Bioventing Treatment at Refueling Loop E-7, Source Area ST20, Eielson Air Force Base, Alaska

Site Name:

Eielson Air Force Base


Fairbanks, Alaska

Period of

Status - Ongoing
Report covers - 7/91 to 7/94


Field Demonstration


Ronald M. Smith
Northwest Labs
Richland, WA

Bioventing - Bioventing conducted in conjunction with several soil warming techniques - Four experimental plots tested: passive warming, active warming, surface warming, and control

Cleanup Authority:
CERCLA and State: Alaska - Federal Facilities Agreement - ROD Date: 9/92

SIC Code:
9711 (National Security)
Point of Contact:
Capt. Timothy Merrymon
2258 Central Ave., Suite
1 Eielson AFB, Alaska 99702

Total Petroleum Hydrocarbons (TPH) and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX) - Soil TPH levels averaged 1,500 mg/kg - Contamination is concentrated in areas greater than 5.25 feet below ground surface

Waste Source:
Spills and Leaks of JP-4 Jet Fuel

Type/Quantity of Media Treated:
Soil - Thickness of contamination in saturated zone - 6.1 meters - Soil consists of interbedded layers of loose to medium dense gravel and sands with varying amounts of silt to 6-9 feet - Underlain by 600 feet of medium dense to dense sandy gravel - No permafrost encountered at site

Purpose/Significance of Application:
Bioventing with various soil warming techniques to demonstrate technology effectiveness in a subarctic environment.

Regulatory Requirements/Cleanup Goals:
TPH - 200 mg/kg in soil - Benzene - 2 lbs/day in extracted soil gas - Remedial activities to be conducted in accordance with a Federal Facilities Agreement between U.S. Air Force, U.S. EPA, and the Alaska Department of Environmental Conservation

Bioventing project not complete at time of this report - Preliminary results indicate that bioventing with soil warming stimulates in situ biodegradation year round in a subarctic environment - Active warming achieved higher biodegradation rates than passive or surface warming - Ambient air samples showed no detectable concentrations of benzene 4 feet and 6 feet above ground level

Cost Factors:
Estimated Capital Costs - $758,077 (including floating fuel collection devices, soil bioventing equipment, composting site development, mobilization, groundwater remediation and engineering design) - Estimated Annual Operations and Maintenance (O&M) Costs - $177,160 (O&M of three components - floating fuel (5 year duration), soil bioventing (10 year duration), groundwater monitoring (30 year duration), including sample analysis and monitoring of each component).

As a result of spills and leaks of JP-4 jet fuel at a refueling complex at Eielson Air Force Base (AFB) in Fairbanks, Alaska, soil was contaminated with total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). In November 1989, Eielson AFB was added to the National Priorities List (NPL) with the fuel-saturated area within the Refueling Loop E-7, Source Area ST20 designated as CERCLA Operable Unit 1. A field demonstration of bioventing and three soil warming techniques began in July 1991 including active warming, passive warming, and surface warming. Specific cleanup goals include TPH (200 mg/kg in soil), and benzene (2 lbs/day in extracted soil gas).

The field demonstration of the bioventing system was on-going as of July 1994. Available respiration test data for oxygen consumption rates confirmed the occurrence of biological degradation processes. Preliminary results indicate that bioventing with soil warming achieves biodegradation year round in a subarctic environment. Active warming was found to achieve a higher biodegradation rate than passive or surface warming. It was noted that biodegradation is enhanced by adequate soil oxygen, moisture, and nutrient levels; that injection wells are impractical at source areas with a naturally high concentration of iron in the groundwater; and that high soil moisture content interferes with soil gas monitoring and reduces the number of soil gas monitoring points that can be sampled.

The estimated capital cost of this application was approximately $758,000 and the estimated annual operations and maintenance costs are $177,160. Full-scale remedial activities at the site will be conducted in accordance with a Federal Facilities Agreement between the U.S. Air Force, U.S. EPA, and the Alaska Department of Environmental Conservation.