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4.2 Soil Sourced Vapor Intrusion 1 <br /> 'i <br /> 4.2.1 Soil Sourced Vapor Intrusion—UST A <br /> UST A was removed in 1985 and approximately 70 yd of impacted soil was excavated from the <br /> location in 1994 (Minney, 2010). Two soil gas samples were collected on June 30, 1994. The `, t <br /> soil gas samples indicated that no analyzed constituent was present above laboratory detection <br /> limits. There is no risk to human health or the environment from soil sourced vapor intrusion. <br /> 4.2.2 Soil Sourced Vapor Intrusion—UST B <br /> Approximately 1,200 yd of impacted soil was excavated from the UST B location between <br /> January and February 2011. Benzene concentrations in the final sidewall samples ranged from <br /> not detectable in the second southeast wall sample to 5.8 mg/Kg in the northwest wall sample <br /> (Table 4). TPHg concentrations in the final sidewall samples ranged from not detectable in the <br /> second southeast wall sample to 5,500 mg/Kg in the northwest wall sample. There were no <br /> detectable levels of MTBE. <br /> Additional soil was excavated from the east wall and the south wall and there was a 99% ! <br /> reduction of benzene and TPHg concentrations between the first and second southeast sample. A <br /> J&E model was developed for benzene using the average concentration from'': the sidewall <br /> samples assuming below detection limits in the southwest portion of the excavation and a 60% <br /> reduction in the east wall. The results show an incremental risk from vapor intrusion of 3.0E-05 I <br /> (within acceptable range of 10-4 and 10-6) and a hazard quotient of 4.2E-01 (within the acceptable ' <br /> range of<1). The J&E model spreadsheet is included as Attachment 1. <br /> l <br /> 4.2.3 Soil Sourced Vapor Intrusion —Bunker <br /> Approximately 500 yd3 of impacted soil was excavated from the location in February 2011. No <br /> volatiles were detected above ESLs. There is no risk to human health or the environment from soil 11 <br /> sourced vapor intrusion. <br /> 5.0 SENSITIVE RECEPTORS <br /> I i <br /> • There are no off-site wells within 1,500 feet of the Site (Minney, 2010) <br /> • There are no schools within 4,200 feet of the Site (Google EarthTM) <br /> a There are no churches within.5,000 feet of the Site (Google EarthTM) F <br /> • There are no hospitals within 1.8 miles of the Site (Google EarthTM) <br /> ii <br /> t. <br /> l� <br /> I� <br /> - 16- <br /> I' <br /> �1 <br /> y _ v <br />