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Confirmation Sampling Investigation Work Plan STAND Affordable Housing Page 4 be flush with the pavement and constructed to prevent accidental damage or vandalism. A typical soil vapor well construction diagram is included on Figure 4,Appendix A. 4.4 SOIL VAPOR SAMPLING PROCEDURES Soil gas sampling will be conducted in general accordance with the DTSC's Advisory - Active Soil Gas Investigations, dated July 2015. The soil gas samples will be collected into laboratory-supplied summa canisters and shipped under chain-of-custody procedures to a California-certified analytical laboratory. Soil gas samples will be analyzed for VOCs by EPA Method TO-15. The potential constituents of concern are PCE and its associated breakdown products, as well as gasoline constituents (total petroleum hydrocarbons as gasoline [TPH-G],benzene,toluene,ethylbenzene, and xylenes [BTEX],and oxygenated gasoline additives). Laboratory detection limits will be sufficient to compare detected VOCs with their respective CHHSLs. A leak detection indicator (1,1-difluoroethane or isopropyl alcohol) will be used during sampling and will also be analyzed in order to qualify sampling apparatus integrity. The purpose of the soil vapor sampling is to evaluate the soil vapor intrusion risk to future Site building(s). The soil vapor wells will be purged, leak tested, and sampled at least 48 hours after installation. The soil vapor samples will be collected into laboratory-supplied Summa canisters for laboratory analysis by TO-15. The sample train for each soil vapor well will consist of new, disposable, rigid-wall nylon tubing,new brass compression fittings, and a soil vapor manifold directed from either the Summa canister or a syringe. Prior to purging, each sample train will be tested for leaks. Each soil vapor well will then be purged with a syringe or Summa canister obtained for that purpose to remove a minimum of one borehole/tubing volume at approximately 100 millimeters per minute (ml/min), and one soil vapor sample will be collected from each well into a 1-liter Summa canister using a laboratory- supplied flow controller set to 100 mUmin. During each well purge and Summa canister sample collection, isopropyl alcohol, or another suitable tracer gas, will be used to evaluate potential leaks of ambient air into the sampling train. Isopropyl alcohol will be applied to a cloth and placed around the sample train near the connection in order to detect any leaks in the sample train. Alternatively, a suitable tracer gas will be sprayed/injected into the sampling shroud during active sampling. Following sample collection, the Summa canisters will be shipped under chain-of-custody protocol to a state-certified laboratory. The field technician will maintain a field log containing sample identification, date and time of sampling, sampling depth, weather conditions, sampling method, purge volume, apparent moisture content, and other pertinent observations. 4.5 LABORATORY ANALYSES Collected soil samples will be analyzed for volatile organic compounds (VOCs) by EPA Method 8260B, including the chlorinated solvents PCE, TCE, and associated daughter products, as well as the petroleum constituents benzene, toluene,ethylbenzene, and xylenes (BTEX), selected gasoline oxygenates/additives, including methyl-tert-butyl ether(MTBE), and naphthalene. The soil vapor samples collected into the Summa canisters will be analyzed by EPA Method TO-15 using GC/MS for the analytes listed above. 4M 14 4- 4t_;� �� CONDOR