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• Field Duplicate Comparison • Detection Limits Summary of Findings: All samples were analyzed according to the accompanying chains of custody and all analytical holding times were met. QC data were reviewed for laboratory and instrument precision and accuracy from LCS/LCSD recoveries and relative percent differences (RPDs) and MS/MSD sample recoveries and RPDs. All quality control elements were found to be within acceptable limits with the following exceptions: • The MS/MSD percent recoveries associated with the analysis of MW-204(S-8)were less than the lower control limit for hexavalent chromium. Hexavalent chromium was detected in the sample and was qualified as estimated (J). • The MS percent recovery associated with the metals analysis of MW-303 was less than the lower control limit for iron. Iron was detected in the sample and was qualified as estimated (J). • The MS/MSD percent recoveries and RPDs associated with the metals analysis of EW-1 were not meaningful for manganese. The concentration of manganese in the parent sample was greater than four times the concentration used for the spike. Therefore, the criteria were not evaluated. • The MS/MSD percent recoveries and RPD associated with the analysis of MW-324 (1-10) and MW-204 (S-8) were not meaningful for sulfate. The concentration of sulfate in the parent samples was greater than four times the concentration used for the spike. Therefore, the criteria were not evaluated. Field sampling precision was also evaluated by using the calculated RPD between results reported for the field duplicate pairs, which are listed above. All RPD results were found to be within the acceptable limits for precision for all methods with the following exception: • The field duplicate pair MW-102 and MW-102 Dup had an RPD that was greater than the control limit for arsenic; the results were qualified as estimated (J) in the both samples. No target analytes were detected in any method blank or field QC samples with the following exceptions: • Field Blank collected on January 24, 2013 was associated with the analysis of eleven samples and had TOC detected at 0.1 milligrams per liter (mg/L). MW-320 had TOC detected below the reporting limit and less than five times the blank result, and was qualified as not detected (U) at the reporting limit. • Equipment Rinse and Field Blank collected on January 25, 2013 were associated with the analysis of 18 samples and had TOC detected at 0.4 and 0.3 mg/L, respectively. MW-303, TW- 16, and TW-16 Dup had TOC detected below the reporting limit and less than five times the blank result, and were qualified as not detected (U) at the reporting limit. TW-17, TW-14, and TW-12 had TOC detected above the reporting limit, but less than five times the blank concentration, and were qualified as estimated (J). Page 2of6