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_ density according to AASHTO Specification T99-74 or ASTM Test Designation D-698 in <br />maximum 24inch lifts. Attached in Appendix A are results of a Standard Proctor compaction <br />test (ASTM 0-698) performed on a sample of coal mine waste obtained from the Sanborn <br />Creek Mine. Since coal mine waste may be variable in material properties, it is suggested that <br />coal mine waste placed in the waste bank be checked for assurance of proper placement in <br />regular intervals. <br />A dual purpose Somerset Cemetery road and waste bank haul road beginning in the existing <br />employee parking lot, at about EI. 8,090 ft will climb at a 10 percent grade to the west as <br />shown on Drawing 95255-01 to EI. 6,190 ft. Until the coal mine waste bank reaches EI. <br />6,190 ft., waste will be transported to this elevation of the haul road, then dumped onto the <br />top surface of the existing waste bank below where it will be spread and compacted in proper <br />lifts to a 2 horizontal to vertical (2H:1 V) outer slope. At EI. 6,100 ft, a 10-foot bench will be <br />constructed for erosion control and stability. When the waste bank is constructed to the EI. <br />6,150 ft level, a 30-foot wide bench will traverse the waste. Coal mine waste will continue <br />to be end dumped from the haul road, then spread and compacted until the waste is brought <br />to EI. 6,190 ft. Another 30-foot bench will be constructed at EI. 6,200. Then, coal mine <br />• waste will be placed up to the final crest elevation of 8,240 ft by constructing a portion of the <br />haul road on the coal mine waste bank. When the final crest elevation is reached, the crest <br />will be reclaimed and the final coal mine waste placed will fill in the haul road on the waste <br />bank. <br />4.1.2 Underdrain System <br />An underdrain system is a requirement according to Rule 4.10.311). Although there are no <br />recorded springs within the draw, and diversions ditches will be constructed upland that will <br />prevent the flow of runoff water within the draw, an underdrain system has been developed <br />to ensure the full drainage of the coal mine waste bank. A detail of the underdrain is shown <br />in Drawings 95255-03. Borrow material suitable for use in the underdrain must be sand and <br />gravel with cobbles and boulders and less than 5 percent fines. Calculations indicate that the <br />minimum permeability requirements for the material must be 1 centimeter per second (cm/sec) <br />or greater. Because of the large grained material used for underdrain construction, a <br />geosynthetic filter must be placed between and coal mine waste. A 12 to 14 once per square <br />yard non-woven geofabric filter will be placed between the coal waste and the underdrain. <br />• <br />95266/1424.RPT Coel Mine Waste Bank Design for the Sanborn Creek Mina <br />October 1998 WESTEC, Inc. ~ <br />