ARCHIVED REPORTS XR0001316 - Laserfiche WebLink

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Date August 2,2004 Quarter 2nd Quarter,2004 DISCUSSION: Gasoline range organics (GRO) 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 cis-1,2-dichloroethene, trichloroethene (TCE), and chloroform 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, cis-1,2- dichloroethene concentrations increased relative to the previous quarter but remain significantly below historic high ranges GRO concentrations decreased and benzene, isopropylbenzene, n-propylbenzene, n-butylbenzene, and sec- butylbenzene were reported as below method detection limits (at a 5 dilution factor) in MW-4 this quarter MtBE was reported at the lowest concentration in MW-7 since September 2003 GRO concentrations increased in MW-8M but remain within historic ranges In MW-9D, cis-1,2-dichloroethene was reported as below method detection limits for the first time since December 2002 MtBE was reported as below method detection limits in MW-9M and MW- 12D this quarter In MW-10D, chloroform was reported above method detection limits for the first time historically and cis-1,2-dichloroethene and TCE were reported at the lowest levels historically MtBE concentrations decreased to the lowest level reported historically in MW-11M TCE and cis-1,2-dichloroethene concentrations increased to the highest levels reported historically in MW-I ID this quarter Groundwater monitoring wells MW-13M and MW-13D were installed in May 2004 and added to the quarterly groundwater monitoring schedule In MW-13M, cis-1,2-dichloroethene was reported at 28 micrograms per liter (µg/L) and TCE was reported at 19 µgIL In MW-13D, cis-1,2-dichloroethene was reported at 12 pg/L No other analytes were reported above method detection limits in the groundwater samples collected from monitoring wells MW-13M or MW-13D Groundwater elevations in the site wells generally decreased 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 I Groundwater Elevation Contours Figure 2 Groundwater Analytical Summary APPENDICES Appendix A Field and Laboratory Procedures Appendix B Laboratory Analytical Reports,Chain-of-Custody Documentation, and Field Data Sheets Appendix C GeoTracker Upload Confirmation Pa rye 2 K lwprocescUS BM P ARCD1D931Qn uaerlyl2 QTR 0414493 GWMR 2Q04 dnc y