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APPENDIX 2.05.3-8A <br />• IMPOUNDMENT CERTIFICATION - "AS-BUILT" <br />SUN COAL COMPANY - MEADOWS N0. 1 <br />ROUTT COUNTY, COLORADO <br />Sun Coal Company, operator of Meadows No. 1 mine, applied for and received <br />authorization from the Colorado Mined Land Reclamation Board to construct two <br />.sedimentation ponds in the mine-disturbed area. The mine is located in Routt <br />County, approximately 10 miles southeast of the town of Hayden, Colorado. The <br />two impoundments have been designed in series to control the runoff from the <br />10-year, 24-hour storm from the mine-disturbed area. The impoundments were <br />designed, constructed, and maintained to provide storage for the 10-year, <br />24-hour storm event plus an adequate storage capacity for sediment. The struc- <br />tures were designed and constructed with one foot freeboard and an automatic <br />dewatering devise ensuring the base of the dewatering devise did not extend into <br />• the sediment storage area. In addition, the impoundment is designed with a <br />principal and emergency spillway to convey the peak runoff from the 100-year, <br />24-hour storm event. The principal and emergency spillways are protected to <br />convey the designed storm without causing erosion to the outlet structure. Each <br />structure was designed and inspected during construction under the supervision <br />of, and certified after construction by, a qualified registered professional <br />engineer. Impoundment certification is appended to this report. Impoundment <br />structures were constructed in accordance with standard engineering practices <br />ensuring the following methods were followed: <br />1. The embankment foundation area was cleared of all organic matter, all <br />surfaces sloped to no steeper than lv:lh, and the entire foundation <br />surface scarified. <br />2. The fill material was free of sod, large roots, and other large vegeta- <br />• tion matter. <br />3. Fi11 material was placed in 6-inch lifts in horizontal layers to facil- <br />itate compaction from the lowest point of the foundation to the <br />designed height. <br />- 261 - (Rev. 5/86) <br />