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' EXECUTIVE SUMMARY s ' Condor Earth Technologies, Inc. (Condor) prepared this Problem Assessment Report (PAR) to summarize the investigation of the release of petroleum hydrocarbons to soil and groundwater, and to evaluate remedial alternatives for mitigation, at the Eckert Cold Storage facility (site) located at 757 Moffat Boulevard, Manteca, California. The site occupies approximately ten acres of property and is utilized for the purpose of processing vegetables and the cold storage of the processed product. In July 1986 one 500-gallon capacity underground storage tank (UST), identified as TK4, was removed ifrom the site. Analyses of soil samples collected from the UST removal area in April 1987 indicated the soil was impacted with petroleum hydrocarbons. In February 1988, three remaining USTs were removed from the vicinity of the former location of TK4. Analyses of the soil samples collected during the 1988 removal of the three remaining USTs did not detect the presence of petroleum contamination. Eight monitor wells (MW-1 through MW-8) have been installed on-site from 1995 through 1999. Since 1995 multiple investigations have essentially defined the lateral and vertical extent of subsurface contamination. Quarterly monitoring of the groundwater monitoring wells is continuing. In general, interbedded silts and sands with discontinuous lenses of silty to sandy clay underlie the site. Groundwater beneath the site is unconfined and the depth to the water table in September of 2002 was approximately 17 feet. The groundwater gradient historically measured at the site has generally been to the northwest. On October 10 and 11, 2002, Condor conducted additional groundwater investigation at the site using direct push boring methods [Cone-Penetrometer (CPT) and Hydropunch]. Condor supervised the -� installation of ten hydropunch borings and two deep CPT boring pairs. The ten hydropunch borings were advanced to a depth sufficient to collect a groundwater grab sample to investigate the lateral extent of contamination in shallow groundwater. The two CPT boring pairs were advanced in two locations to a depth sufficient to adequately evaluate the vertical extent of groundwater contamination in the vicinity of the former USTs and at the anticipated leading down-gradient edge of the plume. ' The suggested contaminant migration pattern is consistent with the site's apparent groundwater gradient to the northwest. Laboratory analytical data indicate that the groundwater is the predominant mechanism for contaminant distribution and that the groundwater plume is generally confined to the site. The highest concentrations of petroleum constituents in the groundwater were identified in the vicinity of the UST area and northwest of the UST area (down-gradient). The highest concentrations of petroleum constituents in the soil were identified in the vicinity of the UST area, at or near the groundwater surface, and typically decreased with depth in the borings advanced at the site. ' Evaluation of the remedial alternatives for soil and groundwater at the site is presented below. The remedial alternatives are limited by the site use constraints. Based on the contaminants of concern and 1 the limitations noted, the following alternatives have been considered: 1. In situ attenuation through passive biodegradation; ' 2. Enhanced in situ bioremediation and/or chemical oxidation; 3. Soil Vapor Extraction; 4. Air Sparging; ' 5. Ex situ groundwater treatment(pump and treat); and 6. Combinations of Alternatives 2 through. 5. IL'' CONDOR