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Impoundment Certification -Meadows No. 1 Mine <br />Sun Coal Company <br />5440 Ward Road Suite 110 <br />Arvada, Colorado <br />80002 <br />Background <br />Sun Coal Company operator of Meadows No. 1 Mine applied for <br />and received authorization from the Colorado Mined Land <br />Reclamation Board to construct two sedimentation ponds in the <br />mined disturbed area. The mine is located in Routt County, <br />approximately 10 miles southeast of the town of Hayden, Colorado. <br />The two impoundments have been designed in series to control the <br />runoff from the SO year 24 hour storm from the mine disturbed <br />area. The impoundments were designed, constructed and maintained <br />to provide storage for the 10 year 24 hour storm event plus an <br />adequate storage capacity for sediment. The structures were <br />designed and constructed with one foot freeboard and an <br />automatic dewatering devises ensuring the base of the dewatering <br />devise did not extend into the sediment storage area. In <br />addition the impoundment is designed with a principal and <br />emergency spillway to convey the peak runoff from the 100 year 24 <br />hour storm event. The principal and emergency spillways are <br />protected to convey the designed storm without causing erosion to <br />the outlet structure. Each structure was designed and inspected <br />during construction under the supervision of, and certified after <br />construction by, a qualified registered professional engineer. <br />Impoundment certification is appended to this report. <br />Impoundment structures were constructed in accordance with <br />standard engineering practices ensuring the following methods <br />were followed: <br />1. the embankement foundation area was cleared of all <br />organic matter, all surfaces sloped to no steeper than lv:lh and <br />the entire foundation surface scarified. <br />2. the fill material was free of sod, large roots, and <br />other large vegetation matter. <br />3. fill material was placed in 6 inch lifts in <br />horizontal layers to facilitate compaction from the lowest point <br />of the foundation to the designed height. <br />4. the embankment is one foot above the water surface <br />in the pond with the emergency spillway flowing at design depth <br />5. the combined upstream and downstream side slopes of <br />the settled embankment are not less that lv:5h with neither slope <br />steeper than lv:2h. <br />6. the impoundment structures have been topsoiled and <br />revegetated immediately after construction and the principal <br />spillway riprapped. <br />7. the minimum top width is 15 which is consistent <br />with the guideline where the top width is not less than the <br />quotient of (H + 35)/5 where H, in feet, is the height of the <br />embankment as measured from the upstream toe the embankment. <br />8. sedimentation ponds will not be removed until the <br />reclaimed area is revegetated in accordance with the approve <br />(AMRADRD 12/5/86) <br />