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45 Farmington Valley Drive <br /> CONESTOGA-ROVERS Plainville, Connecticut 06062 <br /> & ASSOCIATES Telephone: (860)747-1800 Fax: (860) 747-1900 <br /> www.CRAworld.com <br /> MEMORANDUM <br /> To: Daniel Lescure REF. No.: 060223 <br /> FROM: Kathy Shaw/eew/20-NF Sra'I DATE: September 10, 2014 <br /> RE: Analytical Data Assessment and Validation <br /> Quarterly Groundwater Sampling <br /> Shell Cordes Ranch <br /> Tracy, California <br /> July 2014 <br /> 1.0 Introduction <br /> The following document details a reduced validation of analytical results for residential well samples <br /> collected in support of the Quarterly Groundwater Sampling at the Shell Cordes Ranch Site in <br /> Tracy, California during July 2014. Samples were submitted to Eurofins/Calscience, located in <br /> Garden Grove, California. A sample collection and analysis summary is presented in Table 1. A summary of <br /> the analytical methodology is presented in Table 2. <br /> Evaluation of the data was based on information obtained from the finished data sheets, raw data, <br /> calibration data, blank data, recovery data from surrogate spikes, laboratory control samples (LCS), matrix <br /> spikes, and file quality assurance/quality control (QA/QC) samples. The assessment of analytical and <br /> in-house data included checks for: data consistency by observing comparability of duplicate analyses; <br /> adherence to accuracy and precision criteria; transmittal errors; and anomalously high and low parameter <br /> values. <br /> The QA/QC criteria by which these data have been assessed are outlined in the document entitled: <br /> i) "USEPA Contract Laboratory Program National Functional Guidelines for Superfund Organic Methods <br /> Data Review", USEPA 540-R-08-01,June 2008. <br /> 2.0 Sample Holding Time and Preservation <br /> The sample holding time criteria for the analyses is summarized in Table 2. Sample chain of custody <br /> documents and analytical reports were used to determine sample holding times. All samples were <br /> prepared and analyzed within the required holding times. <br /> NeaunNEN nNrur raw <br /> ISO 9001 <br /> EQVPL EMPLMM ENT WMRTJNITV EMPWrtF ENGINEERING DESIGN <br />