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Attachment B: Data Usability Summary and Laboratory Chemical Analytical Report Data QC Objectives SAIC evaluated the project analytical data according to the following parameters in order to determine their usability: • Precision • Accuracy • Representativeness • Completeness • Comparability Data Usability Summary The following sections summarize the findings of the data evaluation process. Precision and Accuracy The precision and accuracy of field and laboratory QC samples were evaluated. The calculated relative percent difference (RPD)of laboratory control samples and laboratory control sample duplicates(LCS/LCSDs)provided information on the precision of laboratory analyses. Evaluation of the percent recoveries(%Rs) of LCS/LCSDs and surrogates provided information on accuracy. All LCS/LCSD and surrogate%Rs and RPDs were within the laboratory control limits. Project-specific matrix spike and matrix spike duplicate samples were not submitted with the samples. Field Duplicates Sample WFSMW-I-WD-060503 is a field duplicate of sample WFSMW-I-W-060503. TPHd were the only analytes detected in the field and field duplicate sample. The RPD for TPHd was 17 percent. Representativeness Representativeness was assessed through the evaluation of method blank samples,trip blank samples, equipment blank samples, chain-of-custody forms,preservation, and holding times. Method Blank Results All laboratory method blanks were free of contamination. Field QC Results Field QC included equipment rinsate blanks and trip blanks. The equipment rinsate and trip blank were free of contamination,with the exception of a trace concentration of naphthalene in equipment rinsate sample QA-R-060503. Naphthalene was detected at 0.019 micrograms per liter(µg/L),between the method detection limit(MDL) and reporting limit. The result was"J" flagged to indicate the concentration is an estimate. Naphthalene was not detected in any of the associated samples, and the detection does not affect the usability of the data. Chain-of-Custody Forms Sample analytical results were evaluated for agreement with the chain-of-custody form. Based on the evaluation, all samples were received at the lab in the appropriate containers and in good condition with the chain-of-custody form filled out properly.