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DRAFT Geosyntec <br /> consultants <br /> 4.2 Soil 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 sample results is presented in Table 1 and in Figure 2. <br /> The data collected during the soil boring investigation indicated that TPHg was detected at a <br /> concentration of 1,100 mg/kg in soil sample SS-817B-04A-4 which is above the LTCP media- <br /> specific criteria for vapor intrusion to indoor air. The concentrations of benzene, ethylbenzene, <br /> and naphthalene were below the direct contact and outdoor air exposure for <br /> commercial/industrial concentrations of petroleum constituents listed on Table 1 of the LTCP <br /> (SWRCB, 2012). <br /> Based on this elevated concentration of TPHg detected in the soil, the CVRWQCB requested <br /> that a soil vapor investigation be conducted to determine if UST 817B is eligible for closure in <br /> accordance with the LTCP. In response to this request, Geosyntec prepared the Soil Vapor Work <br /> Plan, which was approved by the CVRWQCB on May 21, 2019 (CVRWQCB, 2019b). <br /> The soil vapor investigation is summarized in Section 5. <br /> 4.3 Groundwater Results and Evaluation <br /> In June 2018, Geosyntec collected groundwater samples from groundwater monitoring wells <br /> 917-03, 917-04, 917-10 located adjacent to the UST 817B Site (Geosyntec, 2018b). These <br /> samples were analyzed for TPH and VOC by USEPA Method 8260B. TPHg, TPHd,benzene, <br /> ethylbenzene, and xylenes were detected in the samples collected from each monitoring well. <br /> Toluene was only detected in the groundwater sample collected from monitoring well 917-10. <br /> Naphthalene was not detected in the groundwater samples collected from these wells. The <br /> analytical results are presented in Figure 4. <br /> Draft Soil and Soil Vapor Investigation 9 August 30,2019 <br />