United States Office of Research and Office of Solid Waste and

Environmental Protection Development Emergency Response

Agency Washington, DC 20460 Washington, DC 20460

EPA/540/F-95/506A September 1995

Bioremediation Field

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 operated 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 performance 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 aquifer. 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.

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

Printed on paper that contains at least

50 percent recycled fiber.

Proposed

Boundary

Injection

System

Pilot

Injection

System

Bioreactor

Housing

Rock

Filter

Infiltration Trench

Waste Pit Area

Contaminant

Plume

Monitoring Well

Extraction Well

Injection Well

Regional

Ground Water

Flow

N

Scale (feet)

0 300 600

LTU LTU

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).
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 contaminant levels are achieved within each lift. Evaluation of the effectiveness of the land treatment

includes sampling the soil in the LTU, studying

field-scale treatment and toxicity reduction, analyzing the influence of moisture and temperature,

and evaluating the downward migration of PAH

and PCP within the LTU.

LTU soil analysis data will be used to determine the

statistical significance, confidence, and extent of

biodegradation as well as any downward migration at this site. Degradation kinetics and toxicity

reduction studies will generate data that can be

used to help assess overall bioremediation effectiveness and predict performance of similar bioremediation 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 reoxygenated prior to reinjection through an infiltration trench. The Initiative will be monitoring the

performance of the bioreactors, including flow

composited sampling, analysis of biofilm dynamics, calculation of mass balance of contaminants,

and treatment optimization.

In Situ Bioremediation of the Aquifer. The in situ bioremediation system involves addition of hydrogen

peroxide and inorganic nutrients to stimulate

growth of contaminant-specific microbes. Evaluation of this process will include determining dissolved 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 nutrient 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 contaminated 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; however, contamination is present as non-aqueous

phase liquid (NAPL). Reduced inorganic compounds present in the water phase and degassing

of hydrogen peroxide within the soil indicated abiotic 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.

Figure 2. Land treatment unit.

2