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ATTACHMENT B: <br /> DATA USABILITY SUMMARY AND LABORATORY ANALYTICAL RESULTS <br /> (JANUARY 2008) <br /> INTRODUCTION <br /> SAIC evaluated the analytical data for groundwater samples collected at the Vernalis Pump Station <br /> location in Vernalis, California. This data usability summary presents the results of the data validation <br /> process. SAIC collected environmental samples on behalf of Chevron Environmental Management <br /> Company to delineate the lateral and vertical extent of petroleum-affected groundwater. Samples were <br /> collected on January 29,2008: <br /> • QA-R-080129 <br /> • MW-2-W-080129 <br /> • MW-3-W-080129 <br /> • MW-5-W-080129 <br /> • MW-6-W-080129 <br /> • MW-6-W-080129MS <br /> • MW-6-W-080129 MSD <br /> • MW-6WD-W-080129 <br /> • MW-7-W-080129 <br /> Groundwater samples were analyzed for one or more of the following analyses: <br /> • Polynuclear aromatic hydrocarbons(PAHs)by EPA Method SW8270C with selective ion <br /> monitoring(SW8270C-SIM). <br /> • Total petroleum hydrocarbons quantified as diesel(TPHd), carbon range CIO-C25,by EPA Method <br /> SW8015B modified; a silica gel-cleanup procedure based on EPA Method SW3630 was also <br /> performed on samples with TPHd detections to remove non-target biogenic compounds. <br /> The data was evaluated in general conformance to the requirements of project objectives specified in the <br /> following documents: <br /> • Quality Assurance and 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 for petroleum releases attributed <br /> to Chevron's historical pipeline system. For contaminant delineation decision-making, soil and <br /> groundwater laboratory analytical results were compared to "action levels,"or levels above which further <br /> evaluation to define the extent of contamination 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 />