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<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). The liner borrow material shall also meet the following criteria; <br />a) Percent fines (should contain at least 20% fines on a dry weight <br />basis). <br />b) Percentage of gravel (material retained on a No. 4 sieve should not <br />exceed 10%). <br />c) Stones and rocks (no rocks larger than 2 inches should be in the liner <br />material). <br /> <br />A drain pipe will then be installed at the toe of the mining highwall and into the <br />weathered shale with a filter pack which will be in hydraulic communication with <br />the gravel layer to facilitate dewatering during liner construction. The Keyway <br />surrounding the perimeter of the excavation and offset approximately 6ft from the <br />toe of slope will then be excavated as specified in Figure 6.4.5 – 1 Typical <br />Section. Once the borrow material is within the moisture specification (0 to +3% <br />of optimum moisture content), the compacted clay liner will then be constructed <br />by making passes with Miskin Scrapers towed by JD 9520’s in 8” lifts. This type <br />of scraper will provide significant compaction energy to bring each lift to 95% <br />standard proctor maximum dry density. Following placement, each lift shall be <br />scarified to a depth approximately 2” to ensure adequate bonding between lifts. <br />Scarification shall be achieved with disking equipment. Once the compacted clay <br />liner is completed to the approximate geometry/specifications given in Figure <br />6.4.5 – 1 Typical Section, the slope will be backfilled to 3H:1V with overburden <br />stored to the west of Reservoir #2. This controlled backfill shall be placed in 8” <br />lifts to 95% standard proctor maximum dry density at 0 to +3% optimum moisture <br />content. Following backfilling of the slopes, a protective shell shall be <br />constructed from the ground surface above to 10ft below the normal pool <br />elevation. The specifications for the protective shell are given in Figure 6.4.5 – 1 <br />Typical Section. Following Mining of Cell 4, reclamation / construction of <br />Reservoir #4 will occur in the same fashion as Reservoir #2. <br />Table 6.4.5-2. Weathered Claystone Geotechnical Data <br />BORING CELL DEPTH <br />MOISTURE <br />CONTENT <br />DRY <br />DENSITY <br />LIQUID <br />LIMIT <br />PLASTICITY <br />INDEX <br />PASSING <br />#200 <br />SIEVE <br />PERME <br />- <br />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