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• <br />1�1 <br />Detailed Design <br />Design Parameters: <br />Type Coal Mine Waste Disposal Area <br />Original is Gob Pile No. 2 <br />West Expansion is also known as Gob Pile No. 4 <br />Capacity Original - 2,000,000 cubic yards <br />West Expansion - 450,000 cubic yards <br />Slopes Original - No steeper than 3h:1 v slopes with 15' wide terraces on <br />50' intervals with the first 50 foot sloped no steeper than 2.5hA v. <br />West Expansion - No steeper than 3h:1v slopes with 15' wide <br />terraces on 50' intervals with the first 50 foot sloped no steeper <br />than 2.5h:1 v. All on a borrow (cut) slopes no steeper than 2H:1 V. <br />Terraces Slope 5% back towards the pile and 2 to 5% towards collection <br />ditches <br />Compaction 90 percent of the maximum dry density to prevent spontaneous <br />combustion and to provide the strength required for stability of the <br />refuse pile. Dry densities will be determined in accordance with <br />AASHTO T99 -74. <br />Haul Road 10 percent maximum overall grade <br />Diversion Ditches Flows from the 100 -year, 24 -hour storm event. Upper diversion <br />ditches are designed to flow into the east and west collection <br />ditches and then into the sediment pond. <br />Subdrainage <br />System <br />TR -64 <br />`Pr 6 ED <br />V 2-'S /a 7 <br />Original - Lateral drains as per the Stability Analysis section of this <br />report and an alternate rock under -drain system as per Rule <br />4.10.3(5). See page 5 Water Control Measures. <br />West Expansion — No subdrainage system. <br />-3- <br />08/09 <br />