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L & M OPERABLE UNIT-THIRD QUARTER 2014 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Groundwater Monitoring and Sampling October 31, 2014 2.3.2.4 Quality Assurance/Quality Control Samples Stantec's equipment blanks (QCEB-I-PV, QCEB-2-PV, QCEB-3-PV, and QCEB-4-PV) were analyzed for the presence of petroleum hydrocarbons compounds. All constituents were reported as non-detect at or above the laboratory MRL in the equipment blanks, indicating that no cross-contamination occurred during the sampling activities. Duplicate samples QCDUP-1 and QCDUP-3 were collected from L&M OU A-Zone wells MW-18 and MW-21, respectively, during the 3Q14 sampling event. A comparison of the samples is shown on the following table. Analyte Sample # Sample # % Difference MW-18 QCDUP-1 TPH (mg/L 3.5 3.5 Oho TPHd (mg/L 1.3 1.3 Oho TPHo (mg/L 0.063 0.083 +/- 27.47o Benzene <0.0005 <0.0005 Oho m /L MTBE (mg/L <0.0005 <0.0005 Oho TBA (mg/L <0.005 <0.005 0% Analyte Sample # Sample # 7o Difference MW-21 QCDUP-3 TPHg (mg/L) <0.50 <0.50 Oho TPHd (mg/L) 0.81 0.80 +/- 1.247o TPHo (mg/L 0.068 0.06 +/- 12.57o Benzene <0.0005 <0.0005 Oho (mg/L) MTBE (mg/L <0.0005 <0.0005 0% TBA (mg/L) <0.005 <0.005 Oho The calculated Relative Percent Difference (RPD) between sample MW-18 and QCDUP-1 were within the acceptable limit (-20%), except for the concentrations of TPHo (-27.40), which was slightly outside the preferred quality control range. The calculated Relative Percent Difference (RPD) between sample MW-21 and QCDUP-3 were within the acceptable limit (-20%). These concentrations are consistent with historical data and only slightly outside the recommended acceptable % difference range; thus, the data can be considered representative. 2.3.2.5 General Laboratory Notes The following validation notes are consistent with the shallow zone quality assurance and quality control. Each set of issues corresponds directly with the denoted report (Appendix E). 5ta ntec 2.6