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Reservoir #2 shall be reclaimed first. Following mining of Cell 2, reclamation will <br />begin by constructing a the subsurface drain as specified in engineering <br />documents in the existing permit. Following installation of the drain, preparation <br />of the borrow material on the excavation floor will be performed by disking the <br />weathered claystone in preparation for moisture conditioning. Geotechnical <br />investigations conducted by CTL Thompson indicate the weathered claystone is <br />a suitable borrow material with plasticity indices near or above 20 (see Table <br />6.4.5-2). A drain pipe will then be installed at the toe of the mining highwall and <br />into the weathered shale with a filter pack which will be in hydraulic <br />communication with the gravel layer to facilitate dewatering during liner <br />construction. The Keyway surrounding the perimeter of the excavation and offset <br />approximately 6ft from the toe of slope will then be excavated as specified in <br />Figure 6.4.5 — 1 Typical Section. Once the borrow material is within the moisture <br />specification (0 to +3% of optimum moisture content), the compacted clay liner <br />will then be constructed by making passes with Miskin Scrapers towed by JD <br />9520's in 8" lifts. This type of scraper will provide significant compaction energy <br />to bring each lift to 95% standard proctor maximum dry density. Once the <br />compacted clay liner is completed to the approximate geometry/specifications <br />given in Figure 6.4.5 — 1 Typical Section, the slope will be backfilled to 31-1:1V <br />with overburden stored to the west of Reservoir #2. This controlled backfill shall <br />be placed in 8" lifts to 95% standard proctor maximum dry density at 0 to +3% <br />optimum moisture content. Following backfilling of the slopes, a protective shell <br />shall be constructed from aft above to 1 Oft below the normal pool elevation. The <br />specifications for the protective shell are given in Figure 6.4.5 — 1 Typical <br />Section. Following Mining of Cell 4, reclamation / construction of Reservoir #4 will <br />occur in the same fashion as Reservoir #2. <br />Table 6.4.5-2. Weathered Claystone Geotechnical Data <br />MOISTURE DRY LIQUID PLASTICITY <br />BORING CELL DEPTH CONTENT DENSITY LIMIT INDEX <br />PASSING PERME <br />200 - <br />SIEVE ABILITY <br />ft] [%] [PCF] [%] [cm/sec] <br />TH-2 4 24 12.6 124 39 22 <br />TH-3 4 24 9 120 36 19 <br />Topsoil Replacement Depth <br />TH-5 4 <br />1 ft <br />121 44 25 91 <br />TH-5 4 29 12.7 123 <br />Topsoil Replacement Volume 7,017.29 yd <br />TH-9 4 24 11.9 121 41 23 77 <br />Reservoir #2 shall be reclaimed first. Following mining of Cell 2, reclamation will <br />begin by constructing a the subsurface drain as specified in engineering <br />documents in the existing permit. Following installation of the drain, preparation <br />of the borrow material on the excavation floor will be performed by disking the <br />weathered claystone in preparation for moisture conditioning. Geotechnical <br />investigations conducted by CTL Thompson indicate the weathered claystone is <br />a suitable borrow material with plasticity indices near or above 20 (see Table <br />6.4.5-2). A drain pipe will then be installed at the toe of the mining highwall and <br />into the weathered shale with a filter pack which will be in hydraulic <br />communication with the gravel layer to facilitate dewatering during liner <br />construction. The Keyway surrounding the perimeter of the excavation and offset <br />approximately 6ft from the toe of slope will then be excavated as specified in <br />Figure 6.4.5 — 1 Typical Section. Once the borrow material is within the moisture <br />specification (0 to +3% of optimum moisture content), the compacted clay liner <br />will then be constructed by making passes with Miskin Scrapers towed by JD <br />9520's in 8" lifts. This type of scraper will provide significant compaction energy <br />to bring each lift to 95% standard proctor maximum dry density. Once the <br />compacted clay liner is completed to the approximate geometry/specifications <br />given in Figure 6.4.5 — 1 Typical Section, the slope will be backfilled to 31-1:1V <br />with overburden stored to the west of Reservoir #2. This controlled backfill shall <br />be placed in 8" lifts to 95% standard proctor maximum dry density at 0 to +3% <br />optimum moisture content. Following backfilling of the slopes, a protective shell <br />shall be constructed from aft above to 1 Oft below the normal pool elevation. The <br />specifications for the protective shell are given in Figure 6.4.5 — 1 Typical <br />Section. Following Mining of Cell 4, reclamation / construction of Reservoir #4 will <br />occur in the same fashion as Reservoir #2. <br />Table 6.4.5-2. Weathered Claystone Geotechnical Data <br />MOISTURE DRY LIQUID PLASTICITY <br />BORING CELL DEPTH CONTENT DENSITY LIMIT INDEX <br />PASSING PERME <br />200 - <br />SIEVE ABILITY <br />ft] [%] [PCF] [%] [cm/sec] <br />TH-2 4 24 12.6 124 39 22 <br />TH-3 4 24 9 120 36 19 94 <br />TH-5 4 24 13.6 121 44 25 91 <br />TH-5 4 29 12.7 123 39 22 93 6X10-8 <br />TH-9 4 24 11.9 121 41 23 77