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SECTION 2 IU FU-03 Base and Final Grading 2.1 General The limits of WMU FU-03 were determined based on the site's operational needs, the landfill site development plan (BAS et A., 2003), and the October 2002 site topographic map. The southern limit was offset 50 feet from the property line to allow for an access road and for the future final cover. The northern limit was based on connecting the interface slope liner with the interim cap for the former Austin Road Landfill. The western limit of WMU FU-03 was determined based on the permitted waste limits and sizing of the WMU F-West leachate impoundment and desilting basin and the eastern limit was based on site operational considerations for airspace. Other design criteria and reasoning included: • Title 27 requires a minimum 5-foot barrier between waste in WMU FU-03 and groundwater. Additionally, the site WDRs require that no waste be discharged below an elevation of 7 feet above MSL. The lowest elevation of the WMU FU-03 base liner is in the primary sump and was set to comply with the WDRs at an elevation of 7 feet MSL. • According to the San Joaquin County Flood Control District, the historic high groundwater table is approximately 10 feet below MSL. If the historic high were to occur, a waste to groundwater separation of approximately 17 feet would be maintained. • Leachate collected in WMU ART-03 will ultimately be routed through the WMU FU-03 base LCRS(blanket granular drainage material)to the permanent sump. • The WMU FU-03 access ramp will run along the southern property boundary and grade down to the cell base at approximately 5 percent. • WMU FU-03 will be graded to drain to north-south trending leachate collection pipes that lead to a permanent sump. The maximum drainage distance to LCRS pipes is approximately 110 feet (see the Construction Drawings in Appendix A). • As outlined in the Preliminary Closure and Postclosure Maintenance Plan (CH2M HILL, 1994), abrupt differential foundation settlement is not anticipated. The estimated maximum differential foundation settlement is 2 feet in 550 feet, or approximately 0.36 percent. Since the minimum drainage grades on the base of WMU FU-03 are greater than 1 percent and the net effective slope to the LCRS pipes is at least 2 percent, positive drainage grades would remain even if the estimated maximum differential settlement were to occur. • The eastern edge of the WMU FU-03 liner includes a termination berm that will protect the edge of the liner (see Construction Drawings in Appendix A) and allow connection of the WMU FU- 03 lining system to adjacent future WMUs.The berm also defines the limits of waste placement. FORWARD LANDFILL WMU F-03 AND F-WEST DESIGN REPORT 2-1