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16 October 2014 AGE Project No. 13-2675 Page 8 of 9 established Commercial California Human Health Screening Level (CHHSL) of 122 pg/m3 for benzene in soil gas (Table 3). • Toluene, ethylbenzene, and total xylene concentrations detected in 134-Vapor, B5-Vapor and 136-Vapor were all significantly below the established SFBRWQCB Commercial ESLs and the established Commercial CHHSLs for soil gas (Table 3). • PCE concentrations detected in 135-Vapor and 136-Vapor were significantly below the established SFBRWQCB Commercial ESL of 2,100 p�/m3 for PCE in soil gas and the established Commercial CHHSL of 603 pg/m for PCE in soil gas (Table 3). • None of the sixteen additional VOCs detected in B4-Vapor, 135-Vapor and 136-Vapor were above their respective SFBRWQCB Commercial ESLs (Appendix B). • Tracer compound, IPA was detected at a concentration of 18,000 pg/m3 in sample B5-Vapor and at a concentration of 63 pg/m3 in sample B6-Vapor; IPA was not detected above laboratory reporting limits in sample 134-Vapor. IPA was detected in 136-Vapor just above the reporting limit of 50 pg/m3; and IPA was detected in B5-Vapor approximately seven (7) times greater than the reporting limit of 2,500 pg/m3. IPA was not detected at concentrations greater than ten times the reporting limit in any of the soil-vapor samples collected from the site. Based on the findings from the previous investigation performed in October 2013 and the most recent investigation in October 2014, there is minimal or diminimis risk to human health from residual petroleum hydrocarbon impacted soil and groundwater or from soil-vapor intrusion, under the current site conditions. We do not recommend further investigation at the site. LIMITATIONS AGE's professional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings were based primarily upon analytical results provided by an independent laboratory. Evaluations of the geologic/hydrogeologic conditions at the subject property for the purpose of this investigation were made from a limited number of available data points (i.e., soil borings and soil-vapor and groundwater samples) and subsurface conditions may vary beyond these data points. No other warranty, expressed or implied, is made as to the professional recommendations contained in this report. Advanced GeoEnvironmental,Inc.