ARCHIVED REPORTS_GROUNDWATER MONITORING REPORT - THIRD QUARTER 2013

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Paye 4 CRA MEMORANDUM TPH All method blank results were non-detect,indicating that laboratory contamination was not a factor for this investigation. SURROGATE SPIKE RECOVERIES In accordance with the methods employed,all samples,blanks and QC samples analyzed for VOCs,and TPH are spiked with surrogate compounds prior to sample extraction and/or analysis. Surrogate recoveries provide a means to evaluate the effects of individual sample matrices on analytical efficiency. VOCS All samples submitted for VOC determinations were spiked with four(4)surrogate compounds prior to sample analysis. All surrogate recoveries were within the laboratory control limits. TPH All investigative samples submitted for TPH determinations were spiked with the surrogate compound n-Octacosane prior to sample preparation and analysis. All surrogate recoveries were within the laboratory control limits. INTERNAL STANDARDS(IS)ANALYSES Internal standard data were evaluated for all VOC sample analyses. VOCS To ensure that changes in the GC/MS sensitivity and response do not affect sample analysis results, internal standard compounds are added to each sample prior to analysis. All results are then calculated as a ratio of the internal standard responses. The sample internal standard results were evaluated against the following criteria: i) The retention time of the internal standard must not vary more than±30 seconds from the associated calibration standard ii) Internal standard area counts must not vary by more than a factor of two(-50 percent to +100 percent)from the associated calibration standard All internal standard recoveries and retention times met the above criteria. LABORATORY CONTROL SAMPLE(LCS)ANALYSES LCS and/or laboratory control sample duplicates(LCSD)are prepared and analyzed as samples to assess the analytical efficiencies of the methods employed,independent of sample matrix effects. The relative percent difference(RPD)of the LCS/LCSD recoveries is used to evaluate analytical precision. For this study the LCS(LCSD)was analyzed at a minimum frequency of one per 20 investigative samples and/or one per analytical batch.