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Attachment C:Data Usability Summary and Laboratory Analytical Reports <br /> 1 <br /> INTENDED USES OF THE DATA <br /> ' Laboratory data are being used for site evaluation and decision malting for petroleum releases <br /> attributed to Chevron's historical crude-oil and Bunker C fueI-oil pipelines. The data generated <br /> will be compared to Central Valley Regional Water Quality Control Board water quality <br /> ' objectives and may be used for risk assessment purposes. <br /> DATA QC OBJECTIVES <br /> ' SAIC-Benham evaluated project analytical data according to the following parameters 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. Data were <br /> qualified E in this data set to indicate the reported value is estimated due to associated QC <br /> results. <br /> ' A summary of qualified data is provided in Table C-1. Data validation reason codes for all <br /> qualified data are also presented and defined on Table C-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 field duplicate and matrix spike/matrix spike duplicate <br /> ' (MS/MSD)pairs provided information on the precision of sampling and analytical procedures. <br /> The RPDs for laboratory control sample samples/laboratory control sample duplicates <br /> (LCS/LCSDs)provided information on the precision of the analytical procedures. Evaluation of <br /> 1 the percent recoveries (%Rs) of MS/MSDs, LCS/LCSDs, and surrogates provided information <br /> on accuracy. <br /> ' LCS/LCSDs <br /> An LCS was analyzed with each analytical batch of samples. An LCSD was analyzed with the <br /> samples analyzed for TPHd. The %Rs for all LCS and LCSDs were within the laboratory <br /> ' control limits with one exception: the %R for 2-methylnaphthalene was 67 percent, below the <br /> laboratory advisory control limit of 70 percent. The control limit for the compound is advisory <br /> because the laboratory has not generated a significant number of data points to construct a <br /> ' statistical control chart. The LCS recovery of 57 percent is within the range of control limits for <br /> the other compounds analyzed by this method; therefore, it is not likely the data are significantly <br /> biased low. No data were qualified. <br /> ' Surrogates <br /> Surrogate recoveries were evaluated for all methods. All surrogates were within laboratory <br /> ' control limits, with one exception: the surrogate orthoterphenyl, used in the analysis of TPHd, <br /> was above the control limit in sample MW-7-W-100105. The sample was re-extracted outside <br /> the method-required holding time and the surrogate was within the required holding time. <br /> 1 C-2 <br /> 1 <br />