Recommendations for Remedial Action at Everest, Kansas.

Abstract

On September 7, 2005, the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) presented a Scoping Memo (Argonne 2005) for preliminary consideration by the Kansas Department of Health and Environment (KDHE). This document suggested possible remedial options for the carbon tetrachloride contamination in groundwater at Everest, Kansas. The suggested approaches were discussed by representatives of the KDHE, the CCC/USDA, and Argonne at the KDHE office in Topeka on September 8-9, 2005, along with other technical and logistic issues related to the Everest site. In response to these discussions, the KDHE recommended (KDHE 2005) evaluation of several remedial processes, either alone or in combination, as part of a Corrective Action Study (CAS) for Everest. The primary remedial processes suggested by the KDHE included the following: (1) Hydraulic control by groundwater extraction with aboveground treatment; (2) Air sparging-soil vapor extraction (SVE) in large-diameter boreholes; and (3) Phytoremediation. As a further outcome of the 2005 meeting and as a precursor to the proposed CAS, the CCC/USDA completed the following supplemental investigations at Everest to address several specific technical concerns discussed with the KDHE: (1) Construction of interpretive cross sections at strategic locations selected by the KDHE along the main plume migration pathway, to depict the hydrogeologic characteristics affecting groundwater flow and contaminant movement (Argonne 2006a); (2) A field investigation in early 2006 (Argonne 2006c), as follows: (a) Installation and testing of a production well and associated observation points, at locations approved by the KDHE, to determine the response of the Everest aquifer to groundwater extraction near the Nigh property; (b) Groundwater sampling for the analysis of volatile organic compounds (VOCs) and the installation of additional permanent monitoring points at locations selected by the KDHE, to further constrain the existing contaminant plume; and (c) Resampling of all existing permanent monitoring points for VOCs and biodegradation parameter analyses, at the request of the KDHE. On the basis of these studies (Argonne 2006a,c) and the CCC/USDA's past investigations at Everest (Argonne 2006b), the CCC/USDA concluded that groundwater extraction is not an effective remedial option for this site, and the KDHE concurred (KDHE 2006). As outlined in the next section, the CCC/USDA also believes that air sparging does not represent a viable remedial alternative. The CCC/USDA therefore proposes to collect the technical data required to evaluate the potential viability of a phytoremediation approach for this site and, if appropriate, to support the development of a remedial design.