Pump and Treat and Soil Vapor Extraction
- Groundwater was extracted using 3 wells, located on site, at an average total pumping rate of 103 gpm
- Extracted groundwater was treated with air stripping and reinjected using an infiltration trench with 600 ft of surface area
- SVE was used as a source control activity
- MNA currently in progress
- Interim ROD dated September 30, 1994
|EPA Remedial Project Manager:|
U.S. EPA Region 4
61 Forsyth Street, SW
Atlanta, GA 30303-3104
|Navy Point of Contact:|
Southern Division, Naval Facilities
North Charleston, SC 29419-9010
Petroleum products and chlorinated solvents
- 1,2-dichlorobenzene as high as 18 mg/kg
- Napthalene as high as 19 mg/kg
- 2-methylnapthalene as high as 47 mg/kg
Disposal of waste fuel and oil
Type/Quantity of Media Treated:
Soil - 11,768 tons
Purpose/Significance of Application:
Mobile thermal desorption unit used to treat soil contaminated with fuel and solvents
Regulatory Requirements/Cleanup Goals:
- Total recoverable petroleum hydrocarbon (TRPH) level of 50 mg/kg provided that total polycyclic aromatic hydrocarbons (PAH) were less than 1 mg/kg and total volatile organic hydrocarbons were less than 50 mg/kg.
- Particulate emissions of 0.04 grains per dry standard cubic foot (gr/dscf)
- 110 of 115 post-treatment samples met the cleanup goal of 50 mg/kg TRPH after one pass.
- For the five post-treatment samples that did not meet the cleanup goal, the five batches of soil (724.5 tons, or approximately 6% of the total) were re-treated. All samples of the re-treated soil met the cleanup goals.
- The total cost for the application was $1,946,122.
- This represents a unit cost of $165 per ton of soil treated for treatment of 11,768 tons of contaminated soil.
Naval Air Station (NAS) Cecil Field, established in 1941, provides facilities, services, and material support for the operation and maintenance of naval weapons, aircraft, and other units of the operating forces. NAS Cecil Field includes several operable units (OU) and contaminated sites, including Site 17 in OU2. Site 17 reportedly was used for two or three years during the late 1960s and early 1970s for the disposal of waste fuel and oil, possibly including oil contaminated with solvents and paints. Soil at Site 17 was found to be contaminated with petroleum products and chlorinated solvents. In September 1994, EPA signed an interim Record of Decision (ROD) for Site 17 specifying that soil be excavated and treated by thermal desorption.
The thermal desorption unit used at Site 17 was a mobile unit provided by Dustcoating, Inc. of Maple Plain, Minnesota. The unit, a propane-fired Gencor Model 232 rotary drum dryer modified to thermally process contaminated soil, consisted of a 60-inch-diameter-by-20-foot-long rotary dryer with burner (direct-fired), a primary collector baghouse, and an afterburner system. The nominal system throughput for this unit was 25-50 tons/hour; the actual system throughput during this application was 17 tons/hour. The desorber treated contaminated soil at approximately 825 °F with an average residence time of 3.5 minutes. An afterburner operated at a temperature of at least 1,500 °F with a retention time of approximately two seconds to destroy organic compounds in the off-gas. A total of 115 post-treatment soil samples were collected and analyzed. All but five of these samples met the cleanup goal after the first pass. The five samples were retreated and all met the cleanup goal. According to the EPA RPM, no specific operational problems were identified as causing the failure to meet the cleanup goals on the first pass; however, the contractor suspects that this was caused by elevated levels of moisture in the soil.