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-95/506H September 1995

Bioremediation Field

Initiative Site Profile:

Reilly Tar and Chemical

Corporation Superfund Site

Background

This Bioremediation Field Initiative project is under way in St. Louis

Park, Minnesota, at the former site of Reilly Tar and Chemical Corporation’s coal tar distillation and wood preserving plant. From 1917 to

1972, wastewater discharges and dumping from this plant contaminated about 80 acres of soil and the underlying ground water with

wood preserving wastes. In 1978, the Minnesota Department of

Health discovered significant concentrations of polycyclic aromatic

hydrocarbons (PAHs) in six municipal drinking water wells neighboring the Reilly Tar plant. St. Louis Park currently is pumping and

treating the contaminated ground water plume, but without an effort

to control the source of PAHs, pumping and treating might be necessary for several hundred years.

This Initiative project is evaluating bioventing of PAH-contaminated

soil through the U.S. EPA Superfund Innovative Technology Evaluation (SITE) Program and the U.S. EPA National Risk Management

Research Laboratory’s (NRMRL) Biosystems Program. Bioventing

has proven effective at remediating lightweight petroleum distillates

such as JP-4 jet fuel; this is the first evaluation of bioventing’s effectiveness for remediation of larger molecular weight hydrocarbons.

Characterization

The SITE program conducted a preliminary site characterization,

including soil sampling, soil gas monitoring, and in situ respiration

testing, in August 1992. Soil sampling revealed PAH contamination

in sandy vadose soil ranging from 3 to 10 ft below the surface. Soil

gas monitoring and respiration tests indicated that the soil’s aerobic

microbial activity and air permeability are high enough for successful bioventing.

Field Evaluation

In November 1992, baseline soil sampling was conducted and a

full-scale bioventing system installed on a 50-ft by 50-ft plot (see

Figure 1). A control plot of equal size and contaminant levels also

was established to gauge the effectiveness of the bioventing system.

The system consists of one air injection well with screening 5 to 10

ft below ground level (see Figure 2), a 2.5-hp blower, a network of

SITE FACTS

Location: St. Louis Park,

Minnesota

Laboratories/Agencies: U.S.

EPA National Risk Management

and Research Laboratory

(NRMRL), Superfund Innovative

Technology Evaluation (SITE)

Program, U.S. EPA Region 5,

Minnesota Pollution Control

Agency

Media and Contaminants:

Polycyclic aromatic

hydrocarbons (PAHs) in soil

Treatment: Bioventing

Date of Initiative Selection:

October 1992

Objective: To evaluate the

effectiveness of bioventing

PAH-contaminated soil

Bioremediation Field Initiative

Contacts: Paul McCauley and

Richard Brenner, U.S. EPA

NRMRL, 26 West Martin

Luther King Drive, Cincinnati,

OH 45268

Regional Contact: Daryl

Owens, U.S. EPA Region 5,

Waste Management Division, 

77 West Jackson Boulevard,

Chicago, IL 60604

Printed on paper that contains at least

50 percent recycled fiber.
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: Libby Ground Water Superfund site, Libby, MT; 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; 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 1. Layout of bioventing installation on experimental plot. Figure 2. Schematic of air injection vent well.

54 soil gas sampling probes, and a system to monitor soil temperature and ground-water elevation.

The blower and vent well deliver 100 ft3

 of air per

hour to the contaminated soil.

Personnel from the City of St. Louis Park inspect

the site for malfunctions every 2 weeks. In situ

respiration tests are being conducted four times per

year by NRMRL. At the completion of the project,

final soil samples will be collected from the experimental and the control plots.

Status

Quarterly shut-down respiration tests over the first

2 years have ranged from below detection to 0.48

percent O2/hr. The highest respiration rates were

found in the western half of the treatment area

where PAH contamination was also the heaviest.

Current average measured respiration rates are

consistent with a 14 percent reduction in PAH contamination per year. After 2 years bioventing, 70

soil borings were taken from a 25-ft x 25-ft section

in the northwest corner of the test plot. PAH analysis

of these soil borings was statistically inconclusive.

The demonstration project is expected to last 3

years, at which point it is estimated that soil core

samples must show at least a 27 percent reduction

in PAH levels to be statistically significant. If

bioventing successfully biodegrades PAHs at this

rate, complete bioremediation of the site would

take 10 to 15 years if large-scale bioventing is undertaken. The results of this study will help determine whether bioventing can be considered at

Superfund sites as a cost-effective treatment for

remediating PAH-contaminated soils.