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Geological rechtda Inc. Page 4 ' Groundwater Monitoring Report Project No 425 2 • January 31, 2006 • The lithology between 40 and 80-feet bgs is comprised of alternating layers of clay-sand mixtures and sand-gravel mixtures approximately 2 to 8 feet in thickness 1.4 Hydrology of Site ' 1.4.1 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 ' In accordance with the requirements in AB2886, the depth-to-water measurements were uploaded to the GeoTracker system on January 23, 2006 The confirmation number is 4377577066 1.4.2 Horizontal Groundwater Gradients Zone A The average groundwater elevation for the October 2005 monitoring event is 74 00 feet above mean sea level (AMSL) This represents an increase in elevation of 0 30 feet since the ' July 20, 2005 monitoring event The zone-specific groundwater gradient and bearing was 0 0012 ft/ft and NOTE, respectively A review of historical groundwater data in Zane A show groundwater bearing and slope average N 19°E at 0 0012 ft/ft, respectively ' Table 2 of Appendix A summarizes Zone A groundwater elevations, gradients and bearings Figure 3 illustrates the October 30, 2005 groundwater gradient for Zone A Figure 4 is a rose ' diagram summarizing historical groundwater bearing and slope information Figure 8 contours the TPH-G contamination in Zone A Zone B The average groundwater elevation for the October 2005 monitoring event is 74 07 feet ' AMSL and indicates an increase of 0 75 feet from the previous monitoring event The groundwater gradient and bearing for Zone B during the October 30, 2005 monitoring event was 0 0037 ft/ft flowing N30°W, respectively The predominant groundwater flow is to the ' north-northwest with the slope averaging 0 0066 ft/ft Table 3 of Appendix A summarizes Zone B groundwater data and Figure 5 shows the ' groundwater gradients for October 30, 2005 groundwater monitoring event Figure 6 is a rose diagram summarizing historical groundwater bearing and slope information