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GeO&gk.3I7'eckiks Inc Page 4 ' Groundwater Monitoring Report Project No 425 2 November 8, 2005 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 a 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 q P uploaded to the GeoTracker system on November 7, 2005 The confirmation number is 5589172184 1.4.2 Horizontal Groundwater Gradients Zone A The average groundwater elevation is 73 70 feet above mean sea level (AMSL) This represents an increase in elevation of 0 52 feet since the April 11, 2005 monitoring event The zone-specific groundwater gradient and bearing was 0 0020 ft/ft and N10°E, respectively A review of historical groundwater data in Zone 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 July 20, 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 is 73 32 feet AMSL and indicates an increase of 0 29 feet from the previous monitoring event The groundwater gradient and bearing for Zone B during the July 2005 monitoring event was 0 0115 ft/ft flowing N32°E, respectively The predominant groundwater flow is to the north-northwest with the slope averaging 0 0070 ft/ft ' Bearing and slope data was recalculated for the Zone B monitoring wells The new calculations show the last three quarters have bearings more easterly than previously thought ' Adjustments have been made to the tables and maps using these calculations Table 3 of Appendix A summarizes Zone B groundwater data and Figure 5 shows the groundwater gradients for July 20, 2005 groundwater monitoring event Figure 6 is a rose diagram summarizing historical groundwater bearing and slope information 1