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DRAFT Geosyntec <br /> consultants <br /> 5.1.7 Soil Vapor Sampling and Analysis <br /> After completion of shut-in testing, leak testing, and purging, soil vapor samples were collected <br /> through dedicated NylaflowTM tubing attached to each well with airtight fittings into 1-liter <br /> SummaTM canisters. Soil vapor samples were collected until the vacuum on the SummaTM <br /> canister decreased from 30 inches of mercury to approximately 5 inches of mercury. Duplicate <br /> samples were collected with a"tee"-fitting that split the soil vapor sample to two canisters. <br /> SummaTM canisters were submitted to TestAmerica Laboratories, Inc. of West Sacramento, <br /> California under standard chain-of-custody procedures for analysis of VOCs by USEPA Method <br /> TO-15 and helium by ASTM International D1946. <br /> Following sampling, the temporary soil vapor sampling tubing was extracted from the borehole <br /> and the borehole backfilled with Portland cement and the ground surface was finished to match <br /> the existing pavement. <br /> 5.2 Soil Vapor Analytical Results and Evaluation <br /> Results of the analytical laboratory testing are presented in the laboratory reports included in <br /> Appendix D. A summary of the soil vapor sample results is presented in Table 2 and in <br /> Figure 3. <br /> Soil vapor analytical results indicate that all analyzed constituents except naphthalene were <br /> detected in at least one sample. The maximum concentrations were detected in the sample <br /> collected from soil vapor probe SVP-3 as follows: <br /> • TPHg: 3,700,000,000 micrograms per cubic meter(µg/m3); <br /> • Benzene: 2,300,000 gg/m3; <br /> • Ethylbenzene: 860,000 µg/m3; <br /> • Toluene: 340,000 µg/m3; <br /> • m,p-Xylenes: 190,000 µg/m3; <br /> • o-Xylene: 75,000 µg/m3; and <br /> • Naphthalene: <780,000 gg/m3. <br /> The soil vapor analytical results indicate that concentrations of benzene, ethylbenzene, and <br /> naphthalene exceed the LTCP screening level for vapor intrusion to indoor air for sites with no <br /> bioattenuation zone and commercial receptors, as listed in Appendix 4 of the LTCP (SWRCB, <br /> 2012). These exceedances indicate that UST 817B Site is not eligible for closure in accordance <br /> with the LTCP. <br /> 5.3 Investigative Derived Waste <br /> Soil cuttings generated as a result of the subsurface investigation activities will be properly <br /> disposed by American Integrated System on behalf of the Port of Stockton. <br /> Draft Soil and Soil Vapor Investigation 12 August 30,2019 <br />