PROPOSED NO ACTION PLAN FOR

STOCKPILE D FIN E SLAG

U.S. Environmental Protection Agency Region VIII , ; -'"

September 1996

Arkansas Valley Smelter Slag Pile California Gulch Superfun d Site Leadville, Colorado

389141 EPA Announces Its Preferred Alternative

T he U.S. Environmental Protection Agency (EPA) requests

public comment on its preferred alternative for stockpiled

fine slag at die Arkansas Valley smelter slag pile of Operable Unit 3 (OU3) within the California Gulch Superfun d Site in Leadville, Colorado. EPA is the lead

agency and is assisted by the Colorado Department of Public Health and Environment (CDPHE) , which is the support agency at this site.

The preferred alternative for stockpiled fine slag at the Arkansas Valley slag pile is "No Action," with a contingency for future utilization of the slag, as described more

fully later in this plan. EPA recommends this alternative

based on the results of the risk assessment and after a careful evaluation of site data. The CDPHE has reviewed this

plan and concurs with the proposed approach. Thi s

Proposed Plan fulfill s the requirements of the Comprehensive Environmental Response Compensation,

a nd Liability Act (CERCLA) Section 117 (a) (notice of

availability).

Thi s Proposed Plan summarizes information that can be

found in greater detail in the Final Stockpiled Fine Slag Feasibility Study Report (FS), which is available for your

review at the information repositories listed below. The Proposed Plan is based on the conclusions of the FS and

applies only to the stockpiled fine slag at the Arkansas Valley pile. During the remedial investigation, site data

were used to assess the viability of five potential contaminant release mechanisms (or transport pathways) identified

in the conceptual site model (CSM) for the slag piles: wind,

leaching, mixing by human activities, runoff of particulates,

MAR K YOU R CALENDAR : OPPORTUNITIE S FO R PUBLI C INVOLVEMEN T

Public Meeting: Thursday, Octobers, 1996, 7:00p.m. National Mining Hal l of Fame and Museum

(10th Street Entrance) Leadville, Colorado

Public Comment Period: September 27 - October 28, 1996

Send Comments to: Rebecca Thomas (8EPR-SR) EPA Remedial Project Manager

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

K ey Contacts: Rebecca Thomas E PA Remedial Project Manager

(303)312-6552 Toll-fre e (800) 227-8917 x 6552

Russell Alie n CDPHE State Project Officer (303) 692-3382

Information Repositories:

The Proposed Plan and other documents

in the Administrative Record are available

at the following locations:

Lake County Public Library

1115 Harrison Avenue Leadville, Colorado 80461

Colorado Mountain College Library Learning Resource Center Leadville, CO 80461

EPA Superfund Records Center

999 18th Street

5 th Floor, North Terrace Denver, CO 80202

(303) 312-6473
and direct contact. Of these, only one potential release

mechanism, leaching, was retained for the slag piles. Therefore, a remedial action objective was established 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 FS report provides a detailed analysis of the three alternatives considered for stockpiled fine slag at the Arkansas Valley pile. These alternatives, which were retained following screening in 1993, are no action, institutional controls,

and resource utilization. EPA encourages community

involvement in the remedy selection process and invites

public comment on all alternatives.

PUBLI C INVOLVEMENT PROCESS

EPA encourages residents and other interested parties to

read and comment on this Proposed Plan, the Final Report for Lead Slag Pile Remedial Investigation at the California Gulch Site, Leadville, Colorado (RI), and the F S. These documents describe the results of site investigations and the cleanup alternatives considered. The Proposed Plan is based on findings of the RI, the FS, and

other pertinent documents. These reports are located in

the information repositories and are included in the Administrative Record for the California Gulch Superfun d Site. The Administrative Record contains all

of the information upon which the selection of the remedy will be based.

EPA will make its final remedy selection only after considering all state and community comments. EPA may

modify the preferred alternative, select another alternative presented in this plan, or select a more appropriate

alternative based on new information or public comments. EPA encourages the public to review and comment on all identified alternatives, as well as to provide

a ny new information for EPA's consideration. Later this

year, EPA will publish a Record of Decision (ROD) that

responds to community comments and documents

EPA Announces Preferred Alternative .................. .p. 1 Public Involvement Process ........p. 2 Site Background ............... .p. 2 Assessment of Site Risks ........ .p. 5 Summary of Alternatives ..........p. 7 Cleanup Evaluation Criteria .......p. 8 Comparison and Evaluation

of Alternatives ................p. 9 Description of Preferred Alternative .................. .p. 9 Acronyms/Glossary ............. .p. 10

the rationale for its decision. The ROD will contain

responses to comments on the Proposed Plan.

This Proposed Plan is prepared to fulfill EPA's public participation responsibilities under Sections 113(k) and

117(a) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as

amended by the Superfun d Amendments and Reauthorization Act (SARA) of 1986.

Comments on the Proposed Plan and FS may be submitted either orally or in writing at the October 3,1996 public meeting, or you may send written comments, postmarked no later than October 28, 1996, to Rebecca Thomas at the address provided on page 1. Upon timely

request, the comment period may be extended. Such

requests should be submitted in writing to Rebecca Thomas at the EPA address provided on page 1 and must

be postmarked no later than October 28, 1996.

SIT E BACKGROUN D

Site History. The California Gulch Superfun d Site (hereafter, the site) is located in and around the community of Leadville, Colorado, about 100 miles southwest of Denver (Figure 1). Beginning in about 1860, the Leadville area was used extensively for mining, milling,

and smelting operations. Silver, gold, copper, lead, and

zinc were mined by underground and placer methods

from within the site. Approximately 17 smelter facilitie s

are reported to have once operated on site. Most operations ceased by about 1900, although some facilitie s continued to operate into the 1920's, such as Western Zinc,

and the into the 1960's, such as the Arkansas Valley Smelter. At present, nearly all of the mines within the site

boundaries are inactive; only a few small to moderatesized mining operations exist. All of the mill s and

smelters once situated on site have been demolished.

Due to historic mining, milling, and smelting operations,

t he site contains many tailings impoundments, fluvial

deposits , slag piles , waste rock piles , and mine water

drainage tunnels. Slag on site is the mineralized waste

byproduct of smelting and results from the processing of

lead ore in high temperature furnaces. Three major slag

pile s and several smaller piles remain at the site (Figure

2). In 1961, the Denver and Rio Grande Western Railroad (D&RGW ) purchased the Arkansas Valle y 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
Leadville

California Gulch NPL Site

Lake County

Leadvllle/»r

! CONTINENTA L DIVID E

FIGUR E 1 General Site Location

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FIGURE 2 SLAG PIL E LOCATION MAP

Source: TERRANEXT 1996
in 1983. This Proposed Plan addresses only fine slag

stockpiled as a subpile of the Arkansas Valley slag pile.

Regulatory History. In 1983, ERA. placed the California Gulch site on the National Priorities List (NPL), because

of concerns about the impact of mine drainage on surface

waters in the California Gulch and the impact of heavy

metals loading to the Arkansas River. Subsequent investigations revealed the presence of heavy metals in soils and

waste piles in and around residential and commercial

areas of Leadville. A preliminary risk assessment indicated that contaminant levels, particularly levels of

arsenic and lead, were high enough to be of potential

human health concern.

On December 3,1991, EPA and D&RGW entered into an Administrative Order on Consent (AOC) for the perfor- mance of a remedial investigation/feasibilit y 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 that addressed

seven lead slag piles , including the Arkansas Valley , Harrison, and La Plata slag piles , and one zinc slag pile. Followin g the RI, a Site-Wide Screening Feasibility Stud y (SFS) was undertaken as a joint effort between the

potentiall y responsible parties and EPA. The SFS was

completed in March 1993. It screened several remediation alternatives for all types of slag located on the site

based on specific criteria, such as relative cost, imple- mentability, and effectiveness . The three retained alternatives for further evaluation were: no action, institutional controls, and resource utilization (materials reuse).

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 paniculate release during ballast operations as a

potential human health exposure pathway. The consent

decree required D&RGW to perform a feasibilit y 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 operations plan to EPA. Followin g EPA's approval of the plan, ballast operations

commenced in August 1995. Ballast operations involve

the sorting of larger slag so that the size fraction of

greater than 3/8 inch and less than 2 1/2 inches is produced for railroad ballast. The undersized fraction (i.e.,

less than 3/8 inch), or sorted fine slag, that is produced by

the sorting process is stockpiled along with the previously sorted fine slag at the Arkansas Valley pile.

During the early part of 1995, a baseline human health

risk assessment was undertaken that further assessed

potential human health risks from exposure to heavy metals at the site. A result of the final baseline risk assessment was a Proposed No Action Plan for commercial and

recreational land uses at the site. The Proposed Plan

addresses areas within the site currently zoned commercial/industrial and areas used for non-residential recreational purposes. Five commercial/industrial areas at the

site, including the Arkansas Valley slag pile, were specifically excluded from the 1995 Proposed No Action Plan

because of concerns related to high levels of lead. Two

other properties within OU3, the former D&RGW railyard and the easement through town, were included in the

areas which carry the no action designation. The concentrations of lead in soils within the railyard were below

the level of concern, although D&RGW has identified a

small area with fine slag in the railyard. D&RGW has

prepared a plan which addresses removal and control of

fine slag from this area. The fine slag is to be removed

from the railyard and consolidated with the stockpiled

fine slag at the Arkansas Valley pile. The easement

through town was evaluated and determined not to contain concentrations of lead which would be of concern in

a recreational setting. As long as land use remains recreational or commercial/industrial, no action will be necessary.

In May of 1996, D&RGW submitted a feasibility study

f or the stockpiled fine slag (the FS) at the Arkansas Valley

pile, according to the terms of the Consent Decree. The

existing fine slag subpile and fine slag potentiall y generated from future ballast production were the focus of the F S. The FS provided a detailed analysis of the three

retained remediation alternatives from the SFS as applied

to the stockpiled fine slag.

ASSESSMENT OF SIT E RISKS

T he preliminary risk assessment identified lead and

arsenic as the primary chemicals of potential concern at

the 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 exposures. Therefore, a baseline human health risk assessment was

completed to incorporate all reliable data into a final risk

assessment for the site: Part A evaluates risks to residents

from lead; Part B evaluates risks to residents from metals other than 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 fol5
lowing paragraphs summarize results of the final baseline

risk assessment as they relate to the stockpiled fine slag

at the Arkansas Valley pile.

RESIDENTIA L RISK ASSESSMEN T

Exposure pathways determined to be the most important

for contact with mine-related waste at the site included

inadvertent ingestion of contaminated soil and dust, inadvertent ingestion of material at waste piles (such as, waste

rock, tailings, or slag), and ingestion of impacted groundwater. Other pathways of exposure to mine-related waste

(i.e., inhalation of airborne particulates, dermal contact

with contaminants in soil or dust, ingestion of homegrown vegetables, and ingestion of fish from contaminated surface waters) were judged to be sufficiently minor

that quantitative evaluation was not warranted.

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 into 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;

however, model estimates suggested the effec t could be

substantial, depending on the concentration of lead in the

waste pile and the frequency and extent of contact. It was

further concluded that waste piles can contribute to exposure not only through direct exposure to children who

play on the piles, but also indirectly by serving as a

source of lead contamination in nearby yards and homes

(contaminant migration to nearby yards and homes by

transport of airborne particulates).

Wind erosion and direct contact were not considered

viable release mechanisms for the stockpiled fine slag in

the SFS. However, based on the results of the risk assessment, EPA maintains some concern about the potential

f or paniculate release and human exposure should

resource utilization of the stockpiled fine slag be undertaken. (For example, inhalation of slag particles could

occur if the material is disturbed from its current state). If the resource utilization option is exercised, measures

would be required to prevent contaminant releases.

6

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

ground water in the area near the slag piles. When the

groundwater exposure pathway was evaluated in the 1996

final baseline risk assessment, data indicated that ingestion of the water from the shallow aquifer beneath some

of the large tailings piles along California Gulch would

be of very high concern to children. However, the 1996 FS determined that testing in 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 aquifer is

not currently used for drinking, and it is relatively unlikely that it will be used for drinking in the future. EPA has

determined that there is minimal potential for release of metals in leachate from the stockpiled fine slag, and that

the stockpiled fine slag poses, at most, an insignificant

impact on water quality. NON-RESIDENTIA L RISK ASSESSMENT

Leadville official s and business leaders expressed concern about possible risks and liabilities associated with

commercial and recreational uses within the site. Therefore, in the final baseline risk assessment, EPA

evaluated the 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 areas in and around

the community. The assessment was conducted to determine if environmental contamination was of concern at

any site locations presently zoned commercial/industrial

and to address concerns regarding the development of a

proposed bike path around the community.

Recreational User Exposure to Slag. The EPA proposed no action for non-residential recreational uses at

the site in the 1995 Proposed No Action Plan, based on a

comparison of action levels derived in the risk assessment

for recreational land use and measured and predicted surficial soil concentrations for both lead and arsenic. The

no action response applied to all areas of the site that are

used for recreational activities such as hiking, biking,

hunting, and rock hounding, and included that area of the

site proposed for construction of the Mineral Belt Bike Path. The slag pile area is situated in an area presently

zoned as industrial/mining and is not considered a recreational use area.
Worker Exposure to Slag. The area of the Arkansas Valley, Harrison, and La Plata slag piles were excepted

from the 1995 Proposed No Action Plan because of concerns about extensive levels of lead and potential exposure to workers in the commercial/industrial area of the

community. The worker risk assessment used the following approach:

• Lead and arsenic were evaluated as the chemicals

of concern. Even though other metals occur at

increased concentrations in the environment

around Leadville, experience at other sites, as

well as results of preliminary calculations, indicated that lead and arsenic are the "risk drivers."

• The ingestion pathway was evaluated as the

major pathway of concern. Exposure to soil and

dust was evaluated for workers. Exposure to

other media such as waste piles, surface water,

and sediments and exposure to soil/dust via other

pathways such as skin contact and inhalation of

airborne particulates were considered to be of

minor concern for workers.

• Because of uncertainties regarding actual levels

of exposure of workers, EPA did not calculate a

single concentration (action level) that would

identify an area as being of concern, but rather

calculated a range of soil concentrations that

could be considered protective for the commercial/industrial land use. While all of the values

within the range are credible, values from the

central portion were considered to be more likely

appropriate than values at the low end or the high

end.

• The potential for health risks for lead and arsenic

was evaluated by comparing risk levels from the

central portion of the range with maps showing

the measured or estimated concentrations of lead

and arsenic across the site. Areas where the concentrations were below the central range of risk

levels were judged to pose no unacceptable health

risks, while areas with potential for extensive

contamination above the central range of action

levels were considered to be of concern, requiring

further remedial response. It is also important to

note that it is the average concentration over

defined exposure areas that was compared to the

decision criterion, rather than values measured at

specific sampling locations.

For evaluation of lead exposure, the risk assessment

focused on female workers who were pregnant or might

become pregnant, based on health-based data that the

fetus of a pregnant worker is especially susceptible to the

effect s of lead. In order to determine lead action levels,

the risk assessment calculated levels of lead in soil that

would ensure that the mother would have a low chance of

having a blood lead level that might expose the fetus to

unacceptable levels of lead. The risk assessment estimated that lead action levels for pregnant workers could

range from 2,200 parts per million (ppm) to 19,100 ppm,

with central tendency values in the 6,100 to 7,700 ppm

range. After comparing the central tendency levels to

measured or estimated concentrations of lead in soils,

EPA proposed no action for commercial uses of the site,

with the exception of five site areas including the Arkansas Valley slag piles.

A lead action level in a commercial/industrial application

was proposed at 7,000 ppm in the FS for remediation of

soils in and around the slag piles. Based on the results of

subslag sampling conducted during the RI, the maximum

concentrations of lead in all subslag samples was 794

milligrams per kilogram (mg/kg is equal to ppm), well

below the lead action level.

Action levels were determined in the risk assessment for

arsenic in soil and 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. The EPA determined that there

are no identified areas within the site which contain

arsenic at levels of concern under a commercial/industrial scenario.

SUMMAR Y OF ALTERNATIVES

A wide range of cleanup options were considered in the SFS. Some were eliminated during preliminary screening because they would not effectivel y address contamination, could not be implemented, or would have had

excessive costs compared to other protective alternatives. Followin g screening, three alternatives were retained for

further evaluation for the fine slag sub-pile of the

Arkansas Valle y smelter slag pile. These alternatives

were: (1) no action, (2) institutional controls and fenci ng of the stockpiled fine slag, (3) resource utilization . These alternatives were compared and evaluated using

EPA's nine evaluation criteria described in the next

section.
CLEANU P EVALUATION CRITERIA

The three alternatives retained for stockpiled fine slag were evaluated in the FS using the nine criteria summarized below. In assessing alternatives, all must meet Criteria No. 1 and No. 2.

1. Overall Protection of Human Health and the Environment

addresses whether a remedy is protective and describes how risks

posed through each pathway are eliminated,

reduced, or controlled.

5. Reduction of Toxicity, Mobility,

or Volume through Treatment

refers to the preference for a remedy that reduces health hazards, the

movement of contaminants, or the

quantity of contaminants at the site through

treatment.

2.

3.

Compliance with Applicable or Relevant and Appropriate Requirements (ARARs) addresses

whether a remedy will meet all

applicable federal and state environmental laws and other relevant and appropriate requirements and/or provide grounds

for a waiver.

Short-Term Effectivenes s addresses the period of time needed to

complete the remedy, and any

adverse effect s to human health and

the environment that may be caused

during the construction and implementation

of the remedy.

Implementability refers to the

technical and administrative feasibility of an alternative or a remedy. It includes the availability of materials and services needed to carry

out a remedy. It also includes coordination of

federal, state, and local governments to work

together to clean up the site.

Cost Effectivenes s evaluates the

estimated capital , operation, and

maintenance costs of each alternative in comparison to other protective

alternatives.

State Acceptance indicates

whether the state agrees with,

opposes, or has no comment on the

preferred alternative.

4. Long-Term Effectiveness and Permanence refers to the ability of

a remedy to provide reliable protection of human health and the environment over time.

9. Community Acceptance includes

determining which components of

the alternatives interested persons

in the community support, have

reservations about, or oppose. Thi s assessment may not be completed until

public comments on the proposed plan are

reviewed.
COMPARISON AN D EVALUATION OF ALTERNATIVES

The FS was developed to address the alternatives evaluation for the stockpiled fine slag at the Arkansas Valley slag

pile at the site. The FS performed a detailed analysis of

t he three alternatives retained from the SFS using EPA's

nine evaluation criteria. A summary of the analysis of

each retained alternative is provided below.

Alternative 1; No Action. Generally, the No Action Alternative is provided for consideration as a baseline

against which other technologies can be compared, in

accordance with the National Contingency Plan (NCP). F or the stockpiled fine slag, the No Action Alternative is

proposed to leave the material in place with no remediation, engineering controls, institutional controls, or longterm maintenance. No action is protective of human

health and the environment and is considered effective

because no complete human exposure pathways were

identified for the stockpiled fine slag and because the

potential for release of metals in leachate from the stockpiled fine slag is minimal. Thi s alternative is technically

feasible and cost effective, since it does not rely on any

technology and has no cost.

Alternative 2: Institutional Controls/Fencin g of the Stockpiled Fine Slag. Institutional controls involve

restricting access or activities that could increase the

potential for leaching from stockpiled fine slag, for example, fencing, land-use restrictions, or deed restrictions. Deed restrictions are already recorded for the stockpiled

fine slag. The option considered is to fence and maintain

t he stockpiled fine slag located at the Arkansas Valley slag

pile. Fencing would eliminate the potential direct contact

pathway with the fine slag piles. Fencing would be protective of human health and the environment because no

complete human exposure pathways would exist (that is,

children would not have access to the piles) , and because

the potential for release of metals in leachate from the

stockpiled fine slag would remain minimal. Fencing

would be technically feasible. Costs associated with fencing are $161,000 with inspection and maintenance costs of

$8,500 for a 30-year period.

Alternative 3; Resource Utilization. Two options for

resource utilization (materials reuse) were identified in the F S: 1) to process slag for use as a concrete or asphal t

aggregate in construction, and 2) to use slag materials for

a stand-alone material in construction, such as backfil l or

pipe bedding. Resource utilization would be protective of

human health and the environment because appropriate

environmental controls for particulates emissions and

stormwater would be required to control contaminant

releases. Resource utilization may marginally decrease

the minimal metals concentrations in the stockpiled fin e

slag leachate through overall volume reduction. However,

the effectivenes s and implementability of this alternative

would be affected by the regional market demand for the

material. Effort s conducted to identify markets have been

unsuccessful to date, but a potential for future markets

exists and, therefore, this alternative is proposed as a contingency with "No Action" as the preferred alternative. Cost effectivenes s 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.

DESCRIPTION OF NO-ACTION PREFERRED ALTERNATIVE

The FS used a comparative analysis of alternatives to qualitatively evaluate each alternative and identify the advantages and disadvantages of each alternative relative to the

others, as well as to identify key tradeoffs . 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

t he 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. Selection of the No Action Alternative was based on these results.

T he No Action Alternative leaves sources in their existin g

condition with no control or cleanup planned and is selected for resources that pose no risk to human health or the

environment. The No Action Alternative is preferred with

the contingency that resource utilization may be undertaken in the future. Resource utilization involves use or reuse

of the source material as a commercial product which

removes the source partially or totally from the site.

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. Reuse of the

stockpiled fine slag would marginally reduce any possible

residual risk because of volume reduction.
ACRONYMS

AOC Administrative Order on Consent

ARARs Applicable or Relevant and Appropriate Requirements

CDPHE Colorado Department of Public Health

and Environment

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act of 1980

C SM Conceptual Site Model

D&RGW Denver and Rio Grande Western Railroad

EPA U. S. Environmental Protection Agency

FS Final Stockpiled Fine Slag Feasibility Study

OU3 Operable Unit 3

PRP Potentially Responsible Party

RI Remedial Investigation

RI/FS Remedial Investigation/Feasibility Stud y

ROD Record of Decision

N CP National Contingency Plan

N PL National Priorities List

p pm parts per million

SARA Superfun d Amendments and Reauthorization Act of 1986

S FS Site-Wide Screening Feasibility Study

GLOSSAR Y

Action Level: In the Superfun d program, the level of

contaminant concentration in the environment high

10

enough to warrant action or trigger a response under CERCLA/SARA and the NCP.

Administrative Order on Consent (AOC): A legal

agreement signed by EPA, the potentially responsible

party (PRP) for a site, and sometimes the state. Under a Consent Order, the violator agrees to pay for correction

of violations, take the required corrective or cleanup

actions, or refrain from an activity. It describes the action

to be taken and can be enforced in court.

Administrative Record: A file that is maintained, and

contains all information used, by the lead agency to make

its decision on the selection of a response action under

CERCLA. Thi s file is made available for public review

at one or more information repositories near the site. A

duplicate file is held in a central location, such as an EPA Regional Office.

Aquifer: An underground geological formation or group

of formations containing useable amounts of groundwater that can supply wells or springs.

Arsenic: A grayish white element found naturally in the

environment. It is a byproduct of copper, zinc, and lead

smelting. Doses taken over long periods can cause birth

defect s and genetic damage in test animals; there is evidence that it can cause skin and lung cancer in humans.

Ballast: Gravel or broken stone laid in a railroad bed or

used in making concrete.

Baseline Risk Assessment: A CERCLA study conducted at the same time as the remedial investigation (and

contained in the RI/FS report) that determines and evaluates risks that site contamination poses to public health

and the environment in the absence of remedial action.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA): A federal law

passed in 1980 and modified in 1986 by the Superfun d Amendments and Reauthorization Act (SARA). It sets

up a program to identify sites where hazardous substance

have been, or might be, released into the environment and

to ensure they are cleaned up.

Conceptual Site Model: A process in which information

about waste sources, release mechanisms, exposure pathways, and receptors at or near a site is used to develop a

conceptual understanding of the site, in order to evaluate

potential risks to human health and the environment.
Consent Decree: A legal document, approved and

issued by a judge , that formalizes an agreement reached

between EPA and potentially responsible parties (PRPs)

where PRPs will perform all or part of a Superfun d site

cleanup. The consent decree describes actions that PRPs

are required to perform.

Feasibility Study : A CERCLA study which identifies ,

screens, compares, and evaluates differen t alternatives for

cleaning up site contamination.

Heavy Metals: A group of chemical elements characterized by their ability to conduct electricity and heat.

Exposure to some heavy metals can have toxic effect s on

the body and can cause adverse impacts on fish and other

aquatic communities. Heavy metals can be highly toxic

at relatively low concentrations.

Human Health Risk Assessment: The portion of the

baseline risk assessment that addresses potential risks to

human receptors at or near the site.

Institutional Controls: A legal and enforceable restriction or agreement that enhances and complements the

permanence of a cleanup remedy. Examples are laws, and

zoning, land use, and deed restrictions.

Leachate: A liquid resulting when water, such as

stormwater or rainwater, collects contaminants as it trickles down through wastes or contaminated soil.

Lead: A metal that is hazardous to health, if breathed or

swallowed. Its use in gasoline, paints, and plumbing

compounds has been sharply curtailed or restricted by

federal laws. Children less than six years of age are considered the most susceptible to lead poisoning. Lead

accumulates in the body, and exposure to low levels of

lead over long time periods may cause brain, bone, or

nerve damage or learning disabilities in children.

National Oil and Hazardous Substances Pollution Contingency Plan (NCP): The federal regulation that

guides the CERCLA/SARA program.

Parts Per Millio n (ppm) : A unit of measure used to

express very small concentrations of contamination in

soil, sediments, water, air, or other media.

Proposed Plan: A document requesting public input on

a proposed remedial alternative.

Record of Decision: A document which is a consolidated source of information about the site, the remedy selection process, and the selected remedy for a cleanup under

CERCLA.

Release Mechanism: The means by which a contaminant can be released from a source of contamination.

Examples include spills , soil disturbance, or leaching to

groundwater.

Remedial Investigation: A study conducted to identif y

the types, amounts, and locations of contamination at a

facility . It also evaluates possible risk to public health

and the environment from exposure to contamination.

Resource Utilization: The use of certain waste materials, such as fine slags, for commercial purposes such as

aggregate in concrete or backfil l material.

Screening of Alternatives: During the feasibilit y study,

alternatives are evaluated to verify that they are protective, meet regulatory requirements, and are implementable.

Slag: The solid, nonmetallic, glasslike byproduct formed

in a blast furnace or smelter when melting metals or

reducing ores. Slag float s as a liquid on top of the

process, and after it is cooled and solidified, may be used

as an aggregate in concrete or for other purposes such as

backfill .

Smelter: A facilit y in which ore is smelted, that is, melted in order to separate out the metal.

Superfun d Amendments and Reauthorization Act

(CERCLA) : Modification s to CERCLA enacted on October 17, 1986.

Tailings: The portion of mineral ores that is separated

out during the millin g of ore and disposed.

Transport Pathways: The means by which contaminant

migration may occur once released from a source of contamination, for example via windblown dust or surface

water runoff .

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