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Groundwater Sampling ana Analysis Plan <br /> Former Texaco Service Station <br /> Chevron Site ID 309075 <br /> January 14, 2011 <br /> (supplied by the laboratory) which remains unopened with field samples throughout the <br /> sampling event. Trip blanks will only be analyzed for volatile organic compounds (VOC). Trip <br /> blank samples shall be identified with a `T" designation and followed by the date in the yymmdd <br /> format. An example of a sample identification number for a trip blank sample collected on April <br /> 30, 2011 is T-110430. <br /> 5.2 ANALYTICAL LABORATORY QUALITY CONTROL CHECKS <br /> Internal laboratory quality control checks will be used to monitor data integrity. These checks will <br /> include method blanks, matrix spike/matrix spike duplicate (MS/MSD), and surrogate spikes. In <br /> addition to the laboratory quality control checks, ARCADIS will request a QA/QC reporting <br /> package from the laboratory. <br /> 5.2.1 Method Blanks <br /> Sources of contamination in the analytical process, whether specific analyses or interferences, <br /> need to be identified, isolated, and corrected. The method blank is useful in identifying possible <br /> sources of contamination within the analytical process. For this reason, it is necessary that the <br /> method blank is initiated at the beginning of the analytical process and encompasses all aspects <br /> of the analytical work. As such, the method blank would assist in accounting for any potential <br /> contamination attributable to glassware, reagents, instrumentation, or other sources which could <br /> affect sample analysis. One method blank will be analyzed with each analytical series <br /> associated with the monitoring well network. <br /> 5.2.2 MS/MSDs <br /> MS/MSDs will be used to measure the accuracy of analyte recovery from the sample matrices <br /> and will be site-specific. MS/MSD pairs will be analyzed at a 5% frequency. When MS <br /> recoveries are outside quality control limits, associated control sample and surrogate spike <br /> recoveries will be evaluated, as applicable, to attempt to verify the reason for the deviation and <br /> determine the effect on the reported sample results. <br /> 5.2.3 Surrogate Spikes <br /> Surrogates are compounds which are unlikely to occur under natural conditions that have <br /> properties similar to the analytes of interest. This type of control is primarily used for organic <br /> samples analyzed by GC/MS and gas chromatography (GC) methods and is added to the <br /> samples prior to purging or extraction. The surrogate spike is utilized to provide broader insight <br /> into the proficiency and efficiency of an analytical method on a sample-specific basis. This <br /> control reflects analytical conditions that may not be attributable to sample matrix. If surrogate <br /> spike recoveries exceed specified quality control limits, the analytical results need to be <br /> evaluated thoroughly in conjunction with other control measures. In the absence of other control <br /> measures, the integrity of the data may not be verifiable and reanalysis of the samples with <br /> �+ \\CA5FP\Data\Aproject\ENV\CHEVRON\309075\6 Deliverables\Work Plan\SAP\309075_SAP_6671110950.doc 8 <br />