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Attachment D: Data Usability Summary ' <br /> INTENDED USES OF THE DATA , <br /> Laboratory data are being used for site evaluation and decision making for petroleum releases <br /> attributed to Chevron's historic crude-oil and Bunker C fuel-oil pipelines. The data generated ' <br /> will be compared to Regional Water Quality Control Board Environmental Screening Levels and <br /> EPA Regional Screening Levels and may be used for risk assessment purposes. <br /> DATA QUALITY OBJECTIVES , <br /> SAIC evaluated project analytical data according to the following parameters in order to <br /> determine their usability: ' <br /> • Precision <br /> • Accuracy ' <br /> • Representativeness <br /> • Completeness <br /> • Comparability ' <br /> DATA USABILITY SUMMARY <br /> The following sections summarize the findings of the data evaluation process. The following , <br /> data validation qualifiers were used in the data evaluation: <br /> ualifier Description <br /> E Indicates the reported value is estimated due to associated quality ' <br /> control(QC) results. <br /> J Indicates the reported value is an estimated concentration detected ' <br /> between the method detection limit(MDL) and laboratory <br /> reporting limit(RL). <br /> A summary of qualified data is provided in Table D-1. Data validation reason codes for all ' <br /> qualified data are also presented and defined on Table D-1. <br /> PRECISION AND ACCURACY <br /> The precision and accuracy of field and laboratory QC samples were evaluated. The calculated <br /> relative percent differences (RPDs) for matrix spike/matrix spike duplicate (MS/MSD)pairs <br /> provided information on the precision of sampling and analytical procedures. The RPDs for ' <br /> laboratory control sample samples and laboratory control sample duplicates (LCS/LCSDs) <br /> provided information on the precision of the analytical procedures. Evaluation of the percent <br /> recoveries (%Rs)of MS/MSDs, LCS/LCSDs, and surrogates provided information on accuracy. ' <br /> Field duplicates were not collected as part of this field effort. <br /> LCS/LCSDS <br /> An LCS and LCSD were analyzed with each analytical batch of samples. The%Rs for all LCS ' <br /> and LCSDs were within the laboratory control limits. <br /> Surrogates ' <br /> Surrogate recoveries were evaluated for all methods. All surrogates were within laboratory <br /> control limits. Surrogate recoveries were not evaluated for samples that were diluted by a factor ' <br /> of 10 or greater. <br />