Section One
SITE REMEDIATION
1    IN-SITU VENTING OF JET-FUEL-CONTAMINATED SOIL
Michael G. Elliott, Environmental Research Engineer
Air Force Engineering and Services Center
Tyndall AFB, Florida 32403
David W. DePaoli, Development Engineer
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37831
INTRODUCTION
The Air Force Engineering and Services Center is performing a field demonstration of in-situ soil
venting at a 27,000-gallon jet fuel spill site at Hill AFB, Utah. In-situ soil venting is a soil cleanup
technique which uses vacuum blowers to pull large volumes of air through contaminated soil. The air
flow sweeps out the soil gas, disrupting the equilibrium existing between the contaminants on the soil
and in the vapor. This causes volatilization of the contaminants and subsequent removal in the air
stream. In-situ soil venting has been used for removing volatile contaminants such as gasoline and
trichloroethylene, but a full-scale demonstration for removing jet fuel from soil has not been
reported.
This paper describes our initial site characterization, the one-vent pilot test, and the design and
preliminary results of our full-scale in-situ soil venting system.
SITE CHARACTERIZATION
On January 9, 1985, in a fuel yard at Hill AFB, Utah, approximately 27,000 gallons of jet fuel (JP-
4) spilled on the ground after an automatic filling system malfunctioned and underground storage
tanks overfilled. JP-4 is made by blending various proportions of distillate stocks such as naphtha,
gasoline and kerosene to meet military and commercial specifications. In general, it has more heavy
molecular weight hydrocarbons and is less volatile than gasoline and other contaminants which have
previously been investigated for remediation by in-situ soil venting.
An initial surface cleanup effort at the spill site resulted in the recovery of about 1,000 gallons of
JP-4 with the remaining portion infiltrating into the soil. A soil sampling study conducted in December 1985 delineated the areas of soil having greater than 1 °'o fuel in the soil. Based on this study, a
decision was made to excavate the highly contaminated soil near the underground storage tanks and
place the tanks in an aboveground concrete enclosure.
To determine if the JP-4 had the potential for reaching the water table, further investigations were
completed to evaluate the site's geohydrological characteristics and the contaminant level in the soil.
Investigations included seismic and resistivity tests, soil vapor surveys, and core boring analysis.
Based on past geophysical investigations at Hill AFB, it was known that the Provo formation
comprises the surface strata beneath the spill site. The Provo formation consists of medium to fine
sands with thin interbedded layers of silty clay. Regionally, these sands are underlain by clay layers
which extend to a depth of 600 feet below land surface (BLS) at a well located 500 feet south of the
spill site.
A total of 43 soil borings were performed for characterization of the spill site. The lithologic logs
describe a surface layer of brown silty sand about 4 feet thick, underlain by brown sand to a depth of
23 to 35 feet throughout the spill area. Variable-spaced clay layers were reported at depths between 23
and 42 feet.
The Delta aquifer, at an average depth beneath Hill AFB of about 600 feet, is the regional aquifer
of greatest significance as a water-bearing unit because of its high permeability. The Sunset aquifer, at
44th Purdue Industrial Waste Conference Proceedings, © 1990 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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