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Stantec <br /> L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2012 SITE STATUS, <br /> REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT <br /> February 1, 2013 <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 FOURTH QUARTER 2012 <br /> On October 19, 2012, soil vapor samples were collected from 12 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 points APSV-2, APSV-4, and <br /> APSV-5 were not sampled due to water infiltration in the sampling tube during 4Q12 sampling <br /> event. Soil vapor point UPSV-4 was destroyed, in concurrence with the CRWQCB-CVR, during <br /> fourth quarter 2006 due to its location which interfered with the installation of an additional <br /> remediation system on Site. Samples were collected following guidance provided by the <br /> California Department of Toxic Substance Control (DTSC) and Los Angeles RWQCB <br /> Advisory-Active Soil Gas Investigations, dated January 28, 2003. Soil vapor analytical results <br /> from this monitoring event are presented in Table 22 and Figure 35 and are summarized below. <br /> Laboratory analytical reports for 4Q12 are provided in Appendix J. <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 12 of 15 soil vapor points <br /> (UPSV-1, UPSV-2, UPSV-3, UPSV-5, UPSV-6, APSV-1, APSV-3, and APSV-6 through <br /> APSV-10) on October 19, 2012. 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 826013; 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-9 during 4Q12 event. <br /> I:\Tidewater\TW Stockton(P2A)\QMRs\2012\4Q12-Ann ual\4Q12 and Annual QSSR QRSR QMR Stockton_FINAL.doc 4.1 <br />