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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 />Analyte <br />Sample # <br />MW -23 <br />Sample # <br />QCDUP-3 <br />% Difference <br />TPHg (mg/L) <br /><0.05 <br /><0.05 <br />0% <br />TPHd (mg/L) <br />0.41 <br />0.31 <br />NA <br />TPHo (mg/L) <br />0.13 <br />0.07 <br />NA <br />Benzene (mg/L) <br /><0.0005 <br /><0.0005 <br />0% <br />MtBE (mg/L) <br />0.0005 <br />0.00051 <br />+/-2.0% <br />TBA (mg/L) <br /><0.005 <br /><0.005 <br />0% <br />Analyte <br />Sample # <br />MW -31 <br />Sample # <br />QCDUP-7 <br />% Difference <br />TPHg (mg/L) <br /><0.05 <br /><0.05 <br />0% <br />TPHd (mg/L) <br />0.30 <br /><0.05 <br />+/-142.9% <br />TPHo (mg/L) <br />0.64 <br /><0.05 <br />+/-171.0% <br />Benzene (mg/L) <br /><0.0005 <br /><0.0005 <br />0% <br />MtBE (mg/L) <br /><0.0005 <br /><0.0005 <br />0% <br />TBA (mg/L) <br /><0.005 <br /><0.005 <br />0% <br />2.3.3.6 General Laboratory Notes <br />The following validation issues are consistent with the shallow zone quality assurance and <br />quality control. Each set of issues corresponds directly with the denoted report (Appendix C). <br />Validation issues with report number 73822: <br />Relative percent difference (RPD) values associated with samples 2AMW-12, MW -21, MW -22, <br />MW -28, MW -31, MW -34, and QCDUP-7 for the analytes 1,2,4-Trimethylbenzene and Styrene <br />were outside of the stated quality control (QC) limits. This may indicate a possible bias for the <br />reporting precision. The Matrix Spike (MS) and Matrix Spike Duplicate (MSD) results and <br />laboratory control sample recoveries were within QC limits indicating accuracy in reporting. <br />Because RPD was not run in the laboratory controlled spike (LCS) for these analytes, precision <br />could not be confirmed. However, since neither analyte was detected in site samples, during <br />this event and historically, the reported values are not considered to be affected. <br />Validation issues with report number 73851: <br />Relative percent difference values associated with samples MW -23 and MW -30 for the analytes <br />Methanol and Vinyl Chloride were outside of the stated QC limits. This may indicate a possible <br />bias for the reporting precision. The MS/MSD results and laboratory control sample recoveries <br />were within QC limits indicating accuracy in reporting. Because RPD was not run in the LCS for <br />these analytes, precision could not be confirmed. However, since neither analyte was detected <br />in site samples, during this event and historically, the reported values are not considered to be <br />affected. <br />I:\Tidewater\TW Stockton (Parcel 2A-0415)\Reports\QMR\2010\3010\3010QSSRORSROMR Stockton_FINAL.doc 2.7 <br />