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' Appendix D.1: Data Usability Summary <br /> The data was evaluated in general conformance to the requirements of project objectives specified in the <br /> following documents: <br /> • Quality Assurance &Quality Control: Sample Collection, Handling, and Analysis Guidelines; <br /> ' ChevronTexaco Historical Pipeline Portfolio Sites, California,April 2007; <br /> • SAIC Technical Procedure TP-DM-300-7,Data Validation; and <br /> ' • SAIC Technical Procedure TP-DM-300-14,Evaluation of Field and Analytical Data. <br /> INTENDED USES OF THE DATA <br /> ' Laboratory data are being used for site evaluation and decision making concerning soil and groundwater <br /> affected by Chevron's historical crude oil and Bunker C fuel oil pipelines (i.e.,the Old Valley Pipeline <br /> and Tidewater Associated Oil Company pipelines). For delineation decision making, soil and <br /> groundwater laboratory analytical results were compared to health-based and aesthetic "screening levels," <br /> ' or levels above which further evaluation to define the extent of any affected media is appropriate. <br /> DATA QC OBJECTIVES <br /> ' SAIC evaluated project analytical data according to the following parameters in order to determine their <br /> 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 is a <br /> summary of the data verification and validation qualifiers 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 /> ' U Indicates the analyte was analyzed for but not detected above the level of <br /> the associated value. <br /> A summary of qualified data is provided in Table D-1. Data validation reason codes for all qualified data <br /> ' 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 relative <br /> percent differences (RPDs) for field duplicate and MS/MSD pairs provided information on the precision <br /> of sampling and analytical procedures, and the RPDs for laboratory control sample/laboratory control <br /> sample duplicate(LCS/LCSD)pairs provided information on the precision of the analytical procedures. <br /> ' Evaluation of the percent recoveries (%Rs) of MS/MSDs, LCS/LCSDs, and surrogates provided <br /> information on accuracy. <br /> ' MSIMSDs <br /> Percent recoveries for several MS/MSD sample were not with the laboratory's QC limits. Since project- <br /> specific MS/MSD samples were not collected with the field samples, %Rs that did not meet QC criteria <br /> ' Page D.1-2 <br /> From Science to Solutions <br />