ARCHIVED REPORTS XR0011892 - Laserfiche WebLink

Home Browse Search

CVYATC A S S O C I A T E S I N C ether (DIPS), ethyl-tert-butyl ether (ETBE), 1,2-dichloroethane (1,2-DCA), and 1,2- dibromoethane(EDB)by EPA Method 8260B. LABORATORY ANALYTICAL RESULTS TPHg was detected in the groundwater sample collected from MW-2 at a concentration of 270 micrograms per liter (gg/1). Benzene was detected in the groundwater samples collected from MW-2, MW-3, and MW-4 at concentrations of 180 gg/1, 38 pg/l, and 0.5 µg/1, respectively. Toluene was detected in the groundwater sample collected from MW-2 at a concentration of 4.9 gg/l. Ethyl benzene was detected in the groundwater samples collected from MW-2, MW-3, and MW-4 at concentrations of 2.9 gg/1, 2.1 µg/1, and 3.3 gg/1, respectively. Xylenes were detected in the groundwater samples collected from MW-2 and MW-4 at concentrations of 7.2 [Ig/1 and 1.6 pg/l, respectively. MTBE was detected in the groundwater samples collected from MW-1, MW- 2, MW-3, MW-5, MW-7, and MW-8 at concentrations of 4.0 gg/1, 6.6 Pg/l, 4.1 Pg/l, 2.9 gg/1, 1.0 gg/l, and 1.0 gg/1, respectively. The laboratory analytical results indicate constituents of concern (COCs) were detected in the groundwater samples collected from. all of the monitoring wells except MW-6. Only the groundwater samples collected from wells MW-2 and MW-3 contained benzene at concentrations that exceeded the Maximum Contaminant Level (MCL) of 1.0 gg/1. All of the other constituents were reported well below their respective MCLS. MTBE was detected in the groundwater samples collected from wells MW-1, MW-2, MW-3, MW-5, MW-7, and MW-8. Only the groundwater sample collected from well MW-2 contained MTBE at a concentration that exceeded the Secondary MCL of 5.0 gg/1. Groundwater analytical results are summarized in Table 2. The laboratory analytical reports are included in Attachment 2. lsoconcentration maps depicting benzene and MTBE concentrations detected in the groundwater samples are shown in Figures 4 and 5,respectively. GEOTRACKER DATA UPLOAD The monitoring well survey data for MW-1 through MW-8 were submitted electronically to the State Water Resources Control Board (SWRCB) Geotracker database (confirmation numbers 9663589298 and 6114750504). The depth to water and laboratory data associated with the second quarter 2005 sampling event were also submitted electronically to the SWRCB Geotracker database (confirmation numbers 1054722428 and 6150645971, respectively). Documentation of the data submittal and the surveyor's report is contained in Attachment 3. CONCLUSIONS AND RECOMMENDATIONS The laboratory analytical results of the groundwater samples collected on April 6, 2005, are generally consistent with recent historical results. The concentrations of CDCs detected in the samples collected from the monitoring wells both increased and decreased with respect to the L s:\Environmental\17861\reports\2gmr2005.doc 4 ATC Associates Inc.