ARCHIVED REPORTS_FOURTH QUARTER_ANNUAL 2008 GROUNDWATER MONITORING REPORT

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Fourth Quarter/Annual ARCADIS 2008 Groundwater Monitoring Report Chevron Bulk Fuel Terminal 100-1621 ' 22888 Kasson Road Banta,California east-northeast at an approximate horizontal hydraulic gradient of 0.002 foot per foot (fVft)(Figure 3). Recently the predominant flow direction in the Upper A zone has been towards the northeast, as depicted on the groundwater flow direction rose diagram presented in Appendix B(Figure 1). Changes in Upper A groundwater elevations ' across the site since the third quarter of 2008 have ranged from a decrease of 1.07 feet(MW-3UA)to a decrease of 1.83 feet(MW-41 UA)with an average decrease of 1.45 feet. A zone groundwater elevations ranged from 14.21 (MW-52A)to 16.27(MW-6A)feet AMSL.The groundwater flow direction was calculated towards the northeast at an ' approximate horizontal hydraulic gradient ranging from 0.001 to 0.004 ft/ft(Figure 4). Recently the predominant flow direction in the A zone has been towards the northeast, as depicted on the groundwater flow direction rose diagram presented in Appendix B ' (Figure 2).Changes in A zone groundwater elevations across the site since the third quarter of 2008 ranged from a decrease of 0.70 feet(MW-54A)to a decrease of 1.79 feet(MW-27A)with an average decrease of 1.34 feet. ' B zone groundwater elevations ranged from 13.92(MW-50B)to 14.56(MW-65B)feet AMSL. The groundwater flow direction was calculated towards to the north-northeast at ' an approximate horizontal hydraulic gradient of 0.001 ftlft(Figure 5). Recently the predominant flow direction in the B zone has been towards the north, as depicted on the groundwater flow direction rose diagram presented in Appendix B(Figure 3). ' Changes in the B zone groundwater elevations across the site since the third quarter of 2008 ranged from a decrease of 0.93 feet(MW-12B)to a decrease of 0.99 feet (MW-65B),with an average decrease of 0.96 feet. ' Hydrographs depicting changes in groundwater elevations over time are presented in Appendix C(Figures 1 through 3). Groundwater flow data for the Fourth Quarter 2008 Monitoring and Sampling Event is generally consistent with historical data. Historical ' groundwater gradient data is presented in Table 2. Well construction details are summarized in Table 3 and shown graphically on Figure 6(with the exception of the newly installed wells). ' Vertical Hydraulic Gradient Evaluation ' The vertical hydraulic gradient is the ratio of the difference in depth to water measured concurrently in two adjacent wells and the vertical distance between the two measuring points, specified here as the midpoint of each screened interval.The midpoint between the top of the water column and bottom of the screen is used as the reference point ' 7of17