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GeoSyntec Consultants 2. PROJECT DESCRIPTION Forward is currently placing non -hazardous, Class III waste over the previously inactive, unlined landfill unit WMU B. Based on current waste streams, the proposed final grades in the partial final closure plan are anticipated to be reached in the spring of 2001. A final cover will be placed over the existing and new WMU B side slopes and top deck, as well as over the neighboring D-87, D -88-N, D -88-S, and WMU C waste slopes. Class III waste has been disposed in each of these areas. The approximate closure area, including slope correction factors, is approximately 18.8 -acres. The proposed final cover system for the closure of the unlined WMU B area is the prescriptive design for solid waste landfills outlined in §21090 of Title 27. A drainage layer will be added on the steeper 2H:1 V slopes to meet slope stability requirements. A surface water drainage system consisting of ditches and pipes will be constructed as well. The proposed final cover consists of (from top to bottom): • Grass mixture and organic layer • 1 -foot thick vegetative layer • Geocomposite drainage layer (for 2:1 V side slopes only) • 1 -foot thick compacted clay liner (hydraulic conductivity of 1 x 10"6 cm/s or less) 2 -foot thick compacted soil foundation layer The foundation layer will be placed by Forward as an intermediate soil cover over the waste. On-site soils will be compacted to a minimum relative compaction of 90% (ASTM D1557). Soil materials for the clay liner and vegetative layer will be obtained from on-site excavations for the construction of other WMUs, or existing soil stockpiles. The geocomposite drainage layer will be purchased from a geosynthetic manufacturer. An approximately 1 to 2 -ft thick soil foundation layer is currently in place over the existing waste slopes. Forward will verify the soil thickness on these slopes and, if necessary, will place additional on-site soils to meet the minimum 2 -ft thickness. Existing vegetation will be cleared and grubbed prior to placing additional soil. This ]:WLLIEDXFORWARD\CLOSURE\REPORT\CQA REPORT 2-1 99.11.30