

0.7513

0.6830

0.6209

0.5645

0.5132

0.4665

0.4241

0.3855

0.3505

0.3186

0.2897

0.2633

0.2394

0.2176

0.1978

0.1799

0.1635

0.1486

0.1351

0.1228

0.1117

0.1015

0.0923

0.0839

0.0763

0.0693

0.0630

0.0573

Present

Worth

$33,600

$2.273

$2.066

$1.878

$1.708

$4.558 S1.41 1

$1,283

$1,166

51.060

52.830 S876 S797

5724

$658

$1.757

$544

$495 S450

$409

$1.091

$338

$307

$279

$254

$677

5210

5191

$173

$158

$421

@ 10%

564,641
APPENDIX A

RESPONSIVENES S SUMMAR Y
RESPONSIVENES S SUMMAR Y

O U 5 EGVVA SITES

CALIFORNIA GULCH SUPERFUN D SIT E LEADVILLE , COLORADO

1.0 OVERVIEW

T he U.S. Environmental Protection Agency (EPA) has prepared this Responsiveness Summary to

document and respond to issues and comments raised by the public regarding the Proposed Plan

f or the Operable Uni t 5 (OU5) for Elgi n Smelter, Grant/Union Smelter, Western Zin c Smelter an d Arkansas Valle y South Hillside Slag Pile sites (collectivel y known as the "EGWA" sites) of the California Gulch Superfun d Site. EPA' s preferred alternative an d the remedy selected in the Record of Decision (ROD) involves institutional controls, which consists of measures to provide

information to current and/or future land owners regarding the environmental condition s at the

site through a zoning "overlay district,", and to ensure that if the site is developed any necessary

special precaution s or requirements are followed. Any samplin g or response actions will be

conducted or funded by ASARCO , Inc., consistent with the developmen t plans . A publi c meetin g

was held on August 1, 2000 at 7:00 p.m. at the Minin g Hall of Fame and Museum in Leadville , Colorado to present the preferred alternative to the public . Comments were received durin g the

public comment period, which was from July 27 through August 28, 2000.

Comments received during the public comment period and EPA's responses, are outlined in thi s

document. By law, the EPA and the Colorado Department of Public Health and Environment

(CDPHE) must consider public input prior to making a final decision on a cleanup remedy. Once

public comment is reviewed and considered, the final decision on a cleanup remedy is documented

in the ROD. Thi s document includes the followin g sections:

• Background on Recent Community Involvemen t

• Summary of Public Comments Received During Public Comment Period and

Agency Responses

• . Remaining Concerns

2 .0 BACKGROUN D ON RECENT COMMUNITY INVOLVEMEN T

T he OU5 EGWA Proposed Plan was published in July 2000 and describes the preferred cleanup

alternative for EGWA sites. Based upon consideration of National Oil and Hazardous Substance s Pollutio n Contingency Plan (NCP) criteria, EPA determined that Alternative 2 - Institutional Control s is the appropriate remedy for slag and non-residential and residential area soil s at the O U5 EGWA sites. A portion of the public meeting held on August 1, 2000 was dedicated to

acceptin g formal oral comments from the public , however, no oral comments were received. The

only written comments received during the public comment period were from the CDPHE in a

letter dated August 28, 2000.

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3 .0 SUMMAR Y OF PUBLI C COMMENT S RECEIVED DURING PUBLIC

COMMENT PERIOD AND AGENC Y RESPONS E

T he followin g written comments were received from the CDPHE during the public comment

period. No oral comments were received. The comments are presented in italicized type and the

responses are presented in regular type.

N o. 1:

As previously presented in draft Proposed Plan comments submitted to EPA dated JO/25/99, 7/5/00, 7/11/00, and the CDPHE proposed Hot Spot Removal Plan, 3/28/00, since

contamination has been identified above EPA 's action levels for reasonably anticipated uses, CDPHE believes that there are advantages to expeditiously removing the hot spots and

proceeding with immediate deletion of the EGWA sites. If the proposed Institutional Control Overlay (ICO) District is selected, it is not clear when these sites would be eligible for deletion. It should also be noted that the proposal for the use of the overlay district is currently in the

developmental stage, making it impossible at this time for the state or public to provide

meaningful comments on the adequacy of this approach. If EPA consistently applied this logic

of deferring clean-up to sites nation-wide, contamination would simply remain in-place

indefinitely awaiting development. This is clearly not the approach contemplated in the NCP

and CERCLA (as discussed in our previous comments submitted by EPA).

Response:

Under current land use, there is no unacceptable risk associated with the contamination left in

place at the EGWA smelter sites. It is possible that land use could change for some of the

properties associated with these sites. The proposed institutional control overlay district would

insure that any future land use will follo w any necessary precautions or requirements associated

with the waste left in place. The requirements would include condition s that must be met to

ensure protectiveness and may require additional samplin g and response actions consistent with

t he future use or developmen t plans .

E PA is currently preparin g an institutional control analysis and design, which includes the

proposed institutional control overlay district . Thi s document will be available for public review

a nd comment. It is anticipated that once the institutional control program is in place, these sites

m ay be deleted from the National Priorities List . Note that thi s approach is consistent with the

institutional control overlay district proposed for Residential Soil s within Operable Uni t 9 of thi s Superfun d Site as well as other areas of the Site where waste is left in place.

E PA disagrees that removal of these "hot spots" offer s significan t advantages over the selected

institutional control remedy. Removal would be limited to a depth of two feet and would still

likel y require institutional controls to ensure that any future developmen t remains protective of

human health and the environment.

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No. 2:

/ is not clear how costs were determined. More explanation is needed (such as an itemized

breakout of capital costs and O&M activities) for what constitutes "capital costs" and what

activities would be covered by O&M. Please clarify if developer or county costs for sampling/analysis and review/approval activities have been determined and are included.

Response:

As shown on Table 7, Detailed Cost Estimate: Alternative 2 - Institutional Controls , of the OU5

EGWA ROD, direct capital costs include program developmen t and program implementatio n of

institutional controls. Indirec t capital costs include administratio n costs, construction

management costs, and permit costs. A contingency is applied to both direct and indirect capital

costs. The operation and maintenance (O&M) costs include annual administrative costs and five

year review costs, which includes labor, travel, per diem, laboratory, and office/administrative

costs. A contingency is applied to the five year review costs.

ASARCO Inc. (Asarco), the responsible party, will be responsible for any sampling, laboratory

analysis, and response costs. EPA will review and approve any response plans . The samplin g and

response costs funded by Asarco and the cost for EPA's review and approval effor t were not

included in the cost estimate because of the many uncertainties associated with these activities .

4 .0 REMAINING CONCERN S

Remainin g Concerns

Based on review of the written comments received during the public comment period (no oral

comments were received), there are no outstandin g issues associated with implementatio n of the

proposed remedial action.

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