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Exhibit 19(22) <br />WEST DWDA (DWDA #3) <br />A new development waste disposal area (DWDA) will be created directly west of the west ventilation fan, and <br />south of the old west portal warehouse. The west DWDA will be a maximum of 90 feet high, with a capacity of <br />approximately 155,000 CY. <br />Runoff from the DWDA will be routed to expanded Containment area No.2. Expanded containment area No. 2 <br />has been redesigned to contain the 25 -year storm event. <br />A new soil stockpile area has been designed north of the DWDA in order to stockpile material for reclamation of <br />the west DWDA. The new stockpile will be approximately 50 feet high with a capacity of approximately 30,000 <br />CY. Runoff from the new stockpile will be routed to containment area no. 2. <br />A topsoil stockpile has been situated east of the ventilation fan haul road. A berm will be placed at the toe of <br />the stockpile. <br />Notes - West DWDA: <br />1. Runoff from approximately 13.14 acres will be routed to containment area no. 2. <br />2. The 25 year event is 3.4 inches and has been used to size containment area no. 2. Containment no. 2 <br />has been designed to contain the 25 -year event, per Rule 4.05.9(2)(e). Water collected in the pond <br />will be hauled back to Pond 7 for discharge. <br />3. The 100 -year event is 4.2 inches and has been used to design the majority of the ditches near the <br />DWDA. Ditches 27 and 46 (5 %) have been designed for the 10 -year event (3.0 inches). <br />4. Undisturbed upland drainage west of the pile is diverted around the pile in ditch D49. Peak flows for <br />D49 were calculated using the 100 -year event and portions of the ditch were sized using Manning's <br />Equation in Excel because SedCad cannot handle such a large peak flow. Two sections of D49, the <br />30% and 64% sections will be 12" grouted riprap. <br />5. Upland drainage east of the pile is routed to containment area no. 2. <br />6. Pond (Containment area no. 2) sizing calculations are attached. <br />7. Pond plan view and sections are attached. <br />Notes - Soil Stockpile area: <br />8. Runoff from approximately 1.3 acres associated with the new soil stockpile and will be routed to <br />containment area no. 2. <br />9. Ditches have been designed using the 10 -year event. <br />Two temporary culverts have been designed to go in D41 for construction access to DWDA #3. Sizing was <br />based on the 10 -year event for D41. <br />Curve numbers are summarized on page EXH 19(22) -2. <br />ENGINEER'S CE RXD0 <br />O ••.0000...,. , <br />The calculations and i rmre �� ges EXH. 19(22) -1 through 19(22) -58 with a dates of 04/17/12 <br />and 06/15/12 were pi ar* y me duri e nths of April and June, and the information presented is true and <br />correct to the best o V & d ' 91ief. <br />-is -1Z <br />Tam Nit VISMAIAWo Date <br />State of Colorado No. 43402 <br />TR -65 Page EXH. 19(22) -1 06/1512012 <br />