United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
Office of Solid Waste and
Emergency Response
Washington, DC 20460
&EPA
SITE FACTS
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Location: Fairbanks, Alaska
Laboratories/Agencies: U.S.
Air Force, U.S. EPA National
Risk Management Research
Laboratory (NRMRL), U.S. EPA
Region 10
Media and Contaminants:
JP-4 jet fuel in shallow
unsaturated soil
Treatment: Bioventing with
active and passive soil warming
Date of Initiative Selection:
Spring 1991
Objective: To examine the use
of soil-warming technologies to
enhance the effectiveness of
bioventing jet fuel-contamin-
ated soil in a cold climate
Bioremediation Field Initiative
Contact: Gregory Sayles, U.S.
EPA NRMRL, 26 West Martin
Luther King Drive, Cincinnati,
OH 45268
Regional Contact: Mary Jane
Nearman, U.S. EPA Region 10,
1200 Sixth Avenue, Seattle, WA
98101
EPA/540/F-95/506B
September 1995
Bioremediation Field
Initiative Site Profile:
Eielson Air Force Base
Superfund Site
Background
Eielson Air Force Base (AFB) in Fairbanks, Alaska, is one of about 4,300 Air Force
sites contaminated with petroleum hydrocarbons in soil. In 1988, the U.S. Air
Force initiated a study at Hill AFB to examine the potential of bioventing to
remediate JP-4 jet fuel-contaminated soils. Promising results prompted a joint
U.S. EPA and Air Force study at Hill AFB (see separate fact sheet, EPA/540/F-
95/506C)) as well as Air Force studies at more than 125 sites across the United
States. Based on early successes at warm-weather sites, the Air Force and the U.S.
EPA National Risk Management Research Laboratory (NRMRL) became inter-
ested in using bioventing in cold climates. Because microbial degradation occurs
slowly at low temperatures, they decided to study soil warming to enhance the
effectiveness of bioventing at a cold-weather site—Eielson AFB.
Characterization
Prior to bioventing, the soil at the Eielson site consisted of sand and silt contaminated
with JP-4 jet fuel from a depth of roughly 2 ft to the water table at 6 to 7 ft. Total
petroleum hydrocarbon (TPH) levels ranged from 100 to 3,000 mg/kg. Although the
site is not in the permafrost region, soil temperatures in winter drop to nearly 0°C.
Researchers hypothesized that using soil warming to promote high-rate, year-round
bioremediation at this site would cost less overall than sustaining low-rate bioreme-
diation at ambient temperatures for an extended period.
Field Evaluation
In summer 1991, the Air Force and NRMRL began operating a bioventing system at
Eielson, using a blower to inject air into the contaminated soil at a rate of 25 ft /min.
To evaluate bioventing with and without soil warming, they constructed four 50-ft
square test plots in the contaminated area (see Figure 1):
Warm water test plot. Ground water was pumped through an electric heater, heated
to about 35°C, then pumped through soaker hoses buried 2 ft underground at a rate
of 1 gpm. Insulation was placed over the ground to retain heat.
Heat tape test plot. Strips of heat tape were buried at a depth of 3 ft to warm the soil
directly. The total heating rate was about 1 watt per square foot. Insulation was
placed over the ground to retain heat.
Solar test plot. Insulation was placed over the ground during the winter months, then
replaced with plastic mulch sheeting during the spring and summer months to
capture solar heat and passively warm the soil.
Control test plot. The control test plot received no soil warming.
All four test plots contained air injection/extraction wells (distributed at 30-ft intervals
to provide uniform aeration), thermocouples for monitoring soil temperature, and
three-level soil gas monitoring points for monitoring oxygen delivery andfor sampling
soil gas during in situ respiration tests. During quarterly in situ respiration tests,
the Air Force and NRMRL shut off air injection for several days and monitored
soil gas oxygen and carbon dioxide levels; they used these measurements to calculate
Printed on paper that contains at least
50 percent recycled fiber.
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Figure 1. Schematic plan view of warm water, heat tape, solar, and control test plots.
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