a rnft Libby Asbestos Superfund Site
^tnr\ OU1 - Former Export Plant
U.S. EPA, Region 8 - Denver, Colorado
September 2009
Proposed Plan for Public Comment
Introduction
The public is invited to review and c omment on
this Proposed Plan to address environmental
cleanup at Operable Unit 1 (OU1) of the Libby
Asbestos Superfund Site in Libby, Montana. OU1
is the former Export Plant and is located on the
banks of the Kootenai River in central Libby,
Montana. OU1 is one of eight OUs at the site
(Exhibit 1). The investigation and cleanup are
being done by the U.S. Environmental Protection
Agency (EPA), in consultation with the Montana
Department of Environmental Quality (DEQ)
under the Superfund law. This Proposed Plan
provides an overview of the site history, site
contamination, and risk; summarizes the
remedial alternatives EPA is considering; and
details EPA's preferred remedial alternative and
supporting rationale.
Exhibit 1. Libby Asbestos Site OUs
ou#
Name
1
Former Export Plant
2
Former Screening Plant and nearby areas
3
Former Vermiculite Mine
4
Libby, MT (Residential, commercial, industrial,
and public properties)
5
Former Stimson Lumber parcel
6
Burlington Northern and Santa Fe Railroad
7
Troy, MT
8
State Highways
Issuance of this plan starts the public comment
period (September 9 to October 16 2009). At the
end of that period, EPA will review and consider
all comments provided.
Based on that consideration, EPA may select the
preferred cleanup alternative, modify it, select
another response action, or develop other
alternatives if public comment warrants or if new
material is presented.
Information on how to provide your comments
or questions to EPA is provided on page 12,
along with details on where you can get more
information and attend a public meeting. To help
you better understand the plan, page 13 provides
a list of commonly used environmental terms
that appear in BOLD thought this Proposed Plan.
This Proposed Plan focuses on OU1. For
additional information on the Libby Asbestos Site
as a whole, please contact the EPA Information
Center in Libby or visit EPA's web site.
Understanding the
Superfund Process
Issuance of the Proposed Plan is part of a detailed
process that includes everything from site
discovery through cleanup (Exhibit 2). EPA will
continue to work with local residents on this
process over the coming months.
The remedial investigation (RI) and feasibility
study (FS) for OU1 were completed in July and
August 2009 using data collected since 1999.
These documents are prepared concurrently, as
data collected in the RI influences development
of remedial alternatives in the FS. The RI
characterizes the site conditions, determines the
nature and extent of the waste, and assesses risk
to human health and the environment.
The FS identifies, develops, screens, and
evaluates remedial alternatives to address risks
to human health and the environment from soil
contaminated with Libby Amphibole asbestos
(LA).
1

-------
The general FS process follows the steps
summarized in the following bullets:
•	Identify remedial action objectives (RAOs)
•	Identify and screen potential remedial
technologies that will satisfy these RAOs
•	Assemble remedial alternatives that can
provide protection of human health and the
environment from the retained remedial
technologies
•	Screen the alternatives based on
effectiveness, im piemen la hi lily, and cost
•	For alternatives that make it through the
screening process, conduct a detailed
analysis against seven of nine evaluation
criteria (the two threshold criteria and the
five primary balancing criteria) and a
comparison between alternatives
After the FS is finalized, a preferred alternative
for the site is presented to the public in a
Proposed Plan (this document). The Proposed
Plan briefly summarizes the alternatives studied
in the detailed analysis phase of the RI/FS and,
highlights the key factors that led to identifying
the preferred alternative. The 30-day public
comment period allows the State of Montana
(through DEQ) and the community to provide
comment on the preferred alternative.
The final phase of the RI/FS process is to prepare
a Record of Decision (ROD). Following the
receipt and evaluation of public comments and
any final comments from DEQ, EPA selects and
documents the remedy for the site in a ROD.
Exhibit 2. The Superfund Process
The Superfund Process
"The Road to the ROD"
g-j.	National
lSPl,
Remedial Investigation (Rl)
Remedial
Action (RA)
Remedial
M
Public
Comment
Design (RD) l-|j
Record of
Decision and
Responsiveness
Summary
Feasibility
|| Study (FS)
You Are
Here
NPL
Deletion
Operation and Maintenance (O&M)
2

-------
Site Background
LA contamination in Libby is primarily linked to
operations at the nearby vermiculite mine, most
recently owned and operated by W. R. Grace
Company (Grace). LA is a naturally occurring
contaminant in the vermiculite deposits at the
mine. Vermiculite ore was transported from the
mine to the former Screening Plant and then to
local and nationwide processing facilities. The
ore was processed by heat expansion and was
then exported to market via truck or rail. From
the early 1960s to approximately 1990, the Export
Plant (OU1) was used for stockpiling and
distributing vermiculite concentrate to Grace's
plants and customers nationwide. Ownership
was transferred to the City of Libby in the mid-
1990s. Expansion operations ceased prior to 1981,
although buildings on the site were used to bag
and export milled ore until 1990.
Portions of OU1 were also leased to various
parties. From 1977 to 1997, organized youth
baseball events were held at ball fields on the
property. From 1987 to 2000, the Millwork West
Company, a retail lumberyard and building
material supplier, leased part of the site. Other
uses of the site reportedly included a metal scrap
dealer and a larch tree gum manufacturer.
In November 1999, in cooperation with the
Agency for Toxic Substances and Disease
Registry and DEQ, EPA began an emergency
response action to protect public health. The
Libby Asbestos Site was subsequently listed on
the National Priorities List (NPL) in October
2002.
Interim removal actions, such as the removal of
LA-contaminated dust, soil, and debris, were
performed at the site in conjunction with site
investigation activities and emergency response
actions. A total of 19 actions have been
i m piemen Led at OU1. These have included
multiple investigations, pre-removal sampling,
and three removals. Removals were intended to
provide protection while investigations and
studies were being conducted to determine final
remedial actions (Exhibit 3). For a description of
the specific areas referenced in the table, see Site
Characteristics on next page.
Exhibit 3. Actions Taken to Date at OU1
Date
Investigation/Action Activity
Area 1 - Former Export Plant
1999, Dec
Soil sampling
2000, Mar/Apr
Soil and stationary air sampling
2000, June
Activity-based sampling
2000, Oct/Nov
(Grace)
Removal of vermiculite and contaminated
dust, soil, and debris
2001, Mar/Apr/Aug
Soil, bulk material, and dust sampling
2001, Sept/Oct
(Grace)
Demolition of historic buildings and removal
of contaminated soil
2002, April/May
Bulk materials and soil sampling
2002, Oct - Dec
(Grace)
Demolition of remaining historic building and
removal of additional contaminated soil
2006, June
Soil sampling
2006, Jun - Sept
Water line installation (City of Libby)
2007, Sept/Oct
RI data gap sampling, site-wide soil
sampling and indoor ABS
Area 2 - Riverside Park
2003, May/July
Soil sampling
2003, Sept/Oct
Contaminant screening study (CSS), and
pre-removal soil sampling
2003, Oct/Nov
Removal of contaminated soil
2007, July
(City of Libby)
Placement of rock cover in areas of
observed vermiculite
2007, Sept
RI data gap and site-wide soil sampling
2008, May
Site work for placement of pavilion footers
2008, July
Removal of contaminated soil
Area 3 - Highway 37 Embankments
2007, Sept
RI data gap and soil sampling
Except where noted, activity was conducted by EPA
Nature and Extent of
Contamination
The RI provides a detailed summary of the
nature and extent of contamination in OU1. LA
has been detected in all media sampled. This
includes indoor air and dust, outdoor ambient
air, outdoor air near disturbed soil, and soil. The
indoor air and dust samples were taken from the
search and rescue building. The outdoor air
samples near disturbed soil were taken during
bush hogging activities.
In surface soil samples, detectable concentrations
of LA range from trace (<0.2%) to less than 1
percent (>0.2% but <1%) level. Vermic ulite is
visible with the naked eye in some samples.
3

-------
Site Characteristics
OUl covers roughly 17 acres on the south side of the Kootenai River, just north of the downtown area of
the City of Libby, Montana (Exhibit 4). It is bounded by the Kootenai River on the north, Highway 37 on
the east, the BNSF railroad thoroughfare on die south, and State of Montana property on the west.
There are three primary areas within the OU that are carried through all discussions of the remedial
alternatives:
•	Area 1. The area of OUl west of Highway 37 is divided into two areas by the partially-paved City
Service Road. Area 1 is the 12-acre area south of the road. It is a primarily undeveloped area that is
currently owned by the City of Libby. In 2004, the David Thompson Search and Rescue organization
constructed a building containing a main office and a five-bay garage on the northwest portion of the
site on the south side of City Service Road. This area is currendy fenced.
•	Area 2. Area 2 is the 4.7-acre area north of the road, known as Riverside Park. It is also owned by the
City of Libby and is developed as a recreational facility. The main features of the park include two boat
ramps, two pavilions, picnic tables, and a pump house.
•	Area 3. Area 3 is made up of the embankments of City Service Road and Highway 37 (on and adjacent
to die OU). The embankments adjacent to the OU are included because of their proximity and the
known presence of LA and verniiculite in this area.
Exhibit 4. OU1 Site layout map.
fArea 2 - River si daP.ark
David Thornpson
Search and Rescue Building
Pumphouse
¦Kj / 4? // ZyHpi
Area! -Former ExportjFjlantj
Areara^Embankments
Legend
^3 Area 1 - F ormer E ^port P lant
Area 2 - Riverside Park
n Area 3 - Embankments
~HI OU 1 Boundary
7W5 (TOCtCttS t>f HtfOKtS tO/tSl p/ffX)SeS
s,td fi\ ay ito tfs been frefsreci fix itecpi',
englfteef/fi# or wwjttog fxfpises.
Users of tits iWcvriiS to it sAoMd re "rfew cv
consi/tttie puma rye/Bis attci {Rtomstioa
source to ascertitft fie nsabttttyot tits
tftomattoti.
7?ie OUbotJ/tctB/tesdeffclscisK; based o/t
tie tfeM'ttoftsto ttftd/ii tie Libby Asbestos
Cottcepbal site iVS&iLtar. Because to vestgatto/t
of tie na lire and ertett f of co/i-Saw to-sib ¦?
con tones, tie OUboi/ttcbrtes we sublet to
Gtetfge. Tfiese OU bowc/artes aie cm tas
OfhGrctl2QD0.
4

-------
Conceptual Site Model
The conceptual site model (CSM) is a basic
description of how contaminants enter the
environment, how they are transported, and
what routes of exposure to organisms and
humans occur. It also provides a framework for
assessing risks from contaminants, developing
remedial strategies, determining source control
requirements, and methods to address
unacceptable risks. LA is the dominant
environmental concern at the site. A pictorial
representation of the CSM for current and future
receptors at OU1 is presented in Exhibit 5.
Sources of Vermiculite
Vermiculite and/ or vermiculite concentrate was
transported to OU1 from the mine for stockpiling
and staging prior to distribution. It is also
believed that vermiculite materials were used to
fill in low lying areas of the site. The potential
contaminated media of concern for OU'l include:
indoor air, dust in air of vehicles, outdoor air
near disturbed soil, general (ambient) outdoor
air, and dust in air from disturbances of roofing
or other outdoor surfaces.
Exhibit 5. Pictorial Representation of the CSM
Migration Routes and Exposure
Pathways
Current potential human receptors at the site
include rescue volunteers, commercial workers,
trades people, and recreational visitors. The
rescue volunteers are part of die David
Thompson Search and Rescue team . This team's
support building is on OU1 and is used to store
equipment between responses. Recreational users
include people who use the boat ramp area to
launch boats into the Kootenai River, fish along
the banks of the Kootenai River along the reach
that forms the northern boundary of the site, and
use recreational facilities at Riverside Park.
The exposure route of chief concern for asbestos
is by inhalation of asbestos fibers in air. People at
the site may be exposed to asbestos in air by
three main pathways:
•	Inhalation of fibers released during activities
that disturb soil
•	Inhalation of fibers in indoor air
•	Inhalation of fibers in outdoor (ambient) air
Inhalation exposure resulting from active soil
disturbance is believed to be the most significant
of these pathways.
LA exposure to maintenance
workers, park visitors, and

workers, pant visitors, ana
fishing guides from disturbed L i \
contaminated soil	|	*
LA exposure to maintenance
workers, park visitors, and
fishing guides from general
ambient air

LA exposure to rescue
volunteers from
contaminated soil tracked
inside the building
Search & Rescue
5

-------
Summary of Site Risks
The RI report contains a baseline human health
risk assessment for OU1. The risk assessment
uses available data to estimate the health risks to
people who may breathe asbestos in air while
working in or visiting OU1, either now or in the
future, based on the conditions that currently
exist within OU1. The methods used to evaluate
human health risks from asbestos are in basic
accord with EPA guidelines for evaluating risks
at Superfund sites, including recent guidance that
has been specifically developed to support
evaluations of exposure and risk from asbestos.
The RI report contains detailed explanations of
the steps used to conduct the risk assessment for
OU1. This includes background information on
asbestos, the basis for concern, the exposure
model, a toxicity assessment, quantification of
exposure and risk, and a listing of uncertainties
inherent in the process. This Proposed Plan
provides a very brief summary of the conclusions
of the risk assessment.
Methods for quantification of cancer risk from
inhalation exposure to asbestos are still under
development. However, risk predictions that are
based on the best methods and data that are
currently available indicate the following:
•	Estimated excess cancer risks from inhalation
exposure to outdoor ambient air at OU1 are
all well below EPA's risk range of 1E-04 (one
per ten thousand) to 1E-06 (one per million).
Based on this, exposure to outdoor ambient
air in OU1 is unlikely to be of significant
health concern to any human receptor.
•	Estimated excess cancer risks to volunteers
who work indoors at the David Thompson
Search and Rescue facility range are below or
within EPA's risk range. Based on this,
exposure to indoor air, taken alone, is likely
to be of low concern. However, volunteers in
the building may be exposed to LA by other
pathways, and so risk evaluations must
consider the total risk.
•	Estimated cancer risks from inhalation of LA
caused by disturbance of soils at OU1 are
difficult to quantify with confidence, but it
seems likely that risks to individuals who
repeatedly disturb soil in OU1 may approach
or exceed EPA's risk range. Based on this,
this pathway is considered to be of potential
concern.
•	Subsurface soils at OU1 contain buried
vermiculite. In the future, if this buried
vermiculite became exposed (e.g., because of
soil erosion or soil excavation activities),
excess cancer risks from soil disturbance
might be substantially higher than under
current conditions.
•	Non-cancer risks from inhalation exposure to
LA cannot be quantified at present, but it is
anticipated that non-cancer risks may be of
similar or possibly even greater concern than
cancer risks.
EPA is working to develop a reference
concentration that will allow non-cancer
exposure risk for inhalation exposure to LA to be
quantified. Therefore, the risk assessment does
not include an evaluation of non-cancer risk.
However, studies in Libby reveal that the
incidence of asbestos-related non-cancer effects
(e.g., pleural calcification, pleural thickening and
opacities) is increased in workers and residents.
These findings emphasize that, despite the
present inability to provide a quantitative
calculation, non-cancer effects are a significant
human health concern in the community. Thus, it
should not be presumed that cancer risk is the
"risk driver" at OU1 or other parts of the site.
Ecological risk has not yet been addressed
separately for OU1. EPA will be conducting a
comprehensive assessment of ecological risks as
part of OU3 (the mine site) that will address
ecological risk for OU1.
6

-------
Remedial Action
Objectives
Remedial Action Objectives (RAOs) are goals
developed by EPA to protect human health and
the environment at the Libby Asbestos Site.
These RAOs are the overarching goals that all
cleanup activities selected for OU1 should meet
(Exhibit 6). EPA considers current and future use
of the site when determining RAOs.
Exhibit 6. RAOs for OU1
RAOs for OU1
1.	Mitigate the potential for inhalation exposures to
asbestos fibers that would result in risks that
exceed the target cancer risk range specified by
EPA of 1E-06 to 1E-04 (one in one million to one
in ten thousand).
2.	Control erosion of contaminated soil by wind and
water from source locations to prevent the spread
of contamination to unimpacted locations and
media.
3.	Implement controls to prevent uses of the site that
could pose unacceptable risks to human health or
the environment or compromise the remedy.
Future land use for Area 1 is assumed to be non-
residential (likely commercial or recreational).
The City expects that David Thompson Search
and Rescue will continue to use the northwest
portion of Area 1, and development of the
remainder of Area 1 is under consideration by
the City's planning department. Future use of
Areas 2 and 3 is unlikely to change. Area 2 will
continue to be Riverside Park and serve
recreational visitors. Area 3 is likely to remain
undeveloped, as use of the embankments is
restricted by the steep topography and its
location within the rights-of- way for the City
Service Road and Highway 37.
In evaluating potential future activities at the site,
the final condition of the remediated area must
be considered. For each of the alternatives
evaluated, institutional controls (ICs) would be
implemented to provide continued protection to
human health and the environment. ICs are
actions, such as restrictive covenants, zoning
ordinances, easements, deed restrictions, and
building permits, that help minimize the
potential for human exposure to contamination
by ensuring appropriate land or resource use.
EPA's goal is to protect public health or welfare
or the environment from exposure to LA in a
way that is consistent with the City's intended
use of the property. EPA will perform cleanup to
provide protection to the public and the
environment, but will not otherwise create
improvements to the property. The RAOs for
OU1 are based on anticipated future use.
Summary of Remedial
Action Alternatives
A number of proven, remedial technologies and
process options were used to develop remedial
alternatives for cleanup. The eight remedial
alternatives that were screened during the FS
consisted of varying combinations of those
technologies and process options (Exhibit 7).
Exhibit 7. Technologies and Process Options Used in
Site Remedial Alternatives
Remedy Component Used
Remedial Alternative
1
2
3
a
3
b
4
a
4
b
5
a
5
b
In-Place Containment of
Contaminated Soil


•
•




Partial Removal of Contaminated
Soil




•
•
•
•
Removal of Contaminated
Surface and Subsurface Soil for
Utility Corridors



•

•

•
Offsite Disposal at the Former
Libby Vermiculite Mine



•
•
•


Offsite Thermo-Chemical
Treatment and Reuse of Treated
Material






•
•
ICs and Monitoring








Engineered Controls

•






5-year Review








The shaded alternatives were eliminated from consideration
prior to detailed analysis
The main differences in the use of various
remedy components in the remedial alternatives
relate to the following:
• Is contaminated surface soil across the OU
capped in place (3a and 3b) or removed
(Alternatives 4a, 4b, 5a, and 5b)?
7

-------
•	Is contaminated soil in the utility corridors at
OU1 addressed (Alternatives 3b, 4b, and 5b)?
•	Is the removed soil disposed at the former
mine (Alternatives 4a and b) or is the soil
treated and returned to OU1 (Alternatives 5a
and 5b)?
Each of the eight alternatives shown in Exhibit 7
was evaluated in the FS to determine its ability to
provide protection to human health and the
environment through overall effectiveness,
implementability, and cost. Alternatives that
were deemed to have lower than moderate
effectiveness or implementability and/ or high
cost were eliminated from further consideration
(Alternatives 2, 5a, and 5b). Alternative 2 was
eliminated because it would not be entirely
effective at protecting human health and the
environment. Alternatives 5a and 5b differed
from Alternatives 4a and 4b only through use of
a treatment technology (thermochemical
treatment) and they were eliminated because of
issues related to the availability of the
technology, applicability to this medium, and
excessively high costs relative to other protective
alternatives. Further explanations on those
determinations can be found in the FS.
The remaining five remedial alternatives were
retained for detailed analysis and are discussed
below. Costs for these alternatives are rounded
up to the nearest thousand. These costs are
presented for purposes of comparing one
alternative to another and are not developed with
the level of detail necessary to be estimated
completion costs. Typically, costs developed for
FS purposes are as much as 30 percent lower to
50 percent higher than completion costs.
ICs would be used for all alternatives except
Alternative 1. The choice of which specific ICs to
use would be made in the remedial design phase
in consultation between the EPA, Montana DEQ,
and the City of Libby.
Alternative 1
•	No Action
Est. Total Capital Costs: None
Five-year Review Costs (first 30 years): $288,000
Est. Construction Timeframe: None
Est. Total Alternative Cost (Present Value):
$104,000
Superfund requires that EPA retain a no-action
alternative as a baseline for comparison to other
alternatives. This alternative would require that
current site operations be suspended and no
further action be taken. Five-year site reviews
would be performed as required under CERCLA.
This alternative is not protective of human health
or the environment and does not comply with the
RAOs.
Alternative 3a
•	In-Place Containment of Contaminated
Surface Soil
•	ICs with Monitoring
Est. Total Capital Costs: $2,297,000
Est. Total O&M Costs (first 30 years, inc. 5-yr
reviews): $955,000
Est. Construction Timeframe: less than one
construction season (May - October)
Est. Total Alternative Cost (Present Value):
$2,514,000
Alternative 3a provides protection of human
health through in-place containment (cover) of
contaminated surface soil. The covers would be
designed to break any potential exposure
pathway. Depending on the final design, covers
would be hard (e.g., concrete) or soft (e.g., sod)
based on their ability to protect human health
and the environment under the land use
designated in a future land use plan. Clean cover
soil would be brought from an offsite borrow
source outside of the Libby valley. Existing
riprap along the riverbank would be temporarily
removed and replaced after the remedy is put in
place, if needed to ensure permanence of the
riprap. Long-term O&M would maintain the
integrity of covers and riprap.
ICs would be used to provide protection of
human health and protect the remedy.
Monitoring (inspections) and five-year site
reviews would continue to ensure that the
remedy remains protective.
Alternative 3b
•	In-Place Containment of Contaminated
Surface Soil
•	Removal of Contaminated Soil in Utility
Corridors and Other Planned Excavations
•	Offsite Disposal at the Former Libby
Vermiculite Mine
•	ICs with Monitoring
Est. Total Capital Costs: $2,824,000
8

-------
Est. Total O&M Costs (first 30 years, inc. 5-yr
reviews): $955,000
Est. Construction Timeframe: less than one
construction season (May - October)
Est. Total Alternative Cost (Present Value):
$3,007,000
Alternative 3b uses the same remedial strategy as
Alternative 3a (containment). The scope and
protectiveness are higher due to the addition of
partial removal and offsite disposal of subsurface
soil (assumed to be up to 5 feet) in utility
corridors and other planned excavations (e.g.,
building footings) under a designated future land
use plan. This removal would provide
uncontaminated areas to mitigate potential future
risks to workers installing underground utilities
or conducting other excavation work. Removal of
subsurface soil would only be performed in
Areas 1 and 2 (assumed to be 10 percent of the
surface of those areas).
The utility corridors and other planned
excavations would involve removal of
contaminated soil and backfill with
uncontaminated material. Specialized trucks
(with covered tops) would transport removed
contaminated soil to the Former Libby
Vermiculite Mine. The mine is currently used for
disposal of contaminated soil generated during
ongoing cleanup activities performed in other
OUs on site. Long-term O&M would maintain
the integrity of the covers and riprap.
ICs would be similar to Alternative 3a.
Monitoring (inspections) and five-year site
reviews would continue.
Alternative 4a
•	Partial Removal of Contaminated Surface
Soil
•	Offsite Disposal at the Former Libby
Vermiculite Mine
•	ICs with Monitoring
Est. Total Capital Costs: $3,128,000
Est. Total O&M Costs (first 30 years, inc. 5-yr
reviews): $955,000
Est. Construction Timeframe: One to two
construction seasons (May - October)
Est. Total Alternative Cost (Present Value):
$3,291,000
Unlike the previous alternatives, Alternative 4a
provides protection of human health through
partial removal of contaminated soil (primarily
surface soil) within OU1. The contamination
would be removed from the surface of the entire
OU to an assumed depth of 12 inches. All
excavations would be backfilled with clean soil.
As with Alternative 3b, offsite disposal would be
at the former mine. Existing riprap along the
riverbank would be temporarily removed and
replaced after the remedy is put in place, if
necessary to ensure permanence of the riprap.
Long-term O&M would be required to maintain
the integrity of the backfilled areas and riprap.
ICs would be similar to Alternatives 3a and 3b.
Monitoring and five-year site reviews would
continue to evaluate effectiveness of the remedy.
Alternative 4b
•	Partial Removal of Contaminated Surface
Soil
•	Removal of Contaminated Soil in Utility
Corridors and Other Planned Excavations
•	Offsite Disposal at the Former Libby
Vermiculite Mine
•	ICs with Monitoring
Est. Total Capital Costs: $3,820,000
Est. Total O&M Costs (first 30 years, inc. 5-yr
reviews): $955,000
Est. Construction Timeframe: One to two
construction seasons (May - October)
Est. Total Alternative Cost (Present Value):
$3,938,000
Alternative 4b uses the same remedial strategy as
Alternative 4a (site-wide partial removal of
contaminated soil). The scope and protectiveness
of this alternative are higher than Alternative 4a,
due to the addition of removal and offsite
disposal of subsurface soil on a limited basis for
utility corridors (assumed depth of 5 feet) and
other planned excavations under a designated
future land use plan. As with Alternative 4a,
offsite disposal of the removed contaminated soil
would be to the Former Libby Vermiculite Mine
and riprap would be removed and replaced if
necessary to ensure permanence. Long-term
O&M would maintain the integrity of backfilled
areas and riprap.
As with Alternatives 3a, 3b, and 4a, ICs would be
used to provide protection of human health to
the extent possible and to protect the remedy put
in place. Monitoring and five-year site reviews
would continue to evaluate effectiveness.
9

-------
Evaluation of Remedial Alternatives
The remedial alternatives that made it through the initial screening process (1, 3a, 3b, 4a, and 4b) were
evaluated in detail with respect to seven of the nine evaluation criteria. The nine criteria fall into three
groups: Threshold, Primary Balancing, and Modifying. Each alternative (except no-action) must meet the
threshold criteria. The primary balancing criteria are used to weigh major trade-offs among alternatives,
and the modifying criteria may be fully considered only after State and public comment is received on the
Proposed Plan. Exhibit 8 presents the comparative analysis of alternatives against the seven criteria. The FS
provides a detailed summary of how the comparison of alternatives was made.
Alternatives 3a, 3b, 4a, and 4b are expected to comply with the chemical-, location, and action-specific
applicable or relevant and appropriate requirements (ARARs) identified in the FS. No key ARARs that
significantly differ between these alternatives were identified. In addition, Alternatives 3a, 3b, 4a, and 4b
are not expected to require ARAR waivers pursuant to NCP 300.430(f)2(iv).
Exhibit 8. Detailed Evaluation of the Retained Remedial Alternatives
Remedial Alternative
Description
Threshold Criteria
Primary Balancing Criteria
Overall Protection
of Human Health
and the
Environment
Compliance with
ARARs
Long-Term
Effectiveness and
Permanence
Reduction of
Toxicity, Mobility,
or Volume through
Treatment
Short-Term
Effectiveness
Implementability
Present Value Cost
(Dollars^
1
No Action
Q
Q
Q
Q
Q
©
$
$104,000
3a
In-Place Containment of Contaminated
Soil, and ICswith Monitoring
©
0
©
©
©
©
$$
$2,514,000
3b
In-Place Containment of Contaminated
Soil, Partial Removal of Contaminated
Soil for Utility Corridors, Offsite Disposal
at the Former Libby Vermiculite Mine,
and ICswith Monitoring
©
0
9
©
©
©
$$
$3,007,000
4a
Partial Removal of Contaminated Soil,
Offsite Disposal at the Former Libby
Vermiculite Mine, and ICs with
Monitoring
©
o
©
©
©
©
$$
$3,291,000
4b
Partial Removal of Contaminated Soil,
Additional Removal for Utility Corridors,
Offsite Disposal at the Former Libby
Vermiculite Mine, and ICs with
Monitoring
©
o
9
©
O
©
$$
$3,938,000
1.	Numerical designations for the qualitative ratings are used to illustrate a range of compliance with that criterion. They are not additive.
2.	Detailed cost spreadsheets for each alternative are presented in the FS (within a -30 to +50 percent accuracy range based on the
scope presented). Costs are prepared solely to facilitate relative comparisons between alternatives for FS evaluation purposes..
Legend for Qualitative Ratings System:
Threshold and Balancing Criteria (Excluding Cost)	Balancing Criteria (Present Value Cost in Dollars)
©
None
©
None ($0)
o
Low
$
Low ($0 through $2M)
©
Low to Moderate
$$
Low to Moderate ($2M through $5M)
e
Moderate
$$$
Moderate ($5M through $8M)
o
Moderate to High
$$$$
Moderate to High ($8M through $10M)
e
High
^ ^ ^
\P\P\P\P\P
High (Greater than $10M)
10

-------
EPA's Preferred Alternative - A Combination of
Alternatives 3b and 4a
EPA's preferred alternative for cleanup of c ontamination at OU1 is a combination of two alternatives:
Alternative 3b (In-Place Containment of Contaminated Soil, Removal of Contaminated Soil for Utility
Corridors, Offsite Disposal at the Former Libby Vermiculite Mine, and ICs with Monitoring) and Alternative
4a (Partial Removal of Contaminated Soil, Offsite Disposal at the Former Libby Vermiculite Mine, and ICs
with Monitoring).
As discussed earlier, Alternative 3b provides protection of human
health through in-place containment of contaminated soil in OU1
and additional removal of subsurface contaminated soil from utility
corridors in Area 1 and Area 2. Alternative 4a provides protection
of human health through partial removal of contaminated soil
(primarily contaminated surface soil). Disposal of removed
contaminated soil would be at the Former Libby Vermiculite Mine.
Riprap would be removed and replaced if necessary to ensure
permanence. Long-term O&M would be required to maintain the
integrity of the covers, backfilled areas and riprap. ICs would be
used to provide protection of human health to the extent possible
and to protect the remedy. Monitoring (inspections) and five-year
site reviews would continue to evaluate effectiveness of the
remedy. Combining Alternatives 3b and 4a provides the flexibility
to accommodate future land uses, as the City of Libby more clearly
defines redevelopment options in a future land use plan.
Est. Total Capital Costs: $3,295,000
Est. Total O&M Costs (first 30 years, inc. 5-yr reviews): $955,000
Est. Construction Timeframe: One to two construction seasons
(May through October)
Est. Total Alternative Cost (Present Value): $3,447,000
Approximate quantities of materials were used in the evaluation of
the remedial alternatives in the FS process and include: 9 acres of
surface area for covers, 22,250 loose cubic yards (cy) of
contaminated soil removed, 22,600 loose cy of backfill for
excavations and covers, and 14,550 loose cy of topsoil for
excavations and covers. The one-way distance to the mine is
assumed to be 13 miles. Final quantities will be determined in the
design process and may differ significantly.
The combination of Alternatives 3b and 4a performs as well or better than more expensive alternative (4b). It has a
higher level of long-term effectiveness and permanence than the less expensive alternatives (due to the removal of
contamination from surface excavations and utility corridors) (Exhibit 8).

Overall protection of human health and the environment
© Moderate
Compliance with ARARs
© Moderate to High
Long-term effectiveness and permanence
© Moderate to High
Reduction of toxicity, mobility, or volume through treatment
© None
Short-term effectiveness
©Low to Moderate
Implementability
©Low to Moderate
Cost
$$ Low to Moderate
11
Implementation Details
•	During construction, water- or
chemical-based suppression would
be used to prevent LA from
becoming airborne.
•	Temporary lay down areas and gravel
access roads would be constructed
to limit contaminated soil disturbance
during removal.
•	Clean soil for covers and for backfill
of excavations would be brought from
a borrow source outside the Libby
Valley and would be tested before
use.
•	A visible marker layer would be
placed at the bottom of the cover and
the utility excavations to denote the
backfill extent.
•	ICs and monitoring would be used.
Engineered controls would not be
required.
•	The community would be kept
informed during remedy
implementation and during 5-year
reviews. Reviews are required as
contaminated soil left below covers or
backfilled areas) prevents
unrestricted use of the site.

-------
Opportunities for Public Involvement
Public Meeting
EPA will provide a short presentation about the proposed
plans for both OU1 and OU2 at a public meeting in
September 2009. It's a great opportunity to learn more about
the details.
Libby Asbestos Superfund Site
Public Comment Meeting
Monday, Sept. 28, 2009
7:00 to 9:00 pm
Little Theater
724 Louisiana Ave.
(School Administration Building)
Libby, MT
If you like, you can provide your comment orally at the public
meeting, and the meeting stenographer will record it.
OUs 1 & ^
Contacts
If you have questions or need additional
help, please feel free to contact the following
representatives:
Rebecca Thomas, Project Manager
U.S. EPA, Region 8
1595 Wynkoop Street
Denver, Colorado 80202
(303) 312-6552
1-800-227-8917, ext. 6552
Thomas.rebecca@epa.gov
Ted Linnert, Community Involvement
Coordinator
U.S. EPA, Region 8
1595 Wynkoop Street
Denver, Colorado 80202
(303) 312-6119
1-800-227-8917, ext. 6119
linnert.ted@epa.gov
Catherine LeCours, Project Officer
Montana DEQ
P.O. Box 200901
Helena, MT 59601
(406) 841-5040
clecours@mt.gov
Written Comments and Extensions
The public comment period runs from September 9 to
October 16, 2009, and may be extended 30 days with a
formal request to EPA. You can submit a comment in writing
(by mail, email, or at the public meeting). The mailing
address for written comments is:
Ted Linnert
Office of Communications & Public Involvement
U.S. EPA, Region 8-80C
1595 Wynkoop Street
Denver, Colorado 80202
Email: linnert.ted@epa.gov
Documents
All public project reports and documents
are available for viewing at EPA's web
site or at one of the document
repositories. These are also excellent
sources for all sorts of project
information (fact sheets, brochures,
etc.).
www.epa.gov/libby
EPA Superfund Records Center
1595 Wynkoop Street
Denver, CO 80202
(303) 312-6473
EPA Information Center
108 E. 9th Street
Libby, MT
(406)293-6194
12

-------
Useful Terms
Understanding environmental cleanup can be daunting for the average person. The following are
definitions of commonly used terms at the Libby Asbestos Site to aid your understanding of this document.
•	Applicable or relevant and appropriate requirements (ARARs). Any state or federal statute that
pertains to protection of human life and the environment in addressing specific conditions or use of a
particular cleanup technology at a Superfund site.
•	Exposure. The amount of pollutant present in a given environment that represents a potential health
threat to living organisms.
•	Exposure Pathway. The path from sources of pollutants via, soil, water, or food to man and other
species or settings.
•	Feasibility Study (FS). The FS is the mechanism for the development, screening, and detailed
evaluation of alternative remedial actions. It is conducted concurrently with the RI.
•	Five-Year Review. Remedial actions that result in hazardous substances, pollutants, or contaminants
remaining at a site above levels that allow for unlimited use and unrestricted exposure are required to
be reviewed every five years to ensure protection of human health and the environment.
•	ICs and Engineered Controls. ICs are actions, such as restrictive covenants, zoning ordinances,
easements, deed restrictions, and building permits, that help minimize the potential for human
exposure to contamination by ensuring appropriate land or resource use. Engineered controls are
physical controls, such as fencing. Both types of controls are used to help preserve the integrity of the
remedy.
•	Libby Amphibole Asbestos (LA). The term used to differentiate asbestos fibers originating from the
W.R. Grace Mine from other types of asbestos. LA fibers have no odor, smell, or taste. They are not
flammable. They do not evaporate in air, dissolve in water, or breakdown in dirt.
•	National Priorities List (NPL). EPA's list of the most serious uncontrolled or abandoned hazardous
waste sites identified for possible long-term remedial action under Superfund. A site must be on the
NPL to receive money for remedial action.
•	Operable Unit (OU). A designation based on geography or other characteristics that defines a specific
area of a site and enables the Superfund process to move forward in different areas at different times,
speeding up the overall cleanup process at the site.
•	Operation and Maintenance (O&M). Activities conducted after a Superfund site action is completed to
ensure that the action is effective for the long-term.
•	Present Value. The present value (of a sum payable in the future) calculated by deducting interest that
will accrue between the current and future date.
•	Remedial Investigation (RI). The investigation phase of the Superfund process that determines the
nature and extent of contamination and assesses the risk to human health and the environment.
•	Remedial Action (RA). The actual construction or implementation phase of a Superfund site cleanup
that follows remedial design. The remedial design is the design phase of a Superfund site cleanup that
follows the signing of the ROD and precedes the RA.
•	Interim Removal Action. Short-term immediate actions taken to address releases of hazardous
substances that require expedited response.
•	Record of Decision (ROD). A public document that explains which cleanup alternative(s) will be used
at NPL sites.
•	Superfund. The program that funds and carries out EPA solid waste emergency and long-term
removal and remedial activities. These activities include establishing the NPL, investigating sites for
inclusion, determining priority, and conducting and/ or supervising cleanup and other actions.
13

-------
US Environmental Protection Agency	ppsrt std
Region 8 - 80C	Postage and Fees
1595 Wynkoop Street	P^m^NoTss
Denver, Colorado 80202	Helena, MT
Attn: Ted Linnert


dmj
PROlt0
See inside for details on the
Proposed Plan
for cleanup of OU1 (the former Export Plant)
Libby Asbestos Superfund Site
The public comment period begins on September 9, 2009
The public meeting is on September 28, 2009
Also, watch your mail next week for the Proposed Plan for OU2
(the Former Screening Plant and Adjacent Areas).

-------