SITE INFORMATION AND CORRESPONDENCE

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PUBLIC t1EALTH SERVICES SAN JOAQUIN COUNTY 2: Z ENVIRONMENTAL HEALTH DIVISION Ernest M. Fujimoto, M. D., M.P.H., Acting Health Officer 304 E. Weber Ave., Third Floor • P. O. Box 388 • Stockton, CA 95201-0388 c'c/FORa P 209/468-3420 -- DWIGHT DAVIS PEGASUS GROUP MAILED NOV 0 91995 1840 SAN MIGUEL DR STE 100 WALNUT CREEK CA 94596 RE: Village West Marina SITE CODE: 1098 6649 Embarcadero Drive Stockton, CA 95219 San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD), has reviewed the August 8, 1995 Problem Assessment Report & Project Status Report of Ground Water Monitoring, prepared by W.W. Irwin, Inc., for the above referenced site. In the report, W.W.Irwin, Inc. has tabulated all analytical data to date and described the recent investigation, which includes the drilling of four hydropunch borings, and the installation of monitoring wells MW-7 and MW-8. The purpose of this investigation, was to define the lateral and vertical extent of soil contamination, and lateral extent of ground water contamination. The conclusion stated in the report regarding soil contamination, is that there is soil contamination in the former UST over excavation, and the contamination present in the defined area of the outbound soil plume limits is minimal. Figures 4 and 5 in the report, depict the lateral extent of benzene contamination in soil, at the 15 and 20 foot depths respectfully. Figure 4 illustrates that the outbound soil plume extends to MW-7 to the north and HP-9 to the east. Figure 5 illustrates that the deeper outbound soil plume is slightly smaller. W.W. Irwin states that the outbound soil contamination is insignificant, and does not merit additional remediation, making soil vapor extraction unsuitable for this site. W.W. Irwin recommends that borings should be drilled in the former UST overexcavation near the north wall and south bottom of the former excavation so that soil samples can be collected. They expect soil sample results to show that natural attentuation has occurred. The conclusion stated in the report regarding groundwater contamination is that it has been defined north and south. W.W. Irwin states that definition of the groundwater plume cannot be achieved to the west because of the proximity to the slough, and the plume cannot be defined to the east because it appears to extend beneath the condominium building. Figure 5 illustrates the lateral extent of benzene contamination in groundwater. This figure illustrates that the plume may extend beneath the condominium building, and may also be leaching into the surface waters of the slough. W.W. Irwin recommends that a remedial action plan should be prepared to address the groundwater contamination. A Division of San Joaquin County Health Care Services