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PAR-Eckert Cold Storage,Manteca,CA November 25,2002 ' Page 8 Monitor well and CPT and direct push boring locations with groundwater Iaboratory analytical results for the September 30, 2002 and October 10 and 11, 2002 events are presented in Figures 3 and 4, Appendix 1 A 7.0 INVESTIGATION RESULTS ' The groundwater plume in 2002 is illustrated by the plan view distribution of 1,2-DCA, MTBE, and total BTEX in Figures 5, 6, and 7, Appendix A. Generalized geological sections have been constructed from the boring logs for the site monitor wells and soil borings. The cross-section locations are shown in ' Figure 8, Appendix A. Lithologic cross-sections A-A' and B-B' are shown in Figures 9 and 10, Appendix A. In general, the site subsurface is composed of a sequence of interbedded sands and silts with discontinuous lenses of silty to sandy clays. ' 7.1 DISTRIBUTION OF GROUNDWATER CONTAMINATION Screen intervals for the monitor wells are shown in Figures 1 I through 16, Appendix A, depicting cross- sectional views reflecting 1,2-DCA, MTBE, and total BTEX distributions. The suggested migration pattern is consistent with the site's apparent groundwater gradient to the northwest. ' 7.2 DISTRIBUTION OF SOIL CONTAMINATION Analytical data for samples collected from soil borings and borings for monitor wells were used to 1 investigate the distribution of soil contamination in the subsurface resulting from the release of petroleum hydrocarbons. Installation of the monitor wells and soil borings were documented in Underground Tank Investigation Continued Phase I Report of Findings and Report of Findings prepared by WHF and dated November 26, 1997 and January 3, 2002. Soil samples were collected for laboratory analysis during the lie installation of each monitor well (MW-1 through MW-8). In addition, WHF completed four shallow soil borings (B-1 through B-4) in November 1999 to further investigate the vertical and lateral extent of soil contamination. Monitor well and soil boring locations with soil laboratory analytical results for TPH-G and BTEX concentrations (WHF data; 1995, 1997, 1999) are shown in Figure 17. The distribution of BTEX and TPH-G soil contamination in plan view is shown in Figures 18 and 19, Appendix A, and in cross section, within the vadose zone, in Figures 20 and 21, Appendix A. ' The boring logs for WHF monitor wells MW-1 through MW-8 and soil borings B-1 through B-4 are included in Appendix E. 8.0 GROUNDWATER RECEPTOR SURVEY The WHF Receptor Survey report dated November 23, 1998, indicates that known three receptors are located within a 2,000-foot radius of the subject site. Two City of Manteca deep wells, designated as Well #7 and Well #19, were located to the east and northeast within 1,000 feet of the site. Wcil #7 was considered a "stand-by" source for the City of Manteca, and was not normally in operation. Well 97 and Well #19 were described as fully cased down to approximately 120-130 feet bgs, respectively. A third well was located approximately 500 feet east of the subject site on Trinity Street. This well was drilled for Pacific Gas & Electric as a cathodic protection well. All of these wells are situated in up-gradient or '1 cross-gradient positions with respect to the groundwater gradient at the subject site. A facility drinking water well is located in the northwestern quadrant of the site property (Figure 2, ' Appendix A). This well is located approximately 420 feet northwest of the former UST area in a down- gradient position with respect to the general groundwater gradient at the site. No information was available as to the total depth, screening interval, or host lithology of the domestic well; however, 1 ' �� CONDOR