Technology:
In Situ Soil Vapor Extraction
- Eastgate: Between 1994 and 1996, system operated under pulse venting techniques, involving turning off the system for shorter periods of time. The 2001 trial period involved 24-hour per day operations, with an airflow rate of 300 cfm. A 6-hour per day pulse mode was initiated in March and continued until cessation of operations in June. A total of 2,000 lbs of granular activated carbon was used to treat the soil vapor.
- Oxboro: In situ SVE system included soil venting wells and a blower system operation checked weekly during first three weeks of operation and monthly thereafter; monitoring included air flow rates, vacuum, and total organic vapor; no specific operating data provided
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Cleanup Authority:
State
Contacts:
Varied by site |
Contaminants:
1,1-Dichloroethene (1,1 DCE), 1,2-Dichloroethene (1,2 DCE), cis-1,2-Dichloroethene (cis-1,2 DCE), Methylene Chloride, Tetrachloroethene (PCE); Trichloroethene (TCE), Vinyl Chloride, Benzene, Toluene, Acetone, Napthalene
Eastgate:
- Plume size = 120,000 ft2
- Halogenated Volatiles - 1,1-DCE- 13 g/L; 1,2-DCE - 1,300 g/L; cis-1,2-DCE - 1,000 g/L; methylene chloride - 0.55 g/L; PCE - 2,100 g/L; TCE -1,200 g/L; vinyl chloride - 1.1 g/L; PCE soil concentrations - 7,170 g/kg
- Non-Halogenated Volatiles - benzene- 1.7 g/L; toluene - 0.63 g/L; acetone - 37,000 g/L
Oxboro:
- Halogenated Volatiles - 1,1-DCE - 13 g/L; 1,2-DCE - 3.4 g/L; PCE - 37 g/L; TCE - 58 g/L
- Non-Halogenated Volatiles: Napthalene - 2.2 g/L; Acetone - 24 g/L; PCE in soil - 1 g/kg |
Waste Source:
Waste and wastewater from dry cleaning operations |
Type/Quantity of Media Treated:
Soil, Groundwater
Eastgate:
- Depth to groundwater - perched groundwater at 40 ft with a basal fluvial aquifer at 70 ft
- Subsurface geology - Loess deposits of 20 to 25 ft of clayey silts overlying fluvial material (50 to 80 ft) underlain by the Jackson-upper Claiborne confining bed, encompassing the Jackson Clay and the Cockfield Cook Mountain Formations (125 ft thick)
- Conductivity - 2.55x10-5 to 3.97x10-5 ft/day (depths between 8 and 28 ft)
- Groundwater gradient - 0.001 to the ESE (perched zone)
Oxboro:
- Depth to groundwater - 40 ft
- Subsurface geology - Tan and black gravel/silt (0-2 ft); Dark red sand/gravel (5-35 ft); sand/cobbles (35-40 ft) |
Purpose/Significance of Application:
Use of in situ SVE to treat soil and groundwater contaminated with chlorinated solvents at dry cleaner facilities. |
Regulatory Requirements/Cleanup Goals:
Eastgate:
- Groundwater- PCE - 5 g/L; TCE - 5 g/L; 1,1 DCE - 7 g/L; cis-DCE - 70 g/L; 1,2 DCE total - 70 g/L
- Soil- PCE - 500 g/kg
Oxboro:
Clean up goals not identified |
Results:
Eastgate:
- Approximately 1,350 lbs of PCE and TCE were removed during initial operations (1994-1996).
- During 2001 trial period, approximately 0.16 lbs of total PCE and TCE was recovered from both deep and shallow extraction wells. The system was terminated upon verification that a negligible volume of mass was entering the system; next step is natural attenuation to further reduce contamination.
Oxboro:
- Soil - PCE concentration decreased from 160 mg/m3 on October 20, 1997 to 2.3 mg/m3 on May 8, 1998.
- DCE was detected at a concentration of 7.2 mg/m3 in the October 20, 1998 sample, but was not detected in the remaining samples.
- Cleanup goals were reported to have been met "within a couple of years" |
Cost Factors:
- Eastgate: $34,500 (trial period)
- Oxboro: $182,906.63 (total cost for clean up) |
Description:
In situ SVE was conducted at two dry cleaner sites contaminated with chlorinated organic compounds from leaks, spills, or dumping of dry cleaning solvents or waste waters. The concentrations of PCE and TCE contamination varied by site with levels of PCE in groundwater as high as 2,100 g/L and TCE in groundwater as high as 1,200 g/L. Levels of PCE in soil were as high as 7,170 g/kg and 1 g/kg, respectively. The remediations included full-scale in situ SVE and a trial period where the in situ SVE system was operated under pulse venting techniques, involving turning off the system for shorter periods of time.
At the Eastgate site, approximately 1,350 lbs of PCE and TCE were removed during the 2-year full-scale operation. An additional 0.16 lbs of contaminants were removed during the trial period. The system operation was terminated in June 2001 based on the negligible amount of contaminant mass entering the system. Natural attenuation is planned to further reduce the contaminant levels.
At the Oxboro site, as of October 1997, soil vapor concentrations of PCE decreased from 160 mg/m3 to 2.3 mg/m3. As of October 1998, soil vapor concentrations of DCE decreased to 7.2 mg/m3 in one sample and was not detected in remaining samples. |
