2009-11-30_REVISION - M2000156 (7)

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6.4.5 Exhibit E — Reclamation Plan 6) Following backfilling Phase 2 Cell 3, begin constructing the clay liner for the main lake by ripping weathered shale from pit floor and placing on the slopes and compacting. 7) Replace topsoil as shown in Exhibit F — Reclamation Plan (40,333 cy). 8) Disk, seed and fertilize areas as shown in Exhibit F — Reclamation Plan. Pond Liner Design and Specification The purpose of this section is to provide design specifications for the pond liner. The objective is to design a post- mining, compacted clay liner that will prevent groundwater leakage into the pond, at a rate greater than or equal to 0.03 feet / day / feee. The borrow source for the compacted clay liner will be the weathered zone of Pierre shale occurring an average of 17 feet below ground surface. Texturally and mineralogically continuous in a lateral direction, the Pierre shale is flat lying in this area (Porter, 1976). The weathered zone is a friable silty clay consisting of illites and small amounts of smectites (Gill et al, 1996). Approximately 69,000 cy of weathered Pierre shale will be required to construct the clay liner for the 55 acre lake and 11,500 cy with be required for the 2 acre lake. Source Material Sampling /Laboratory Analysis A 5- gallon sample of weathered Pierre shale was collected from a gravel operation to the west. Collected from the upper 3 to 4 feet of the weathered horizon, the shale appeared very consistent with respect to color and texture with that of the weathered shale within the proposed excavation area. Moreover, personal communication with local excavators and drillers confirm the consistency of the Pierre shale throughout eastern Loveland. This consistency is most likely due to the flat lying nature of the shale in this region. If the source material shows any variability with respect to color, texture, or content from the sampled material, a full suite of geotechnical tests will be performed. Field data recorded during sample collection included: Color— dark gray Texture — Very fine- grained clay and silt with larger clumps that are friable with moderate pressure between fingertips Plasticity — Low Moisture — Moist The field sample was delivered to Aguirre Geotechnical Engineers of Englewood, Colorado, and the following tests were performed: