ARCHIVED REPORTS XR0009993 - Laserfiche WebLink

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Date: February 5,2003 Quarter 4`h Quarter,2002 i Groundwater Samples Collected on 12/19/2002: Based on the review of the analytical and hardcopy data (chain-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 reporting limits for tert-butyl alcohol (TBA)in samples VW-12,MS-1B,MS-2A,MS-2B,MS-3A and MS-3B have been raised due to instrument contamination which may cause false positive results • The elevated reporting limits for the Method 8260 analysis of sample VW-8 were due to the presence of high Ievels of non-target compounds(possibly 2-methyl pentane) • The elevated reporting limits for the Method 8260 analysis of sample VW-10 were due to the presence of high levels of non-target compounds (probably total petroleum hydrocarbons as gasoline (TPHg) and/or benzene,toluene,ethylbenzene,total xylenes(BTEX)) • The reported results for 'IBA, methyl tert-butyl ether (MtBE), di-isopropyl ether (DIPE), ethyl tert- butyl ether (EtBE) and tert-butyl ether (TAME) in samples VW-2, VW-8,VW-10 and VW-11 may be biased low since the analyses for these samples were performed 2 days beyond the U S EPA recommended holding time of 14 days • The reported result for MtBE in sample MS-3B may be biased high as demonstrated by a high surrogate recovery due to matrix interference • Although not noted on the associated sample receipt form, sample MSAA was not received nor analyzed by the Iaboratory • DISCUSSION: TPHg, BTEX, and the fuel oxygenates MtBE, TBA, and DIPE were reported in samples from site wells for this reporting period TPHg, ethylbenzene, and MtBE were reported at historic highs in well VW-7 at concentrations of 160, 13, and 11 Ag/L,,respectively Historic highs of MtBE concentrations were also reported in wells VW-1 and VW-12 (6 4 and 2 6 ug/L, respectively) With the exceptions noted above, analyte concentrations were generally consistent with historic data The approximate direction of groundwater flow was to the southeast with an average hydraulic gradient of 0 002 ft/ft This report is based on data, site conditions, and other information that are generally applicable as of the date of the report,and the conclusions and recommendations herein are therefore applicable only to that time frame TABLES Table 1 Groundwater Monitoring Data Table 2 Groundwater Analytical Results for Oxygenates Table 3 Groundwater Gradient Data FIGURES Figure I Groundwater Elevation Contours Figure 2 Groundwater Analytical Summary APPENDICES Appendix A Field and Laboratory Procedures Appendix B Laboratory Analytical Reports,Cham-of-Custody Documentation, and Field Data Sheets K VS BP ARC0+02130\Quaner1yW_QrR 02\213WWMR4Q02 doe Page 2