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Soil-Gas Investigation Workplan July 6, 2015 200 N. Beckman Rd. Page 3 ALFA employed the services of a State of California Certified Laboratory who uses the procedures of the EPA-approved Test Methods. TASK 2 - PROPOSED SOIL-GAS SAMPLING AND ANALYSES The proposed two (2) soil-gas boring locations designated S4 and S5 are located in the former vehicle service area where PCE solvents were likely used. The soil-gas survey will be conducted in accordance with the California Department of Toxic Substances Control (DTSC) Advisory - Active Soil Gas Investigations dated April 2012. The methodology for the collection of the soil- gas samples will be as follows: • Upon reaching the sampling depth (five foot) as described above, the direct-push drive rod will be sealed at the surface using bentonite, which will be allowed to hydrate prior to purging; • For each soil vapor sample, the system will be purged of approximately three system volumes prior to sampling to ensure that a representative soil gas sample is collected; • Immediately prior to sampling, a tracer gas will be applied to the direct push rods at the ground seal to check seal integrity. The tracer gas will be included in the analytical suite to verify soil gas sample reliability; • Each soil gas sample will be collected in a 1-liter Summa"" canister provided by the laboratory as certified clean using EPA Method TO-15 protocols and will be obtained using a flow rate of 100 to 200 milliliters per minute and a pressure of less than 20 inches of mercury; • All reusable sampling equipment will be decontaminated prior to each sampling event using a steam cleaning process; • Upon completion of the field sampling activities, the samples will be immediately transported to Torrent Laboratory, Inc. (ELAP #1991) in Milpitas, California, for analysis of Volatile Organic Compounds (VOCs), using EPA Method TO-15; Environmental and Remediation Services since 1992! 0 0