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directed to the channels indicated, and will enter the excavation at only the one location shown. During this regrading process the refuse side slopes of the excavation will be regraded to a maximum slope of 2:1 horizontal to vertical. The existing northern slope of the excavation, which is an excavated earth surface and not a working face, cannot be modified under current site conditions. Drawing 3 shows the proposed surface of the site after placement of 12 inches of cover soil over the northern half, as discussed during the site visit on March 4, 1993. The cover soil will be placed so as to maintain the drainage patterns established during the regrading process. In addition, berms to a minimum height of one foot will be placed as shown on the drawing. These berms will help mark the top of slopes for safety, will discourage crossing the slopes anywhere except at designated site roads, and will prevent drainage across the slopes, reducing erosion. Drawing 3 also shows the anticipated surface water elevation at the bottom of the existing excavation, caused by runoff from the 10 year, 24 hour, storm event over an area of approximately 8.4 acres. Drawings 4 and 5 show cross sections through areas of the site as indicated. Each cross section shows the existing ground surface, the surface after regrading of existing material for drainage, and the proposed site surface after the addition of 12 inches of intermediate cover. Final fill elevations are not shown on the cross sections because a postclosure development plan has not been prepared, so final fill grades are conjecture at this point. The RDSI states that the final fill grade is 16 feet over the northern portion of the site. This fill elevation may be revised in the RDSI amendment. The site drainage proposed in the above drawings has been laid out so as to reduce site erosion and reduce subsequent maintenance requirements. It has also been laid out with an eye toward future facility operations to decrease potential interference with site filling and reduce the need for additional regrading to accommodate future operations. It is anticipated, during the interim period preceding approval of plans for the site to receive additional wastes, that the runoff from the clean intermediate cover will accumulate at the bottom of the excavation and either evaporate or infiltrate into to soil below the site. As discussed in the Report of Waste Discharge (RWD) for the facility, the area at the bottom of the existing excavation where run- off will accumulate is not underlain by refuse. From the discussion of the effects of storm water infiltration through refuse to the groundwater in Appendix J of the Report of Disposal Site Information (RDSI) it is not anticipated that the run-off accumulating in the refuse free bottom of the existing excavation will have a significant effect on groundwater quality. However, a water sample will be collected from the bottom of the existing excavation after the first significant storm event which accumulates water following placement of the 12 inch intermediate cover. The water sample will be analyzed for electrical conductivity (EC), dissolved solids, and chlorides as indicator parameters for the effectiveness of the intermediate cover. It is not anticipated that this site drainage configuration will continue for more than one wet season before filling operations and site closure, with associated drainage configurations, are approved and initiated. However, should more than one wet season pass, continued maintenance of the proposed drainage patterns and intermediate cover integrity should ensure that continued accumulation of run-off water in the bottom of the existing excavation will not significantly impact the groundwater around the site. The grading described above is intended to stabilize the site as an interim measure prior to approval of the facility for receipt of inert construction/demolition debris. It is anticipated that placement of this inert material will continue until the site surface is brought to a level above the surrounding topography. This will then allow the site to be closed in a manner that will CLI -60 (1993) Page 2 of 3 24-215600-F02 Copyright 1993 Kleinfelder, Inc. KLEINFELDER 3077 Fite Circle, Sacramento, CA 95827 (916) 366-1701