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aantec <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 /> 1 <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-27, respectively, during the third quarter 2010 sampling event. A comparison <br /> ' of the samples is shown below. <br /> ' TPI-Ig (mg/L <0.05 <0.05 0% <br /> TPHd (mg/L 0.062 0.073 +/-16.3% <br /> TPHo (mg/L <0.05 <0.05 0% <br /> Benzene (mg/L <0.0005 <0.0005 0% <br /> MtBE (mg/L 0.00098 0.00098 0% <br /> ' TBA mg/L) <0.005 <0.005 0% <br /> TPH (mg/L <0.05 <0.05 0% <br /> TPHd (mg/L <0.05 0.054 NA <br /> TPHo, (mg/L <0.05 <0.05 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 73822: <br /> ' Relative percent difference values associated with samples MW-27 and QCDUP-4 for the <br /> analytes 1,2,4-Trimethylbenzene and Styrene were outside of the stated QC limits. This may <br /> indicate a possible bias for the reporting precision. The MS/MSD results and laboratory control <br /> ' sample recoveries were within QC limits indicating accuracy in reporting. Because RPD was <br /> not run in the LCS for these analytes, precision could not be confirmed. However, since neither <br /> analyte was detected in site samples, during this event and historically, the reported values are <br /> not considered to be affected. <br /> ' Validation issues with report number 73851: <br /> ' Relative percent difference values associated with samples MW-24, MW-29, MW-44, and <br /> QCDUP-2 for the analytes Methanol and Vinyl Chloride were outside of the stated QC limits. <br /> This may indicate a possible bias for the reporting precision. The MS/MSD results and <br /> laboratory control sample recoveries were within QC limits indicating accuracy in reporting. <br /> ' hndew lerVW Stockton(Parcel 2A-0415)\Reports\QMR1 010r Q10\3Q10QSSRQRSRQMR Sloal n_RNAL.doc 2.11 <br />