ARCHIVED REPORTS_SITE INVESTIGATION AND WELL DESTRUCTION PERMIT

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Page 3 CRA MEMORANDUM 5.0 Continuing Calibration - organic Analyses GC/MS To ensure that instrument calibration for VOC analyses is acceptable throughout the sample analysis period, continuing calibration standards must be analyzed and compared to the initial calibration curve every 12 hours. The following criteria were employed to evaluate continuing calibration data: i) All RRF values must be greater than or equal to 0.05 ii) Percent difference (%D)values must not exceed 25 percent Calibration standards were analyzed at the required frequency, and the results met the above criteria for instrument sensitivity and stability. GC To ensure that the calibration of the instrument for organic analyses by GC is valid throughout the sample analysis period, continuing calibration standards are analyzed and evaluated on a regular basis. To evaluate the continued linearity of the calibration, %D values are calculated for each compound. As specified in the methods, all %D values should not exceed 15 percent. To ensure that compound retention times do not vary over the analysis period, all retention times for continuing calibration compounds must fall within the established retention time windows. All continuing calibration standards were analyzed at the required frequency. All %D values and compound retention times met the above criteria indicating acceptable instrument calibration throughout the analysis period. 6.0 Laboratory Blank Analyses Method blanks are prepared from a purified matrix and analyzed with investigative samples to determine the existence and magnitude of sample contamination introduced during the analytical procedures. For this study, laboratory method blanks were analyzed at a minimum frequency of 1 per 20 investigative samples and/or 1 per analytical batch. All method blank results were non-detect, indicating that laboratory contamination was not a factor for this investigation. EQUAL EMPLOYMENT OPMRWNM EMKO R