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Stantec <br /> L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2010 SITE STATUS, <br /> REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT <br /> Groundwater Monitoring and Sampling <br /> January 31, 2011 <br /> 2.4.2.4 Semi-volatile Organic Compounds <br /> There were no SVOCs with concentrations at or above the MRLs in the 15 wells sampled during <br /> 4Q10. <br /> 2.4.2.5 Dissolved Metals <br /> Analysis for dissolved metals is not required during the second and fourth quarter per MRP <br /> No. R5-2004-0820. <br /> 2.4.2.6 Quality Assurance/Quality Control Samples <br /> Duplicate samples QCDUP-2 and QCDUP-4 were collected from L&M OU deep zone wells <br /> MW-44 and MW-60, respectively, during 4Q10 sampling event. A comparison of the samples is <br /> shown below. <br /> Analyte Sample # Sample # % Difference <br /> MW-44 QCDUP-2 <br /> TPHg (mg/L) <0.05 <0.05 0% <br /> TPHd (mg/L) <0.05 <0.05 0% <br /> TPHo (mg/L) <0.05 <0.05 0% <br /> Benzene (mg/L) <0.0005 <0.0005 0% <br /> MtBE (mg/L) 0.0012 0.0013 +/- 8.0% <br /> TBA (mg/L) <0.005 <0.005 0% <br /> Analyte Sample # Sample # % Difference <br /> MW-60 QCDUP-4 <br /> TPHg (mg/L) <0.05 <0.05 0% <br /> TPHd (mg/L) 0.088 0.082 +/- 7.1% <br /> TPHo (mg/L) 0.078 0.072 +/- 8.0% <br /> Benzene (mg/L) <0.0005 <0.0005 0% <br /> MtBE (mg/L) <0.0005 <0.0005 0% <br /> TBA (mg/L) <0.005 <0.005 0% <br /> 2.4.2.7 General Laboratory Notes <br /> The laboratory validation issues are consistent with the deep 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 75022: <br /> MS/MSD results associated with samples MW-56, MW-57, and MW-58 for the analytes MtBE <br /> and TBA were outside of the stated QC limits for percent recovery. This may indicate a possible <br /> bias for the reporting accuracy. The RPD values for MtBE and TBA are within range indicating <br /> precision in reporting. The LCS percent recoveries were within QC limits, for the analytes MtBE <br /> and TBA, indicating accuracy in reporting; therefore, the reported values are considered valid. <br /> I:\Tidewater\TW Stockton(Parcel 2A-0415)\Reports\QMR\2010\4010-Annual\4Q10 and Annual QSSRQRSRQMR Stockton_F I NAL.doc 2.10 <br />