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J ' 3.0 Laboratory Testing The soil vapor samples will be shipped under chain-of-custody to a California-certified laboratory. The soil vapor samples will be analyzed by EPA Method TO15 (5 and 20 ppbv) for BTEX compounds plus MTBE and for TPHG by TP3. Sampling train effectiveness (short-circuiting) will be evaluated by including the leak check gas in the analysis (TO-15 for isopropyl alcohol). Also the two representative soil samples will be submitted to McCampbell Analytical and Cooper Testing Laboratory who will be instructed to analyze them for bulk density, porosity, moisture content, grain size distribution and total organic carbon (TOC). The testing will be conducted using established methods (e.g., ASTM, etc.). 4.0 Soil Vapor Well Destruction The soil vapor wells will be destroyed following collection of all samples and laboratory data are reported to the City and Wright. A brief summary of the destruction procedure tallows: Wright will hand auger through the boring backtill and remove the soil vapor sample tube. Soil, sand and bentonite recovered from each well will be placed in sealed waste containers, labeled and properly disposed. Each boring will be backfilled and sealed using a neat cement mixture of Portland cement from the bottom to the top of the boring using a tremie line. Borings completed through sidewalk or asphalt pavement will be finished with about 4-inches of Portland cement concrete matching the finish of the surrounding surface. 5.0 Tentative Schedule, Data Evaluation and Report Following EHD approval of this Work Plan (and receipt of approved drilling permits), it is anticipated that the vapor sampling will occur within two weeks thereafter. However, this is subject to potential weather delays since the vapor sampling should not occur w-thin five days of a storm producing significant (approximately 0.5-inch or more) of rain. The fieldwork is estimated to be a two-day process (with an intervening 48-hour is about two weeks. equilibration period) o dhe fie dworksampl ng and chemhe laboratory analysis o al analysis and discussion g ht will prepare a report of the results. The analytical results will be evaluated with respect to general, conservative risk-based sc-eening levels such as those set forth by the RWQCB (May 2008 revision). Our comparison will be with screening levels for commercial exposure since that is the Site's predominant land use. Based on this evaluation we will either (a) contract with a toxicologist and Certified Industrial Hygienist to prepare a human health risk assessment, which will incorporate site-specific factors such as the physical soil properties and the site particulars; or (b)proceed directly to report preparation. Page 4 of 8