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Weldon Church Site Background Information Page 7 of 12 A total of seven soil vapor samples (V-1 through V-7) were collected and analyzed during the soil vapor investigation performed at the site on 16 September 2010. The following is a summary of findings: • TPH-g were detected in all seven vapor samples (V-1 through V-7) at concentrations ranging between 54,000 micrograms per cubic meter (pg/m3) [V-6 and V-7] and 5,150,000 pg/m3 (V-3). • BTEX compounds were detected in all seven soil vapor samples at maximum concentrations of 2,700 pg/m3 benzene, 7,100 pg/m3 toluene, 2,000 pg/m3 ethylbenzene and 9,400 pg/m3 total xylenes (V-3). • TPH-g concentrations detected in soil vaporsamples collected from V-1 through V-7 were above the established San Francisco Bay Regional Water Quality Control Board's (SFBRWQCB) Residential Environmental Screening Levels (ESL's) [Table 1 and Appendix E]. • Benzene concentrations detected in soil vapor samples collected from V-1 through V-5 were above established SFBRWQCB residential ESL's (Table 1 and Appendix E). Soil vapor concentrations for benzene in samples collected near the former UST area, approximately 15 to 20 feet south of the building (residence) at 104 West Beverly Place, Tracy, CA were below SFBRWQCB ESLs. • Toluene and xylene concentrations detected in soil vapor samples collected from V-1 through V-7 were below SFBRWQCB residential ESL's (Table 1 and Appendix E). • Ethylbenzene concentrations detected in soil vapor samples collected from V-1, V-2, and V-4 through V-7 were below the SFBRWQCB residential ESLs. However, ethylbenzene concentrations in samples collected from V-3 were detected above the SFBRWQCB residential ESLs (Table 1 and Appendix E). • TPH-g and benzene were detected above SFBRWQCB ESLs in soil vapor samples collected from the borings (V-1 through V-5) surrounding the building (residence) at 104 West Beverly Place, Tracy, CA. • Tracer compound, IPA was not reported in any of the soil vapor samples analyzed. MARCH 2011 On 09 March 2011, temporary soil vapor sampling points V-1 through V-3 were sampled using a portable pump and a single use, '/4-inch diameter disposable polyethylene tubing. The portable pump was used to purge the exposed soil column for a minimum of 60 seconds. Prior to collecting soil-vapor samples an organic vapor meter (OVM) equipped Advanced GcoEnnironmental,Inc.