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

This Proposed Plan identifies DHEC's preferred alternative and rationale for cleaning up contaminated groundwater at the Castlebridge Properties site, a former warehouse with office space. To achieve the RAOs proposed for the site (i.e., U.S. EPA MCLs for PCE, TCE, and their breakdown products), DHEC recommends a combination of Alternative 4 (enhanced reductive dechlorination, or ERD) and Alternative 2 (institutional/land-use controls). With Alternative 4, carbon sources, such as molasses, emulsified vegetable oil, or cheese whey, are introduced to the aquifer via injection wells. During the ERD process, microorganisms in the subsurface use carbon as an energy source, and the contaminants provide one of the respiratory substrates during metabolism, ideally leading to a non-toxic end product, such as ethene. ERD can treat both dissolved and sorbed contaminants, is not limited to a fixed area because it can move with the contaminant plume and is often less expensive than other remediation options. Alternative 2 would be effective in protecting human health on the property because access to the property would be limited by fencing around the site and 24-hour active, manned security measures. Deed restrictions would prohibit future use of the property for residential purposes and future use of groundwater as a potable water supply, eliminating the groundwater exposure pathway. The net present value of these combined alternatives is $265,000. http://wwwprod.dhec.sc.gov/HomeAndEnvironment/Docs/Castlebridge/2018-03-09_37_Proposed%20Plan%20for%20Site%20Remediation.pdf