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SITE FACTS
Location: Libby, Montana
Laboratories/Agencies: U.S.
EPA National Risk Management
Research Laboratory (NRMRL),
Utah State University (USU),
U.S. EPA Region 8
Media and Contaminants:
Pentachlorophenol (PCP) and
polycyclic aromatic
hydrocarbons (PAHs) in soil
and ground water
Treatment: Surface soil
bioremediation, aboveground
fixed-film bioreactor, in situ
bioremediation
Date of Initiative Selection:
Fall 1990
Objective: To evaluate the
performance of three
biotreatment processes for
degradation of PCP and PAHs
Bioremediation Field Initiative
Contact: Scott Huling, U.S.
EPA NRMRL, P.O. Box 1198,
Ada, OK 74820
Regional Contact: Jim Harris,
U.S. EPA Region 8, Montana
Office, 301 South Park, Federal
Building, Drawer 10096, Helena,
MT 59626
United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
Office of Solid Waste and
Emergency Response
Washington, DC 20460
EPA/540/F-95/506A
September 1995
Bioremediation
Initiative Site Profile:
Libby Ground Water
Superfund Site
Background
The Libby Ground Water Superfund site in Libby, Montana, is located in
part at the site of an operating lumber mill that was owned by Champion
International Corporation. A wood preserving facility for- merly oper-
ated at the site contaminated soil and ground water with two wood
preservatives: pentachlorophenol (PCP) and creosote (PAHs). PAHs and
PCP are the primary contaminants of concern associated with the soil
phase. PAH-contaminated soils from three primary source areas have
been excavated and moved to a central waste pit.
The U.S. EPA National Risk Management Research Laboratory, in
cooperation with Utah State University (USU), is carrying out a per-
formance evaluation of three biological treatment processes at the
Libby site: (1) surface soil bioremediation in a lined, prepared-bed land
treatment unit (LTU); (2) ground water treatment in an aboveground
fixed-film bioreactor; and (3) in situ bioremediation of the upper aqui-
fer. Each process is being evaluated with regard to design, operation,
monitoring, and performance. Figure 1 is a plan view of the site,
showing the LTU, bioreactor, and ground water injection systems.
Contaminant
Plume
Infiltration Trench
LTU
LTU
Scale (feet)
0 300 600
+ Monitoring Well
O Extraction Well
,—» Regional
l«s\Ground Water
Flow
^Injection Well
Figure 1. Plan view showing LTU, bioreactor, and ground water injection system (from
Piotrowski, M.R. 1991. Full-scale in situ bioremediation at a Superfund site: a progress
report. Second Annual West Coast Conference, Hydrocarbon Contaminated Soils and
Ground Water. Newport Beach, CA. March 1991).
Printed on paper that contains at least
50 percent recycled fiber.
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Field Evaluation
Surface Soil Bioremediation. The LTU consists of two
adjacent 1-acre cells, lined with low-permeability
materials to minimize leachate infiltration from the
unit (see Figure 2). Contaminated soil is applied to
the cells in 9-in. lifts and treated until target con-
taminant levels are achieved within each lift. Evalu-
ation of the effectiveness of the land treatment
includes sampling the soil in the LTU, studying
field-scale treatment and toxicity reduction, ana-
lyzing the influence of moisture and temperature,
and evaluating the downward migration of PAH
and PCP within the LTU.
Figure 2. Land treatment unit.
LTU soil analysis data will be used to determine the
statistical significance, confidence, and extent of
biodegradation as well as any downward migra-
tion at this site. Degradation kinetics and toxicity
reduction studies will generate data that can be
used to help assess overall bioremediation effec-
tiveness and predict performance of similar biore-
mediation processes at other sites.
Aboveground Fixed-Film Bioreactor. Aboveground
treatment of ground water occurs in two fixed-film
reactors, which operate in series. The effluent from
these reactors is amended with nutrients and re-
oxygenated prior to reinjection through an infiltra-
tion trench. The Initiative will be monitoring the
performance of the bioreactors, including flow
composited sampling, analysis of biofilm dynam-
ics, calculation of mass balance of contaminants,
and treatment optimization.
In Situ Bioremediation of the Aquifer. The in situ biore-
mediation system involves addition of hydrogen
peroxide and inorganic nutrients to stimulate
growth of contaminant-specific microbes. Evalu-
ation of this process will include determining dis-
solved oxygen and other terminal electron acceptors
across the site, sampling aquifer material to identify
contamination, distinguishing between abiotic and
biotic effects, and correlating temperature and nutri-
ent status with biodegration rate and extent.
Status
Currently remediation of each lift of soil applied to
the LTU takes 32 to 163 days. Downward migration
of target chemicals as a result of the application of
additional lifts was not observed, and contami-
nated soil was detoxified to background levels as a
result of treatment. Performance of the fixed-film
bioreactors indicates that effective PAH and PCP
removal is taking place, and that removal efficiency
is a function of loading rate and retention time. In
situ treatment was observed in the water phase
under the influence of the injection system; how-
ever, contamination is present as non-aqueous
phase liquid (NAPL). Reduced inorganic com-
pounds present in the water phase and degassing
of hydrogen peroxide within the soil indicated abi-
otic loss pathways for oxygen that was injected to
stimulate bioremediation.
The Bioremediation Field Initiative was established in 1990 to expand the nation's field experience in bioremediation technologies.
The Initiative's objectives are to more fully document the performance of full-scale applications of bioremediation; provide
technical assistance to regional and state site managers; and provide information on treatability studies, design, and operation of
bioremediation projects. The Initiative currently is performing field evaluations of bioremediation at eight other hazardous waste
sites: Park City Pipeline, Park City, KS; Bendix Corporation/Allied Automotive Superfund site, St. Joseph, MI; West KL Avenue
Landfill Superfund site, Kalamazoo, MI; Eielson Air Force Base Superfund site, Fairbanks, AK; Hill Air Force Base Superfund site,
Salt Lake City, UT; Escambia Wood Preserving Site, Brookhaven, MS; Reilly Tar and Chemical Corporation Superfund site, St.
Louis Park, MN; and Public Service Company, Denver, CO. To obtain profiles on these additional sites or to be added to the
Initiative's mailing list, call 513-569-7562. For further information on the Bioremediation Field Initiative, contact Fran Kremer,
Coordinator, Bioremediation Field Initiative, U.S. EPA, Office of Research and Development, 26 West Martin Luther King Drive,
Cincinnati, OH 45268; or Michael Forlini, U.S. EPA, Technology Innovation Office, Office of Solid Waste and Emergency Response,
401 M Street, SW., Washington, DC 20460.
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