ARCHIVED REPORTS XR0001299 - Laserfiche WebLink

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Date. February 5, 2003 Quarter 0 Quarter,2002 ,. • Elevated reporting luruts were due to dilutions performed by the laboratory in order to quantitate a target analyte • In the TPHg analysis of sample MW-4 and MW-7 the hydrocarbon pattern present is within the gasoline quantitation range but does not resemble the pattern for gasoline • In the TPHg analysis of sample MW-2 the surrogate was outside recovery limits due to matrix interference The results for TPHg in these samples should be considered estimated DISCUSSION: A dual-completion groundwater monitoring well (MW-11MID) was installed on the sidewalk east of EI Dorado street to monitor the downgradient extent of MtBE impacted groundwater Fourth quarter analytical results indicate that MtBE was detected at 55 parts per billion (ppb) in the rind-depth well (MW-11M) and at 2 2 ppb in the deeper well (MW-11D) In other wells, concentrations of TPHg, benzene, ethylbenzene, xylenes (total), methyl tent-butyl ether (MtBE), and volatile organic compounds (VOCs) were consistent with previous quarterly monitoring events Groundwater elevations decreased during the quarter Groundwater flow direction and gradient were consistent with previous quarters 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 Elevation and Analytical Data Table 2 Fuel Oxygenates Analytical Data Table 3 Volatile Organic Compounds Analytical Data Table 4 Groundwater Gradient Data FIGURES Figure 1 Groundwater Elevation Contour Map Figure 2 Groundwater Concentration Map APPENDICES Appendix A Field and Laboratory Procedures Appendix B Laboratory Analytical Reports,Cham-of-Custody Documentation,and Field Data Sheets K V5$P ARC0\044931Quarteriy\4_QTR 0254493 GWMR4Q02 doc Page 2