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Stantec <br /> L & M OPERABLE UNIT-THIRD QUARTER 2011 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Soil Vapor Sampling <br /> October 28, 2011 <br /> TPHg observed in well UPSV-6 (Figure 39). There have been no other apparent trends <br /> associated with reported concentrations in the UPSV wells. <br /> 4.2.4 Quality Assurance/Quality Control-Samples and General Laboratory Notes <br /> Duplicate samples APSV-10-D and UPSV-3D were collected from two soil vapor points <br /> (APSV-10 and UPSV-3, respectively) during 3011 sampling event. A comparison of the <br /> detected analytes in the samples is shown below. <br /> Analyte Sample # Sample # % Difference <br /> APSV-10 APSV-1 OD <br /> TPHg (ppmV) 102.7 107.6 +/-4.7 % <br /> Methane (ppmV) 83,000 82,000 +/- 1.2 % <br /> Analyte Sample # Sample # % Difference <br /> UPSV-3 UPSV-3D <br /> TPHg (ppmV) 17.1 17.4 +/- 1.7 % <br /> Methane (ppmV) 150,000 150,000 0 % <br /> The trip blank did not contain analytes at or above laboratory reporting limits. <br /> 4.2.5 Conclusions and Recommendations <br /> All reported TPHg concentrations were non-detect (less than 2.4 ppmV) in the APSV and UPSV <br /> wells during the reporting quarter with the exception of UPSV-2, UPSV-3, UPSV-5, APSV-9, <br /> and APSV-10. Historically, UPSV-2 has not had detections of TPHg and UPSV-3, APSV-9, and <br /> APSV-10 has continued to have sporadic detections of low level TPHg. BTEX, naphthalene <br /> and the five fuel oxygenates (MtBE, DIPE, EtBE, TBA, and TAME) were not detected at or <br /> above laboratory MRLs during 3Q11. Methane has been sporadic in both APSV and UPSV <br /> wells. <br /> Based on data presented in this report, Stantec recommends continuing with the soil vapor <br /> monitoring schedule as presented in the Work Plan prepared by SECOR and entitled Revised <br /> Work Plan for Soil Vapor Assessment and Response to RWQCB-CVR Letter Dated May 3, <br /> 2005. Results of future sampling will be provided in Stantec's corresponding quarterly Site <br /> monitoring and sampling reports. <br /> I:\Tidewater\TW Stockton(P2A)\QMRs\2011\3Q11\3011 QSSR QRSR QMR Stockton_FINAL.doc 4.3 <br />