South Carolina Dept. of Health and Environmental Control (DHEC), 9 pp, 2018

The Proposed Plan identifies DHEC's preferred alternative for cleaning up toluene-contaminated soil and groundwater at the Wix Dillon site, a manufacturing facility. An air sparge/soil vapor extraction system began operation in December 2009, but this approach was not effective in removing contamination. Wix entered into a Voluntary Cleanup Contract with DHEC in 2013. DHEC has identified Alternative 3—soil excavation followed by aggressive fluid/vapor recovery (AFVR) and monitored natural attenuation (MNA)—as the preferred alternative to address the site's soil and groundwater contamination. Following excavation and off-site disposal of source area soils to remove the principal contamination source, the excavated area would be backfilled with gravel (in lieu of native or borrow soil) to create a highly permeable treatment zone for groundwater containing residual toluene concentrations. Stockpiled clean native soil or borrow soil would be used to backfill the upper 2 ft of the excavation area (0-2 ft bgs). A 4-in diameter extraction well would be installed within the gravel backfill for AFVR application. AFVR is a physical treatment using a truck- or trailer-mounted mobile high-pressure vacuum system to extract groundwater and vapors from extraction and/or monitoring wells. The extracted vapors are treated on site using a catalytic converter on the vacuum truck prior to venting to the atmosphere, while the extracted fluid is managed within a tank and transported off site for treatment and disposal. An initial AFVR event would be conducted to determine the technology's effectiveness. Following mass removal via excavation and AFVR, MNA would be implemented to monitor the physical, chemical, or biological reduction of residual toluene mass at the site. If monitoring indicates that MNA alone is not effective, additional AFVR events might be required. http://wwwprod.dhec.sc.gov/HomeAndEnvironment/Docs/WIX/2018-04-16_78_Proposed%20Plan%20FINAL.pdf