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XVIII. Coal Processino Waste and Non-Coal Proce:~sina Waste <br />Empire Energy Corporation proposes the disposal of coal <br />processing waste material in a waste structure located within <br />the boundary of the Eagle Mine Complex permit area. This coal <br />processing waste pile, which is eventually projected to achieve <br />a maximum volume of 1,000,000 cubic yards in approximately 20 <br />years, is located on a foundational slope of less; than 6:1 <br />(Horizontal to vertical). The pile has been designed with <br />maximum outslopes of 4:1 (horizontal to vertical) and a maximum <br />height of 55 feet. The stability analysis, performed by CTL / <br />Thompson, Inc., ascertained a minimum static slope safety factor <br />of 3.6 assuming an angle of internal friction of 42° and a <br />cohesion of zero. Actual laboratory testing of the shear strength <br />of waste material determined an angle of interal friction of 42° <br />and a cohesion of 1,500 pounds per square foot. The safety factor <br />determination is therefore conservative in nature. and well <br />exceeds the required 1.5 minimum acceptable value. <br />The foundation area of the coal processing waste pile will <br />be prepared by removal of topsoil and unacceptable subsoils and <br />the installation of a toe drain. The installation of the peripheral <br />toe subdrain is intended to preclude invasion of ground water <br />from beneath the pile. Waste material will be placed in lifts <br />of less than 24 inches and compacted to achieve 90 percent of <br />maximum dry density as determined by AASHTO specification T-99. <br />The operator has requested a variance from the four foot thick <br />non-toxic cover requirements of Rule 4.10.4(4), based upon a <br />commitment to submit' semi-annual chemical analyses to verify <br />