Technology:
Dynamic Underground Stripping (DUS) - Combination of three technologies: steam injection at periphery of contaminated area to drive contaminants to centrally-located vacuum extraction locations; electrical heating of less permeable soils; and underground imaging to delineate heated areas - Six steam injection/electrical heating wells approximately 145 feet deep, 4-inch diameter, screened in upper and lower steam zones - Three electrical heating wells approximately 120 feet deep, 2-inch diameter - One groundwater and vapor extraction well, approximately 155 feet deep, 8-inch diameter - Extracted water processed through an air-cooled heat exchanger, oil/water separators, filters, UV/H2O2 treatment unit, air stripping, and GAC - Extracted vapors processed through heat exchanger, demister, and internal combustion (IC) engines
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Cleanup Authority:
CERCLA and Other: Bay Area Air Quality Management District
SIC Code:
5541 (Gasoline service station) | Licensing Information:
Kathy Willis
University of California
Office of Tech Transfer
1320 Harbor Bay Parkway, Suite 150
Alameda, CA 94501
(510) 748-6595
Kathy Kaufman
Tech. Transfer Init. Program, L-795
University of California
Lawrence Livermore Nat'l. Laboratory
7000 East Avenue
P.O. Box 808
Livermore, CA 94550
(510) 422-2646 |
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Contaminants:
Benzene, Toluene, Ethylbenzene, Total Xylenes (BTEX) - Concentrations of fuel hydrocarbons (FHC) in gasoline as high as 5,100 ppm in saturated sediments near center of vadose zone (indicates likely presence of free-phase gasoline) - Benzene levels in groundwater greater than 1 ppb found within 300 feet of release point - Benzene levels in soil greater than 50 ppm |
Waste Source:
Underground Storage Tanks |
Type/Quantity of Media Treated:
Soil and Groundwater - 100,000 cubic yards heated to at least 200xF - 4 hydrogeologic units and 7 hydrostratigraphic layers identified near gas pad - Hydraulic conductivity ranged from <5 gpd/ft[Sub 2] (low permeability) to 1,070 gpd/ft[Sub 2] (very high to high permeability) - Low groundwater velocities kept contamination confined to a relatively small area |
Purpose/Significance of Application:
Commercial-scale demonstration of dynamic underground stripping. Results compared to pump and treat, and pump and treat with vacuum extraction technologies |
Regulatory Requirements/Cleanup Goals:
Groundwater cleanup levels established based on California MCLs:
- Benzene 1 ppb
- Ethylbenzene 680 ppb and xylenes 1,750 ppb
- Remediation was required until soil contaminant concentrations were identified as not adversely impacting groundwater
- Air permits were issued by the BAAQMD for the air stripper, GAC, IC engine, and for site-wide benzene |
Results:
- Over 7,600 gallons of gasoline removed during demonstration effort - Most of the gasoline was recovered in the vapor stream and not from extracted groundwater |
Cost Factors:
- Overall program costs for the field demonstration, including all research and development costs, were $1,700,000 for before-treatment costs (project management, characterization and compliance monitoring), and $8,740,000 for treatment activities (process monitoring, subsurface wells, steam generation and electrical heating surface equipment, aboveground treatment systems, utilities, and labor and material costs) |
Description:
The 800-acre Lawrence Livermore National Laboratory (LLNL) site was used as a flight training base and aircraft assembly and repair facility by the Navy beginning in 1942. In 1951, the Atomic Energy Commission converted the site into a weapons design and basic physics research laboratory. Initial releases of hazardous materials occurred in the mid- to late-1940s.
Between 1952 and 1979, up to 17,000 gallons of leaded gasoline were released from underground storage tanks beneath a gasoline filling station in an area now designated as the Gasoline Spill Area (GSA). Soil and groundwater in the GSA were found to be contaminated with BTEX (benzene, toluene, ethylbenzene, and xylenes) and fuel hydrocarbons.
A commercial-scale field demonstration of Dynamic Underground Stripping (DUS) was completed at the GSA from November 1992 to December 1993. DUS is a combination of three technologies: steam injection at the periphery of a contaminated area to drive contaminants to a centrally-located vacuum extraction location; electrical heating of less permeable soils; and underground imaging (primarily Electrical Resistance Tomography) to delineate heated areas. The DUS system used at the GSA employed 6 steam injection/electrical heating wells, 3 electrical heating wells, and 1 vacuum extraction well, as well as above ground water and vapor treatment equipment.
Over 7,600 gallons of gasoline were removed by the DUS system in the demonstration effort. Most of the gasoline was recovered in the vapor stream and not from the extracted groundwater. Potential cost savings of $4,000,000 were identified for applying DUS at the same site in the future (taking into account the benefits of the lessons learned and without research-oriented activities). |
