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' Stantec <br /> L & M OPERABLE UNIT-THIRD QUARTER 2010 SITE STATUS, REMEDIAL SUMMARY, <br /> AND GROUNDWATER MONITORING REPORT <br /> Groundwater Monitoring and Sampling <br /> October 27, 2010 <br /> ' 2.6.2.6 Quality Assurance/Quality Control Samples <br /> Duplicate sample QCDUP-6 was collected from L&M OU D-Zone well MW-69 during the third <br /> quarter 2010 sampling event. A comparison of the samples is shown below. <br /> 1 <br /> ' TPH (mg/L <0.05 <0.05 0% <br /> TPHd (mg/L 0.093 0.077 +/- 18.8% <br /> TPHo (mg/L) 0.056 <0.05 NA <br /> ' Benzene (mg/L <0.0005 <0.0005 0% <br /> MtBE (mg/L <0.0005 <0.0005 0% <br /> TBA m /L <0.005 <0.005 0% <br /> 2.6.2.7 General Laboratory Notes <br /> ' The laboratory validation issues are consistent with the D-Zone quality assurance and quality <br /> control. Each set of issues corresponds directly with the denoted report. All laboratory reports <br /> are included in Appendix C. <br /> Validation issues with report number 73872: <br /> Matrix Spike and MSDresults associated with sample MW-55 for the analyte MtBE were outside <br /> of the stated QC limits. This may indicate a possible bias for the reporting accuracy. The RPD <br /> values are within range indicating precision in reporting. The LCS recoveries were within QC <br /> tlimits indicating accuracy in reporting. Therefore, the reported values are considered valid. <br /> 2.7 THIRD QUARTER 2010 SEPARATE PHASE HYDROCARBONS AND <br /> HYDROCARBON CONCENTRATION TRENDS <br /> 2.7.1 Shallow Zone <br /> The following sections summarize trends for detected petroleum hydrocarbons, fuel oxygenates, <br /> and observed SPH for shallow (A-Zone)groundwater beneath the Site. <br /> 2.7.1.1 Separate Phase Hydrocarbons <br /> ' Measurable SPH or SPH-sheen has historically been observed in shallow, A-Zone wells <br /> MW-10, 2AMW-13, 2AMW-14, MW-19, and DPE-1 through DPE-13. Due to the quantity and <br /> viscous nature of the SPH, and the presence of emulsified SPH and groundwater in some of <br /> these wells, the depth to groundwater/SPH interface and corresponding SPH thickness have <br /> historically been difficult to accurately measure. This is evident by the inability to obtain SPH <br /> thickness measurements from wells 2AMW-14 and DPE-4 in December 2002, from well DPE-8 <br /> in February 2004, and from wells DPE-8 and DPE-10 in May 2005. Variations in measured <br /> 1 <br /> ' 19Titlex 199 IW Stockton(Parcel PA-0615)%Repotls\QMRQ01013010\3p10pSSRoRSROMR Sto bn_FINALaoc 2.18 <br />