ENGINEERING EVALUATION/COST ANALYSIS

RESPONSE ACTION
UNDERTHE

COMPREHENSIVE ENVIRONMENTAL RESPONSE
COMPENSATION AND LIABILITY ACT

UNION PACIFIC RAILROAD
WALLACE-MULLAN BRANCH

January 15, 1999

Environmental Protection Agency
Region 10


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TABLE OF CONTENTS

LIST OF FIGURES 	 iv

LIST OF TABLES 	 iv

LIST OF APPENDICES	 iv

LIST OF ACRONYMS	v

EXECUTIVE SUMMARY	1

1.0 INTRODUCTION 	1

2.0 SITE CHARACTERIZATION	3

2.1	SITE LOCATION 	3

2.2	TYPE OF FACILITY & OPERATIONAL STATUS 	3

2.2.1	Historic Construction of the Wallace-Mullan Branch 	4

2.2.2	Operational Activities 	4

2.3	STRUCTURES	4

2.4	GEOGRAPHY AND TOPOGRAPHY	5

2.4.1	Geography 	5

2.4.2	Topography	5

2.5	GEOLOGY & SOIL	7

2.5.1	Regional Geologic Setting	7

2.5.2	Soils	8

2.6	SURROUNDING LAND USE & POPULATION 	8

2.7	METEOROLOGY	9

2.7.1	Climate	9

2.7.2	Hydrology	9

2.8	ECOSYSTEMS 	10

2.8.1	Coeur d'Alene Basin Ecosystem	10

2.8.1.1	Rivers and Streams	10

2.8.1.2	Riparian Zone 	11

2.8.1.3	Wetlands	11

2.8.1.4	Lateral Lakes	11

2.8.1.5	Lake Coeur d'Alene	12

2.8.1.6	Uplands	12

2.8.2	Flora and Fauna of the Coeur d'Alene Basin	13

2.8.2.1	Vegetation	13

2.8.2.2	Wildlife	14

2.8.2.3	Fisheries 	15

2.9	PREVIOUS REMOVAL AND RESPONSE ACTIONS 	17

2.10	SOURCE, NATURE & EXTENT OF CONTAMINATION 	17

2.10.1	Source of Contamination	17

2.10.1.1	Mainline Construction 	18

2.10.1.2	Siding Activities	19

2.10.1.3	Flood plain Soils/Sediments	19

2.10.2	Nature and Extent of Contamination (Analytical Data)	19

2.10.2.1 Soil Sampling Procedures 	20

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TABLE OF CONTENTS
(Continued)

2.10.2.2 Soil Sampling Results 	20

2.10.3 Fate And Transport Of Contaminants 	22

2.11 STREAMLINED RISK EVALUATION 	23

2.11.1	Human Health Risk	23

2.11.2	Ecological Risk	24

2.11.3	Risk Management	25

3.0 IDENTIFICATION OF RESPONSE ACTION OBJECTIVES	27

3.1	STATUTORY LIMITS	27

3.2	SCOPE, GOALS AND OBJECTIVES 	27

3.2.1	Scope of the Response Action 	27

3.2.2	Goals and Objectives of the Response Actions	27

3.2.3	Compliance with ARARs and Other Criteria 	28

3.3	RESPONSE ACTIVITIES SCHEDULE 	29

4.0 IDENTIFICATION AND ANALYSIS OF RESPONSE ACTIONS	31

4.1	IDENTIFICATION OF POSSIBLE RESPONSE ACTIONS	31

4.2	INITIAL SCREENING OF POSSIBLE RESPONSE ACTIONS	32

4.2.1	No Action 	32

4.2.2	ICs 	33

4.2.3	Protective Barriers 	33

4.2.4	Removal and Disposal/Consolidation 	34

4.2.4.1	Removal 	34

4.2.4.2	Disposal/Consolidation	35

4.2.5	Treatment	37

4.3	IDENTIFICATION OF RESPONSE ALTERNATIVES 	38

4.3.1	ICs 	38

4.3.2	Protective Barriers 	39

4.3.3	Removals and Disposal/Consolidation 	39

4.4	ANALYSIS OF ALTERNATIVES	40

4.4.1	ICs 	40

4.4.1.1	Implementability	40

4.4.1.2	Effectiveness	42

4.4.1.3	Cost	43

4.4.1.4	Conclusions	44

4.4.2	Protective Barriers 	44

4.4.2.1	Implementability	45

4.4.2.2	Effectiveness	46

4.4.2.3	Cost	48

4.4.2.4	Conclusions	50

4.4.3	Removal and Disposal/Consolidation 	50

4.4.3.1	Removals 	50

4.4.3.1.1	Implementability 	51

4.4.3.1.2	Effectiveness 	51

4.4.3.1.3	Cost	53

4.4.3.2	Disposal/Consolidation	54

4.4.3.2.1	Implementability 	55

4.4.3.2.2	Effectiveness 	55

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TABLE OF CONTENTS
(Continued)

4.4.3.2.3 Relative Cost 	56

4.4.3.3	Conclusions	57

5.0 COMPARATIVE ANALYSIS OF REMOVAL ACTION ALTERNATIVES	58

6.0 RECOMMENDED REMOVAL ACTION ALTERNATIVE	59

6.1	ICs	59

6.1.1	Controls on Use of and Access of the ROW	60

6.1.2	Educational Programs	60

6.1.3	Signage 	61

6.1.4	Fencing/Barricades	61

6.2	PROTECTIVE BARRIERS 	61

6.2.1	ACP - Main Line Rail Bed 	62

6.2.2	Gravel/Soil Barriers - Residential 	62

6.2.3	Gravel/Soil Barriers - Rural Sidings	63

6.3	REMOVAL AND DISPOSAL/CONSOLIDATION 	63

6.3.1	Concentrate Accumulations 	64

6.3.2	Track and Tie Removal/Salvage	64

6.3.3	Sidings	64

6.3.4	Upland Areas (Reservation) 	65

6.3.5	Complementary to Barrier Placement 	65

6.3.6	Disposal/Consolidation 	65

6.4	SUMMARY	65

7.0 REFERENCES	67

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LIST OF FIGURES

Figure Title
Wallace-Mullan Branch Site Location

Wallace-Mullan Branch Coeurd'Alene Indian Reservation Section

Wallace-Mullan Branch Lower Basin Section

Wallace-Mullan Branch Upper Basin Section

Typical Rail Bed Cross-Section

Schematic Mainline and Siding Sampling Plan

Schematic Railbed Vertical Sampling Intervals

Lead Concentrations Within the Reservation

Lead Concentrations Within the Lower Basin

Lead Concentrations Within the Upper Basin

Lead Concentrations at Depth Within the Mainline Railbed

Conceptual Trail Construction Plan

Conceptual Residential Barrier - Mainline & Siding Section

Conceptual Residential Barrier Plan

Conceptual Rural Siding Removal & Barrier Plan

LIST OF TABLES

Table Title

1996/1997 Right-of-Way Soil Sampling Data - Soil Sampling Location Key
1996/1997 Right-of-Way Soil Sampling Data - Mainline Sampling Locations
1996/1997 Right-of-Way Soil Sampling Data - Siding Sampling Locations
1996/1997 Right-of-Way Soil Sampling Data - Sampling at Depth
1997 Right-of-Way Soil Sampling Data - QA/QC Data
Potential Chemical-Specific ARARs
Potential Location-Specific ARARs
Potential Action-Specific ARARs

Summary of Initial Screening Analysis of Response Actions
Summary of Detailed Analysis of Response Actions
Summary of Comparative Analysis of Response Actions
Removal Volume Estimate

LIST OF APPENDICES

Appendix Title
Streamlined Risk Assessment

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LIST OF ACRONYMS

ACP - asphalt concrete pavement
AMSL - above mean sea level
AOC - area of contamination

ARARs - Applicable or Relevant and Appropriate Requirements

BHSS - Bunker Hill Superfund Site

BLM - U.S. Bureau of Land Management

BMPs -best management practices

CDR - Coeur d'Alene River

CERCLA - Comprehensive Environmental Response, Compensation and Liability Act

C.F.R. - Code of Federal Register

CIA - Central Impoundment Area

CITU - Certificate of Interim Trail Use

CLCC - Clean Lake Coordinating Council

cy -cubic yard

ea - each

EE/CA - Engineering Evaluation and Cost Analysis

EPA - U.S. Environmental Protection Agency

ICs - Institutional Controls

ICC - Interstate Commerce Commission

IDAPA - Idaho Administrative Procedures Act

IDEQ - Idaho Division of Environmental Quality

KSF - thousand square feet

LDRs - Land Disposal Restrictions

If - linear foot

MFG - McCulley, Frick & Gilman, Inc.

MP - Milepost

NCP - National Contingency Plan

NFCDR - North Fork of the CDR

NRDA - Natural Resource Damage Assessment

NRRB - National Remedy Review Board

O&M - operation and maintenance

OTM - other track materials

oz/sy - ounces per square yard

PAHs -polycyclic-aromatic-hydrocarbons

PCBs - poly-chlorinated biphenyls

ppm - parts per million

PTM - Principal Threat Materials

QA/QC - Quality Assurance/Quality Control

RAOs - response action objectives

RCRA - Resource Conservation and Recovery Act

RI/FS - Remedial Investigation/Feasibility Study

RME - Reasonable Maximum Exposure

ROD - Record of Decision

ROW - Right-of-Way

SAIC - Science Applications International Corporation

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LIST OF ACRONYMS (Continued)

SFCDR - South Fork of the Coeur d'Alene River

STB - Surface Transportation Board

|jg/dl - micrograms per decaliter

UPRR- Union Pacific Railroad

U.S.C. - United States Code

USDA SCS - U.S. Department of Agriculture Soil Conservation Service
USDC - U.S. Department of Commerce
USFS - U.S. Forest Service
USGS - U.S. Geological Survey

USHUD - U.S. Department of Housing and Urban Development
WWP - Washington Water Power

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EXECUTIVE SUMMARY

This Engineering Evaluation and Cost Analysis (EE/CA) addresses contamination within the
approximately 71.5-mile long right-of-way (ROW) for the main line track and related sidings of Union
Pacific Railroad's (UPRR) Wallace-Mullan Branch, which extends across the panhandle of northern
Idaho. The purpose of the EE/CA is to evaluate alternatives for the purpose of selecting an
appropriate response action to address contamination of portions of the ROW with mine waste found
at various locations along the ROW. For purposes of this EE/CA the term "Mine Waste" includes
jig and flotation tailings, waste rock, concentrates and ores all of which are derived from mining
activities.

This EE/CA addresses the main line and related sidings of the Wallace-Mullan Branch ROW.
The 7.9 mile section of the ROW within the Bunker Hill Superfund Site (BHSS) has been addressed
as part of the BHSS Record of Decision (ROD) (EPA, 1992), and is excluded from this EE/CA. The
response action does not address: any spurs or connecting branch lines outside of the Wallace-
Mullan ROW; non-siding areas of the Wallace Yard outside a 26-foot-wide corridor bracketing the
main line; and areas of the Hecla Mine tailings impoundment and the Morning Mine Rock Dump that
may encroach on the ROW. These areas will be addressed within the Bunker Hill Basin Wide
Remedial Investigation/Feasibility Study (RI/FS) and/or other response actions.

The response actions described in this EE/CA will be conducted pursuant to the
Comprehensive Environmental Response, Compensation and Liability Act of 1980 as amended by
the Superfund Amendments and Reauthorization Act of 1986 (CERCLA). This EE/CA has been
prepared in accordance with the National Contingency Plan (NCP) and the U.S. Environmental
Protection Agency's (EPA) Guidance on Conducting Non-Time-Critical Removal Actions Under
CERCLA (EPA, 1993) (the EE/CA Guidance).

The ROW passes through a wide variety of settings, terrain and conditions. Through
approximately 80 percent of its length, the ROW generally follows the Coeur d'Alene River and is
mostly within the flood plain. For the remaining 20 percent of its length, the ROW is adjacent to Lake
Coeur d'Alene or in the upland areas of the Coeur d'Alene Indian Reservation. These various
settings can generally be characterized into three sections: (1) the upper South Fork of the Coeur
d'Alene River Basin (the Upper Basin) which includes the western portion of the Mullan Branch
extending from Mullan (Milepost [MP 7]) to Wallace (MP 0) and the eastern most portion of the
Wallace Branch extending from Wallace (MP 80) to west of Enaville (MP 62); (2) the lower Coeur
d'Alene River Basin (the Lower Basin) which starts downstream of the confluence of the South and
North Forks of the Coeur d'Alene River west of Enaville (MP 62) to Harrison (MP 31); and (3) the
east shoreline of Lake Coeur d'Alene beginning at Harrison (MP 31) and the upland rolling hills west
of Lake Coeur d'Alene to Plummer Junction (MP 6).

The rail line was constructed in the late 1800s to serve the mining industry in the Silver
Valley. In some locations within the Upper Basin, the line was constructed on top of a pre-existing
mantle of fluvially deposited tailings, and in other areas mine waste rock was used as fill material
to elevate the line above the river level. Tailings and waste rock were also used as a component
of the rail bed ballast throughout the length of the line. Originally, approximately 168,000 cubic yards
of ballast were placed along the rail bed. The original ballast was comprised of a mixture of tailings,
waste rock and locally available gravels. Most of the original ballast is still in place, isolated by the
track structure and ballast material that was subsequently placed during the active life of the line.
In the Upper Basin, waste rock and tailings were used as fill to construct portions of the railroad
subgrade. In the Lower Basin, subgrade materials were obtained from local quarries.

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The rail line primarily served the mining industry in the Silver Valley, transporting ores and
concentrates to and from the mines and mining process facilities. At various locations along the rail
line, and in particular at sidings and loading/unloading areas, there is evidence of spillage of these
ores and concentrates (which have higher concentrations of lead and other heavy metals than the
tailings and waste rock).

Lead-bearing tailings are pervasive throughout the river flood plain and, thus, throughout
much of the lateral zones of the ROW. It is reported that more than 72 million tons of tailings have
been transported down the river from upstream source areas as a result of more than 80 years of
mining activities (Tetra Tech et al, 1987). Analytical data from representative soil sampling along
the ROW verify the existence of tailings in the flood plain, including a layer beneath the railroad
subgrade embankment in some locations. The data also confirm the use of tailings and waste rock
in the original ballast and portions of the subgrade embankment in the Upper Basin.

The goals of the EE/CA are to effectively address the identified contamination within the
ROW in a manner that is protective of human health and the environment and in compliance with
Applicable or Relevant and Appropriate Requirements (ARARs) to the extent practicable. The
objectives of the response actions considered within the EE/CA are to minimize the potential for
direct exposure to Mine Waste, and limit the potential for the environmental transport of
contaminants. The analysis presented herein builds upon the knowledge gained through
investigation, design and implementation of remedial actions within the 7.9-mile segment of the
ROW that passes through the BHSS.

The ROW and many of the areas that would be accessed from the ROW are already being
used, to some extent, for recreational purposes. Contamination throughout the ROW and adjacent
areas is extensive. In addition, the ROW between Enaville and Harrison is subject to potentially
significant recontamination due to flood events until complete, non-ROW, source control measures
are implemented in upstream areas. Appropriate response actions combined with appropriate
management of the ROW corridor offers the opportunity to reduce the risks associated with potential
exposures to these contaminants.

The ROW is a long, narrow corridor that passes through a variety of settings, conditions, and
terrain. Accordingly, several alternative response actions have been identified for consideration
within the EE/CA. It was expected that no single response action alternative would be universally
applicable to the entire length of the ROW. The categories of response actions considered are as
follows:

No action (baseline),

Institutional controls (ICs),

Protective barriers,

Removal and disposal/consolidation, and
Treatment.

In accordance with the EE/CA Guidance, all of the potential response actions were evaluated
and screened with respect to implementability, effectiveness, and cost. The following response
action categories survived the initial screening and were retained for further evaluation:

Institutional controls (ICs),

Protective barriers, and
Removal and disposal/consolidation.

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The surviving categories of potential response actions were further evaluated for their
applicability, either individually or in combination, to the specific settings and conditions found along
the ROW. Again, each category was evaluated individually with respect to implementability,
effectiveness, and cost.

The conclusions of the detailed analysis are generally as follows:

ICs, if properly established and enforced in conjunction with other physical response
actions, can effectively increase the protectiveness and durability of the physical
response actions. The benefits of ICs would likely be maximized if implemented
uniformly throughout the length of the ROW, consistent with the setting and
anticipated future use at a given location.

In-situ containment of contaminated materials beneath a suitable protective barrier
is an efficient and cost-effective means of protecting human health and the
environment along the ROW. Selection of an appropriate barrier material must
reflect consideration of the setting, conditions, and anticipated future use of that
particular area of the ROW where the barrier is to be applied.

Selective removal with disposal and/or consolidation of contaminated soils from key
areas of the ROW, particularly in preparation for implementation of other response
actions, will serve to enhance the effectiveness and acceptability of those response
actions.

In addition to the individual evaluations, a comparative analysis of the potential response
actions was also made. The comparative analysis builds upon the detailed analyses by examining
the performance of each alternative relative to the other response actions within the context of each
of the evaluation criteria (implementability, effectiveness and cost). The findings of the comparative
analysis are as follows:

Response actions involving selective removals and disposal/consolidation of
contaminated material, placement of protective barriers, and ICs are implementable
with certain constraints. The relative implementability of each will depend upon
appropriately matching one or more of the various possible response actions to the
particular settings and conditions that are found along the ROW.

Selective removals of contaminated materials will provide effective long-term
protection for human health and the environment; however, the practicality of wide-
spread removal of large quantities of contaminated materials varies within some
portions of the ROW, particularly in flood plain areas. The long-term effectiveness
of removals in the flood plain areas may be reduced due to possible recontamination
of the areas prior to completion of source control actions upstream.

Placement of clean soil barriers in selected areas, to contain and isolate
contaminated materials, will be an effective response action, provided that the barrier
materials are chosen appropriately and ICs are implemented to ensure the long-term
integrity of the barriers.

ICs are generally of limited effectiveness when implemented in the absence of other
actions, such as removals or barrier placement; however, they are useful to
complement or supplement the effectiveness of the physical response actions. In

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some situations, however, ICs may be effective as stand-alone actions, such as use
of fencing and signs to restrict access to small areas of particular concern.

The relative unit costs of the possible response action alternatives will vary
depending upon the materials used (such as physical components of ICs or
protective barrier materials) and the relative location of the work area (which affects
the cost of disposal of excavated materials). In order of increasing range of unit
costs, ICs are the least expensive response actions, with a significant jump in cost
for protective barriers and removal actions. The total costs of response actions will
vary depending upon the scope of the actions implemented throughout the entire
length of the ROW.

An additional important consideration in the evaluation of the response action alternatives
is the potential future use and ownership status of the ROW. In 1992, the Interstate Commerce
Commission (ICC) determined that UPRR could discontinue rail service on the Wallace-Mullan
Branch. In a 1994 decision the ICC clarified that UPRR could not engage in track salvage activities
(the first step in implementation of the response actions) and thereby complete abandonment of the
Wallace-Mullan Branch until compliance with certain conditions relating to the environmental impact
of the proposed salvage were achieved and reviewed by the ICC. Since 1992, UPRR has, with
various parties, discussed the possibility of the line being converted to non-rail use through an
application for a Certificate of Interim Trail Use (CITU). Under a CITU, the UPRR ROW would be
transferred to a third party for interim recreational or conservation purposes. In 1992 an application
for a CITU was filed by the Transcontinental Trails Association. A second application for issuance
of a CITU was filed by the Rails-to-Trails Conservancy in 1995. The Surface Transportation Board
(STB), the successor agency to the ICC, denied the Rails-to-Trails Conservancy application without
prejudice to a subsequent applicant that would assume responsibility for the ROW and the trail.

The State of Idaho and Coeur d'Alene Tribe are contemplating entering into a joint
arrangement to have the CITU and control of the right of way transferred to them. Because a CITU
is deemed by statute to preserve the ROW as a potential rail corridor and not to constitute an
abandonment of the line, any reversionary interests in the ROW property are not effected.
Alternatively, if a CITU is not issued by the STB and UPRR completes the abandonment process,
the property may revert to persons or entities holding the reversionary property interest; thus,
breaking the property up among potentially many land owners.

The issuance of the CITU is an action to be taken by the STB and not part of the CERCLA
decision process addressed by this EE/CA. However, since this EE/CA has been prepared to
determine what response actions are needed to address human health and environmental concerns
along the ROW, the potential issuance of a CITU for the ROW affects the control of and
consequently the types of exposures to contamination that residents of the Coeur d'Alene Basin and
others coming onto the ROW may experience in the future. The human health risk assessment
incorporated into this EE/CA has taken such potential impacts on human health into consideration.
Furthermore, while conversion of the ROW to recreational purposes under a CITU is not in of itself
a CERCI.A response action, the EE/CA evaluation has determined that the response actions under
consideration may be more readily implemented in the context of such a conversion. Additionally,
as previously stated, if a CITU transfer of the ROW for recreational or conservation purposes were
not implemented, the ROW may revert to persons or entities holding the reversionary property
interest. The effects of such a reversion of the ROW on the implementability and effectiveness of
response actions under consideration are also discussed, as relevant, in this EE/CA.

Based on the findings of the individual and comparative analyses, three categories of
response actions were identified as being protective and compliant with ARARs and therefore

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appropriate for implementation at various locations along the ROW. These response action
categories include:

Institutional controls,

Protective barriers, and

Removal and on-site disposal or consolidation.

The selection of specific actions within the recommended response action categories
considered the configuration of the ROW, its position within and between various communities, and
the historic and probable future use of the ROW as a recreational trail, as well as the probable
influence of off-ROW conditions including possible future flood impacts. The recommended actions,
grouped by response action category, are generally as follows:

Institutional Controls

Restrictions to regulate access to and use of the ROW, and to ensure that
the physical components of the response action remain intact and function
as intended.

Educational programs and health monitoring, as necessary, to increase
public awareness of conditions and potential hazards and to alert ROW users
of location-specific issues and concerns.

Signs to provide location-specific warnings to ROW users of potential
exposures beyond the portions of the ROW where Mine Waste has been
removed or capped.

Fencing/barricades to provide a physical barrier against access to potentially
hazardous areas where Mine Waste has not been removed or capped.

Protective Barriers

Asphalt concrete pavement (ACP) barrier, complete with an appropriate clean
gravel base layer and shoulder caps, will be constructed over the main line
ballast material throughout the length of the ROW in the Upper and Lower
Basin areas. The ACP will provide for durable containment of ballast material
containing Mine Waste, as well as a desirable traffic surface for the
contemplated future use of the ROW as a trail.

Gravel and/or vegetated soil barriers in residential and other areas to provide
protection against direct contact with potentially contaminated materials. The
gravel and/or vegetated soil barriers will provide protection in areas where the
frequency and duration of activities within the ROW would be expected to be
highest due to the proximity of dwellings and the ease of access to the ROW.

Gravel and/or vegetated soil barriers in former siding areas due to
considerations of potential use and contaminant concentrations. Sidings
represent areas where the potential for elevated concentrations of
contaminants is highest due to past loading/unloading activities. The siding
locations represent natural stopping points for ROW users because of their
intermittent location between communities and their wider, more level
topography.

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Removal and Disposal/Consolidation

Selective removals are recommended from: sidings and other areas where
the potential for the presence of concentrates is greatest; areas where the
ballast material and/or identifiable accumulations of concentrates are the
primary sources of Mine Waste within the ROW (e.g., the mainline and siding
ballast along the east shore of Lake Coeur d'Alene and within the upland
areas west of the lake); and areas where protective barrier layers must be
recessed into the native soils so that the finished surface grade will be
compatible with adjacent areas (transitional areas within residential and
siding areas, as necessary) or to preserve existing surface drainage paths.

The recommended disposal alternatives for these removals are on-site
consolidation and containment and/or disposal.

The recommended response actions were also evaluated within a streamlined risk
assessment to determine the protectiveness of the actions relative to human health. The risk
assessment evaluated the incremental human health risks associated with the contemplated future
use of the ROW as a trail under the no-action scenario as compared to the use of the ROW after
the implementation of the recommended response actions. The streamlined risk assessment
determined that there are three primary exposure scenarios and resulting categories of risk
management required for the ROW. These risk management categories are: (1) residential
exposure management; (2) recreational exposure management; and (3) occupational exposure
management. The risk assessment determined that the removal/disposal and protective barrier
response actions combined with long-term maintenance of the barriers effectively provides for the
necessary residential risk management. Although these physical response actions will reduce risks
in the recreational and occupational categories, the institutional control program is a critical
component for managing risks associated with these two exposure scenarios.

The EE/CA analysis, including the streamlined risk assessment, has determined that the
above recommended response actions for the ROW will mitigate the identified human health
concerns and are compliant with ARARs. The EE/CA has also determined that the conversion of
the ROW to a recreational trail will enhance the implementability and effectiveness of the response
actions.

The EE/CA has not made a detailed evaluation of ecological risks; however, the
recommended response actions are expected to be beneficial in mitigating ecological risks that may
be associated with contaminants found within the ROW. Ecological risks that may exist throughout
the Coeur d'Alene Basin will be evaluated and appropriately addressed as part of the ongoing Bunker
Hill Basin Wide RI/FS and/or other response actions.

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