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ATC Associates Inc. <br /> 1117 Lone Palm Avenue,Suite 201 <br /> Modesto,California 95351 <br /> w 209-579-2221 <br /> fax:209-579-2225 <br /> AS SOCI ATES I N C. <br /> V <br /> ANALYTICAL RESULTS <br /> Ir Soil Vapor Analytical Results <br /> Freon 12 was detected in the soil vapor samples collected from SG-1, SG-3, and SG-4 at <br /> concentrations ranging from 7.1 micrograms per cubic meter (µg/m3) to 140 Ng/m3. Acetone <br /> +r was detected in the soil vapor samples collected from SG-1, SG-3, and SG-4 at concentrations <br /> ranging from 67 pg/m3 to 920 pg/m3. Carbon disulfide was detected in the samples collected <br /> from SG-1 through SG-4 at concentrations of 18 pg/m3, 62 Ng/m3, 52 pg/m3, and 8.7 Ng/m3, <br /> ar respectively. MTBE and methylene chloride were detected in the sample collected from SG-1 at <br /> concentrations of 6.4 Ng/m3 and 3.6 Pg/m3, respectively. Benzene was detected in the samples <br /> collected from SG-1 through SG-4 at concentrations of 63 Ng/m3, 47 Ng/m3, 51 pg/m3, and 37 <br /> Ng/m3, respectively. Toluene was detected in the samples collected from SG-1 through SG-4 at <br /> ~' concentrations ranging from 130 pg/m3 to 210 pg/m3. Tetrachloroethene was detected in the soil <br /> vapor samples collected from SG-1 through SG-4 at concentrations ranging from 8.2 pg/m3 to <br /> 22 Pg/m3. Ethylbenzene was detected in the samples collected from SG-1 through SG-4 at <br /> 6.„ concentrations ranging from 17 µg/m3 to 35 Ng/m3. Total xylenes were detected in the samples <br /> collected from SG-1 through SG-4 at concentrations ranging from 48 Ng/m3 to 141 pg/m3. 4- <br /> Ethyltoluene was detected in the sample collected from SG-1 at a concentration of 5.7 Ng/m3. <br /> 1,3,5-Trimethylbenzene was detected in the samples collected from SG-1 and SG-2 at <br /> 6" concentrations of 7.1 pg/m3 and 5.2 Ng/m3, respectively. 1,2,4-Trimethylbenzene was detected <br /> in the samples collected from SG-1 through SG-4 at concentrations ranging from 5.5 Ng/m3 to <br /> 20 pg/m3. The leak detection compound 1,1-DFA was not detected in any of the samples. <br /> 6+ Analytical results of the vapor samples are summarized in Table 1. Laboratory data and chain- <br /> of-custody documentation associated with the soil vapor samples are included in Appendix B. <br /> 6W GEOTRACKER DATA UPLOAD <br /> The laboratory data associated with the soil vapor samples collected from SG-1 through SG-4 <br /> were submitted electronically to the State Water Resources Control Board (SWRCB) <br /> Geotracker database (confirmation number 6325013160). Documentation of the data submittal <br /> is contained in Appendix B. <br /> INDOOR AIR RISK ASSESSMENT <br /> Tier 1 Evaluation <br /> The soil vapor concentrations detected in the samples collected from soil vapor points SG-1, <br /> SG-2, SG-3, and SG-4 were compared to the Tier 1 Environmental Screening Levels (ESLs) <br /> values published in the November 2007 (revised May 2008) Screening For Environmental <br /> Concerns at Sites with Contaminated Soil and Groundwater, prepared by the San Francisco <br /> Bay Regional Water Quality Control Board (SFBRWQCB); and the Use of California Human <br /> Health Screening Levels (CHHSLs) in Evaluation of Contaminated Properties, dated January <br /> 2005. <br /> Maximum concentrations of analytes detected in the soil vapor samples collected from SG-1, <br /> SG-2, SG-3, and SG-4 are summarized in the following table. Benzene was detected in the <br /> samples collected from all four sampling points at concentrations (63 Ng/m3, 47 Pg/m3, 51 <br /> S:\Environmental\625771Reports\2011 Soil Gas.doc 5 ATC Associates Inc. <br /> it <br /> rr <br />