Soil Vapor Extraction and Bioventing for Remediation of a JP-4 Fuel Spill at Site 914, Hill Air Force Base, Ogden, Utah

Site Name:

Hill Air Force Base

Location:

Ogden, Utah

Period of
Operation:

October 1988 - December 1990

Cleanup
Type:

Full-scale cleanup

Vendor:

Not Available

Technology:
Bioventing Preceded by SVE - Bioventing - 4 vent wells (Numbers 12-15) located on the southern perimeter of the spill area; 31 monitoring wells; 3 neutron access probes (for soil moisture monitoring) - Vent wells approximately 50 feet deep with 4-inch diameter PVC casings, screened from 10 to 50 feet below ground surface - Monitoring wells - ranged in depth from 6 to 55 feet with 1-inch diameter PVC casings, screened from 10 to 50 feet below ground surface - No treatment of extracted vapors required (hydrocarbon concentrations <50 mg/L; use of catalytic incinerator not required) - Air flow - 250 acfm - Soil moisture - 6 to 12% - Nutrients added - C:N:P ratio of 100:10:10

SVE - 7 vent wells (Numbers 5-11 located in areas of highest contamination), 31 monitoring wells, 3 neutron access probes (soil moisture monitoring) - Vent wells approximately 50 feet deep with 4-inch diameter PVC casings, screened from 10 to 50 feet below ground surface - Plastic liner installed over part of spill area surface to prevent local air infiltration and bypassing of air flow to the vent well directly from the surface - Monitoring wells - range in depth from 6 to 55 feet with 1-inch diameter PVC casing and a 2-foot screened interval to the bottom of the well - Catalytic incinerator for extracted vapor - Air flow - 1,500 acfm (maximum), 700 acfm (typical)

Cleanup Authority:
State: Utah

SIC Code:
9711 (National Security)
Point of Contact:
Robert Elliot
OO-ACC/EMR
7274 Wardleigh Road
Hill AFB, Utah 84055

Contaminants:
Total Petroleum Hydrocarbons (TPH) - TPH concentrations in untreated soil ranged from <20 to 10,200 mg/kg with average soil TPH concentration of 411 mg/kg

Waste Source:
Spill of JP-4 Jet Fuel

Type/Quantity of Media Treated:
Soil - 5,000 yds[Sup 3] contaminated by spill (surface area of 13,500 ft[Sup 2]) - Approximate extent of 10,000 mg/kg JP-4 contour covered area 100 by 150 feet - Formation consists of mixed sands and gravels with occasional clay lenses - Air permeability ranged from 4.7 to 7.8 darcies

Purpose/Significance of Application:
One of the early applications involving sequential use of SVE and bioventing technology.

Regulatory Requirements/Cleanup Goals:
38.1 mg/kg TPH - Cleanup conducted under Utah Department of Health's "Guidelines for Estimating Numeric Cleanup Levels for Petroleum-Contaminated Soil at Underground Storage Tank Release Sites"

Results:
Achieved specified TPH levels - Average TPH soil concentrations in treated soil reduced to less than 6 mg/kg; - 211,000 lbs of TPH removed in approximately 2 years of operation; - Removal rate ranged from 20 to 400 lbs/day

Cost Factors:
Total costs of $599,000, including capital and 2 years of operating costs - Capital costs - $335,000 (including construction of piping and wells, other equipment, and startup costs) - Annual operating costs - $132,000 (including electricity, fuel, labor, laboratory charges, and lease of equipment for 2 year operation)

Description:
In January 1985, an estimated 27,000 gallons of JP-4 jet fuel were spilled at the Hill Air Force Base Site 914 when an automatic overflow device failed. Concentrations of total petroleum hydrocarbons (TPH) in the soil ranged from <20 mg/kg to over 10,000 mg/kg, with an average concentration of about 400 mg/kg. The spill area covered approximately 13,500 ft[Sup 2].

The remediation of this spill area was conducted from October 1988 to December 1990 in two phases: the soil vapor extraction (SVE) phase followed by the bioventing phase. The SVE system included 7 vent wells (Numbers 5-11) located in the areas of highest contamination, 31 monitoring wells, and a catalytic incinerator. The typical air flow rate through the vent wells was 700 acfm, with a maximum of 1,500 acfm. In addition, a plastic liner was installed over part of the spill area surface to prevent local air infiltration and bypassing of air flow to the vent well directly from the surface. Within a year, the SVE system removed hydrocarbons from the soil to levels ranging from 33 to 101 mg/kg. Further reduction of the hydrocarbon concentration in the soil, to levels below the specified TPH limit, was achieved by using bioventing for 15 months. The bioventing system included 4 vent wells (Numbers 12-15), located on the southern perimeter of the spill area, and the monitoring wells used for SVE system. Because hydrocarbon concentrations were <50 mg/L in the extracted vapors, the catalytic incinerator was not required for this phase. Biodegradation was enhanced by injecting oxygen, moisture, and nutrients to the soil. Average TPH concentrations in the treated soil were less than 6 mg/kg.

The total capital cost for this application was $335,000 and the total annual operating costs were $132,000. In monitoring biodegradation rates, oxygen depletion was found to be a more accurate estimator of biodegradation rate than carbon dioxide formation. Carbon dioxide sinks, such as biomass, solubility in water, and reaction with the soil, limited the usefulness of carbon dioxide formation as a process control parameter.