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(see Appendix A), these base grades will be from 96 to more than 118 feet above existing ground -water elevations. The base of excavation will be sloped towards the perimeter at 2 percent minimum with a cross -slope of 2 percent into the cen- ter of each module. A temporary runoff containment sump outside the limits of the active module will be excavated to collect runoff from within the active fill and excavation modules. Based on the proposed excavation grades, the total of approximately 9,000,000 cubic yards of soil far exceeds the estimated soil needs for landfill op- eration and final soil cover. However, the additional excavation will provide greater volume for refuse filling, thus extending the service life of the site. Ex- cess excavated soils will be disposed of off site, at areas designated by the County, or sold. 5.3.2 Earthfill Earthfill will be required at the landfill for various design features such as perimeter berms, foundations for access roads, and drainage facilities over refuse fill. Areas to receive earthfill will be stripped of vegetation and topsoil, scarified, and compacted before placing the initial layer of earthfill. Earthfill will then be placed by spreading the specified soil in uniform layers not over 8 inches thick. Each soil layer will be watered or dried as needed to bring the soil to the specified moisture content and compacted with suitable equipment to at least 90 percent relative compaction (ASTM Test Designation D1557-78). 5.3.3 Stockpile and Screening Berms Selective stockpiling of excavated soils will be necessary for later use as final cover material. A screening berm north of the landfill limits is planned to screen landfill operations from Harney Lane. The proposed locations of soil stockpiles and screening berms are shown on Drawing 1. Screening berms will be placed as earthfill as described in the preceding section. PJ9 9390218A.00W 40 Rev. 0 July 20, 1989