PB99-963107
EPA541-R99-033
1999
EPA Superfund
Explanation of Significant Difference
for the Record of Decision:
Idaho Pole Co.
Bozeman, MT
11/3/1998
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION 8, MONTANA OFFICE
FEDERAL BUILDING, 301 S. PARK, DRAWER 10096
HELENA, MONTANA 59626-0096
Ref: 8MO
November 23, 1998
MEMORANDTTM
SUBJECT: Explanation of Significant Differences for the Idaho Pole Company Superfund
oite
FROM: Jim Harris, 81 .
Remedial Projfec/Manager
TO: Max H. Dodson, ARA
Office of Ecosystems Protection and Remediation
Attached is an Explanation of Significant Differences (ESD) for the Idaho Pole Company
Superfund Site located in Bozeman, Montana for your signature. The purpose of the ESD is to
modify the scope of the site cleanup to include areas that were excluded in the 1992 Record of
Decision (ROD).
The 1992 ROD excluded excavation of contaminated soils associated with structures on
the site so that the company could continue operations. Idaho Pole Company announced the
closing of the facility last fall and EPA believes that the remaining contaminated soils identified
during the Remedial Investigation must be remediated. Access to the contaminated soils will
require the demolition of several structures on the site including buildings, tanks, vaults, slabs
and associated utilities.
Concurrence List: B. Fox, 8MO
J. Wardell, 8M
S. Bohan, 8E
C. Rushin,
Attachments:
Printed on Recycled Paper
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EXPLANATION OF SIGNIFICANT DIFFERENCES
Idaho Pole Company Superfund Site
Bozeman, Montana
United States Environmental Protection Agency
November 1998
I. INTRODUCTION
« l Ex*!l™alion of Significant Differences (ESD) for the Idaho Pole Company
Superfund Site (Site) is being issued by the U.S. Environmental Protection Agency (EPA) in
consultation with the Montana Department of Environmental Quality (MDEQ) to explain
modifications to the remedy at the Site contained in the Record of Decision (ROD) issued on
September 28 1992. Specifically, the purpose of this ESD is to document changes to the ROD
A pen f 6 n1ecessitated ^ ** closure °f the Idaho Pole Company plant. This is the
second ESD issued at the Site by EPA. The first ESD was issued on May 15, 1996.
In accordance with Sections 1 17(c) and 121 of the Comprehensive Environmental
Response, Compensation, and Liability Act of 1980 (Superfund), as amended, 42 U.S.C. Section
wui, st sssu (CERCLA), and the regulations at 40 C.F.R. Section 300.435(c)(2)(I), the National
Oil and Hazardous Substances Pollution Contingency Plan (NCP), this ESD has been prepared
for the following reasons:
to provide the public with an explanation of the nature of the changes to the
remedy;
to summarize the circumstances that led to the changes to the remedy; and
to affirm that the revised remedy complies with all statutory requirements.
This document presents only a summary of the changes to the selected remedy and a
synopsis of information on the Site. The Administrative Record, which contains this ESD and its
supporting documentation, is available for public review at the locations indicated at the end of
this report.
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H. SITE HISTORY AND BACKGROUND
The Idaho Pole Company (IPC) wood treating facility began operation in 1945 using
creosote to preserve wood. In 1952, the company switched to pentachlorophenol in carrier oil
(similar to fuel oil) for the wood treating solution. IPC's wood treating operations ceased in
1997.
Throughout the course of wood treating operations, there were various releases of oily
wood treating fluid from the plant. IPC conducted certain investigation and cleanup activities
after contamination was identified, and in 1986, the facility was added to the National Priorities
List of Superfund sites.
In 1989, MDEQ assumed the lead agency role through a cooperative agreement with EPA
and began the remedial investigation and feasibility study (RI/FS) following the EPA approved
Work Plan and EPA guidance. The RI defined the nature and extent of contamination and
provided data to complete the baseline health and ecological risk assessments. The FS included
the development, screening and evaluation of potential site remedies. The ROD was issued by
EPA on September 28, 1992.
* . .
III. SUMMARY OF THE 1992 RECORD OF DECISION
The contaminants of concern at the Site are pentachlorophenol (PCP), polynuclear
aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and polychlorinated
dibenzofurans. The Record of Decision established cleanup levels for those contaminants of
concern at the Site. The major components of the selected remedy, as modified by the May 1996
ESD include:
Soils Component
o Excavation and surface land biological treatment of contaminated soils from the
pasture area, the area between Cedar Street and U.S. Interstate Highway 90 (1-90),
the plant area and the former roundhouse area;
o Ambient temperature water flushing of soils underlying the pole plant facility and
1-90 in order to recover hazardous substances;
o Construction of a land treatment unit (LTU) to treat excavated soils. The total soil
depth on the LTU is less than two feet. The LTU will be operated to treat the
surface soils to approximately one foot in depth and the soils will be removed
when the cleanup levels for PCP and PAHs are met.
o Use of the treated soils for fill material on the plant site. If the soil contains other
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contaminants that exceed the ROD levels, the soil will be isolated from ground
water, will be covered at the surface to prevent direct contact and institutional
controls on future land use will be required. A detailed closure plan for the LTU
will be developed when soil monitoring results indicate that the cleanup levels for
PCP and PAHs have been achieved. The closure plan will identify the areas to be
backfilled with the treated soil and will specify the distance above the ground
water that the treated soil must be placed and the depth of cover required. The
plan will also identify the specific institutional controls to be implemented on the
pole plant facility.
Ground Water Component
o Ground water cleanup using extraction and a granulated activated carbon (GAC)
system and return of water to the ground water aquifer to enhance in situ
biological degradation and to control potential migration of contaminants;
o Treatment of contaminated residential wells exceeding maximum contaminant
levels (MCLs) or risk based concentrations of the contaminants of concern at the
distribution point in addition to institutional controls preventing new access to
contaminated ground water; and
o Continued residential and ground water monitoring to determine movement of
contaminants and compliance with remedial action requirements.
IV. DESCRIPTION OF SIGNIFICANT DIFFERENCES TO THE REMEDY
The significant difference between the remedy described in the 1992 ROD and in this
BSD is that the plant structures including concrete pads, piping, vaults, etc., preventing access to
contaminated soil will be demolished and disposed of in accordance with State of Montana and
EPA requirements and that contaminated soils underlying these areas will be excavated and
treated like the accessible plant soils have been to date.
Idaho Pole Company discontinued active wood treating operations at the Site in 1997
and has indicated to EPA that it has no intention of restarting operations at this location Since
1997, Idaho Pole Company has transferred some of its equipment off-site and is continuing to
decommission the pole plant.
EPA's selection of the remedy for the contaminated soils at the Site was influenced in
large part, by the fact that an active wood treating operation existed on the Site above
contaminated soils. In the Feasibility Study, EPA and the State of Montana evaluated cleanup
options including the destruction of the buildings and excavation of underlying soils The fact
that soils immediately surrounding and perhaps underneath many of the existing structures are
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contaminated is supported by Site operational history which includes boil overs of wood treating
fluids m 1981 and 1987. The known spills were associated with the retort building and the butt
vat Soil sampling during the RI adjacent to and underneath the plant structures confirmed that
soil contamination is present.
When selecting the soils remedy, EPA determined that the direct and indirect costs of
requiring the demolition of the active wood treating operation and excavation of underlying soils
made this option impracticable. EPA understood from IPC that the closing of the facility would
severely compromise IPC's financial viability, and could potentially result in IPC's bankruptcy
EPA sought a comparable remedy which would allow IPC to continue in business and continue
earning money which could be dedicated to the cleanup of the facility. At the time of the ROD
IPC had no plans to close the facility, thus the plant structures were viewed as a de facto cap over
the underlying contaminated soils which, for the foreseeable future, mitigated risks of exposure.
The sekcted remedy called for excavation and treatment of contaminated soils that were
accessible and identified soil flushing/in situ biological treatment as the appropriate remedy to
address soils beneath the plant and the nearby interstate highway (1-90). The ROD contemplated
that institutional controls would be used in conjunction with this remedy to ensure its
protectiveness since soil flushing/in situ biological treatment as a stand alone alternative would
possibly not achieve the 1 x 10 ^ risk level. Soil flushing/in situ biological treatment was
estimated to have a range of removal of contamination of from 40% to 80% - in other words the
selected remedy under the pole plant would not completely clean up all of the soil contamination.
With the closing of the pole plant, the relative certainty about the continued
inaccessibility of soils underlying the plant has diminished markedly. It is unlikely that another
wood treating operation would move onto the property and continue operations. A more likely
scenano isi that the property will be sold and ultimately used for another purpose. Some, if not
all of the buildings will be demolished under this scenario, and the underlying contamination
wi 1 need to be addressed. By leaving contamination under the closed pole plant until some point
in the future when new construction is planned, the cleanup is prolonged, issues involving the
control of access to the property under new ownership arise, and the prospect arises that a new
LTU would have to be constructed at significant cost. In light of these considerations, EPA has
reevaluated the soils remedy at the Site and determined that it is more appropriate to demolish
and dismantle the pole plant structures now and excavate and treat the underlying contaminated
soils Additional soil sampling, excavation and treatment would proceed in accordance with the
procedures established in the selected remedy for accessible soils (Soil Alternative 4) as
amended by the May 15,1996 ESD.
There is no change in the remedy selected for soils underlying 1-90; soil flushing will
continue in this area.
Community members and City of Bozeman representatives requested, prior to the
issuance of the ROD, that the cleanup be expedited. This change to the ROD will expedite the
completion of the remedy. Buildings can be demolished and the underlying soils accessed
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SSV!"1* 6XCTtd " neC6SSary in relativdy Short order> M ^P^ to ^e continuous soil
flushmg process which is estimated to achieve the necessary results in a 5 to 10 year time frame
This change will also reduce the reliance that will be placed on institutional controls such
as and use restnctions At present, there is negligible risk toon-site workers associated ^th
soils underlying the pole plant. However, any future disturbance of the contaminated soilT
±cec±!l tTH" ^rf^ t0 recontaminate *« -eas of the site^d to cr ±an
unacceptable nsk to human health and the environment. This potential threat would remain
whilethe contamination remains beneath the structures. To provide more certainty, E*TL
modifying the remedy to require the demolition of these vacant buildings and theTemovd of
underlying soils that exceed the action levels set forth in the ROD.
OF
natio?±h°Ve' ^ ^ ^^^ She devel°P^ts that serve as the basis for this
EPA °n "* — MDE^ — have been
Comn^r6^ ^f d t0 thiS ESD "* Part °f ^ Admi™trative ^cord for the Idaho Pole
Company Site The Administrative Record will also contain any written public comments that
^^^
U.S. EPA Montana Office Bozeman Public Library
Federal Building, Room 192 220 East Lamme Street
30 South Park, Box 10096 Bozeman, Montana 59717
Helena, Montana 59626-0096 (4061 58? 240n
° (Library hours vary.)
a.m.to 5:00 p.m.
VI. AFFIRMATION OF STATUTORY REQUIREMENTS
Considering the new situation with respect to the closure of the pole plant and the
changes that have been made to the selected remedy, EPA, in consultation with MDEQ believes
Aat Ae remedy remains protective of human health and the environment, complies wS Federal
Tr tvot reqUirementS Aat m both *PPIicable or relevant and appropriate to this remedial act?on
or involves appropriate waivers of these requirements, and is cost-effective. In addition the
reused remedy utilizes permanent solutions and alternative treatment technologies to the
maximu
maximum extent practicable for the Site.
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VII. APPROVAL
j 5^ -y-T.
Mafk A. Simonich, Director Date
Montana Department of Environmental Quality
< - i • • ••!• -—MI»-I»I •-» 1.,^, *., n,. n ^ i n f irjaa_jr y j ...™.. 1 ^
Max H. godson, ARA ^ Date
Office of Ecosystems Protection and Remediation
U.S. Environmental Protection Agency
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