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Cost and Performance
Report:
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Preparation of this report has been funded wholly or in part by the U.S. Environmental Protection Agency under Contract Number 68-W3-0001. It has been subject to administrative review by EPA headquarters and Regional staff and by the technology vendor. Mention of trade names for commercial products does not constitute endorsement or recommendation for use.
This report summarizes cost and performance data for a soil vapor extraction (SVE) treatment application at the Well Number 3 Subsite of the Hastings Groundwater Contamination Superfund site. Soil at the site was contaminated with halogenated organic compounds. Contamination was attributed to spills of carbon tetrachloride (CCl4) which had been used in the 1960s and 1970s as a fumigant at a grain storage facility. Concentrations of CCl4 were measured in the soil gas at the site at levels over 1,200 ppmv.
On September 26, 1989, a Record of Decision (ROD) was signed to implement SVE as an Interim Source Control measure. EPA and the Nebraska Department of Environmental Quality established an extraction rate for CCl4 of 0.001 lb/hr as the cleanup goal, with operation of the SVE system required until field analytical results were verified through laboratory analysis and it was confirmed that no rebounding of CCl4 was occurring.
A pilot-scale SVE treatability study was conducted from April to May 1991. The pilot-scale system included 2 deep and 2 shallow extraction wells. During the pilot-scale operation, 45 pounds of CCl4 were removed. The full-scale SVE system consisted of 10 extraction wells (5 deep, 3 intermediate, and 2 shallow), 5 monitoring well probes, an air/water separator, a vacuum pump, and vapor phase granular activated carbon (GAC). The full-scale system design included the two deep extraction wells and one of the shallow extraction wells used in the pilot-scale study.
The SVE system was operated from June 25, 1992 to July 1, 1993 to treat approximately 185,000 cubic yards of soil. The SVE system achieved the 0.001 lb/hr CCl4 extraction rate within 6 months, with confirmation of analytical results and no rebounding of CCl4 by July 1993.
Actual costs for installing and performing the SVE application, including disposal costs for the GAC, were approximately $370,000, which corresponds to $620 per pound of CCl4 removed (600 pounds removed) and $2.00 per cubic yard of soil treated. This large-scale project benefited from treatment of soil with relatively low levels of contaminants in the soil gas.