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t 1 1.0 QA/QC NARRATIVE Site: NCS Stockton (CTO 0162) Laboratory: ChemWest Analytical Laboratories QA Reviewer: Ron Ohta, PRC Review Date: June 26, 1992 SDG No.: 9501 and 9517 Sample No.: NCS -3, NCS -4, NCS -5 Collection Dates: April 20, 1992 and April 24, 1992 Analyses: TPH Gasoline with Benzene, Toluene, Ethylbenene, and Xylenes (BTEX); Ethylene Dibromide (EDB); Total Lead; Organic Lead; and Volatile Aromatic Compounds QC Criteria Reviewed: Holding times, laboratory blanks, surrogate recoveries, matrix spike/matrix spike duplicate, and blank spikes The data were reviewed according to EPA documents "Laboratory Data Validation Functional Guidelines for Evaluating Organic Analyses" (February 1988) and "Laboratory Data Validation Functional Guidelines for Evaluating Inorganic Analyses" (July 1988). Comments Due to holding time problems, the following non-detected analytes are considered estimated (UJ) and usable for limited purposes only. Organic lead in sample NCS -3 and NCS -4 Samples NCS -3 and NCS -4 were analyzed 4 days past the 14 day holding time. The DHS LUFT method for organic lead does not specify a holding time, however, the 14 day holding time for volatile organics was applied. 2. No data were qualified due to blank contamination problems. The method blank for aromatic volatiles (AVBLKOI) contained 0.03 mg/kg of 1,4 dichlorobenzene, however, this compound was not detected in the sample. No further action was necessary. 3. No data were qualified due to surrogate recovery problems. The surrogate recoveries for o-chlorotoluene were 8% and 3.8% for samples NCS -3 and NCS -4 respectively. However. the recoveries for bromochloromethan e were within the acceptance criteria of 50-1500%. Also, since the matrix spike/matrix spike duplicate (MS/MSD) results and blank spike analyses were all well within acceptance criteria, no qualifiers were judged to be necessary. 95019517.162