Case History of a Successful "Brownfields" Site in Wichita, Kansas. Part 2: Innovative Approaches to Remediation

At the Gilbert-Mosley Site in Wichita, Kansas, the groundwater has been contaminated by chlorinated solvents from past industrial activities. Over 3 billion gallons of groundwater have concentrations of tetrachloroethene (PCE) and trichloroethene (TCE) above drinking water standards (maximum contaminant levels [MCLs]). The contamination covers an area of approximately 2,000 acres. The Corrective Action Decision (CAD) approved by the Kansas Department of Health and Environment (KDHE) contained several innovative items, including: (1) the cleanup criteria; (2) the approach to cleanup or the cleanup goal; and (3) the method of cleanup. First, the CAD specified a groundwater cleanup criteria or remedial action goal above the MCLs. This increase was based on a combination of evaluations, including: technical impracticability evaluations, use of institutional controls, risk assessment, and long-term monitoring. The alternate cleanup levels (ACLs) were approved as a cleanup criteria for the groundwater. The use of the higher ACLs (versus MCLs) reduced the amount of groundwater requiring cleanup by 50 percent. The second innovative item addressed in the CAD was the goal of cleanup or the approach to cleanup. Typical decisions require that contaminated groundwater that is a potential drinking water source be restored to MCLs. However, the CAD for the Gilbert-Mosley Site specified that hydraulic control of the migration of the contamination was necessary versus the typically required restoration of all contamination to drinking water standards. Finally, use of innovative technology (bioremediation) was approved in the CAD. Since finalization of the CAD, reductive iron walls, and natural attenuation have also been evaluated. Currently, data are being collected to complete intermediate designs.