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Stantec <br /> ' L & M OPERABLE UNIT-THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> October 27, 2010 <br /> 4.0 Soil Vapor Sampling <br /> 4.1 PREVIOUS SOIL VAPOR SAMPLING ACTIVITIES <br /> Baseline, startup, and monthly soil vapor sampling results were presented in the report entitled <br /> Soil Vapor Well Installation and Soil Vapor Extraction Start-Up Report for events prior to <br /> ' October 2005. Monthly soil vapor sampling results for the October 17 and November 18, 2005 <br /> sampling event were presented in the Fourth Quarter and Annual 2005 Site Status, Remedial <br /> Summary, and Groundwater Monitoring Report. The DPE system was shut down for retrofit on <br /> December 12, 2006, and restarted on May 31, 2007. <br /> 4.2 SOIL VAPOR SAMPLING THIRD QUARTER 2010 <br /> ' On July 23, 2010, soil vapor samples were collected from 14 of the 15 soil vapor monitoring <br /> points located in the adjacent Delta View Apartment complex (APSV locations) and on <br /> ' undeveloped portions of the Site (UPSV locations). Soil vapor point APSV-4 was not sampled <br /> due to water infiltration in the sampling tube during the 3Q10 sampling event. Soil vapor point <br /> UPSV-4 was destroyed, in concurrence with the CRWQCB-CVR, during fourth quarter 2006 due <br /> ' to its location which interfered with the installation of an additional remediation system on Site. <br /> Samples were collected following guidance provided by the California Department of Toxic <br /> Substance Control (DTSC) and Los Angeles RWQCB Advisory -Active Soil Gas Investigations, <br /> dated January 28, 2003. Soil vapor analytical results from this monitoring event are presented in <br /> Table 25 and Figure 35 and are summarized below. Laboratory analytical reports and Stantec <br /> laboratory validation form for the third quarter 2010 sampling event are provided in Appendix F. <br /> 4.2.1 Soil Vapor Sampling <br /> A Transglobal Environmental Geochemistry-Northern California (TEG) mobile lab and a TEG <br /> ' technician were used to collect and analyze soil gas on Site from 14 of 15 soil vapor points <br /> (UPSV-1, USPV-2, UPSV-3, UPSV-5, and UPSV-6, and APSV-1, APSV-2, APSV-3, APSV-5 <br /> through APSV-10) on July 23, 2010. In order to sample the soil vapor points, a syringe with a <br /> ' gas-tight fitting was attached to the '/4 -inch Teflon® tubing inlet at each soil vapor point. The <br /> syringe was used to extract a purge volume of air based on the diameter and depth of inlet <br /> ' tubing. The syringe was then used to collect an air sample and taken to the on-site mobile <br /> laboratory for immediate analysis. Samples were analyzed for the following: <br /> • TPHg using EPA Method 8260B; and <br /> • BTEX compounds, fuel oxygenates (MtBE, DIPE, EtBE, TBA, TAME), and naphthalene, <br /> using EPA Method 8260B. <br /> Duplicate samples were collected from UPSV-3 and APSV-10 during the third quarter 2010 <br /> event. <br /> I Mldmatcrl Stockton(Panal 2A-0415)1Repori QMR1201013QIO\3Ql MSSRQRSRNMR Stockton_FINAL.doc 4.1 <br />