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Certification of Sediment Pond 011 <br />Introduction <br />In accordance with Rule 4.05.9(14), impoundments shall be inspected.by a qualified registered <br />professional engineer or other qualified professional specialist under the direction of a professional <br />engineer. This certification is for the construction of the new sediment pond 011 within the New <br />Horizon Mine permit boundary. <br />Embankment and Excavation <br />The embankment for Pond 011 was constructed of a homogeneous earth fill that was found on the <br />construction site. The top width of the embankment is approximately 12 feet in width with the <br />embankment fill out slopes at a nominal 3h:1v.and interior pond slopes at a nominal 3h:1v. There <br />was a five foot wide by three foot deep key way excavated from beneath the embankment to <br />prevent a water seepage path. Suitable fill material was backfilled and compacted according to the <br />plan into the key way as well as in suitable lifts for the remaining of the embankment. The Primary <br />Spillway consist of a 24inch diameter Corrugated Metal Pipe (CMP) Riser connecting to an equal <br />sized 24inch diameter CMP Barrel. The length of the Barrel is approximate 100 feet. The Riser <br />has a combination anti-Vortex and Trash Rack structure located on the entrance. Two Oft x Oft anti <br />seep collars were installed along the Barrel portion of the Primary Pipe to prevent seepage along <br />the pipe. Twp six inch adjustable gate valves were installed in the elbow of the Riser to act like <br />weep holes. The weep holes allow pond water to decant off slowly and to make the elevation of <br />the permanent pool the same as the weep holes. Three-18inch x 40foot long CMP pipes with flared <br />ends toward the pond side were installed to work as the Emergency Spillway structure. There is <br />approximately 1.5ft of compacted cover between the top of the Emergency Spillway Pipes and the <br />top of embankment. <br />Sediment Pond 011 was designed to be both a passive flow thru and a manual operated pond as <br />special circumstances such as pit pumpage or runoff from irrigation varies throughout the year. <br />Generally the permanent pool elevation will be at the lowest 0-6"diameter gate valve opening, <br />which will be initially set at 5612.00 elevation. One valve will be partially opened while the second <br />valve will normally be closed. The valve that is operational will be adjusted so that the pond will be <br />decanted or dewatered to the elevation of the lowest opening (the operational valve) in a 24hr time <br />frame. With this arrangement, the pond water retention time can controlled and monitored so the <br />Attachment 2.05.3(3)-20-3 <br />