ARCHIVED REPORTS XR0000818 - Laserfiche WebLink

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Date- October 27,2004 Quarter: 3rd Quarter,2004 ANALYTICAL DATA REVIEW: Based on the review of the analytical and hardcopy data (cham-of-custody records,blanks, dilutions, holding times, LCS/LCSD results,MS/MSD results,and surrogate recoveries),the data are acceptable as reported by the laboratory with the following limitations • The reported results for gasoline range organics (GRO) in sample MW-4 is due to chromatographic peaks present in the gasoline quantitation range, however, the peaks present do not resemble the pattern for gasoline • The elevated reporting limits were the result of dilutions performed by the laboratory in order to quantitate a target analyte DISCUSSION: GRO, benzene, toluene, ethylbenzene, total xylenes (BTEX), methyl tert-butyl ether (MtBE), tert-butyl alcohol (TBA), and 1,2-dichloroethane (1,2-DCA) were detected above laboratory reporting lirruts in groundwater samples collected from site monitoring wells this quarter GRO, BTEX, and MtBE concentrations in MW-1 decreased this quarter In MW-4, MtBE concentrations decreased, TBA and 1,2-DCA were detected above laboratory reporting limits, and methanol was not detected above laboratory reporting limits MW-4 was the only monitoring well that had a detection of methanol during second quarter 2004 Total xylenes in MW-6 and MtBE in MW-8 were not detected above laboratory reporting linuts this quarter In VW-1B, benzene, total xylenes, and TBA were detected above laboratory reporting limits in concentrations within historic ranges, ethylbenzene was reported at the highest concentration historically, 1,2-DCA was detected above laboratory reporting limits for the first time historically,and MtBE concentrations decreased BTEX concentrations increased to the highest concentrations reported in VW-2B this quarter and MtBE concentrations decreased In VW-313,GRO,BTEX, and TBA were detected above laboratory reporting limits at concentrations within historic ranges and MtBE decreased to the lowest level reported since December 2002 Other analyte concentrations were generally consistent with historic data Groundwater elevations in wells across the site decreased relative to the previous quarter The inferred groundwater flow direction ranged from the southwest to the southeast at an average hydraulic gradient that ranged from 0 009 to 0 04 ft/ft The SVE system began operations on August 30, 2004 Approximately 93 6 lbs of GRO and 2 4 lbs of MtBE were removed during the third quarter 2004 No benzene was removed due to non-detect influent concentrations The SVE system operated in compliance with the San Joaquin Valley Air Pollution Control District (SJVAPCD) Initial sampling and flow data was submitted to SJVAPCD on September 28, 2004 The system was shutdown on September 7, 2004, due to excessive noise The system will be restarted in the fourth quarter 2004 after corrective action has been taken A performance evaluation of the remedial systems between August 30 and September 23, 2004,are presented as Appendix A K 1WP-ce.V5 HP ARC0021861Qu.ner1y\200413 QTR 0412186 GWMR 3QD4 doe Paige 2