EPA/ROD/R08-98/076
1998
EPA Superfund
Record of Decision:
CALIFORNIA GULCH
EPA ID: COD980717938
OU03
LEADVILLE, CO
05/06/1998
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EPA 541-R98-076
![]()
RECORD OF DECISION
STOCKPILED FINE SLAG
ARKANSAS VALLEY SMELTER SLAG PILE
CALIFORNIA GULCH SUPERFUND SITE (OPERABLE UNIT 3)
LEADVILLE, COLORADO
May 1998
U.S. Environmental Protection Agency
999 18th Street, Suite 500
Denver, Colorado 80202
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RECORD OF DECISION
STOCKPIIiED FINE SLAG
ARKANSAS VALLEY SMELTER SLAG PILE
CALIFORNIA GULCH SUPERFUND SITE (OPERABLE UNIT 3)
LEADVILLE, COLORADO
The U.S. Environmental Protection Agency (EPA), with the concurrence of the Colorado Department of Public
Health and Environment (CDPHE), presents this Record of Decision (ROD) for stockpiled fine slag at the
Arkansas Valley smelter slag pile of Operable Unit 3(OU 3) within the California Gulch Superfund Site in
Leadville, Colorado. The ROD is based on the Administrative Record for California Gulch OU3, including
the Remedial Investigation/Feasibility Study (RI/FS), the Proposed Plan, and the public comments
received. The ROD presents a brief summary of the RI/FS, actual and potential risks to human health and
the environment, and the Selected Remedy. EPA followed the Comprehensive Environmental Response,
Compensation, and Liability Act, as amended, the National Contingency Plan (NCP), and appropriate
guidance in preparation of the ROD. The three purposes of the ROD are to:
1. Certify that the remedy selection process was carried out in accordance with the reguirements of the
Comprehensive Environmental Response, Compensation, and Liability Act, 42 U.S.C. 9601 et seg., as
amended by the Superfund Amendments and Reauthorization Act (collectively, CERCLA), and, to the
extent practicable, the NCP;
2. Outline the engineering components and remediation reguirements of the Selected Remedy; and
3. Provide the public with a consolidated source of information about the history, characteristics, and
risk posed by the conditions of the stockpiled fine slag at the Arkansas Valley Smelter slag pile of
OU 3, 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.
The ROD is typically organized into the following three distinct sections:
1. The Declaration section functions as an abstract for the key information contained in the ROD and is
the section of the ROD signed by the EPA Acting Regional Administrator and the CDPHE Director;
2. The Decision Summary section provides an overview of the OU 3 characteristics, the alternatives
evaluated, and the analysis of those options. The Decision Summary also identifies the Selected
Remedy and explains how the remedy fulfills statutory reguirements; and
3. The Responsiveness Summary section addresses public comments received on the Proposed Plan, and
other information in the Administrative Record. However, since the EPA did not receive any written
public comments, this ROD will not contain a Responsiveness Summary.
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DECLARATION
SITE NAME AND LOCATION
Stockpiled Fine Slag
Arkansas Valley Smelter Slag Pile
California Gulch Superfund Site (Operable Unit 3)
Leadville, Colorado
STATEMENT OF BASIS AND PURPOSE
This decision document presents the Selected Remedy for stockpiled fine slag at the Arkansas Valley
smelter slag pile of Operable Unit 3 within the California Gulch Superfund Site in Leadville, Colorado.
EPA, with the concurrence of CDPHE, selected the remedy in accordance with CERCLA and the NCP. Note that
this decision addresses stockpiled fine slag only. Other activities reguired for OU3, including other
slag piles, the railroad easement, and the railroad yard, are addressed under a Consent Decree with the
Denver & Rio Grande Western Railroad.
This decision is based on the Administrative Record for the stockpiled fine slag at the Arkansas Valley
smelter slag pile of OU 3 within the California Gulch Superfund Site. The Administrative Record (on
microfilm) and copies of key documents are 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 Superfund Records
Center, located at 999 18th Street, 5th Floor, North Terrace in Denver, Colorado.
ASSESSMENT OF THE SITE
The stockpiled fine slag at the Arkansas Valley smelter slag pile does not present an imminent or
substantial endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
The Selected Remedy is the No Action Alternative, which was presented in the Final Stockpiled Fine
Slag Feasibility Study Report (FS) (Terranext, 1996a). The FS used a comparative analysis to evaluate
several alternatives and identify the advantages and disadvantages of each. Selection of the No Action
Alternative was based on this analysis. For the stockpiled fine slag, the Selected Remedy leaves the slag
piles in their existing condition with no remediation, engineering controls, long term maintenance, or
clean up planned. The Selected Remedy is protective of human health and the environment, and is
considered effective because 1) no complete human or ecological exposure pathways were identified for
the stockpiled fine slag and 2) the potential for release of metals in leachate from the stockpiled fine
slag is minimal.
The Selected Remedy provides a contingency for resource utilization, which may be undertaken in the
future if regional market demand exists for the material. Resource utilization involves the
use or reuse of the slag material as a commercial product. Due to concerns about the potential for
release of airborne particulates if resource utilization is undertaken, the EPA has determined that
resource utilization of the stockpiled fine slag is only appropriate if it is encapsulated for reuse.
Encapsulation can include the use of fine slag in concrete or asphalt aggregate; or as road base,
backfill or other construction material as long as the fine slag is chemically bound or physically
separated from any exposure scenario by a barrier consisting of another material. Dust suppressants to
control particulate emissions and best management practices to control stormwater runoff would also be
employed to contain contaminant releases from the fine slag stockpile and during implementation of the
contingency remedy. Resource utilization must also take into consideration any toxic leaching potential
for the fine slag.
DECLARATION STATEMENT
No remedial action is necessary to ensure protection of human health and the environment.
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DECISION SUMMARY
TABIiE OF CONTENTS
LIST OF FIGURES DS-iii
LIST OF TABLES DS-iv
LIST OF ACRONYMS AND ABBREVIATIONS DS-v
1.0 SITE NAME, LOCATION, AND DESCRIPTION DS-1
2.0 OPERABLE UNIT HISTORY AND ENFORCEMENT ACTIVITIES DS-3
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION DS-5
4 . 0 SCOPE AND ROLE OF OPERABLE UNIT DS-7
5.0 SUMMARY OF SITE CHARACTERISTICS DS-9
6.0 SUMMARY OF SITE RISKS DS-13
6.1 RESIDENTIAL EXPOSURE TO SLAG DS-13
6.2 RESIDENTIAL EXPOSURE TO IMPACTED GROUNDWATER DS-14
6.3 RECREATIONAL USER EXPOSURE TO SLAG DS-14
6.4 WORKER EXPOSURE TO SLAG DS-14
6.5 ENVIRONMENTAL EXPOSURE TO SLAG DS-15
6.5.1 AQUATIC EXPOSURE DS-15
6.5.2 TERRESTRIAL EXPOSURE DS-15
7.0 DESCRIPTION OF ALTERNATIVES DS-16
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES DS-18
8.1 EVALUATION AND COMPARISON CRITERIA DS-18
8.1.1 THRESHOLD CRITERIA DS-18
8.1.2 PRIMARY BALANCING CRITERIA DS-18
8.1.3 MODIFYING CRITERIA DS-18
8.2 EVALUATING THE STOCKPILED FINE SLAG ALTERNATIVES ... DS-19
8.2.1 OVERALL PROTECTION OF HUMAN HEALTH AND THE
ENVIRONMENT DS-19
8.2.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND
APPROPRIATE REQUIREMENTS (ARARs) DS-19
8.2.3 LONG-TERM EFFECTIVENESS AND PERMANENCE DS-19
8.2.4 REDUCTION OF TOXICITY, MOBILITY, OR VOLUME
THROUGH TREATMENT DS-20
8.2.5 SHORT-TERM EFFECTIVENESS DS-20
8.2.6 IMPLEMENTABILITY DS-21
8.2.7 COST DS-21
8.2.8 STATE ACCEPTANCE DS-22
8.2.9 COMMUNITY ACCEPTANCE DS-22
8.2.10 SUMMARY DS-22
9.0 SELECTED REMEDY DS-24
10.0 STATUTORY DETERMINATIONS DS-25
10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT DS-25
10.2 COMPLIANCE WITH ARARs DS-26
10.3 COST EFFECTIVENESS DS-26
10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE
TREATMENT TECHNOLOGIES (OR RESOURCE RECOVERY
TECHNOLOGIES) TO THE MAXIMUM EXTENT POSSIBLE DS-26
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT ... DS-26
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES DS-27
12.0 REFERENCES DS-28
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APPENDIX A
ARARs
DS-30
LIST OF FIGURES
FIGURE
Figure 1 General Location Map, California Gulch Superfund Site
Figure 2 California Gulch Superfund Site and Operable Units.
Figure 3 Arkansas Valley Slag Pile Current Surface Areas, Volumes, and Angles of Repose
Figure 4 Arkansas Valley Slag Pile Sample Locations and Reconnaissance Information
LIST OF TABLES
TABLE
Table 1 Estimates of Costs for Remedial Alternatives
Table 2 Grid Comparison Method for Alternatives Analysis
LIST OF ACRONYMS AND ABBREVIATIONS
AMSL Above Mean Sea Level
AOC Administrative Order of Consent
ARAR Applicable or Relevant and Appropriate Reguirements
AV Arkansas Valley
BMP Best Management Practices
CDPHE Colorado Department of Public Health and Environment
CERCLA Comprehensive Environmental Response, Compensation and Liability Act
CFR Code of Federal Regulations
D&RGW Denver and Rio Grande Western Railroad
EPA U.S. Environmental Protection Agency
FS Final Stockpiled Fine Slag Feasibility Study
mg/kg milligram per kilogram
mph miles per hour
NCP National Oil and Hazardous Substances Pollution Contingency Plan
NPL National Priorities List
OU Operable Unit
ppm parts per million
PRPs Potentially Responsible Parties
RI/FS Remedial Investigation/Feasibility Study
ROD Record of Decision
SFS Screening Feasibility Study
SPLP Synthetic Precipitation Leaching Procedure
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1.0 SITE NAME, LOCATION, AND DESCRIPTION
Stockpiled Fine Slag
Arkansas Valley Smelter Slag Pile
California Gulch Superfund Site (Operable Unit 3)
Leadville, Colorado
The California Gulch Superfund Site is located in Lake County, Colorado, in the upper Arkansas River
basin, approximately 100 miles southwest of Denver (see Figure 1). The Site encompasses approximately
16.5 sguare miles and includes the towns of Leadville and Stringtown, a portion of the Leadville Historic
Mining District, and the portion of the Arkansas River from its confluence with California Gulch
downstream to the Lake Fork Creek confluence. The California Gulch Superfund Site has been organized into
12 operable units (OUs). Figure 2 shows the Site boundaries and the location of OU 3.
Operable Unit 3 (Figure 2) includes three slag piles (Arkansas Valley, La Plata, and Harrison St.) owned
by Denver and Rio Grande Western Railroad (D&RGW), a railyard right-of-way through Leadville and a
railyard in the area of Leadville known as Poverty Flats. This Record of Decision (ROD) addresses only
the fine slag 1 stockpiled as a subpile of the Arkansas Valley (AV) Smelter Slag Pile. In addition, D&RGW
has identified a small volume of fine slag in the railyard (Poverty Flats). D&RGW has prepared a plan
which addresses removal of the fine slag from this area to the AV Smelter Slag Pile (EPA, 1996).
The AV Smelter Slag Pile is the largest and westernmost of the three slag piles owned by D&RGW in the
Leadville area (Figure 2). This pile was generated from slag produced primarily by the AV smelter
facility, which operated from 1882 to 1960. The pile covers approximately 40 acres and is approximately
9,800 feet above mean sea level (AMSL). Based upon aerial photography, the pile volume in the late 1950s
was approximately 1.2 million cubic yards. Today, approximately 422,000 cubic yards of slag remain on the
AV Smelter Slag Pile. The volume of stockpiled fine slag at the AV Smelter Slag Pile is approximately
190,000 cubic yards. The slag pile was purchased by D&RGW from ASARCO in 1961 for use as ballast
(Terranext, 1996a).
The AV Smelter Slag Pile is bounded by Leadville Sewage Treatment Plant property and State Highway 24 to
the south, old smelter works to the north, wooded property to the west, and other smelter-related wastes
and Stringtown to the east. California Gulch runs adjacent to the slag pile vicinity for approximately
1/5 its length. D&RGW has performed work near the California Gulch to minimize the direct contact of
surface water with the slag piles. In the vicinity of the AV Smelter Slag Pile, clean fill has been
bermed along the toe of the slag to prevent direct surface water from contacting the slag (Terranext,
1996a).
Lake County is relatively small (380 sguare miles) and is predominately rural, with a 1990 population of
6,007 (U.S. Department of Commerce, 1990). About half of this population resides within the City of
Leadville. The population of Lake County has fluctuated with the mining industry. The population
increased to about 9,000 between 1960 and 1981 and then declined throughout the 1980's. Land surrounding
OU3 is predominately dedicated to mining, commercial, and residential uses.
The climate of Lake County is dry but otherwise typical of most alpine regions in the southern Rocky
Mountains. The average annual maximum temperature in the Leadville area is 50.5 degrees Fahrenheit and
the average annual minimum temperature is 21.9 degrees Fahrenheit, with an annual mean temperature of
37.3 degrees Fahrenheit. The south-central portion of the county, at an elevation near 9,000 feet AMSL,
receives about 10 inches of precipitation annually. Wind is predominantly from the northwest, with speeds
typically from 0 to 30 miles per hour (mph) (WCC, 1993). Populated areas of Leadville are predominantly
upwind of the AV Smelter Slag Pile.
Fine slag is sorted slag which is less than 3/8 inch. Sorted slag is slag that has been
physically separated into size fractions for the purpose of railroad ballast production
(Terranext, 1996a).
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2.0 OPERABLE UNIT HISTORY AND ENFORCEMENT ACTIVITIES
The California Gulch Superfund Site is located in the highly mineralized Colorado Mineral Belt of the
Rocky Mountains. Mining, mineral processing, and smelting activities have produced gold, silver, lead,
and zinc for more than 130 years in the Leadville area. Mining and its related industries continue to be
a source of income for both Leadville and Lake County. The Leadville Historic Mining District includes an
extensive network of underground mine workings in a mineralized area of approximately 8 sguare miles
located around Breece Hill. Mining in the District began in 1860, when placer gold was discovered in
California Gulch. As the placer deposits were exhausted, underground workings became the principle method
for removing gold, silver, lead, and zinc ore. As these mines were developed, waste rock was excavated
along with the ore and placed near the mine entrances. Ore was crushed and separated into metallic
concentrates at mills, with mill tailing generally slurried into tailing impoundments.
Approximately 17 smelter facilities are reported to have once operated within the Site. Most operations
ceased by about 1900, although some facilities continued to operate into the 1960's. At present, nearly
all of the mines within the Site boundaries are inactive; only a few small-to-moderate-sized mining
operations exist. All of the mills and smelters which operated onsite are inactive and/or demolished.
Due to historic mining, milling, and smelting operations, the Site contains many tailings impoundments,
fluvial deposits, slag piles, waste rock piles, and mine water drainage tunnels. Slag on the Site is the
mineralized waste byproduct of smelting, and results from the processing of lead ore in high temperature
furnaces. Three major slag piles and several smaller piles remain at the Site (Figure 2). In 1961, D&RGW
purchased the AV Smelter Slag Pile from ASARCO for use as railroad ballast. D&RGW purchased the La Plata
slag pile from the Leadville Sanitation District in 1970. Additionally, D&RGW purchased the Harrison
Street Slag Pile from NL Industries in 1983 (EPA, 1996).
The California Gulch Site was placed on the National Priorities List (NPL) in 1983), under the authority
of the Comprehensive Environmental Response, Compensation, and Liability 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 loading into the Arkansas River (EPA, 1996). Several
subseguent investigations were conducted within the California Gulch Superfund Site that have addressed
the slag at the three D&RGW-owned piles.
In 1986, the EPA's contractor, CH2M Hill, sampled surface water, groundwater, and numerous mine waste
piles, and three D&RGW slag piles as part of the California Gulch Site Remedial Investigation (RI)(EPA,
1989). The objective of the mine waste and slag sampling was to better characterize the materials in the
California Gulch Superfund Site. This was the first time that the EPA had sampled slag at the Site.
In 1988, James P. Walsh and Associates, Inc. conducted a Soils Investigation. The stated objectives of
this study were to define potential action levels for soil, determine background metals content of soils,
delineate the extent of soil contamination, and determine sources of soil contamination. This study was
initiated by ASARCO, another potentially responsible party (PRP) at the Site. Three samples of slag were
collected as part of this study: one from the Harrison Street pile, one from the La Plata pile, and one
from an area west of Leadville. This study did not include the AV Smelter Slag Pile (MK, 1992).
In May 1989, Jacobs Engineering performed a second sampling of slag for the EPA. The purpose of the study
was to determine the concentrations of metals in the three D&RGW slag piles and to evaluate the potential
for migration of these metals to soil, water or air. Potential hazards to the environment and public
health from the slag in Leadville were evaluated.
On December 3, 1991, EPA and D&RGW entered into an Administrative Order on Consent (AOC), CERCLA - VIII -
92006, for the performance of a remedial investigation/feasibility study (RI/FS) of the lead slag piles.
Prior to the AOC, EPA had studied the slag piles as part of other investigations at the Site. In 1992,
D&RGW performed an RI (MK, 1992) that addressed seven lead slag piles, including the Arkansas Valley,
Harrison, and La Plata slag piles, and one zinc slag pile. Following the RI, a Site-Wide Screening
Feasibility Study (SFS) was undertaken as a joint effort between the PRPs and EPA. The SFS was completed
in March 1993. It screened several remediation alternatives for all types of slag located at the AV
Smelter Slag Pile based on specific criteria, such as relative cost, implementability, and effectiveness.
The three alternatives retained for further evaluation were: no action, institutional controls, and
resource utilization (EPA, 1996).
On December 15, 1993, D&RGW entered into a Consent Decree with EPA to perform the remainder of their site
work. The Consent Decree stated EPA's concerns regarding the fine fraction of the stockpiled slag and the
potential for particulate release during ballast operations as a potential human health exposure pathway.
The Consent Decree reguired D&RGW to perform a feasibility study for stockpiled fine slag and to submit
an operations plan before initiating any ballast operations. In July of 1995, D&RGW submitted a ballast
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operations plan to EPA. Following EPA's approval of the plan, ballast operations commenced in August
1995 (EPA, 1996).
In May of 1996, D&RGW submitted a feasibility study for the stockpiled fine slag (the FS) at the AV
Smelter Slag Pile, according to the terms of the Consent Decree. The existing fine slag subpile and fine
slag potentially generated from future ballast production were the focus of the FS. The FS provided a
detailed analysis of the three retained remediation alternatives from the SFS as applied to the
stockpiled fine slag. The result of the Feasibility Study for the stockpiled fine slag was a Proposed No
Action Plan for the stockpiled fine slag as a subpile of the AV Smelter Slag Pile (EPA, 1996).
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
Public participation is reguired by CERCLA Sections 113 and 117. These sections reguire that before
adoption of any plan for remedial action to be undertaken by EPA, the State, or an individual (PRP), the
lead agency shall:
1. Publish a notice and brief analysis of the Proposed Plan and make such plan available to the public;
and
2. Provide a reasonable opportunity for submission of written and oral comments and an opportunity for a
public meeting at or near the Site regarding the Proposed Plan and any proposed findings relating the
cleanup standards. The lead agency shall keep a transcript of the meeting and make such transcript
available to the public. The notice and analysis published under item #1 above shall include
sufficient information to provide a reasonable explanation of the Proposed Plan and alternative
proposals considered.
Additionally, notice of the final remedial action plan set forth in the ROD must be published, and the
plan must be made available to the public before commencing any remedial action. Such a final plan must
be accompanied by a discussion of any significant changes to the preferred remedy presented in the
Proposed Plan along with the reasons for the changes. A response (Responsiveness Summary) to each of the
significant comments, criticisms, and new data submitted in written or oral presentations during the
public comment period must be included with the ROD.
EPA has conducted the reguired community participation activities through presentation of the RI/FS and
Proposed Plan, a 30-day public comment period, a formal public hearing, and presentation of the Selected
Remedy in this ROD. However, since the EPA did not receive any written public comments on the Proposed No
Action Plan for the Stockpiled Fine Slag, this ROD does not contain a Responsiveness Summary.
The Proposed No Action Plan for Stockpiled Fine Slag at the AV Smelter Slag Pile was released for public
comment on September 27, 1996. The RI/FS and the Proposed No Action Plan were made available to the
public in the Administrative Record located at the EPA Superfund Records Center in Denver and the Lake
County Public Library in Leadville. A formal public comment period was designated from September 27,
through October 28, 1996.
On October 3, 1996, the EPA hosted a public meeting to present the Proposed Plan for Stockpiled Fine Slag
at OU 3 of the California Gulch Superfund Site. The meeting was held at 7:00 pm in the Mining Hall of
Fame in Leadville, Colorado. Representatives from the EPA and D&RGW presented the Proposed Plan. Three
alternatives were discussed: No Action, Institutional Controls, and Resource Utilization. The No Action
alternative was presented as EPA's and D&RGWs preferred alternative. A portion of the hearing was
dedicated to accepting formal oral comments from the public. Only two guestions were raised during this
public meeting. These guestions were in regard to the volume of the fine slag proposed for No Action and
the nature of the soil beneath the Harrison St. slag pile, which is not relevant to this ROD.
4.0 SCOPE AND ROLE OF OPERABLE UNIT
The California Gulch NPL Site covers a wide area (Figure 2). EPA has established the following OUs for
the cleanup of geographically-based areas within the Site. The OUs are designated as:
OU1 Yak Tunnel/Water Treatment Plant
OU2 Malta Gulch Fluvial Tailing/Leadville Corporation Mill/Malta Gulch Tailings Impoundments
OU3 D&RGW Slag Piles/Railroad Easement/Railroad Yard and Stockpiled Fine Slag
OU4 Upper California Gulch
OUS ASARCO Smelter/Slag/Mill Sites
OU6 Starr Ditch/Penrose Dump/Stray Horse Gulch/Evans Gulch
OU7 Apache Tailing Impoundments
OUS Lower California Gulch
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OU9 Residential Populated Areas
OU10 Oregon Gulch
OU11 Arkansas River Valley Floodplain
OU12 Site Water Quality
The purpose of the D&RGW Slag Piles/Railroad Easement/Railroad Yard OU RI/FS was to gather sufficient
information to support an informed risk management decision on which remedies are the most appropriate
for the D&RGW Stockpiled Fine Slag portion of OU3. The RI/FS was performed in accordance with the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal Regulations
(CFR) Part 300, and CERCLA Section 104, 42 U.S.C. ° 9604.
The objectives of the RI/FS were to:
• Determine the nature and extent of metals in source areas and other affected areas within
the D&RGW Slag Piles/Railroad Easement/Railroad Yard OU;
• Define the potential pathways along which metals can migrate, as well as the physical
processes and, to the extent necessary, the chemical processes that control these pathways;
• Determine risk assessment information including potential receptors, exposure patterns, and
food chain relationships; and
• Develop, screen, and evaluate remedial alternatives and predict the conseguences of each
remedy.
Based on the findings of previous investigations and the results of the D&RGW Slag Piles/Railroad
Easement/Railroad Yard OU RI/FS, the sources and areas of environmental contamination at the Stockpiled
Fine Slag (AV Smelter Slag Pile) portion of OU3 have been adeguately delineated.
The remedy outlined in this ROD represents the final remedial action only for the stockpiled fine slag at
the AV Smelter Slag Pile. Remedial actions undertaken at the Stockpiled Fine Slag portion of OU3 are
intended to be consistent with the remedial action objectives and goals identified for the California
Gulch NPL Site and other OU investigations.
5.0 SUMMARY OF SITE CHARACTERISTICS
As a result of D&RGW processing the slag for use as railroad track ballast, the AV Smelter Slag Pile is
actually composed of several sub-piles (Figure 3). The subpiles of the AV Smelter Slag Pile site include
sorted fines, water-guenched fines, ballast-sized material, oversized material, and unsorted air-cooled
slag. The subpiles of sorted fines consist of the less than 3/8 inch diameter slag. The ballast-sized
subpile is composed of material with particle sizes ranging from approximately 3/8 inch to 2-1/2 inches
in diameter. Two subpiles of oversized material from ballast processing consist of slag that is greater
than 2-1/2 inches in diameter, some brick, and some scrap iron. The existing fines piles and fines
potentially generated from future ballast production are the focus of this ROD. Figure 3 also depicts the
location of stockpiled fine slag at the AV Smelter Slag Pile. This and a small amount of fine slag in the
railyard are the only locations within the California Gulch Superfund Site with stockpiled fine slag. The
volume of stockpiled fine slag at the AV Smelter Slag Pile is approximately 190,000 cubic yards. The
volume of stockpiled fine slag at the railyard was estimated at approximately 220 cubic yards (Terranext,
1996b). As noted previously, the small amount of fine slag at the railyard has been moved to the AV
Smelter Slag Pile. The total volume of fine slag moved from the railyard to the AV Smelter Slag Pile was
approximately 1200 cubic yards.
The following paragraphs discuss the primary contaminants of concern, summarize the nature and extent of
contamination, and provide a brief description of contaminant fate and transport.
Site Characterization Summary - Stockpiled Fine Slag
During the Lead Slag Pile RI (MK, 1992) a total of 18 slag samples were collected from the AV Smelter
Slag Pile (Figure 4). Four of these samples were collected from the sorted fines and four from the
water-guenched fines subpiles. These samples were collected from the surface to a depth of 3 feet. In
addition, four subslag samples were collected from four coreholes drilled at the AV Smelter Slag Pile.
Two of these subslag samples were collected from directly below the water-guenched fines subpile. Each
sample was submitted for laboratory compositional and leachability analysis. Material from the
finer-grained slag piles was also submitted for particle size testing. Compositional analyses included
total metals, water-soluble anions, and acid-base accounting. Leachability testing included Synthetic
Precipitation Leaching Procedure (SPLP)(EPA Method 1312) and column leach tests, which were intended to
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simulate, as closely as possible, in situ conditions (Terranext, 1996a) .
Compositional results showed that the slag is an iron magnesium silicate, with residual base metals.
Concentration means for the four primary metals of concern collected from fine slag sample locations at
the Site are as follows:
• Arsenic means; 435 milligram per kilogram (mg/kg) -sorted fines, 909 mg/kg water guenched
fines
• Cadmium means; 11.9 mg/kg-sorted fines, 16.6 mg/kg water-guenched fines
• Lead means; 10,800 mg/kg-sorted fines, 9,650 mg/kg water-guenched fines
• Zinc means; 44,000 mg/kg-sorted fines, 73,000 mg/kg water-guenched fines
Compositional results for the two subslag soil samples (AVB103 and ABV104) collected beneath the
water-guenched fines showed concentrations of metals of concern to be significantly lower than those for
the slag material, and within the range of literature values for metals occurring naturally in soil (MK,
1992-Table 4-15). These samples showed the lowest value for arsenic (5.7 mg/kg), lead (84.8 mg/kg) and
for zinc (188 mg/kg) from all subslag soil samples collected. Site-specific background has not been
established, however, ranges for metals of concern in Colorado soils are as follows: arsenic (1.2-24
mg/kg) , lead 15-150 mg/kg) and zinc (16-300 mg/kg) (Terranext, 1996a) . The subslag soil samples collected
from beneath the water-guenched fine slag at AV exhibited a negative acid-forming potential.
Leaching analysis, which included both SPLP and column leach studies, showed minimal leaching of metals
of concern. Synthetic Precipitation Leaching Procedure results for all elements tested in slag were below
the toxicity characteristic criteria, listed in 40 CFR 261.24. Mean values for the contaminants of
concern were generally two orders of magnitude lower than these regulatory thresholds. Column leach tests
showed similar low levels of leaching (Terranext, 1996a).
Particle size data and site-specific meteorological data were used to determine whether slag in the
fine-grained piles has the ability to become airborne. Threshold friction velocities (the wind speed
above which the surface material becomes airborne) were calculated using the mode of the aggregate size
distribution. Wind data and the height of the piles were used to calculate the friction velocity. Results
for the two fines piles are:
Threshold Friction Velocity
sorted fines
water-guenched fines
Friction Velocity
1.0 meters per second (m/sec)
0.58 m/sec
0.55 m/sec
A friction velocity lower than the threshold friction velocity demonstrates that sustained wind gusts
(0.55 m/sec, MK 1992) in Leadville are not fast enough to cause wind erosion of the fines slag piles.
Groundwater
A site-wide monitoring program will be developed at the California Gulch Superfund Site once all source
areas have been addressed. Groundwater in the vicinity of the stockpiled fine slag has not been fully
characterized. As noted above, the subslag material showed concentrations of metals of concern to be
significantly lower than those for the slag material, and within the range of literature values for
metals occurring naturally in soils. These results suggest that surface water infiltration through the
slag piles does not significantly impact groundwater nor does it impact the soils beneath the slag piles,
as evidenced by the results of the soil analyses (Terranext, 1996a).
Surface Water
No discreet conveyances of surface water runoff from the AV area have been noted. Additionally, the berm
placed along the California Gulch is designed to eliminate surface water runoff from directly entering
the California Gulch (Terranext, 1996a).
Soils
Analysis of subslag soils from beneath the fine slag piles show the lowest concentration for lead,
arsenic and zinc of any of the subslag samples collected (Terranext, 1996a) .
Discussion of Fate and Transport
Existing pathways for potential migration of metals of concern include wind, leaching, mixing by
human activities, runoff, and direct contact.
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Release Mechanism 1 - Wind
The air pathway analysis results indicate that wind erosion is not a viable release mechanism for the
lead slag piles, including the AV water-guenched and sorted fines piles.
Release Mechanism 2 - Leaching
Testing in subslag material does not indicate that leachate from slag contributes to elevated metals
concentrations in the vadose zone beneath the slag piles. This conclusion is supported by the lack of
acid-generating potential and the neutral-to-basic pH of the slag and subslag materials.
Release Mechanism 3 - Mixing by Human Activities
Transport of slag by human activities has occurred, as it was historically used for road maintenance
within the Site by Lake County and the Colorado Department of Transportation. This mechanism will not
continue in the future as reuse of the slag material is controlled as specified in this ROD.
Release Mechanism 4 - Surface Water Runoff
No evidence of transport of slag fines by surface water runoff was observed at any of the examined piles.
Slag does not appear to be transported from piles onto adjacent soils in rivulets or channels. Pile
integrity, especially for fines piles where this is most critical, appears intact. This potential release
mechanism for slag is not a concern at the AV Smelter Slag Pile.
Release Mechanism 5 - Direct Contact
Due to the physical characteristics of the slag piles, direct contact with the slag piles was considered
unlikely in EPA's Preliminary Baseline Human Health Risk Assessment (EPA 1991) . Therefore, it was
eliminated as a release mechanism.
6.0 SUMMARY OF SITE RISKS
In the Preliminary Baseline Human Health Risk Assessment (EPA, 1991) lead and arsenic were identified as
the primary chemicals of potential concern at the California Gulch NPL Site. Since the completion of the
preliminary risk assessment, several important studies were completed that provided more extensive and
more reliable data on environmental concentrations and on human and ecological exposures. Leadville
officials and business leaders expressed concern over possible risks and liabilities associated with
commercial and recreational uses within the Site. Therefore, in the final baseline risk assessment,
risks posed by environmental contamination to current or future workers in the commercial and business
district of the community and to people who engage in recreational activities in and around the
community were evaluated. The assessment was conducted to determine if environmental contamination was of
concern at any locations presently zoned commercial/industrial and to address concerns regarding the
development of a proposed bike path around the community (EPA, 1996).
In 1995, EPA completed two parts of the Baseline Human Health Risk Assessments for the California Gulch
Superfund Site. These are: Part A Risks to Residents from Lead (EPA, 1995b), and Part C Evaluation of
Recreational, Worker Scenarios (EPA, 1995c) . Part A evaluates risks to residents from lead; and Part C
evaluates risks to workers in the commercial and business district and to recreational users in areas in
and around the community. The following paragraphs summarize results of the final baseline risk
assessment as they relate to the stockpiled fine slag at the AV Smelter Slag Pile.
Terrestrial and aguatic risks associated with exposure to site chemicals were also evaluated by EPA.
Aguatic risks were evaluated in the Final Baseline Aguatic Ecological Risk Assessment (EPA, 1995d) and
terrestrial risks were evaluated in the Ecological Risk Assessment for the Terrestrial Ecosystem (EPA,
1997).
6.1 RESIDENTIAL EXPOSURE TO SLAG
The evaluation of exposure to contaminants at waste piles included consideration of slag pile data, with
an exposure scenario conservatively evaluating a child playing on the waste piles who may come in contact
with contaminants through inadvertent ingestion or dermal (skin) contact. The dermal contact pathway was
determined to be minimal and was not considered further. The residential risk assessment also determined
that non-lead metals in most waste piles pose either no risk or only low risk from direct contact while
playing on the piles. For the evaluation of lead exposure at the waste piles, the data were found to be
too limited to derive reliable estimates of the potential impact of direct exposures to children who play
on waste piles. Therefore a guantitative evaluation was not performed. As stated in the preliminary risk
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assessment and the SFS, direct contact of residents with the slag piles is not expected to occur.
Wind erosion and direct contact were not considered viable release mechanisms for the stockpiled fine
slag. However, based on the results of the risk assessment, there is some concern about the potential for
particulate release and human exposure should resource utilization of the stockpiled fine slag be
undertaken. For example, inhalation of slap particles could occur if the material is disturbed from its
current state. If the resource utilization option is exercised, measures would be reguired to prevent
contaminant releases.
6.2 RESIDENTIAL EXPOSURE TO IMPACTED GROUNDWATER
The remedial action objective in the 1993 SFS was to prevent leaching of metals of concern in
concentrations that would have an adverse impact on soils, surface water, or groundwater in the area near
the slag piles. The 1996 FS determined that testing of material under the slag pile did not indicate that
migration of contaminants by leaching from the slag contributes to elevated metals beneath the slag
piles. In addition, the final baseline risk assessment determined that groundwater from this aguifer is
not currently used for drinking, and it is relatively unlikely that it will be used for drinking in the
future. It has been determined that there is a minimal potential for release of metals in leachate from
the stockpiled fine slag, and that the stockpiled fine slag poses an insignificant impact on water
guality (EPA, 1996).
6.3 RECREATIONAL USER EXPOSURE TO SLAG
The AV Smelter Slag Pile area is situated in an area presently zoned as industrial/mining and is not
considered a recreational use area, thus, there is no complete exposure pathway.
6.4 WORKER EXPOSURE TO SLAG
There are no current worker exposure pathways to the stockpiled fine slag. The Selected Remedy provides a
contingency for resource utilization, which may be undertaken in the future. The EPA has determined that
resource utilization of the stockpiled fine slag is only appropriate if it is encapsulated for reuse, to
deter the potential release of airborne particulates and eliminate potential risk associated with
resource utilization activities. Encapsulation can include the use of fine slag in concrete or asphalt
aggregate; or as road base, backfill or other construction material as long as the fine slag is
chemically bound or physically separated from any exposure scenario by a barrier consisting of another
material. Dust suppressants to control particulate emissions and best management practices to control
stormwater runoff would also be employed to contain contaminant releases during implementation of the
contingency remedy.
In response to concerns raised by Leadville officials and business leaders over potential liability
associated with business development within a Superfund Site, EPA developed action levels to determine if
chemical concentrations were of concern at any locations presently zoned for commercial and industrial
purposes. Action levels were developed only for arsenic and lead, the contaminants of most concern at the
Site. The action levels were developed only for soil and dust ingestion; exposure to other media (e.g.,
slag piles, waste piles) and exposure to soil/dust via other pathways (e.g., dermal) are considered of
insignificant concern for workers.
The soil action level for lead based on commercial/industrial exposure to soil and dust ranged from as
low as 2,200 parts per million (ppm) to as high as 19,100 ppm with central tendency values in the 6,100
to 7,700 ppm range. Lead concentrations in soils in and around the slag piles (maximum lead concentration
of 794 ppm) were well below the lead action level (EPA 1996).
Soil action levels for arsenic based on commercial/industrial exposure to soil and dust ranged from as
low as 330 ppm to as high as 1,300 ppm, with central tendency values in the 610 to 690 ppm range. Arsenic
concentrations in soils in and around the slag piles (maximum arsenic concentration of 5.7 ppm) were well
below the lowest arsenic action level.
6.5 ENVIRONMENTAL EXPOSURE TO SLAG
6.5.1 AQUATIC EXPOSURE
There are no aguatic exposure pathways to stockpiled fine slag due to the lack of release mechanisms. No
evidence of transport of slag fines by surface water runoff was observed at any of the examined piles.
Slag does not appear to be transported from piles onto adjacent soils in rivulets or channels. Pile
integrity, especially for fines piles where this is most critical, appears intact. Surface water runoff
is not a potential release mechanism for the AV Smelter Slag Pile.
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Additionally, air pathway analysis results indicate that wind erosion is not a viable release mechanism
for the lead slag piles, including the AV water-guenched and sorted fines piles. Leaching to groundwater
is also not a potential release mechanism. Testing in subslag material indicates that leachate from slag
does not contribute to elevated metals concentrations in the vadose zone beneath the slag piles. This
conclusion is supported by the lack of acid-generating potential and the neutral-to-basic pH of the slag
and subslag materials.
6.5.2 TERRESTRIAL EXPOSURE
Terrestrial exposure pathways to the stockpiled fine slag are unlikely to be significant. The slag piles
do not offer any viable habitat or sustenance for terrestrial receptors. Although terrestrial receptors
(i.e., birds, mammals) could access the slag piles, there is no habitat or food source to attract these
receptors. As stated above, wind erosion, leaching, and surface water runoff are not considered potential
release mechanisms for the slag piles, which considerably reduces the potential for terrestrial receptors
to contact slag in more attractive environs.
7.0 DESCRIPTION OF ALTERNATIVES
A brief description of the three alternatives evaluated in the Stockpiled Fine Slag FS for the AV Smelter
Slag Pile (Terranext, 1996a) is provided below. All alternatives presented in the FS were evaluated
against the nine criteria described in the next section, and then compared with each of the other
options.
Alternative 1; No Action
This alternative leaves the stockpiled fine slag in place 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 protective of human health and the environment, and is considered effective because no
complete human or ecological exposure pathways were identified. However, a site-wide surface and
groundwater monitoring program will be developed once all source areas have been addressed. Monitoring
will continue until EPA determines that such monitoring is no longer necessary to ensure that human
health and the environment are protected. D&RGW would conduct any reguired monitoring at the stockpiled
fine slag pile to ensure that it poses no threat to human health or the environment. This alternative is
technically feasible and cost-effective, since it does not rely on any technology and has no cost (EPA,
1996).
Alternative 2; Institutional Controls
Institutional controls involve restricting access or activities that could result in human contact with
the slag or increase the potential for leaching from stockpiled fine slag. Controls include fencing,
land-use restrictions, or deed restrictions. Additionally, community awareness programs could be
implemented to alert the community to any physical hazards associated with the fine slag. Controls could
be implemented separately or in combination. The option considered is to fence and maintain the
stockpiled fine slag located at the AV Smelter Slag Pile. Fencing would eliminate the potential direct
contact pathway with the fine slag piles, would be protective of human health and the environment because
no complete human or ecological exposure pathways would exist (that is, children would not have access to
the piles), and potential for release of metals in leachate from the stockpiled fine slag would remain
minimal. Fencing would also be technically feasible. Costs associated with fencing are $163,970 with
inspection and maintenance costs of $8,443 for a 30-year period (EPA , 1996).
Alternative 3; Resource Utilization
The utilization of stockpiled fine slag as a resource could involve a number of activities and/or
processes. At present, although options have been identified, it is not possible to ascertain if or when
the entire volume of stockpiled fine slag could be reused. Two options for the resource utilization
(materials reuse) were identified in the FS: 1) to process the slag as aggregate for asphalt or concrete,
2) to use slag materials for stand-alone material in construction, such as backfill for roadbase material
or pipe bedding.
Resource utilization would be protective of human health and the environment because appropriate
environmental controls for particulates emissions and stormwater runoff would be reguired to control
contaminant releases. Consideration must also be given to any toxic leaching potential for the fine slag.
Resource utilization may marginally decrease the minimal metals concentrations in the stockpiled fine
slag leachate through overall volume reduction. However, the effectiveness and implementability of this
alternative would be affected by the regional market demand for the material. Efforts conducted to
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identify markets have been unsuccessful to date, but a potential for future markets exists. Therefore,
the EPA has determined that this alternative should be included as a contingency with "No Action" as the
preferred alternative (EPA, 1996). However, resource utilization of the stockpiled fine slag is only
appropriate if it is encapsulated prior to its use or reuse. Cost effectiveness is hindered by the
distance the slag material is located from a major market and the cost associated with sorting the slag.
Cost for use of the fine slag as aggregate is estimated as a $1,120,000 loss after resale, while the cost
for use as fill material is estimated as a $244,625 loss after resale (EPA, 1996).
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
Section 300.430(e) (9) of the NCP reguires that the agencies evaluate and compare the remedial cleanup
alternatives based on the nine criteria listed below. The first two criteria, (1) overall protection of
human health and the environment and (2) compliance with applicable or relevant and appropriate
reguirements (ARARs) in Appendix A, are threshold criteria that must be met for the Selected Remedy. The
Selected Remedy must then represent the best balance of the remaining primary balancing and modifying
criteria.
8.1 EVALUATION AND COMPARISON CRITERIA
8.1.1 THRESHOLD CRITERIA
1. Overall protection of human health and the environment addresses whether or not a remedy provides
adeguate protection and describes how potential risks posed through each pathway are eliminated,
reduced, or controlled through treatment, engineering controls, or Institutional Controls.
2. Compliance with ARARs addresses whether or not a remedy will comply with identified federal and state
environmental and siting laws and regulations.
8.1.2 PRIMARY BALANCING CRITERIA
3. Long-term effectiveness and permanence refers to the ability of a remedy to maintain reliable
protection of human health and the environment over time.
4. Reduction of toxicity, mobility and volume through treatment refers to the degree that the remedy
reduces toxicity, mobility, and volume of the contamination.
5. Short-term effectiveness 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
implementation period until cleanup goals are achieved.
6. Implementability refers to the technical and administrative feasibilities of a remedy, including the
availability of materials and services needed to carry out a particular option.
7. Cost evaluates the estimated capital costs, operation and maintenance costs, and present worth costs
of each alternative.
8.1.3 MODIFYING CRITERIA
8. State acceptance indicates whether the State (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.
8.2 EVALUATING THE STOCKPILED FINE SLAG ALTERNATIVES
The following is a brief summary of the agencies evaluation and comparison of stockpiled fine slag
alternatives. Additional details evaluating the alternatives are presented in the FS. This section
evaluates the performance of the stockpiled fine slag alternatives against the nine criteria discussed
above, and compares it with the other possible options. Information for this section was obtained from
the Final Stockpiled Fine Slag FS (Terranext, 1996a).
8.2.1 OVERALL PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
This criterion is based on the level of protection of human health and the environment afforded by each
alternative. All of the alternatives are protective of human health. No complete human or ecological
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exposure pathways have been identified. Based upon the chemical composition of the slag and soil sampling
conducted beneath the slag, the potential for release of metals in leachate from the stockpiled fine slag
is minimal. The stockpiled fine slag has, at most, insignificant non-point source impact on water
quality.
The physical features of the slag piles have remained relatively unchanged for many decades. That fact,
combined with the determination that the only potential release pathway is through leachate, suggests
that the status of the slag is not likely to change in the near or long term. Therefore all three
alternatives are protective of human health and the environment.
8.2.2 COMPLIANCE WITH APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARs)
This criterion is based on compliance with chemical-, location-, and action-specific ARARs. ARARs are
presented in Appendix A. All of the alternatives meet ARARs. Groundwater quality is a function of the
active interchange with surface water degraded by the release of more mobile metal species from the
multitude of other contaminant sources in the vicinity. The potential for non-point source metals loading
to surface water from stockpiled fine slag leachate is minimal to nonexistent. The use of institutional
controls on the stockpiled fine slag will not have any effect on groundwater quality. Non-point source,
Best Management Practices (BMP)to-be-considered criteria have been implemented along the slag piles
contacting California Gulch.
8.2.3 LONG-TERM EFFECTIVENESS AND PERMANENCE
This criterion is based on the magnitude of residual risk and adequacy and reliability of controls. No
Action is an effective long-term alternative. The only identified release pathway determined to have any
potential to contribute to human or environmental risks is the potential for metals to leach from the
stockpiled fine slag. Based upon subslag sampling, metals have not leached and will not leach from the
stockpiled fine slag in concentrations that will have an adverse impact on soils, surface water or
groundwater in the vicinity. Based upon the hardness of the slag, the lack of acid-generating potential
and the absence of significant metals in soils beneath the slag, the potential for exposure to metals of
concern found in the slag is unlikely to change in the long term. Institutional controls can be effective
in the long term, but are not permanent. Fencing requires inspections, maintenance and community
awareness, and must be renewed or replaced periodically. Resource utilization represents a reliable
alternative which uses known technologies, limited only by the regional market demand for the stockpiled
fine slag. Resource utilization will not have a dramatic effect on the residual risk, as the pre-resource
utilization risks are minimal.
8.2.4 REDUCTION OF TOXICITY, MOBILITY, OR VOLUME THROUGH TREATMENT
This criterion is based on the treatment process used; the amount of contamination destroyed or treated;
the reduction of toxicity, mobility, and volume; the irreversible nature of the treatment; the type and
quantity of residuals remaining; and the statutory preference for treatment.
Institution controls and No Action do not further reduce the very limited toxicity or mobility of metals
of concern in the stockpiled fine slag. In the absence of complete exposure pathways, there is no
indication that toxicity and mobility of hazardous substances in the slag pose a human health risk. From
a land-use perspective, the slag volume is not an issue as tourists come specifically to observe historic
mining practices. Implementation of institutional controls or the No Action alternative, however, will
not reduce the volume of the fine slag found at the site.
Over time, reuse could reduce the very limited potential toxicity and potential mobility of the
stockpiled fine slag. From a land-use perspective, the change in the total volume of all types of slag
will not be significant if only the stockpiled fine slag is utilized.
8.2.5 SHORT-TERM EFFECTIVENESS
This criterion is based on the degree of community and worker protection offered, the potential
environmental impacts of the remediation, and the time until the remedial action is completed. No action
and institutional controls do not create additional risk to the Leadville community during
implementation. For institutional controls, workers and the community can be adequately and reliability
protected if fencing were to be installed.
Resource utilization can also be implemented with no additional risk to the Leadville community. Workers
and the community can be adequately and reliably protected from fugitive particulates and changes in
storm-water drainage when the stockpiled fine slag is utilized.
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_ IMPLEMENTABILITY
This criterion is based on the ability to perform construction and implement administrative actions. No
Action is technically feasible as it does not rely on any technology. As the status quo, no action is
implementable .
Institutional controls are technically feasible, as reliable fencing can be procured and installed
readily by local contractors. Land-use restrictions would require action by either the Lake County
Commissioners or the Leadville Town Council. Therefore, because further action is needed by a third
party, the potential of implementability of land-use restrictions cannot be predicted.
Resource utilization is also technically feasible but there are unknowns as to the marketability of the
resource. Demand for the stockpiled fine slag will be dependant on a number of factors, including but not
limited to, the level of construction activity in the vicinity of Leadville.
COST
Alternative 1; No Action
As there are no costs associated with No Action, it is the most cost effective alternative.
Alternative 2; Institutional Control
Institutional controls involve fencing and maintenance of the stockpiled fine slag located at the AV
Smelter Slag Pile. Fencing the AV pile would have present value capital and labor costs of $161,000 and
inspection and maintenance costs of $8,500 to inspect and maintain over a 30-year period indicated in the
summary in Table 1.
Alternative 3; Resource Utilization
Resource utilization does not presently appear to be a cost-effective option even if market demands for
the material are identified. Efforts conducted to identify markets have been unsuccessful to date. The
options considered are 1) to process slag for use as a concrete or asphalt aggregate in construction, and
2) to utilize slag materials for a stand-alone material in construction, such as a backfill or pipe
bedding.
The cost effectiveness of these options is hindered by the distance the slag material is located from a
major market and the cost associated with sorting the slag. Cost estimates and a cost summary are
included in Table 1. Estimates have been provided for use of the fine slag for aggregate ($1,120,000 loss
after resale) and for use in fill material ($244,625 loss after resale).
8.2.8 STATE ACCEPTANCE
The State has been consulted throughout this process and concurs with the Selected Remedy.
8.2.9 COMMUNITY ACCEPTANCE
Public comment on the RI/FS and Proposed Plan was solicited during a formal public comment period
extending from September 27 to October 28, 1996. It is assumed that the community is generally supportive
of EPA' s No Action alternative since no comments were generated during the formal public comment period.
In addition, only two oral comments were raised during the public meeting held October 3, 1996. These
comments were in regard to the volume of the fine slag pile and the nature of the soil beneath the
Harrison St. slag pile, which is not relevant to this ROD.
8.2.10 SUMMARY
The FS used a comparative analysis to qualitatively evaluate the performance of each alternative in
relation to each specific evaluation criterion. The purpose of this comparative analysis is to identify
the advantages and disadvantages of each alternative relative to one another so that key tradeoffs could
be identified.
A grid comparison method was used to rank the alternatives and their attainment relative to the NCP
criteria set forth in the SFS. Alternatives were ranked on a scale of 1 to 5, with 5 being the highest
attainment of the criterion. Total scores for each alternative were: Alternative 1: No Action at 41;
Alternative 2: Institutional Controls at 39; and Alternative 3: Resource Utilization at 36. Table 2
provides a grid comparison method to rank the alternatives and their attainment relative to the following
criteria.
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• Protection of Human Health and the Environment - All three alternatives are protective of
human health and the environment.
Attainment of ARARs - All three alternatives attain ARARs.
• Long-Term Effectiveness - All three alternatives have similar long-term effectiveness. Reuse
of the stockpiled fine slag would marginally reduce the residual risk because of volume
reduction. None of the alternatives are subject to technology failure from age or wear and
tear.
• Reduction of Toxicity, Mobility or Volume - None of the three alternatives reduce the
toxicity and mobility of metals of concern found in the fine slag.
• Short-Term Effectiveness - All three alternatives can be implemented in a manner which
protects the Leadville community and the workers implementing the remedy. The No Action
alternative eliminates disturbances of the fine grain slag and reguires no workers.
• Implementability - All three alternatives are implementable. Deed restrictions are in
effect. Land use restrictions may not be implementable from and administrative
perspective as they reguire approval by the Lake County Commissioners. Reuse reguires that
there be a commercial market or internal need for the stockpiled fine slag which, at this
time, is uncertain.
• Cost - No Action is the most cost-effective approach to meeting the remedial action
objectives and attaining ARARs. There are essentially no costs associated with this
remedial option.
• State Acceptance - CDPHE has been consulted throughout the RI/FS process.
• Community Acceptance - The community has been consulted throughout the RI/FS process.
Selection of the No Action alternative was based on this analysis.
9.0 SELECTED REMEDY
Based upon consideration of CERCLA reguirements, the detailed analysis of alternatives, and public
comments, EPA has determined that the No Action alternative presented in the Proposed Plan, with no
modifications, is the appropriate remedy for the stockpiled fine slag at the AV Smelter Slag Pile of OU3
within the California Gulch Superfund Site. The No Action alternative leaves the stockpiled fine slag in
its existing condition with no control or cleanup planned. The No Action alternative, as described in the
Proposed Plan, includes a contingency for future utilization of the slag, if it is encapsulated prior to
its use or reuse.
The No Action alternative is protective of human health and the environment, and is considered
effective because no complete human or ecological exposure pathways were identified and because the
potential for release of metals in leachate is minimal. Based on subslag sampling metals have not leached
and will not leach from the stockpiled fine slag in concentrations that will have an adverse impact on
soils, surface water, or groundwater in the area. Slag hardness, the lack of acid-generating potential,
and the absence of any significant metals beneath the slag also indicate that the potential for
exposure to metals of concern found in the slag is unlikely to change in the long term. This alternative
is technically feasible and cost effective, since it does not rely on any technology and has no cost.
Resource utilization would only implemented if future regional market demand exists for the material.
Encapsulation of the fine slag ensures that the contingency remedy is also protective of human health and
the environment. Encapsulation can include the use of the fine slag in concrete or asphalt aggregate; or
as road base, backfill or other construction material as long as the fine slag is chemically bound or
physically separated from any exposure scenario by a barrier consisting of another material. Dust
suppressants to control particulate emissions and best management practices to control stormwater runoff
would also be employed to contain contaminant releases during implementation of the contingency remedy.
10.0 STATUTORY DETERMINATIONS
Under CERCLA Section 121, EPA must select a remedy that is protective of human health and the
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
significantly reduces the volume, toxicity, or mobility of hazardous wastes as a principal element.
However, the Selected Remedy, No Action, does not satisfy the statutory preference for treatment as a
principal element of the remedy. Treatment was considered unnecessary as the Selected Remedy is
protective of human health and the environment. The following sections discuss how the Selected Remedy
meets statutory reguirements.
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10.1 PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT
The selected remedy is protective of human health and the environment because 1) no complete human or
ecological exposure pathways were identified and 2) metals have not leached and will not leach from the
stockpiled fine slag that will have an adverse impact on soils, surface water or groundwater in the area.
Because the estimated action levels for recreational land-use scenarios are significantly above current
surficial soil concentrations for both lead and arsenic, there appears to be relatively little
uncertainty in the conclusion that current surface soils do not pose unacceptable risk levels to
recreational site visitors anywhere within the OU boundaries (EPA, 1995b). In addition, the AV Smelter
Slag Pile area is situated in an area presently zoned as industrial/mining and is not considered a
recreational use area (EPA, 1996).
There are no current worker exposure pathways to the stockpiled fine slag. The Selected Remedy provides a
contingency for resource utilization, which may be undertaken in the future. The EPA has determined that
resource utilization of the stockpiled fine slag is only appropriate if it is encapsulated prior to its
use or reuse, to deter the potential release of airborne particulates and eliminate potential risk
associated with resource utilization activities. Dust suppressants to control particulate emissions and
best management practices to control stormwater runoff would also be employed to contain contaminant
releases during implementation of the contingency remedy.
The soil action level for lead based on commercial/industrial exposure to soil and dust ranged from as
low as 2,200 parts per million (ppm) to as high as 19,100 ppm with central tendency values in the 6,100
to 7,700 ppm range. Lead concentrations in soils in and around the slag piles (maximum lead concentration
of 794 ppm) were well below the lead action level (EPA 1996).
Soil action levels for arsenic based on commercial/industrial exposure to soil and dust ranged from as
low as 330 ppm to as high as 1,300 ppm, with central tendency values in the 610 to 690 ppm range. Arsenic
concentrations in soils in and around the slag piles (maximum arsenic concentration of 5.7 mg/kg) were
well below the lowest arsenic action level.
10.2 COMPLIANCE WITH ARARs
The Selected Remedy will comply with all ARARs identified in Appendix A to this ROD. No waiver of ARARs
is expected to be necessary.
10.3 COST EFFECTIVENESS
Section 360.430(f)(ii)(D) of the NCP reguires evaluation of cost effectiveness. The Selected Remedy is
cost effective because it has no cost.
10.4 UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT TECHNOLOGIES (OR RESOURCE RECOVERY
TECHNOLOGIES) TO THE MAXIMUM EXTENT POSSIBLE
No remedial action is necessary to ensure protection of human health and the environment. The contingency
allows for resource recovery if supported by regional market demand.
10.5 PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT
Treatment of the stockpiled fine slag at the AV Smelter Slag Pile was not considered because the No
Action alternative is protective of human health and the environment.
11.0 DOCUMENTATION OF SIGNIFICANT CHANGES
The Proposed Plan for stockpiled fine slag at the AV Smelter Slag Pile was released for public comment in
September 1996. The Proposed Plan identified Alternative 1, No Action, as the preferred alternative, with
the contingency that resource utilization may be undertaken in the future. Resource utilization of the
stockpiled fine slag would only be appropriate if it is encapsulated prior to its use or reuse. No
comments were received during the public comment period. Subseguently, EPA determined that no significant
changes to the remedy, as it was originally identified in the Proposed Plan, were necessary.
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12.0 REFERENCES
Morrison Knudsen Corporation (MK). 1992. Report for Lead Slag Pile Remedial Investigation at the
California Gulch Site Leadville, Colorado, prepared for Denver & Rio Grande Western Railroad.
December 11.
Terranext. 1996a. Final Stockpiled Fine Slag Feasibility Study, prepared for Denver & Rio Grande Western
Railroad. May 13.
Terranext. 1996b. Work Plan Consolidation of Fine Slag. Prepared for Denver & Rio Grande Western
Railroad. November, 12.
U.S. Department of Commerce. 1990. Selected Population and Housing Characteristics. Bureau of the Census.
U.S. Environmental Protection Agency (EPA). 1997. Ecological Risk Assessment for the Terrestrial
Ecosystem. California Gulch NPL Superfund Site, Leadville, Colorado. Prepared by Roy F. Weston,
Inc., January, 1997.
U.S. Environmental Protection Agency (EPA) . 1996. Proposed No Action Plan for Stockpiled Fine Slag,
Arkansas Valley Smelter Slag Pile, California Gulch Superfund Site, Leadville, Colorado.
September.
U.S. Environmental Protection Agency (EPA). 1995a. Draft Final Findings of Metal Speciation
Investigations at the California Gulch NPL Site, Prepared by John W. Drexler and Roy F. Weston,
Inc., October 1995.
U.S. Environmental Protection Agency (EPA). 1995b. Baseline Human Health Risk Assessment for the
California Gulch Superfund Site - Part A - Risks to Residents from lead prepared by Roy F. Weston,
Inc., Draft final November 6, 1995.
U.S. Environmental Protection Agency (EPA) . 1995c. Baseline Human Health Risk Assessment for the
California Gulch Superfund Site - Part C - Evaluation of Recreational and Worker Scenarios
prepared by Roy F. Weston, Inc., April 17, 1995.
U.S. Environmental Protection Agency (EPA). 1995d. Final Baseline Aguatic Ecological Risk Assessment.
California Gulch NPL Site, Prepared by Roy F. Weston, Inc., September, 1995.
U.S. Environmental Protection Agency (EPA) . 1991. Preliminary Human Health Baseline Risk Assessment for
the California Gulch NPL Site, Leadville, Colorado. Prepared by Roy F. Weston, Inc. for the U.S.
EPA, December 1991.
U.S. Environmental Protection Agency (EPA). 1989. Draft Phase II Remedial Investigation Technical
Memorandum, 1986-1987, California Gulch Site, Leadville, Colorado, U.S. EPA, Prepared by CH2M
Hill, May 1989.
Woodward Clyde Consultants (WCC). 1993. Draft Terrestrial Ecosystem Evaluation Report, California Gulch
Site, Leadville, Colorado. April.
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FICUBES
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TABLES
TABLE 1
ESTIMATES OF COSTS FOR REMEDIAL ALTERNATIVES
OPTION 1
CALIFORNIA GULCH
ARKANSAS VALLEY SLAG PILE
LEADVILLE
INSTITUTIONAL CONTROLS (1)
FENCE THE AV FINE SLAG PILE
ALTERNATIVE:
ITEM:
DIRECT CAPITAL COSTS;
(includes Labor, Equipment and Materials, Unless Otherwise Noted)
TOTAL
Costs
COMPONENT
1. Mobilize Materials
2. Office/Storage trailer (8'x30')
3. Earthwork (450 hp bulldozer)
4. Utilities
Electric
Phone
Sanitary Station
5. Fence Materials
Fencing
Corner Post
Braces
Double Swing Gates
Locks
UNIT
Lump
Lump
Cubic Yards
Month
Month
Month
Lineal Feet
Each
Each
Opening
Each
QUANTITY
1
1
5,000
1
1
1
5,300
50
106
3
3
UNIT
COSTS
$2,700.00
$1,800.00
$2.50
$1,300.00
$6,00.00
$90.00
$16.00
$95.00
$35.00
$970.00
$15.00
CAPITAL
COSTS
$2,700
$1,800
$12,500
$1.300
$600
$90
$84,800
$4,750
$3,710
$2,910
$45
TOTAL DIRECT COSTS
$115,205
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CALIFORNIA GULCH
LEADVILLE, COLORADO
INDIRECT CAPITAL COSTS
TABIiE 1 (Continued)
ESTIMATES OF COSTS FOR REMEDIAL ALTERNATIVES
of Direct Capital Costs)
1.
2.
3.
Engineering and Design (10% of Capital Costs)
Contingency Allowance (20% of Capital Cost)
Other Indirects
Regulatory License/Permits (3% of Direct Capital Costs)
TOTAL INDIRECT COSTS
PRESENT VALUE OF OPERATION AND MAINTENANCE COSTS
Annual Inspection and maintenance
TOTAL COSTS
ASSUMPTIONS/COMMENTS
Year
30
$750.00
$11,521
$23,041
$5,760
$46,082
$8,443
$163,970
1.
2.
3.
4.
5.
Eight (8) loads of fencing materials will be hauled using flatbed trailers.
Includes mob and demob, set-up and leveling, tear-down and monthly leasing charge.
Earthwork consists of consolidating sorted and water-guenched fine slags before fencing: no mob or demob, onsite contractor utilized.
Fencing is 6 ga. Galvanized wire, 6' high, no barbed wire.
Gates are 20' wide and include posts and hardware.
Source: Terranext, 1996a
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CALIFORNIA GULCH
LEADVILLE, COLORADO
ALTERNATIVE:
ITEM:
TABIiE 1 (Continued)
ESTIMATES OF COSTS FOR REMEDIAL ALTERNATIVES
RESOURCE UTILIZATION (1)
FINE SLAG ADDITIVE MATERIAL IN CONSTRUCTION
Aggregate for concrete or asphalt, additive to building materials, additive to
grout, concrete and slurry formations)
DIRECT CAPITAL COSTS:
(Includes Labor, Eguipment and Materials, Unless Otherwise Noted)
COMPONENT
1. Rescreen Material
2. Load and haul
TOTAL DIRECT COSTS
INDIRECT CAPITAL COSTS
UNIT
Cubic Yards
Cubic Yards
QUANTITY
190,000
190,000
COSTS
$5.68
$3.25
TOTAL
COSTS
$1,079,200
$617,500
$1,696,700
of Direct Capital Costs)
1. Engineering and Design (10% of Capital Costs) $169,670
2 Contingency Allowance (20% of Capital Cost) $339,340
3. Other Indirects
Regulatory License/Permits (5% of Direct Capital Costs) $84,835
TOTAL INDIRECT COSTS $593,845
CREDITS FROM SALE OF PRODUCT MATERIAL
1. Additive Cubic Yard 171,000 $6.50 $(1,111,500)
2. Backfill Material Cubic Yard 19,000 $3.10 $(58,900)
TOTAL CREDIT $(1,170,400)
TOTAL COSTS/PROFIT(S) $1,120,145
ASSUMPTIONS/COMMENTS
1. AV fine slag pile volumes are used to compute costs.
2. 90% of material will be suitable for use as additive.
3. 10% of material used as backfill material.
4. No operations and maintenance costs are necessary over an extended period.
5. Credits from sale of product material have been reduced to reflect transportation costs to a major market.
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TABIiE 1 (Continued)
ESTIMATES OF COSTS FOR REMEDIAL ALTERNATIVES
CALIFORNIA GULCH
LEADVILLE, COLORADO
ALTERNATIVE:
ITEM:
RESOURCE UTILIZATION (2)
USED AS STAND ALONE MATERIAL IN CONSTRUCTION
(Fill material)
DIRECT CAPITAL COSTS:
(Includes Labor, Equipment and Material, Unless Otherwise Noted)
COMPONENT
1. Load and Haul
TOTAL DIRECT COSTS
UNIT
Cubic Yards
QUANTITY
190,000
CAPITAL
COSTS
$3.25
TOTAL
COSTS
$617,500
$617,500
INDIRECT CAPITAL COSTS
of Direct Capital Costs)
1. Engineering and Design (10% of Capital Costs)
2. Contingency Allowance (2% of Capital Cost)
3. Other Indirects
Regulatory License/Permits (5% of Direct Capitol Costs)
TOTAL INDIRECT COSTS
TOTAL COSTS (Direct plus Indirect)
CREDITS FROM SALE OF PRODUCT MATERIAL
1. Backfill Material Cubic Yard 190,000
TOTAL CREDIT
TOTAL COSTS/PROFIT(S)
ASSUMPTIONS/COMMENTS
1. AV Fine slag volumes are used to compute costs.
2. 100% of materials will be suitable for use as backfill.
3. Load and haul is for conveyance to suitable rail loading dock.
4. Credits from sale of product material have been reduced due to transportation costs to a major market.
5. Annual Operation and Maintenance costs are included in estimate.
$3.10
$61,750
$123,500
$30,875
$216,125
$833,625
$ (589,000)
$ (589,000)
$244,625
Source: Terranext, 1996a
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TABIiE 2
GRID COMPARISON METHOD FOR ALTERNATIVES ANALYSIS
Criterion
1) Protection of Human Health and
Environment
2) Attainment of ARARs
3) Long term Effectiveness
4) Reduction of Toxicity, Mobility or
Volume
5) Short term Effectiveness
6) Implementability
7) Cost
8) State Acceptance
9) Community Acceptance
Total
Notes: Scale of 1-5, where 5 = Highest Attainment
Source: Terranext, 1996a
Alternative 1
No
Action
5
5
4
2
5
5
5
5
5
41
Alternative 2
Institutional
Controls
5
5
4
2
4
5
4
5
5
39
Alternative 3
Resource
Utilization
5
5
5
2
3
3
3
5
5
36
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APPENDIX A
ARARs
SUMMARY OF FEDERAL AND STATE ARARS
Standard, Requirement,
Criteria, or Limitation
Citation
Applicable
Relevant and
Appropriate
Description
FEDERAL
Clean Air Act,
National Primary and Secondary
Ambient Air Quality Standards
40 CFR Part 50
No
No
National Historic Preservation
Act (NHPA)
16 USC ° 470 et seq.
40 CFR ° 6.301(b)
36 CFR Part 63, Part 65,
Part 800
Yes
National ambient air quality standards (NAAQS) are
implemented throuqh the New Source Review Proqram and
State Implementation Plans (SIPs) . The federal New
Source Review proqram address only major sources. There
will be no emissions associated with the chosen remedial
action in OU3. Emissions associated with the continqency
remedy will be limited to fuqitive dust associated with
movinq and sortinq the slaq for reuse. These activities will
not constitute a major source. Therefore, attainment and
maintenance of NAAQS pursuant to the New Source
Review Proqram are not ARARs. See Colorado Air
Pollution Prevention and Control Act concerninq
applicability of requirements implemented throuqh the SIP.
Expands historic preservation proqrams; requires
preservation of resources included in or eliqible for listinq
on the National Reqister for Historic Places.
Executive Order 11593
Protection and Enhancement of
the Cultural Environment
16 USC
470
Yes
Directs federal aqencies to institute procedures to ensure
proqrams contribute to the preservation and enhancement
of non-federally owned historic resources. Consultation
with the Advisory Council on Historic Preservation is
required if removal activities should threaten cultural
resources.
Hazardous materials
Transportation Act
49 USC ° 1801-1813
49 CFR 107, 171-177
Yes
(for continqency
reuse only)
Requlates transportation of hazardous materials.
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SUMMARY OF FEDERAL AND STATE ARARS (Continued)
Standard, Requirement,
Criteria, or Limitation
Citation
Applicable
Relevant and
Appropriate
Description
STATE OF COLORADO
Colorado Air Pollution
Prevention and Control Act
5 CCR 1001, Regulation 1,
Section III.D
Yes
Colorado Air Pollution
Prevention and Control Act
Colorado Air Pollution
Prevention and Control Act
Colorado Air Pollution
Prevention and Control Act
5 CCR 1001-3;
Sections III.D.l.b,c,d.
Sections III.D.2.b,c,e,f,g.
Regulation I
5 CCR 1001-4;
Regulation 2
5 CCR 1001-5
Regulation 3
APENs
Yes (for contingency
reuse only)
Yes (for contingency
reuse only)
Yes (for contingency
reuse only)
Requires all sources of particulate emissions to apply
technically feasible and economically reasonable control
measures. APCD has the authority to ask for a fugitive
emission control plan from any location, if blowing
particulate matter is a problem. The site does not need to
be in active use for this requirement to apply. Technically
feasible and economically reasonable control measures will
be applied to reuse of the stockpiled fine slag.
Regulation No. 1 provisions concerning fugitive emissions
for storage and stockpiling activities, haul roads, and haul
trucks are applicable (5 CCR 1001-3; Sections
III.D,2.b,c,e,f,g.) to the reuse contingency.
Provisions concerning odors would be applicable if
contingency reuse were to cause objectionable odors.
Substantive provisions of APENs will be met.
Colorado Air Pollution
Prevention and Control Act
5 CCR 1001-10
Part C (I)& (II)
Regulation 8
Yes
(for contingency
reuse only)
Regulation 8 sets emission limits for lead. Applicants are
required to evaluate whether the proposed activities would
result in the Regulation 8 lead standard being exceeded.
There are no emissions associated with the chosen remedial
action. The contingency reuse in OU3 is not projected to
exceed the emission levels for lead, although some lead
emissions may occur. Compliance with Regulation 8 will
be achieved by adhering to a fugitive emissions control
plan prepared in accordance with Regulation No. 1.
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SUMMARY OF FEDERAL AND STATE ARARS (Continued)
Standard, Requirement,
Criteria, or Limitation
Citation
Applicable
Relevant and
Appropriate
Description
Colorado Air Pollution
Prevention and Control
5 CCR 1001-14;
Ambient Air Quality
Standards
Yes (for contingency
reuse only)
Colorado Water Quality Control
Act, Storm Water Discharge
Regulations
Colorado Noise Abatement Act
5 CCR 1002-2
CRS °° 25-12-101 to 108
Yes
Yes (for contingency
reuse only)
Provisions concerning State TSP standards and Federal
PM-10 standards would apply if contingency reuse occurs,
or if the Site is the subject of fugitive emission complaints.
In such a case, compliance with the applicable provisions of
the Colorado air quality requirements will be achieved by
adhering to a fugitive emissions control plan prepared in
accordance with Regulation No. 1.
Establishes requirements for storm water discharges (except
portions relating to Site-wide Surface and Groundwater).
Substantive requirements for storm water discharges
associated with construction activities are applicable.
Establishes maximum permissible noise levels for
particular time periods and land use.
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