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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 EW-1 and EW-1 Duplicate were less than the lower control limit for TOC; TOC was qualified as estimated (J) in both samples. • The MS/MSD percent recoveries and RPD associated with the analysis of MW-104 (S-2) were not meaningful for dissolved iron and manganese. The concentration of these metals in the parent sample was greater than four times the concentration used for the spike. Therefore, the criteria were not evaluated. • The MS percent recovery associated with the analysis of MW-321 (1-9) and MW-321 (1-9) Duplicate was less than the lower control limit for sulfate. Sulfate was detected in both samples and was qualified as estimated (J). Additionally, the MS/MSD percent recoveries and RPD associated with metals analysis of these samples were not meaningful for dissolved 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-213 (1-7) were not meaningful for dissolved chromium and manganese. The concentration of the chromium and manganese in the parent sample was greater than four times the concentration used for the spike. Therefore, the criteria were not evaluated. • The MS percent recovery associated with the analysis of MW-4 was less than the lower control limit for TOC; TOC was qualified as estimated (J). 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 EW-1 and EW-1 Duplicate had a calculated RPD that was greater than the control limit for dissolved iron; iron was qualified as estimated (J) in the parent sample. • The field duplicate pairs MW-447S and MW-447S Duplicate, and MW-303 and MW-303 Dup, had RPDs that were greater than the control limit for TOC. TOC was qualified as estimated in both parent samples. • The field duplicate pair TW-14 and TW-14 Dup had a calculated RPD that was greater than the control limit for dissolved arsenic; arsenic was qualified as estimated (J) in the parent sample. No target analytes were detected in any method blank or field QC samples with the following exceptions: • Equipment Rinse and Field Blank, collected on October 22, 2012, were associated with the analysis of two samples and had detectable concentrations of sulfate (5.55 and 4.61 mg/L, Page 2of6