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' 16 October 2014 AGE Project No. 13-2675 Page 7 of 9 ' • Benzene was detected in samples 134-Vapor, 135-Vapor and 136-Vapor at concentrations of 12 pg/m3, 6.8 pg/m3, and 50 pg/m3, respectively. ' • Toluene, ethylbenzene, and total xylenes were detected in samples B4-Vapor, 135-Vapor and B6-Vapor at maximum concentrations of 510 pg/m3, 130 pg/m3, and 520 pg/m3 (136-Vapor). ' • Tetrachloroethene (PCE) was detected in samples 135-Vapor and 136-Vapor at concentrations of 4.2 pg/m3 and 6.4 pg/m3, respectively; PCE was not detected above the laboratory reporting limit in sample B4-Vapor. • Sixteen additional VOCs were detected in samples B4-Vapor, 135-Vapor and 136-Vapor at concentrations ranging between 3.2 pg/m3 and 260 pg/m3. ' • Tracer compound, isopropyl alcohol (IPA) was detected at a concentration of 18,000 pg/m3 in B5-Vapor and at a concentration of 63 pg/m3 in B6-Vapor; IPA ' was not detected above laboratory reporting limits in sample 134-Vapor. No other constituents of concern were reported in the analyzed soil vapor samples. ' Analytical results soil-vapor samples are summarized in Table 3. Laboratory reports (McCampbell Analytical, Inc. Work Order No. 1410163), QA/QC reports and chain of custody forms are included in Appendix B. CONCLUSIONS AND RECOMMENDATIONS ' Based upon data collected during the October 2014 investigation, AGE concludes: P 9 g • No analytes were detected above laboratory reporting limits in the groundwater sample collected from boring B7. Analytical results of groundwater samples ' collected during the October 2013 and October 2014 investigations are summarized in Table 2. • Petroleum hydrocarbon-impacted groundwater at the site is limited to the area surrounding boring 133; the lateral extent of impacted groundwater is generally defined, based on the site analytical data developed. • TPH-g concentrations detected in B5-Vapor and 136-Vapor were significantly below the established San Francisco Bay Regional Water Quality Control Board ' (SFBRWQCB) Commercial Environmental Screening Level (ESL) of 570,000 pg/m3 for TPH-g in soil gas (Table 3). • Benzene concentrations detected in B4-Vapor, 135-Vapor and 136-Vapor were ' significantly below the established SFBRWQCB Commercial ESL of 420 pg/m3 for benzene in soil gas. Additionally, benzene concentrations were also below the Advanced GeoEnvironmental,Inc.