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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 ',taste and Non-Coal Processing Waste - Rules <br /> 2.U5.3(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 ana 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 since 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 pil- <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 /> facial slope and a maximum height of 300 feet. This proposed ultimate <br /> configuration will accommodate approximately 10 million cubic yarns of <br /> coal refuse waste. <br /> In preparing the stability analysis, MMorrison Knudsen, Inc. employed <br /> material strengtn test results obtained by testing performed by A hailer <br /> and associates, Inc. These analyses were performed on specific samples <br /> of waste and foundational materials obtained at the site througn test <br /> augering and pit sampling. The material strength testing was performed <br /> in accordance .aitn acceptaole testing methods. The analysis assumea that <br />