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2.05.3(4) Ponds, Impoundments, and Diversions <br />To control runoff and protect surface water quality, the Operator constructed several <br />collection ditches and a sedimentation pond. The information presented in Exhibit 11 <br />shows the location of the sediment pond and the ditches. The design and specifications <br />are also presented in Exhibit 11, Drainage and Sediment Control Plan. <br />A theoretical detention time of 24 hours was used in the design of the sedimentation pond <br />so that all runoff occurring as a result of the 10 -year, 24 -hour precipitation event will be <br />treated to produce a total of suspended solids (TSS) concentration less than or equal to 35 <br />milligrams per liter. The pond is designed to provide storage for the inflow entering the <br />pond as a result of a 10 -year, 24 -hour precipitation event. <br />The initial phase in the construction of the sedimentation pond was to clear all unstable <br />material from the location of the pond. In no instances was coal processing waste used in <br />the embankment. Embankment material was selected to exclude the presence of sod, <br />large roots, or frozen material. The placing and spreading of the fill material was started at <br />the lowest point of the embankment foundation. <br />The pond will be examined quarterly for structural weakness, erosion, and other hazardous <br />conditions. Maintenance procedures may include mowing or cutting excessive vegetative <br />growth to facilitate inspections and repairs, keeping ditches, culverts, and spillways free of <br />debris, and removing all combustible material other than mulch and other material required <br />for erosion control and surface stability. The accumulated sediment found in the pond will <br />be removed periodically then transported and placed in an approved gob disposal area at a <br />regional mine. The Operator will obtain approval from the Division prior to hauling gob to a <br />regional mine. <br />Sedimentation pond and diversion ditch removal are discussed in Section 2.05.4. <br />The location of the sedimentation pond and diversion structures are shown on the <br />Sedimentation Control Plan, Exhibit 11 -1. This exhibit also shows the location of the <br />watershed boundaries from which, along with other sources, the design criteria was <br />established. Generally, the pond and spillways were sized and constructed according to <br />such hydrological factors as required sediment storage volume and the volume and rate of <br />flow generated by the design storm event. The pond, spillways, and construction methods <br />were designed according to such engineering factors as structural integrity, slope and <br />surface stability. The pond was designed to have adequate height, size and shape to <br />2.05-22 Revised 11/15/2011 <br />TA a 11 <br />12� 30%( l <br />