ARCHIVED REPORTS_SITE INVESTIGATION AND WELL DESTRUCTION PERMIT

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CRA MEMORANDUM Page Calibration standards were analyzed at the required frequency, and the results met the above criteria for instrument sensitivity and stability. 6.0 GC Initial Calibration -Total Petroleum Hydrocarbons (TPH) In order to quantify compounds of interest, calibration of the gas chromatograph/flame ionization detector (GC/FID) over a specific concentration range must be performed. Initially, a calibration curve consisting of a minimum of five concentration levels is analyzed for all single component compounds of interest. Linearity of the calibration curve is acceptable if all RSD values are less than or equal to 30.0 percent or if the correlation coefficient is 0.995 or greater for linear regression curves. Retention time windows are also calculated from the initial calibration analyses. These windows are then used to identify all compounds of interest in subsequent analyses. All initial calibration standards were analyzed at the required frequencies. All retention time, peak resolution and linearity criteria were satisfied as specified in the method. 7.0 GC Continuing Calibration - TPH To ensure that the calibration of the instrument 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 be less than 15 percent. 8.0 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. 9.0 Surrogate Spike Recoveries In accordance with the methods employed, all samples, blanks and QC samples analyzed for organics are spiked with surrogate compounds prior to sample extraction and/or analysis. Surrogate recoveries provide a means to evaluate the effects of laboratory performance on individual sample matrices. EONAL EMPLOYMENT OPPONNNIW EMPLOKP