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' Data Usability Summary Page 2 of 4 <br /> ' INTENDED USES OF THE DATA <br /> Laboratory data are being used for site evaluation and decision making for petroleum releases attributed <br /> to Chevron's historical crude oil and Bunker C fuel oil pipelines. The data generated will be compared to <br /> ' Regional Water Quality Control Board water quality objectives and may be used for risk assessment <br /> purposes. <br /> DATA QC OBJECTIVES <br /> SAIC evaluated the project analytical data according to the following parameters in order to determine <br /> 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 data <br /> validation qualifiers were used in the data evaluation: <br /> ' ualifier Description <br /> E Indicates the reported value is estimated due to associated QC results. <br /> ' J Indicates the reported value is an estimated concentration detected <br /> between the method detection limit(MDL)and limit of quantitation <br /> (LOQ). <br /> ' A summary of qualified data is provided in Table B-1. Data validation reason codes for all qualified data <br /> are also presented and defined on Table B-1. <br /> ' Precision and Accuracy <br /> The precision and accuracy of field and laboratory QC samples were evaluated. The calculated relative <br /> percent differences(RPDs)for MS/MSD pairs provided information on the precision of sampling and <br /> ' analytical procedures. The RPDs for laboratory control sample and laboratory control sample duplicates <br /> (LCS/LCSDs)provided information on the precision of the analytical procedures. Evaluation of the <br /> percent recoveries(%Rs)of MS/MSDs,LCS/LCSDs, and surrogates provided information on accuracy. <br /> ' All LCS/LCSD%Rs,LCS/LCSD RPDs, and surrogate%Rs were within the required laboratory control <br /> limits. <br /> Field Duplicate <br /> ' Sample MW-6-WD-070124 is a field duplicate of MW-6-W-070124. The field duplicate was analyzed <br /> for TPHd and PAHs. Naphthalene was the only compound detected in both the parent sample and field <br /> duplicate. The concentrations detected were below the laboratory LOQ, so an RPD was not calculated for <br /> ' the analyte. Target analytes that are detected below the LOQ are considered estimated values and are not <br /> used to assess precision in field duplicates. <br /> ' MS/MSDs <br /> One MS/MSD sample was collected with field sample MW-7-W-070125 and analyzed for TPHd and <br /> PAHs. The laboratory also randomly selected project samples to prepare MS/MSD samples for several <br /> analyses. All of the%Rs and RPDs were within the required laboratory control limits. The samples in <br /> this data set were not evaluated in terms of the recoveries of the non-project MS/MSDs because they are <br /> not likely representative of the same sample matrix. <br /> Wff <br /> Anwrffll <br /> ' From Science to Solutions <br />