ARCHIVED REPORTS_XR0011294 - Laserfiche WebLink

Home Browse Search

gedogicalTechnics W. Page 3 Groundwater Monitoring Report Project No. 989.2 January 15,2003 ' • Fuel oxygenate suite(MTBE, DIPE, ETBE, TAME, and TBA by EPA method 8260) • 1,2-Dibroinoethane and 1,2-Dichloroethane (1,2 DCA and EDB by EPA method 8260) Th e The fuel oxygenates samples, 1,2 DCA and EDB, were submitted by Sherwood Labs to ' Entech Analytical Labs of Santa Clara, California (DHS # 2346). The detection limits for these compounds are listed in the laboratory data sheets included in ' Appendix C and summarized in Table 2 of Appendix A. A Chain of Custody was completed for all samples collected and tracked to ensure sample integrity. On December 9, 2002, the laboratory data were submitted electronically to GeoTracker as required under A132886. The confirmation number for the electronic submittal is 7213825881. 2.0 FINDINGS AND DISCUSSION 2.1 Hydrology of Site On November 19, 2002, the depth to groundwater was measured in all of the wells prior to purging. Depths to groundwater ranged from a high of 7.72 feet below the top of casing to a low of 9.22 feet below the top of casing. The average depth to water was 8.71 feet below the top of casing and the average groundwater elevation at the site is 1.66 feet below mean sea level. The wells are screened at 5 feet bgs and groundwater surface continues to be ' below the tops of the screens in the nine shallow monitoring wells. Site-specific groundwater gradient was calculated using MW-3, MW-7 and MW-9, and ' found to be N34°W at 0.0039 ft/ft. The calculated groundwater gradient is displayed on the groundwater gradient map, Figure 3. Previous groundwater gradient calculations show a consistent bearing of north-northwest. Bearings have been measured between N05°W and ' N45°W at the site and the slope historically averages 0.0051 ft/ft. Historical groundwater bearing and slope are summarized in Table 1 of Appendix A and are plotted on a Rose Diagram, Figure 4. ' 2.2 Groundwater Analytical Results ' • Low concentrations of BTEX were present in MW-I and MW-4. • Trace amounts of Ethyl benzene and Xylene were detected in MW-3. ' • No constituent of BTEX was found in the remaining monitoring wells. • Low concentrations of TPH gasoline were detected in MW-1 and MW-4. TPH-G was not present in any other monitoring wells.