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Data Usability Summary DATA USABILITY SUMMARY The following sections summarize the findings of the data evaluation process. The following data validation qualifiers were used in the data evaluation: ualifier Description U Indicates the analyte was not detected, or was detected at a concentration that was attributed to cross-contamination(sample result was qualified based on detection of TPHd in the method blank). J Indicates the reported value is an estimated concentration detected between the method detection limit(MDL)and limit of quantitation (LOQ). A summary of qualified data is provided in Table B-1. Data validation reason codes for all qualified data with the associated reasons for qualification are also presented and defined on Table B-1. Precision and Accuracy The precision and accuracy of field and laboratory QC samples were evaluated. The calculated relative percent differences(RPDs) for field duplicate and MS/MSD pairs provided information on the precision of sampling and analytical procedures. The RPDs for laboratory control samples and 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. 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 TPHd were detected at 33 micrograms per liter(gg/L)in the method blank associated with these samples. TPHd were detected in four associated samples: QA-R-061108 at 70 gg/L; MW-3-W-061108 at 60gg/L; MW-5-W-061108 at 77 gg/L; and WFSMW-I-W-061108 at 970 gg/L. Sample results that are within five times the concentration of target analytes detected in method blanks are normally qualified U as non- detect results to indicate the detections are not representative of field conditions. All other laboratory method blanks were free of contamination. 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. Preservation and Holding Times Samples were preserved in the field as appropriate,were received at the laboratory within the acceptance temperature criterion of 4+2 °C, and were prepared and analyzed within specified holding times. The sample preservations,when required by the analysis,were less than the acceptance pH limit of 2. Reporting Limits Data reported for this sampling event were reported with the laboratory MDLs. The MDL represents the lowest concentration point where an analyte can be positively identified,but the quantitation is an estimate. The LOQ is the lowest concentration of an analyte in a sample that the laboratory can report with precision and accuracy. Analytes that were reported between the MDL and LOQ for this data set were qualified J as estimates.