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' CWto kiI Teckda Inc. Pae 2 8 S Groundwater Monitoring Report ' Project No.425.2 March 21,205 ' and MW-106) out of the 13 monitoring wells. The two domestic wells sampled during this event did not contain petroleum hydrocarbon contaminants above laboratory reporting limits. ' A summary of groundwater analytical findings includes: • TPH-G and BTEX concentrations in MW-1 have increased significantly in ' comparison with the previous monitoring events. • TPH-G concentrations have decreased in MW-5 in comparison with the previous three quarterly monitoring events and the well has historically exhibited a trend of ' increasing concentrations. • The concentration of TPH-G in MW-2 increased in comparison with the concentrations detected during the last three monitoring events. • During this monitoring event MW-106 has been detected for MTBE and 1,2 DCE. • Samples were collected from two domestic wells during the January 2004 monitoring event. The domestic wells were non-detect above laboratory reporting limits suggesting contamination has not migrated to the monitored domestic wells. ' 1.0 GROUNDWATER MONITORING M1.1 Hydrology of Site 1.1.1 Zone Divisions ' To define the site more accurately, the aquifer is divided into four zones (Zones A through D) defined by the screen intervals of the sixteen monitoring wells associated with the site. Zone divisions and well construction are summarized in Table 1. • Zone A includes monitoring wells screened between 5 and 22-Feet bgs • Zone B includes monitoring wells screened between 32 and 35-feet bgs ' • Zone C includes monitoring wells screened between 45 to 49.5-feet bgs • Zone D is represented by MW-202 screened between 79 and 81.5-feet bgs - 1.1.2 Horizontal Groundwater Gradients Zone A ' The average groundwater elevation is 73.08 feet above mean sea level (AMSL). This represents a increase of 0.06 feet since the November 2004 monitoring event. The zone- specific groundwater gradient was 0.0011 ft/ft flowing NOO'E. A review of the groundwater ' gradients in Zone A show groundwater bearings varying from north to northeast with the slope ranging from 0.0001 to 0.0044 ft/ft. ' Table 2 of Appendix A summarizes Zone A groundwater elevations, gradients and bearings. Figure 3 illustrates the January 21, 2005 groundwater gradient for Zone A.