ARCHIVED REPORTS_FIELD NOTES AND PERMITS THROUGH 4_4_1997

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U-14L)ILIII P.05/06 Blank Results Laboratory, equipment, and trip blank data were reviewed to assess the presence of contaminants, which affect the sensitivity of the sample results. Of the six method blanks associated with these samples, tetrachloroethylene was detected in three. The concentrations of positive tetrachloroethylene results in the samples associated with the contaminated method blanks were greater than five times the associated blank contamination concentration. Therefore, false positives due to laboratory contamination were not suspected and no qualification of the data was necessary. There were two equipment blanks (MW5-EB and MW30-EB) and 6 trip blanks (TBI through TB6) associated with these samples. Tetrachloroethylene and trichloroethylene were detected in equipment blank MW5-EB, and trichloroethylene was detected in equipment blank MW30-EB and all the trip blanks. The following tetrachloroethylene and trichloroethylene results in the samples listed were detected at concentrations less than five times the concentration detected in the associated field and/or trip blanks: tetrachloroethylene: MW2-50, MW8-59, MW20-110 trichloroethylene: MW1-55, MWI-DUP, MW3-55, MW8-59, MW9-60, MW30-70 The positive results for the compounds in the listed samples were considered to be not detected and qualified with a "U" because false positives were suspected, as indicated by the field and trip blank contamination. These data are usable as not detected results at the reported quantitation limits. Based on the level of contamination suspected in the sample, the quantitation limits for these results were elevated. Quantitation Limits Compound quantitation limits were reviewed to assess if the sensitivity of the results met the project-specific requirements. The values reported by the laboratory (on Form ls) for nondetect results are the method detection limits (MDLs). The summary results for the MDL study, submitted by the laboratory, support the reported detection limits. Eleven of the samples required dilutions in order to quantitate the tetrachloroethylene, trichloroethylene, cis-1,2-dichloroethylene, and/or trans-1,2-dichloroethylene results at concentrations within the instrument calibration range. Some samples required numerous dilutions in order for the tetrachloroethylene, trichloroethylene, cis-1,2-dichloroethylene, and/or trans-1,2-dichloroethylene concentrations to be within the instrument calibration range (1 to 25 pg/L). The following table summarizes the dilution analyses from which the laboratory reported results for tetrachloroethylene, trichloroethylene, cis-1,2-dichloroethylene, and/or trans-1,2- dicidoroethylene in the 11 samples that required dilutions for these compounds. g:\projectsldg19504100.mem 4 Gradient corporation