ARCHIVED REPORTS XR0001317 - Laserfiche WebLink

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Date May 11,2004 Quarter 151 Quarter,2004 DISCUSSION: GRO, benzene, and methyl tert-butyl ether (MtBE) were reported above method detection limits in groundwater samples collected from site wells during this quarterly groundwater monitoring event Additionally, volatile organic compounds isopropylbenzene, n-propylbenzene, n-butylbenzene, sec-butylbenzene, cis-l,2-dichloroethene, and trichloroethene(TCE)were reported above method detection limits in groundwater samples collected from site wells this quarter Analyte concentrations were generally consistent with previous quarterly monitoring events with the following exceptions in MW-1 and MW-2, cls-l,2-dichloroethene concentrations decreased to the lowest levels reported since September 2001 and November 2000, respectively Additionally in MW-2, TCE concentrations continue to exhibit a decreasing trend GRO, benzene, MtBE, isopropylbenzene, n-propylbenzene, n-butylbenzene, and sec-butylbenzene concentrations decreased in MW-4 relative to the previous monitoring event MtBE concentrations increased in MW-5 but remain within historic ranges Tertbutylbenzene was reported as below method detection limits in MW-7 this quarter In MW-8M, GRO, MtBE, isopropylbenzene, and n-propylbenzene concentrations decreased and toluene, ethylbenzene, total xylenes, naphthalene, and 1,2,4-trimethylbenzene were reported as below method detection limits GRO and MtBE concentrations in MW-81) and TCE concentrations in MW-10M and MW-101) increased but remain within historic ranges In MW-I 1M,MtBE concentrations decreased to the lowest level reported since sampling began in December 2002 TCE and cis-l,2-dichloroethene were reported at the highest concentrations historically in MW-I 1D this quarter Groundwater elevations in the site wells generally increased relative to the previous quarter The inferred 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 Detected Volatile Organic Compounds Analytical Data Table 4 Groundwater Gradient Data FIGURES Figure 1 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 Appendix C GeoTracker Upload Confirmation K%Wpm¢essV5 BP ARC0\044931Quaner1y11 QTR 04,4493 GWMR EQ04 doc Page 2