PB96-963108
EPA/AMD/R10-96/146
April 1997
EPA Superfund
Record of Decision Amendment:
Bunker Hill Mining & Metallurgical
Complex (Non-Populated Areas)
Superfund Site, Smelterville, ID
9/9/1996
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,? UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
r REGION 10
1200 Sixth Avenue
Seattle, Washington 98101
Reply To
AtmOf: ECL-111
Septembers, 1996
MEMORANDUM
TO: Chuck Clarke, Regional Administrator
FROM: Michael F. Gearheard, Associate Directoj
Environmental Cleanup Office
SUBJECT: Amendment to the Record of Decision for the Bunker Hill Mining and
Metallurgical Complex (Non-Populated Areas) Superfund Site
The attached ROD Amendment represents a minor overall change to the Bunker Hill
non-pop. ROD. This proposed change updates the stabilization remedy for "principal threat
materials" to containment in order to promote remedy cost effectiveness. Treatment of the
currently estimated volume of PTMs would have cost in excess of $7,000,000. The current
estimate of containment is just over $600,000. The Amended remedy therefore represents a
90 percent cost savings over the 1992 ROD remedy and would achieve the same level of
protectiveness of human health and the environment.
During the public meeting on August 15, no formal comments were received on the
proposed plan. Only one comment letter was received from the Coeur d'Alene Tribe. The
Tribe's comments are addressed in the Responsiveness Summary of the Amended ROD. The
State concurs with this ROD Amendment.
Attachment
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REFERENCE:
COEUR D'ALENE TRIBE
RECEIVED
ROUTE 1 BOX 11-F.A.
TRIBAL HEADQUARTERS 4lip o n 1QOC
PLUMMER, IDAHO 83851 ""0 0 [} 131*0
(20S) 686-1800 Fax (20S) 686-1182
t'«vir«nnu:n,al Cleanup Office
August 26, 1996
Sean Sheldrake, Project Manager
US EPA Mailstop:ECL-lll
1200 Sixth Ave.
Seattle, WA 98101
RE: Proposed Amendment to the Record of Decision, Bunker Hill Mining and Metallurgical
Complex Superfund Site, Shoshone County, Idaho
Dear Sean:
Thank you for the opportunity to comment on EPA's proposed Amendment to the Bunker Hill
ROD. Below are the Coeur d'Alene Tribes comments:
1) This is a unique proposal, because the bottom liner which is outlined in this amendment and
subject to review by the public prior to enacting has already been installed. At a minimum, this
has the appearance of poor coordination or impropriety. I urge EPA to better coordinate its
administrative duties with its construction projects in the future.
2) The Principal Threat Threshold Criteria (PTM) were established as part of the stabilization
option. Because of the differing technologies (stabilization versus containment) it is unclear
whether these numbers should be adjusted in response to the proposed ROD amendment.
3) The Draft Amendment concludes approximately 73,000 yd3 of material will be contained.
The containment cell is estimated at 100,000 yd3. The 73,000 yd3 will expand to an unknown
quantity because of handling and mercury stabilization. Additional space may therefore be
available if expansion is minimal. Additionally, the cell could be expanded upwards to create
space for additional materials. The proposal should consider including additional wastes in the
cell, whether from on-site or off-site. The Tribe has long-held that the Bunker Hill Site should
be used as a regional repository. While EPA has concluded that only on-site wastes will be
disposed on-site, this amendment provides a new occasion to consider the idea.
4) If the containment structure leaks, unlike stabilized materials, the contamination will be
instantaneous and concentrated. Therefore, the existing monitoring plan should be reviewed to
ensure that it takes into account the nature of the disposed materials (chemical availability) and
containment method (HDPE susceptibility and immediacy of release upon breach
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(notwithstanding the clay layer)).
Thank you for considering these comments. Please contact me if you need additional
information.
Sincerely,
Phillip Cemera, Project Manager
Natural Resources Damage Assessment
Coeur d'Alene Tribe
CC: Stu Levit
Chronolog
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United States Environmental Protection Agency
Region 10
1200 Sixth Avenue
Seattle, Washington
Non-Populated Areas
Bunker Hill Superfund Site
Shoshone County, Idaho
Amended Record of Decision
Decision Summary and
Responsiveness Summary
September 1996
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Table of Contents
Section Page Number
Declaration Declaration-1
Site
Statement of Basis and Purpose
Assessment of the Site
Description of the Amendment to the Remedy
Declaration
Decision Summary
Introduction Decision Summary-1
Site Name and Location
Lead and Support Agencies
Statutory Citation for a ROD Amendment
Date of ROD Signature
Need for the ROD Amendment
Public Involvement
Administrative Record
Site History 3
Remedy Selected hi the ROD 4
Description of the Modified Remedy 5
Evaluation of Alternatives 6
Overall Protection of Human Health and the Environment
Compliance with ARARs
Long-term Effectiveness and Permanence
Reduction of Toxicity, Mobility, and Volume Through Treatment
Short-term Effectiveness
Implementability
Cost
State Acceptance
Community Acceptance
Statutory Determination 10
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Tables
Table 1 - Principal Threat Materials Table
Table 2 - Summary of Changes
Table 3 - Monocell Performance Standards
Table 4 - Principal Threat Materials Estimated Quantities
Figures
Figure 1 - PTM Disposal Cell (Grading and Lining Plan)
Figure 2 - PTM Disposal Cell (Section)
Figure 3 - PTM Disposal Cell (Details)
Responsiveness Summary Responsiveness-1
Introduction
Community Involvement
Comments and Responses
Appendices
A: State Acceptance Letter
B: Design Criteria and Performance Standards
C: Geomembrane Quality Assurance/Quality Control Program Requirements
D: Geomembrane Minimum Specifications
11
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Declaration
Non-Populated Areas Operable Unit
of the Bunker Hill Superfund Site
Amended Record of Decision
Site
Non-populated Areas Operable Unit (Mining and Metallurgical Complex), Bunker Hill
Superfund Site, Shoshone County, Idaho.
Statement of Basis and Purpose
This Record of Decision (ROD) Amendment has been developed in accordance with
the Comprehensive Environmental Response, Compensation and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), 42 U.S.C. Section 9601 et seq.. and to the extent practicable, the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP), 40 Code of Federal Regulations
(CFR) Part 300. The decision to amend the ROD is based on the administrative record for
the non-populated areas, which was updated August 14, 1996, to include information that
was generated since the issuance of the ROD in 1992 pertaining to this Amendment.
The State of Idaho concurs with the ROD Amendment.
Assessment of the Site
Actual or threatened releases of hazardous substances in the former Metallurgical
Complex, if not addressed by implementing the selected remedy documented in the ROD as
modified in this ROD Amendment, may present an imminent and substantial threat to human
health, welfare, or the environment.
Description of the Amendment to the Remedy
This decision document changes a component of the selected remedial action for the
Non-populated Areas Operable Unit of the Bunker Hill Superfund Site (Site). The ROD for
this operable unit, signed on September 22, 1992, required treatment of all principal threat
materials (PTMs) at the site. This Amendment to the ROD will require containment of all
Declaration - Page 1
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PTMs, except mercury, in a fully lined monocell rather than treatment followed by capping.
Mercury contaminated materials will still be treated prior to disposal. Unlike the
containment proposal evaluated in the 1992 ROD, which called for consolidation of PTMs
and placement under a simple, surficial cap, this amended remedy will completely isolate the
PTMs from the environment, including groundwater, thereby being protective of both human
health and the environment. Containment satisfies all applicable or relevant and appropriate
requirements. The containment design will also allow for potential future reprocessing of
materials as technology develops. All other elements of the selected remedy set forth in the
ROD are unchanged.
Declaration
Although this ROD Amendment changes a component of the remedy selected in the
ROD, the remedy as amended continues to be protective of human health and the
environment. The remedy as amended complies with Federal and State requirements that are
legally applicable or relevant and appropriate to the remedial action and is cost effective.
The remedy as amended continues to utilize permanent solutions and alternative treatment
technologies to the maximum extent practicable for this site.
Because this remedy will result in hazardous substances remaining on site above
health based levels, a review will be conducted every five years after commencement-of
remedial action to ensure that the remedy continues to provide adequate protection of human
health and the environment.
Chuck Clarke Date
Regional Administrator, Region 10
U.S. Environmental Protection Agency
Declaration - Page 2
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Decision Summary
Non-Populated Areas Operable Unit
of the Bunker HiJl Superfund Site
Amended Record of Decision
Introduction
Site Name and Location
Non-populated Areas Operable Unit (Mining and Metallurgical Complex), Bunker Hill
Superfund Site, Shoshone County, Idaho.
Lead and Support Agencies
The U.S. Environmental Protection Agency (EPA) is the lead agency and the Idaho
Department of Health and Welfare, Division of Environmental Quality (DEQ) is the support
agency for this Amendment.
Statutory Citation for a Record of Decision (ROD) Amendment
. Section 117(c) of CERCLA, 42 U.S.C. Section 9617(c) provides for addressing and
documenting changes to the selected remedy after issuance of a ROD. This ROD
Amendment documents the changes to the remedy set forth in the ROD. Additionally, since
fundamental changes are being made to the remedy, public participation and documentation
procedures specified in the NCP, Section 300.435(c)(2)(ii) have been followed.
Date of ROD Signature
The ROD for the Bunker Hill Mining and Metallurgical Complex (Non-populated
Operable Areas Unit) was signed September 22, 1992.
Need for the ROD Amendment '--.-
EPA selected treatment for materials exceeding the "Principal Threat Material"
(PTM) action levels hi the 1992 ROD. PTMs were defined as contaminants which would be
expected to induce symptomatic health effects (requiring emergency treatment) to an exposed
individual based on a 70 mg/day soil ingestion rate for a short duration (less than three
months). The five metals identified as PTMs and the threshold criteria are listed in Table 1,
below. Materials contaminated with these metals, but at concentrations below the threshold
criteria, were to be consolidated without treatment beneath the Smelter Complex Closure
Cap.
Decision Summary - Page 1
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Table 1. Principal Threat Threshold Criteria
Metal
Antimony
Arsenic
Cadmium
Lead
Mercury
Parts per Million (ppm)
127,000
15,000
71,000
84,600
33,000
Percent
12.7
1.5
7.1
8.5
3.3
The ROD selected cement based stabilization of materials above the threshold criteria
shown in Table 1, above. After treatment, the PTMs were to be disposed of in an on-site
unlined landfill. During the remedial design process for the Industrial Complex Closure in
late 1995 and early 1996, EPA identified an alternative option to stabilization/fixation of
PTMs. Complete containment was identified as a possible alternative which would provide
long-term protectiveness and overall protection of human health and the environment.
Containment satisfies all applicable or relevant and appropriate requirements. Containment
has several advantages over cement based stabilization, including a 90 percent reduction in
cost, faster implementation, and fewer on-site worker exposure concerns. The containment
design will also allow for potential future reprocessing of materials as technology develops.
Since all of the above advantages can be realized without treatment, EPA is modifying the
stabilization remedy of PTMs to containment in a separate, completely enclosed cell beneath
the Closure Cap.
In addition, hi October of 1995, EPA proposed 20 administrative reforms designed to
improve the efficiency and effectiveness of lEhe Superfund Program. One of the 20 reforms
called for EPA to update remedy decisions where there is an opportunity to control remedy
costs and promote cost effectiveness while providing the same protection of human health
and the environment. The remedy changes reflected hi this ROD Amendment will result hi a
faster, more cost effective remediation effort, thus achieving the reform intent.
Public Involvement
EPA issued two newspaper notices, a fact sheet, and a proposed plan on August 2,
1996 to initiate a 30 day comment period. A public meeting was held on August 15 at the
Kellogg Middle School. Attendance was very low. The decision to amend the ROD is
based on the administrative record for the Eton-populated areas, which was updated August
14, 1996, to include information generated since the issuance of the ROD in 1992 pertaining
to this Amendment. Locations where the administrative record may be found are listed
below.
Decision Summary - Page 2
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Administrative Record
This ROD Amendment will become part of the Administrative Record for the Non-
populated Areas, as required by Section 300.825(a)(2) of the NCP, and will be available for
public review on weekdays between 8:30 a.m. and 4:30 p.m. at the information repository
below:
U.S. Environmental Protection Agency
Record Center, 7th Floor
1200 Sixth Avenue
Seattle, Washington 98101
Other copies of the Administrative Record may be viewed at the following two locations
during their respective hours of operation:
Kellogg Public Library
16 W. Market
Kellogg, Idaho 83837
Idaho Department of Health and Welfare
Division of Environmental Quality
1410 North Hilton
Boise, Idaho 83706-1253
Site History
The Bunker Hill Mining and Metallurgical Complex Superfund Site encompasses 21
square miles along Interstate 90 in the Silver Valley area of Shoshone County in northern
Idaho. The Site includes the now active Bunker Hill Mine and the inactive metallurgical and
smelting facility (together called the Bunker Hill Complex), and the cities of Kellogg,
Pinehurst, Smelterville, and Wardner (total population of over 5,000).
The site has widespread contamination from mine tailings, emissions from the Bunker
Hill smelter complex, and blowing dust from tailings piles and other barren areas. Barren
hillsides and open areas within the site contribute to erosion and blowing dust problems.
Extensive soil contamination remains in the residential areas of the above mentioned
communities as well as the surrounding non-populated areas. There are high lead levels in
house dust. There is also extensive heavy metals contamination of ground water and surface
water because of historical mining activities and continued leaching of metals from mine and
mill wastes.
In 1917, the Bunker Hill lead smelter began producing lead, cadmium, silver, and
alloys of tiiese heavy metals. In 1928, an electrolytic zinc plant was also put into
production. Smelter and zinc plant operations resulted in fugitive and stack emissions of
Decision Summary - Page 3
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metals and sulfur dioxide.
In September 1973, a fire in a pollution control device (bag house) at the lead smelter
operated by Gulf Resources and Chemical Corporation (Gulf) resulted in a dramatic increase
in emissions. In the first three months of 1974, approximately 73 tons of lead per month
were emitted into the environment.
In 1974, the average blood-lead level for children under 12 years of age within the
site was 65 micrograms of lead per deciliter of blood. This average is over six times the
Centers for Disease Control and Prevention (CDC) current level of concern. Excessive
amounts of lead in the body has been linked to impaired neuro-behavioral development,
kidney damage, anemia, and hypertension, especially in children.
Health studies were initiated and emergency measures were taken at the Site in the
late 1970's. The Bunker Hill facility was closed in 1981. Due to the human health and
environmental concerns, the Bunker Hill Sujjerfund site was added on the National Priorities
List in 1983.
EPA identified seventeen potentially responsible parties (PRPs), including Gulf, for
site contamination in the 1980's. On September 22, 1992, EPA signed the Record of
Decision (ROD) covering the non-populated portions of the site. Since 1992, Gulf has gone
through bankruptcy proceedings and the majority of the non-populated areas aside from the
Union Pacific railroad right-of-way and parts of the Phosphoric Acid Fertilizer Plant
(Stauffer entities) are being remediated by the EPA using the Superfund.
To date, the bulk of the Smelter Complex has been demolished and the Closure Cap
area is being constructed. EPA is beginning the removal of contaminated soils from the
surrounding gulches for consolidation under the Closure Cap.
Remedy Selected in the ROD
The ROD identified cement based stabilization as the preferred means to reduce the
mobility of PTMs. Since RCRA Land Disposal Restrictions (LDRs) were determined to be
relevant and appropriate to the treatment of PTMs, treatment goals were set at percent
reduction and/or extract concentration goals based on the LDR treatability variance guidance.
The cost of such stabilization was estimated in the original ROD at approximately
$2,600,000. More recent estimates for this work are over $7,000,000 due in large part to
increases in volume of PTMs since the time: of the 1992 ROD. To further limit the mobility
of contaminants, the stabilized material was then to be placed in building foundations or
other structures beneath the Closure Cap. This remedy could be implemented in one to two
years.
/
Hazardous materials that contain metals can often be stabilized using cement-based
Decision Summary - Page 4
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stabilization/fixation technologies. In such a process, wastes are raked with cement and
other additives. The cement hydrates and sets to form a matrix, encapsulating the waste and
physically limiting contact with water which might mobilize the contaminants.
Description of the Modified Remedy
All PTMs except mercury will be contained rather than stabilized. Mercury
contaminated material will be stabilized as stated in the 1992 ROD. Figures one through
three, below, illustrate the high density polyethylene (HDPE) bottom lined and three-ply
copolymer laminate (plastic) top lined monocell which will contain the PTMs. Unlike the
containment proposal evaluated in the ROD, which called for consolidation of PTMs and
placement under a simple, surficial cap, the amended remedy will completely isolate the
PTMs from the environment utilizing a bottom and top sealed plastic liner which will be the
engineered equivalent to a 'ziplock baggie'. This method of containment will seal in the
PTMs and practically lock out water. As seen in the figures, die monocell will also be
covered with a HDPE cap, which will cover the entire Smelter Complex Closure Area. This
top liner will provide a supplemental barrier to infiltration. In addition, upstream surface
and groundwater cutoffs will be in place to ensure that water does not contact the monocell
from the sides. From the bottom, a naturally occurring clay layer will prevent contact with
the monocell by impeding upward migration of groundwater. The monocell will be located
well above the highest location of the local groundwater table (groundwater will be 40 to 50
feet below the monocell). Figure 4 illustrates the selected location for the PTM monocell.
The area depicted for the monocell is roughly three acres, while the size of the overall
Smelter Complex Closure Area is approximately 30 acres. This fully encapsulated PTM
monocell, with supplemental barriers above, below, and to the sides, will prevent both direct
human contact with the PTMs and the PTM's exposure to groundwater thereby being
protective of both human health and the environment.
Performance standards are a key element of this modified remedy for the PTMs.
Appendix B describes the planned design criteria and minimum performance standards for
the HDPE portion of the cell. Appendix C describes the construction quality assurance
(CQA) and quality control procedures that will be required. CQA will be a crucial
component to attaining the performance standards listed in Appendix B. Appendix D lists
the current minimum specifications of the HDPE liner. The liner, once installed to CQA
specifications, will be as impermeable or better than the overall Smelter Complex Closure
Cap, which will have a permeability of 10"7 centimeters per second or less.
The modified remedy will also allow reprocessing of materials should changes in
technology make this option viable in the future.
Two important features of the 1992 ROD remain unchanged. First, mercury
contaminated soils above the PTM threshold will still be treated/stabilized, consistent with
the 1992 ROD, before being placed in the plastic monocell with the other, untreated PTMs.
Decision Summary - Page 5
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LTER CLOSURE
\FINA1. COVER LIMITS
WEST CANYON
SURFACE WATER
DIVERSION BERM
DRAIN PIPE / .,
. WIN
FIBERCLASV '
BOX,-'-. ."
PTM DISPOSAL CELL
GRADING AND LINING PLAN
21 JUl -1996 I? 0?-«9
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SMELTER CLOSURE
FINAL COVER LIMITS '
SOUTH LIMIT
PTM DISPOSAL
APPROX SMELTER CLOSURE
FINAL COVER GRADES (NOT SHOWN
ON PLANS)
FOR TYPICAL SMELTER CLOSURE
COVER SYSTEM SEE
DEMOLITION DEBRIS/
WASTE FILL-
I-SOUTH
CONTAINMENT BERM , .'
PTM DISPOSAL
CELL COVER
SEE
NORTH LIMIT
PTM DISPOSAL
PTM DISPOSAL
VOLUME
SEE NOTE 2
NORTH
CONTAINMENT OERM-.J
EXST GROUND SURFACE
TYPICAL LINING SYSTEM
DETAIL. SEE
SANDY GRAVEL
SILT AND CLAY
COLLECTION
DRAIN PIPE
TO CELL BOX
-ACCESS ROAD
WEST CANYON
SURFACE WATER
DIVERSION BERM
WEST CANYON
DRAINAGE
APPROXIMATE SURFACE
OF CONFINING LAYER
FIGURE 3
-SANDY SILT
AND CLAY (ML/CL1
SECTION
NTS
FIGURE 1
-MAXIMUM OOSERVEO
V/AU.R LEVEL
Figure 2
PTM DISPOSAL CELL
SECTION
rut HUJI 020^002.v
39-JUL-KI96
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DRAIN LAYER (SLAG)
60-MIL TEXTURED
HOPE CEOMEMBRANE
PREPARED SUBGRADE
TYPICAL LINING SYSTEM
DETAIL
PTM CELL
COVER
6" PREPARED SUBGRAOE
PTM
NTS
TYPICAL PTM
CELL COVER
DETAIL
NTS
XXX
-GROWTH
MEDIA
H DRAIN LAYER
(SLAG)
-60MIL TEXTURED
HOPE GEOMEMBRANE
-6" PREPARED SUBCRAOE
TYPICAL SMELTER
CLOSURE FINAL COVER
DETAIL /T\
NTS
Figure 3
PTM DISPOSAL CELL
DETAILS
0?05iOOJ.dl-
20-JlA-t09b I? 04 I?
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<, i/.-'/.
i / / / /
- /ZINC
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f ,* t«n
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'/^ L. ^W&Jf''" ; / '
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Figure 4: Bunker Hill Non-Populated Area Site Map
-Planned PTM Monocell Area -
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Quantities of mercury contaminated soils and debris are currently estimated at up to 5,000
cubic yards of material. Mercury contaminated material, particularly that potentially
containing elemental [liquid] mercury is more likely to remain highly mobile in the
environment than the other PTMs, and warrants stabilization before disposal.
Second, all PTM material may be reprocessed into a commercially valuable material
if the material characteristics are suitable. For example, the copper dross flue dust is
currently being evaluated for use as an ingredient substitute to a pyrometallurgical or
hydrometallurgical process. If reprocessing is not viable for this dust it will be disposed of
within the PTM monocell.
Table 2, below, summarizes the changes to the handling of PTMs.
Table 2. Summary of Changes
Principal Threat
Material
Mercury
contaminated soils
Antimony, Lead,
Cadmium, and
Arsenic
contaminated soils
1992 ROD Remedy
Stabilization /
Reprocessing
Stabilization /
Reprocessing
Remedv Change
None. If stabilized,
disposal will be in
the PTM monocell.
Containment rather
than stabilization.
Comment
No change was
proposed due to the
presence of liquids
necessitating
stabilization if not
reprocessed.
Containment will
involve a completely
sealed plastic cell.
The overall cost to implement the amended remedy is approximately $600,000 and could be
implemented in less than one year.
Evaluation of Alternatives
The NCP establishes nine criteria foir evaluating remedial action alternatives. These
criteria are divided into three categories of weighted importance, which include: threshold,
balancing, and modifying criteria. All remedies must meet the threshold criteria to be
considered. The seven balancing and modifying criteria help describe relative differences
between alternatives. A discussion of the original remedy and modified remedy relative to
the nine criteria evaluation is required by CERCLA. In this section, concrete stabilization
(1992 ROD) will be compared to the amended remedy of containment, relative to each of the
nine criteria.
Decision Summary - Page 6
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In the design process, containment (previously evaluated in a limited fashion in the
Feasibility Study and summarized in the 1992 ROD) was re-evaluated as a potential
alternative to stabilization. Advantages of containment over stabilization include: a level of
long-term protectiveness and overall protection of human health and the environment
comparable to that provided by cement based stabilization, satisfaction of all applicable or
relevant and appropriate requirements (ARARs), a 90 percent reduction in cost, fewer
technical concerns, faster implementation, and fewer on-site worker exposure concerns. The
containment design would also allow for potential future reprocessing of PTMs as technology
develops.
Threshold Criteria
Overall Protection of Human Health and the Environment - Both the original remedy and the
containment approach meet the threshold criterion of protection of human health and the
environment. Both isolate the worst metal contamination from the ground and surface water,
from the food chain, and from direct human contact.
Compliance with ARARs - The original ROD approach and the containment of PTMs will
both comply with the ARARs identified in the 1992 ROD.
Balancing Criteria
Long-term Effectiveness and Permanence - Actual life cycle (beyond 30 year) data on the
endurance of concrete versus plastic is not currently available. However, it is expected that
plastics including HDPE, if kept out of sunlight, can last for hundreds of years similar to the
longevity of a concrete matrix. Operations and maintenance requirements are similar under
both the 1992 ROD and amended remedies. With proper maintenance, the containment and
stabilization alternatives are expected to have similar long term effectiveness and
permanence.
Reduction of Toxicitv. Mobility, and Volume Through Treatment or Recycling - For this
criterion, concrete stabilization is better than containment using plastic in that containment
does not permanently address the mobility of the metals via treatment. Concrete stabilization
does not address toxicity or volume reduction and in fact would increase the volume of the
material. Containment would allow reprocessing of the material in the future as technology
develops.
Short-term Effectiveness - Stabilization would be a greater threat to worker safety due to the
extended handling time inv61ved. Dust generated by the treatment process would increase
the inhalation and dermal exposure risk of on-site workers. If treatability studies are
necessary to implement stabilization, containment could be implemented as much as a year
sooner than the ROD selected remedy. Containment could be implemented 3-5 months faster
than stabilization, if no treatability studies are necessary.
Decision Summary - Page 7
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Implementabilitv - The containment remedy is a proven technology and could be effectively
implemented. Stabilization may not be as successful due to the difficulty in stabilizing both
arsenic and lead in the same stabilization mixture. In earlier attempts to stabilize both
constituents, arsenic has been rendered more soluble by stabilization if lead was immobilized,
and vice versa due to an inverse solubility relationship (McCulley, Frick, and Gillman,
1993). Containment does address the mobility of all metals via engineered controls. In
addition, containment does not increase the volume of the waste material. Stabilization
actually increases the volume of the material by adding cement, lime, and other fixating
agents. This may increase the material volume two to three times, which increases
management costs.
Cost - Principal threat materials accumulated, as seen in Table 3, below, currently exceed
73,000 cubic yards. The cost of stabilization was estimated at $80 per cubic yard in the
Feasibility Study, written in support of the 1992 ROD. Using an updated, conservative
estimate of $100 per cubic yard of PTM, which includes the cost of treatabiliry studies,
treatment of the currently estimated volumes would cost in excess of $7,000,000. The
current estimate of containment is just over $600,000. The containment remedy therefore
represents over a 90 percent cost savings over the ROD selected remedy.
Decision Summary - Page 8
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Table 3. Principal Threat Materials Estimated Quantities'"
*based on July 18, 1996 Morrison Knudsen (MK) estimate
Source
OHM Stockpiles
MK Temporary stockpile
Balloon Flue PTM
East 'Miscellaneous Stockpiles
West Miscellaneous Stockpiles
Mercury PTM
Copper Dross
Area 10B Magnet Gulch West
Area 14
Area 18
Area 2 Boulevard
Area 10A Magnet Gulch East
Area 13 SE of Lead Smelter
Area 15
Bunker Creek #1
Bunker Creek #2
Total Estimated Quantity
Estimated Quantities/cubic yards
15,950
3,003
624
1,320
3,102
5,100
10,495
7,344
7,047
39
6,428
889
1,300
10,686
unknown
unknown
73,328
Modifying Criteria
State Acceptance - The State of Idaho has concurred with this Amendment. The concurrence
letter is attached as Appendix A.
Community Acceptance - EPA issued two newspaper notices, a fact sheet, and a proposed
plan on August 2, 1996 initiating a 30 day comment period. A public meeting was held on
August 15 at the Kellogg Middle School. Attendance was very low. Several questions were
asked regarding the proposal, however no comments were received at the meeting. The
decision to amend the ROD is based on the administrative record for the non-populated
Decision Summary - Page 9
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areas, which was updated August 14, 1996, to include information which has been generated
since the issuance of the ROD in 1992 pertaining to this Amendment. Only one comment
letter was received during the 30 day comment period from August 2 to September 2, 1996
from the Coeur d'Alene Tribe. Comments in the letter from the Tribe are addressed within
the Responsiveness Summary.
Summary
In summary, based on the comparisons between stabilization and containment for each
of the nine criteria, containment is the preferred alternative. The containment alternative met
both of the threshold criteria of protecting human health and the environment and complying
with applicable or relevant and appropriate requirements. The containment alternative was
considered equivalent to stabilization in long-term effectiveness, but fell short of stabilization
in the reduction of toxicity, mobility, and volume through treatment. The containment
alternative was superior to stabilization in short-term effectiveness, implementability, and
cost. The containment alternative also has b
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Compliance with Applicable or Relevant and Appropriate Requirements
No ARARs beyond those listed in the 1992 ROD are triggered by the amended
remedy. The amended remedy complies with all ARARs listed in the 1992 ROD.
Cost Effectiveness
The amended remedy represents a cost savings of over 90 percent from the 1992
remedy at $600,000 and over $7,000,000, respectively. The amended remedy provides an
overall effectiveness proportionate to its costs, such that it represents a reasonable value for
the money that will be spent.
Utilization of Permanent Solutions and Alternative Treatment Technologies
The remedy selected in this ROD Amendment utilizes permanent solutions and
alternative treatment technologies to the extent practicable. In this case, the selected remedy
is containment since the 1992 remedy of treatment was not found to be practicable.
Treatment of the PTMs, except mercury, is not practicable because:
90 percent cost increase;
difficulty in achieving treatment goals;
increased worker exposure risk;
increased implementation time; and
increased material volume.
The 1992 remedy of stabilization will be implemented for mercury contaminated materials.
However, for the remainder of the principal threat materials, stabilization was found not to
be practicable for the reasons listed above. In place of stabilization, PTMs other than
mercury will be contained in an on-site fully encapsulated monocell.
Preference for Treatment as Principal Element
The amended remedy for PTMs, except for the mercury contaminated materials being
stabilized, does not satisfy the CERCLA preference for treatment. Treatment was not judged
to be practicable for the majority of PTMs due to the implementability, short-term
effectiveness, cost, and technical concerns stated above.
Decision Summary - Page 11
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Responsiveness Summary
Non-Populated Areas Operable Unit
of the Bunker Hill Superfund Site
Amended Record of Decision
Introduction
This responsiveness summary meets the requirements of Section 117 of the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as
amended. The purpose of this responsiveness summary is to summarize and respond to
public comments on EPA's proposed Amendment of the cleanup plan for the Non-Populated
Areas of the Bunker Hill Superfund Site. The proposed ROD Amendment, issued on August
2, 1996, presented for public comment proposed changes to a component of the remedy set
forth in the Non-Populated Areas Record of Decision (ROD) issued in 1992.
EPA announced the issuance of the proposed plan on two separate occasions in a
community newspaper. A thirty day comment period was provided for the public to read the
proposed plan, review documents in the administrative record, and submit written comments.
EPA held a public meeting at the Kellogg Middle School on August 15 to answer questions
and accept comments.
The proposed ROD Amendment was to change the stabilization remedy for principal
threat materials (PTMs), except mercury contaminated materials, to containment in a fully
encapsulated monocell. Mercury contaminated materials would be stabilized consistent with
the 1992 ROD.
Community Involvement
Less than two dozen people attended the public meeting on August 15, 1996,
including the Superfund Task Force. EPA presented information on both the proposed ROD
Amendment and the 1992 remedy. Although several people asked questions regarding the
1992 ROD and proposed plan, no formal comments were given at the meeting. A transcript
of the meeting is included in the administrative record. Only one letter was received
commenting on the proposed remedy modification.
Comments and Responses
One letter was received during the 30 day comment period from the Coeur d'Alene
Tribe. Comments and responses follow.
Responsiveness Page - 1
-------
Comment: This is a unique proposal, because; the bottom liner which is outlined in this
amendment and subject to review by the public prior to enacting has already been installed.
At a minimum, this has the appearance of poor coordination and impropriety. I urge EPA to
better coordinate its administrative duties with its construction projects in the future.
Response: The original (1992 ROD) called for the consolidation of PTMs in "concrete
substructures (basements, storage bins, etc.) within the Lead Smelter Complex unless other
areas are determined to be appropriate by U.S. EPA during Remedial Design" (p. 9-10).
After consideration during design of the placement of PTMs in basements or other structures
within the Lead Smelter, EPA determined that a lined cell was a more protective and cost
effective approach to containerizing stabilized PTMs as required in the 1992 ROD. If the
containment proposal had been ill received by the community and the State, EPA would have
placed stabilized PTMs in the lined cell which has already been constructed, consistent with
the 1992 remedy. However, as outlined in this ROD Amendment, PTMs,. except mercury,
will be contained in the lined monocell.
Comment: The Principal Threat Threshold Criteria were established as part of a stabilization
option. Because of the differing technologies (stabilization versus containment) it is unclear
whether these numbers should be adjusted in response to the ROD Amendment.
Response: As described on page one of the Decision Summary of this ROD Amendment and
as part of the Proposed Plan issued on August 2, the PTM levels were selected based on
acute "symptomatic health effects" hi humans. These levels were not selected based on
technical specifications related to stabilization or groundwater impacts. The fully
encapsulated lined cell will prevent exposure of PTMs to humans and groundwater, thus
being protective of human health and the environment.
Comment: The Draft Amendment concludes approximately 73,000 cubic yards of material
will be contained. The containment cell is estimated at 100,000 cubic yards. The 73,000
cubic yards will expand to an unknown quantity because of handling and mercury
stabilization. Additional space may therefore be available if expansion is minimal
Additionally, the cell could be expanded upwards to create space for additional materials.
The proposal should consider including additional wastes in the cell, whether from on-site or
from off-site. The Tribe has long held that the Bunker Hill Superfund Site should be used as
a regional repository. While EPA has concluded that only on-site wastes will be disposed
on-site, this amendment provides a new occasion to consider the idea.
Response: Capacity concerns related to the stabilization of mercury contaminated materials
and the unknown quantities of materials to be consolidated in the Smelter Complex will be
addressed by design engineers and construction managers as cleanup progresses. EPA
maintains that the Superfund cleanup will only deal with wastes residing within the 21 square
mile area designated as the Bunker Hill Superfund Site stated in the 1992 ROD, as amended.
This distinction between "on-site" and "off-site" wastes is necessary due to the liability and
operations and maintenance cost concerns to both the federal and state governments for such
Responsiveness Page - 2
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a regional repository.
Comment: If the containment structure leaks, unlike stabilized materials, the contamination
will be instantaneous and concentrated. Therefore, the existing monitoring plan should be
reviewed to ensure that it takes into account the nature of the disposed materials (chemical
availability) and containment method (HDPE susceptibility and immediacy of release upon
breach (notwithstanding the clay layer).
Response: The fully lined monocell, with supplemental barriers to infiltration by moisture,
will be similar in protectiveness of human health and the environment to stabilization.
However, consistent with your comment/recommendation, EPA and the State had previously
written an additional monitoring plan and installed several new wells to monitor the
performance of the Smelter Complex Closure Area. This monitoring plan will include the
PTM monocell described in this Amendment.
Responsiveness Page - 3
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09/09/98 08:17 02083730576
ID DEQ-2ND FLOOR
ilOOl
IDAHO DEPARTMENT
OF HEALTH AND WELFARE *>'
DIVISION OF
ENVIRONMENTAL QUALITY
utO Morth Melon. Boijo. ID 03700-1235. (soa) 33<-0002
PWio E. SaS. Governor
August 30, 1996
Chuck Clarke
Regional Administrator
US EPA Region X
1200 6th Ave.
Seattle, WA 98101
Subject: State of Idaho Concurrence on the Non-populated Areas, Bunker Hill
Superfund Site Record of Decision Amendment
Dear Mr. Clarke:
We have evaluated the proposed Plan for the alternative method for disposal of the
Principle Threat Materials (PTMs) at the Bunker Hill Superfund site. We concur that
disposal in a fuliy enclosed liner system will be protective of human health and the
environment, allow retrievability for possible future reprocessing, and is more cost
effective than the previously planned cement stabilization. We have also evaluated the
public comments and believe the public is supportive of the Proposed Plan.
Since the State of Idaho is responsible for ten percent of the remedy cost and one
hundred percent of operation and maintenance, we have a direct stake in this decision.
Based upon these findings, the State of Idaho concurs with the proposed alternative for
PTM disposal.
If you have any questions, please contact me or Rob Hanson at (208) 373-0502.
Sincerely,
.
^""^
Wallace N. Cory P.E
Administrator
cc: Rob Hanson, DEQ
Sean Sheldrake, EPA
Post-it* Fax Note 7671
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APPENDIX B
Principal Threat Material Mono-Cell Design Criteria and Performance Standards
Category
Standard
Subgrade Compaction
To ensure an adequate subgrade for placing
the mono-cell liner, the subgrade shall be
compacted to at least 95 percent standard
compaction per ASTM D 698.
Slope Stability
The slope stability of the mono-cell liner
and cover systems shall have a factor of
safety of at least 1.5 under static loading
conditions. For dynamic loading conditions
(i.e., earthquake), the factor of safety shall
be at least 1.1.
Minimum Cover Over Geomembrane
A minimum of 12-inches of soil shall be
placed over the mono-cell liner to protect
the geomembrane from punctures and
damage from vehicles while placing the
PTMs.
Geomembrane Liner Type and Thickness
Geomembrane on the bottom and sides of
the PTM mono-cell shall be a textured high
density polyethylene liner, 60 mils in
thickness.
Geomembrane Cover Type
Geomembrane cover over the placed PTM
material shall be a 3-ply, copolymer
laminate reinforced with a non-woven grid
of high strength nylon cord.
Geomembrane Seaming
The individual geomembrane sheets of the
mono-cell liner will be seamed together in
the field to provide a water-tight cell for
subsequent placement of PTMs. The
geomembrane sheets will be seamed
together using either fusion-extrusion and/or
hot-wedge welding system, equipment, and
techniques.
Geomembrane Installation Quality
Assurance/Quality Control
A QA/QC program will be conducted to
ensure that proper storage, handling, and
installation requirements are met for the
geomembrane-lined mono-cell.
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APPENDIX C
GEOMEMBRANE QUALITY ASSURANCE - QUALITY CONTROL PROGRAM
MINIMUM REQUIREMENTS
PTM Mono-Cell, Bunker Hill Superfimd Site
1. Quality Control Submittals. QC submittals for the mono-cell geomembrane shall
include:
Written Quality Assurance Program: Includes description of geomembrane
manufacturer's and installer's formal programs for manufacturing, fabricating, handling,
seaming, testing, and repairing geomembrane.
Qualifications: Documented evidence of the ability and capacity for the following
services:
- Independent Testing Laboratory : 5 years experience in the field of geomembrane
testing.
- Manufacturer and Fabricator: Successfully manufactured a minimum of 5 million
square feet of the specific type of geomembrane specified for the mono-cell.
- Installer: Successfully installed a minimum of 5 million square feet of the specific
type of geomembrane specified for the mono-cell.
* Manufacturer's Certification of Compliance
Factory Test Results
Testing Equipment: Certified calibrations, manufacturer's product data, and test
procedures.
Certified Test Results from the Independent Laboratory.
2. Field Quality Control
Field Seam Strength Sample Testing: Strength tests of field seams shall be conducted to
verify that seaming equipment and operators are performing adequately. Samples of field
seams of the geomembrane liner shall be tested for shear strength (ASTM D4437-
84/D882-90, Method A (Modified)) and bonded seam strength in peel (ASTM D 4437-
84/D413-82, Method A) at the following frequency:
- Nondestructive Sampling: At the beginning of each shift for each seaming crew; if
seaming has been suspended for more than 1/2 hour; and minimum one sample per
500 feet of field seam.
- Destructive Sampling: Minimum one sample per 500 feet of field seam. Areas
where destructive samples have been taken from the geomembrane liner shall be
repaired in accordance with liner specifications.
In-Place Leak Detection Testing: After individual geomembrane sheets has been seamed
in the field, every inch of every seam shall be tested for leakage potential. Depending
on the seam welding equipment used, the leakage tests shall be conducted using either a
vacuum box testing device, a spark testing device, and/or air channel pressure tests for
double welded seams. Leakage tests shall conform to applicable ASTM standards.
Repair of Geomembrane Seams: Any seams found to be defective either in strength or in
leakage will be repaired and retested until specifications are met.
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APPENDIX D
Minimum HDPE Specifications
Property
Specific Gravity
Required Value
0.941 to 0.936, g/cc; not
more than 15% greater than
base resin density
Test Method
ASTM D792-86, Method A-
1
Textured-Surface, Minimum Properties, Each Direction
Thickness, min. For thinner
areas of textured Sheet
Tensile Stress at Yield
Elongation at Yield
Puncture Resistance
Tear Resistance
Hydrostatic Resistance
Environmental Stress Crack
Bonded Seam Strength in
Shear
Bonded Seam Strength in
Peel
Water Adsorption, Weight
Change/ Adap.
57 mil
2 Ib/mil thickness
12% or greater
1 Ib/mil thickness
0.75 Ib/mil thickness
7.5 Ib/sq in/mil thickness
1,500 hours
1.8 Ib/in-widtn/mil thickness,
min. & F.T.B.
1.2 Ib/in-width/mil thickness
min. & F.T.B.
0.085% max.
ASTM D5 199-91, Modified
(Note 1)
ASTM D638-90
FTMS 101C, Method 2065
ASTM D 1004-90, Die C
ASTM D751-89, Method A
ASTM D 1693-70, Condition
C (100 degrees C)
ASTM D4437-84/D882-90,
Method A, Modified
ASTM D4437-84/D413-82,
Method A
ASTM D570-81
NOTE 1 : Commercially available micrometers may be used that have a 60 degree taper to
a point with a radius of 1/32 inch. The Engineer shall make enough measurements of
thinner areas of textured Sheet to develop a statistical basis for thickness.
NOTE 2: Thickness of 60 mils shall be used in calculating required strength properties.
NOTE 3: The liner must meet the above minimum requirements in addition to the
manufacturer's most recent published specifications.
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September 1996 Bunker Hill Non-Populated Areas ROD Amendment - PTM
Containment
Concurrence
Sheldrake
Yackulic
Kowalski
fA
Krueger
Gearheard
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Initials
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Date
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