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-53- <br /> The Coal Basin mine surface facilities consist of a preparation plant, <br /> explosive storage, methane gas pipeline, sewage treatment facility, water <br /> system, power transmission facilities, and numerous support facilities. <br /> Their locations are shown on Exhibits II-8-2-a through d in Volume 1 . A <br /> list and descriptions of all surface buildings and structures is located <br /> in appendix II-8-6 of Volume 2. <br /> Coal handling procedures are as follows: Raw coal is hauled from the <br /> respective mines to a storage area or to raw coal bins. Raw coal is then <br /> conveyed to the wash plant which separates clean coal from refuse <br /> material using three separate circuits. Depending on the size of the <br /> material , the raw coal either goes through a heavy media bath, deister <br /> tables, or flotation cells. After the refuse is removed, the coal is <br /> dewatered using either a thermal dryer, vacuum filters, or dewatering <br /> screens, depending on coal size. The coal is then stored in bins until <br /> it is transported to the loadout facility. <br /> The proposed operation is in compliance with the requirements of this <br /> section. <br /> XVIII. Coal Processing ',Waste and Non-Coal Processing Waste - Rules <br /> 2.05.3(8) , 2.05.4(2) (f) , 4. 10 and 4. 11 <br /> Coal refuse from the coal preparation wash plant at the Coal Basin Mines <br /> is currently deposited by conveyor and front-end loader in an approved <br /> area to the east of the wash plant. Coal refuse has been deposited at <br /> this site continuously sine 1961 . As of the spring of 1981 , the company <br /> estimated that approximately 1 .5 million cubic yards of coal refuse had <br /> been deposited within this pile, attaining a maximum height of 125 feet <br /> with a facial angle of 380. <br /> Mid-Continent Resources, Inc. had a geotechnical investigation and <br /> stability analysis prepared for the existing and projected waste pila <br /> configurations. Morrison Knudsen, Inc. , and 'Whaller and Associates, <br /> Inc. , participated in the performance of these analyses. The stability <br /> analysis, completed in accordance with the prudent state-of-the-art of <br /> embankment stability analysis, determined that the existing pile <br /> configuration achieved a static slope safety factor of 1 .5. Further, the <br /> analysis projects that a static slope safety factor in excess of 1 .56 <br /> will be achieved for the proposed ultimate pile configuration of a 270 <br /> 'acial slope and a maximum height of NO feet. This proposed ultimate <br /> configuration will accommodate approximately 10 million cubic yards of <br /> coal refuse waste. <br /> In preparing the stability analysis, ",Iorrison Knudsen, Inc. emoloyed <br /> material strengzn test results obtained by testing performed by ,Jhalier <br /> and associates, Inc. These analyses were performeo on specific samples <br /> of 'waste and foundational materials obtained at the site througn test <br /> auyering and pit sampling. The material strength testing was performed <br /> in accordance 4i7ln acceptable testing methods. The analysis assumed that <br />