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L & M OPERABLE UNIT-THIRD QUARTER 2014 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Soil Vapor Sampling <br /> October 31, 2014 <br /> • BTEX compounds, fuel oxygenates (MTBE, DIPE, ELBE, TBA, TAME), and <br /> naphthalene, using EPA Method 8260B; and <br /> • Methane using EPA Method GC/TCD. <br /> Duplicate samples were collected from APSV-10 and UPSV-3 during the 3Q14 event. <br /> 4.2.2 APSV Soil Vapor Concentration Trends <br /> During 3Q14, methane concentrations in vapor samples collected from APSV-3, APSV-9, <br /> and APSV-10 increased from concentrations reported during 2Q14. Benzene <br /> concentrations reported from APSV-9 and APSV-10 increased from concentrations <br /> reported during 2Q14. TPHg concentrations in vapor samples collected during 3Q14 <br /> decreased from 2Q14 in vapor samples collected from APSV-6, APSV-7, APSV-9 and <br /> APSV-10 and remained below method reporting limits in all other APSV wells. <br /> As shown in Table 23, TPHg has historically decreased in APSV-1 through APSV-3, and <br /> APSV-5, since base-line sampling in July 2005 and since start-up of the on-Site <br /> remediation system on May 31, 2007. <br /> 4.2.3 UPSV Soil Vapor Concentration Trends <br /> During 3Q14, TPHg and methane concentrations in vapor samples collected from <br /> UPSV-3 increased slightly from concentrations reported during 2Q14. Methane <br /> concentrations in vapor samples collected from UPSV-5 and UPSV-6 increased and <br /> TPHg concentrations decreased in UPSV-5 from concentrations reported during 2Q14. <br /> TPHg and benzene concentrations remained stable in UPSV-6. <br /> As shown in Table 23, TPHg has historically decreased in wells UPSV-1 and UPSV-2 since <br /> base-line sampling in July 2005 and since start-up of the on-Site remediation system on <br /> May 31, 2007. <br /> 4.2.4 Quality Assurance/Quality Control-Samples and General Laboratory Notes <br /> Duplicate samples APSV-IO-D and UPSV-3-D were collected from two soil vapor points <br /> (APSV-10 and UPSV-3, respectively) during the 3Q14 sampling event. Comparison of <br /> the two are shown on the following tables. <br /> Analyte Sample # Sample # % Difference <br /> APSV-10 APSV-IOD <br /> TPHg (ppmV) 293.4 317.9 8.0 <br /> Methane ppmV 320,000 310,000 3.2 <br /> 5ta ntec 4.2 <br />