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Langston's Market ' 15615 Seventh Street, Lathrop, California October S, 1995 Interim Secondc,,ry Source Removal& Monitoring Mell Replarenresit Page: 8 1 ' (permeability) to determine if this clayey zone is an aquitard ('I able 17, Appendix A) The soil samples were taken using a California Modified Split Spoon sampler with brass liners The sampler was driven continuously by a wire line hammer repeatedly dropping 30 inches The laboratory samples did not have head space and were immediately sealed in their liners using aluminum fbil-lined plastic caps The remaining sample was removed from their liners to be used as an aide to the on-site geologist in logging the material at that depth Soil samples collected for analysis were analyzed using EPA method 5030 LUFT for total petroleum hydrocarbon- in the gasoline range and EPA method 8020 for BTX&E compounds The minimurn detection limits used for each analyte were 005 mg/kg for BTX&E and 1 0 mg/Kg for gasoline (cable 1 1, Appendix A) During this scope of work, analyses were conducted by California Laboratory Services, a State-certified laboratory in Rancho Cordova, California, Monroe Laboratories, Inc , a State-certified mobile lab from San Jose, California, and GeoAnalytical Laboratories, a State-certified laboratory in Modeste, California 3 7 Groundwater Sampling A travel blank provided by the laboratory accompaniLd sample vials fi om the time they were picked up from the lab to the time they weic deliveied io the lab These travel blanks should be listed oii the Chain of Custody but were analyzed only if all samples contain the same contaminants All sampling equipment including the pump, bailer, and cables, used by sampling personnel, were disassembled if appropriate, and steam-cleaned prior to commencement of sampling 'I hese procedures were followed between each well, sampling point, and at the end of the sampling day De-ionized or organic-free Iwater (also provided by the laboratory) was then introduced into the pump or bailer as a final stage of cleaning This water was then pumped or gently poured into sample vials to be used as pump or bailer blanks These blanks were tested only if their corresponding samples are found to contain contaminants I Immediately prior to sampling, water levels and well depth measurements were taken in all wells at the site Cl able 3, Appendix D) Each well was evacuated using a stainless steel bladder pump, which does not introduce air into the water column, or a Teflon bailer The pH, temperature, and electrical conducti,.ity of the water was monitored as the well was evacuated 'These parameters were noted on f