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Certification of Sediment Pond 013 <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 013 within the New <br />Horizon Mine permit boundary. <br />Embankment and Excavation <br />The embankment for Pond 013 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:1 v and interior pond slopes at a nominal 3h:1 v. 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. Two 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 20foot long CMP pipes with <br />flared ends toward the pond side were installed to work as the Emergency Spillway structure. <br />There is approximately 1.5ft of compacted cover between the top of the Emergency Spillway Pipes <br />and the top of embankment. <br />Design <br />Sediment Pond 013 was designed to have the permanent pool elevation at the weep hole elevation. <br />When the 10yr-24hr storm event enters the pond, the water is allowed to rise and if necessary, go <br />through the Primary Structure but not through the Emergency Spillway. After the storm has <br />passed, the pond retains the water for several days while the weep holes slowly dewater the pond. <br />In the case of the 25yr-24hr event ,the inflow of storm water is allowed to enter the pond, some <br />Attachment 2.05.3(3)-21-4 <br />