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DATA QUALITY CONTROL OBJECTIVES SAIC evaluated the project analytical data according to the following parameters to determine their usability: • Precision • Accuracy • Representativeness • Completeness • Comparability DATA USABILITY SUMMARY The following sections summarize the findings of the data evaluation process. Immediately following is the data validation qualifier used in the data evaluation: Qualifier Description E Indicates the reported value is estimated due to associated QC results. A summary of qualified data is provided in Table C-1. Data validation reason codes for all qualified data are also provided and defined in Table C-1. PRECISION AND ACCURACY The precision and accuracy of field and laboratory QC samples were evaluated. The calculated relative percent differences (RPDs) for MS/MSD pairs provided information on the precision of sampling and analytical procedures. The BPDs for laboratory control sample samples/laboratory control sample duplicates (LCS/LCSDs)provided information on the precision of the analytical procedures. Evaluation of the percent recoveries (%Rs) of MS/MSDs, LCS/LCSDs, and surrogates provided information on accuracy. Surrogates and LCS/LCSD Surrogates were spiked for all methods. An LCS was analyzed with each analytical batch of samples, and an LCSD was analyzed for TPHd and TPHd with silica gel analyses. The surrogates used for PAH analysis were not evaluated in any of the samples except for equipment rinsate QA-Boiler-R-090211 because the samples were diluted 100x before analysis. Surrogates are not considered reliable at high dilutions, and are not used to evaluate extraction efficiency. The surrogate %Rs for orthoterphenyl, used in the analysis for TPHd with silica gel, were below the laboratory control limits in samples MW-3-W-090211, MW-3-W-09021 IMS, MW-3-W-090211MSD, and MW-3-WD- 090211. The LCS %R for TPHd with silica gel associated with these samples was 44 percent, which is below the laboratory control limit of 45 percent. The samples were re-extracted for TPHd with silica gel outside the required hold time, and the surrogates and LCS were within the control limits. However, the second set of results did not compare to the first set. The laboratory reported the first set of results for the analysis performed within the hold time. The data were qualified E because of the associated low surrogates and LCS, and because the results were not confirmed by a second extraction. All of the surrogates were within the control limits for the TPHd analysis (non-silica gel cleaned). The LCS %Rs were within the control limits for all other target compounds.