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Introduction An underground gasoline storage tank was excavated and removed from the M & M Automotive site in November, 1991 where contamination was observed in the tank pit Three groundwater monitoring wells exist on-site and some plume definition has been performed by Wright Environmental Services, Inc. (Wright) in a preliminary environmental assessment report dated March 10, 1995 Since some soil contamination was present, and had been mapped into 10th Street, additional subsurface investigation was required by San Joaquin County Public Health Services - Environmental Health Division (PHS-EHD) and is presented to this Problem Assessment Report. Field Activities and Methods - Exploratory Soil Borings Six exploratory soil bonngs were placed downgradient off-site to ascertain presence of contamination and depth to shallow-occurring groundwater (see Figure 1) The borings were drilled, sampled to collect lithologic data from soil samples and hydrogeologic data from groundwater samples for analysis at the analytical laboratory The drilling and sampling were accomplished according to the Wright soil and groundwater sampling protocols (see Appendix A). All drilling and lithologic logging was done under the supervision of a certified engineering geologist, using the Unified Soil Classification System with geologic observations (see Exploratory Boring Logs, Appendix B). The exploratory borings were advanced to the uppermost groundwater bearing strata to collect soil samples, field depth to water measurements and collect reconnaissance groundwater samples. Upon completion of collecting the field data and samples, each borehole was sealed with cement grout and capped with asphalt Exploratory Borings Six exploratory borings were drilled at the locations shown on Figure 1. Drilling and well installation permits were secured from PHS-EHD prior to doing the field work (See Appendix C) The boreholes were drilled with hydraulic push/hammer rig drilling equipment. All drilling equipment and sampling tools were cleaned prior to arriving and before leaving the site. The push points and rods were advanced to the desired sampling depth interval, and a drive sampler was driven ahead of the drill bit. The sampler was then retrieved and dissembled, and the soil filled acetate liner was sealed with plastic endcaps, labeled, logged onto chain-of- custody forms and placed in a chilled ice chest The boreholes were logged using the Unified Soil Classification System under the supervision of a registered geologist using the attached Wright protocol Additional lithologic information was collected to describe the subsurface geology. The samples were collected at five-foot intervals, at intervals of obvious contamination and at stratlgraphic features of interest M&MAutomotive Project No 4070-T Page 3