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SITE FACTS
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j Location: Salt Lake City Utah
'•> ' Laboratories/Agencies: U,^.
*i. Air Force, U.S.SEPA Risk
[ *JReduction. Engineering ' »
|f Laboratory (RREt);tr.S. EPA/ ,
•- • Media and Contaminants:
s-:.' JP-4 jet fuel in unsaturated soil
X Treatment; Bioventing /
::, •; bate of Initiative Selection:
1 Spring 1991 *
^Objective: To evaluate the
effectiveness of bioventing jet
* ^ fuel in deep vadose zone soil
*f * * f
~i* Bioremediation Field Initiative
;vContact: Greg Sayles,U.S. EPA
y, RREL, 26 West Martin Luther
:'• King Drive, Cincinnati, OH
\J$B26&' ' ", t> , wt_ .',
% \ Regional Contact: Robert
C' States, U.S. EPA Region 8,
-. 99918th Street, Denver, CO
-' 80202-2466 ' ' > * ,
United States
Environmental Protection
Agency
Office of Research and
Development
Washington, DC 20460
Office of Solid Waste and
Emergency Response
Washington, DC 2046Q
EPA/540/F-93/510C
September 1993
Bioremediation Field
Initiative Site Profile:
Hill Air Force Base
Superfund Site
Background
Hill Air Force Base (AFB) near Salt Lake City, Utah, is the site for one
of two projects the Bioremediation Field Initiative is undertaking in
cooperation with the U.S. EPA Risk Reduction Engineering Labora-
tory (RREL) and the U.S. Air Force to biovent JP-4 jet fuel spills. The
other, at Eielson Air Force Base in Alaska, is described in a separate
fact sheet.
Bioventing is the process of supplying oxygen in situ to oxygen-de-
prived soil microbes by forcing air through contaminated soil at low
airflow rates. Because bioventing equipment is relatively noninva-
sive, this technology is especially valuable for treating contaminated
soils at military bases, industrial complexes, and gas stations, where
structures and utilities cannot be disturbed.
At Hill AFB, the objectives of the Initiative are to gain experience in
bioventing large volumes of soil and determine the effect of airflow'rate
on biodegradation and volatilization rates. The challenges at this site are
(1) to biodegrade contamination that extends deep beneath the surface
and (2) to biovent the fuel plume under roads, underground utilities, and
buildings.
Characterization
The Hill AFB site is contaminated with JP-4 fuel from a depth of
approximately 35 ft to the ground water, which occurs at 95 ft below
the surface. The contaminated soil is a mixture of sand, silty sand, and
sand interspersed with gravel and day. Soil samples taken in Septem-
ber 1991 revealed an average total petroleum hydrocarbon (TPH)
level of 890 mg/kg, ranging up to 5,000 mg/kg at certain depths.
Ground water samples showed an average TPH concentration of 1.5
mg/L, with TPH concentrations in some wells as high as 10 mg/L.
The contaminated area extends beneath a tool maintenance building,
engine storage yard, and fuel storage yard (see Figure 1).
Field Evaluation
Bioventing performance is being evaluated at three different air injec-
tion rates. Unlike soil venting or soil vacuum extraction technologies,
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WW9
(10.3
CW9
• WW m Ground Water Monitoring Well
O CW» SoS Vapor Cluster Wall
IW-Injection Well
(1.5) •> TPH in Ground Water (mg/L) (9/91)
A-A'« Cross Section Trace
50 feet
Figure 1. Plan mew of contaminated area.
bioventing uses low airflow rates to stimulate
biodegradative activity while minimizing volatili-
zation of contaminants in the soil. Higher air injec-
tion rates stimulate faster and more widespread
biodegradationbut also release more volatile emis-
sions to the surface. Figure 2 shows an air injection
well at the site. Twice a year, the rate of air injection
is reduced to study the tradeoff between the loss in
area of influence of the injected air for bioremedia-
tion and the decrease in volatilization of organics
at the soil surface.
To determine the rate of hydrocarbon loss due to
bioventing, REEL conducts semiannual in situ res-
piration tests. Air injection is shut off for 4 to 8 days,
during which soil gas oxygen levels are carefully
monitored. The rate of oxygen uptake by microor-
ganisms in the contaminated soil, relative to
oxygen loss .observed in an uncontaminated area,
indicates the rate of biodegradation..
RREL has conducted an inert gas tracer study to
determine the transport of gas through the soil.
During this study, researchers temporarily injected
helium instead of air into the vent well. By moni-
toring for the inert gas at the various soil gas wells,
researchers determined how efficiently the injec-
tion well delivers air to the soil.
Status
The U.S. Air Force began bioventing operations in
January 1991. Between July and September 1991,
RREL installed additional wells to monitor biore-
mediation performance over the entire 100-ft depth
of the contaminated vadose zone. The first flow
rate change and in situ respiration test, and the
inert gas tracer study took place in fall of 1992. Final
soil hydrocarbon analyses will be conducted in
summer of 1993. These results will be compared
with the initial soil analysis to document overall
hydrocarbon loss due to bioventing.
Figure 2. Air injection well at the surface.
Tlte 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 treatabilitystudies/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,lCS; 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; Escambia Wood Preserving Site—Brookhaven, Brookhaven, MS; Reilly Tar and Chemical Corppration 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 VVest Martin L'uther King Drive,
Cincinnati, OH 45268; or Michael Forlini, U.S. EPA, Technology Innovation Office, Office of Solid Waste and Emergency Response,
401M Street, SW., Washington, DC 20460. ' » , '' '->'-',, ,//,"> ''
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