2018-06-08_PERMIT FILE - C1981010A (3)

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3.1.4.2 Hi hwall Mining Highwall mining has occurred on a limited basis to the east of East Ashmore pit. In 2007, the H seam on the floor of cut 45 was highwall mined in this pit. In the future, highwall mining may be conducted in the end walls or highwalls of L Pit and N Pit if further geologic and geotechnical studies demonstrate feasibility, and the timing of stripping operations allows access. In the L dip pit wall the K and/or the M and/or the Q seam could be mined, along with the H seam in the area of N Pit previously known as East Ashmore Pit. In the N dip pit wall the L, M and Q seams may be mined. No highwall mining activities are planned for 2018. Use of Mining Technologies' HW H800 Addcar System or a similar system is planned. A launch vehicle platform, which sits on the floor of a conventionally mined cut, controls all functions of the system, rigid conveyor cars, which are each fitted with their own belt conveyor, are fed by a full sized conventional, remote controlled underground continuous miner. Video cameras placed on the miner give real time feedback to the outside operator, a proprietary HORTA Guidance System gives continuous three dimensional locations, and Gamma Sensors in the miner's cutting head provide the ability to sense roof and floor rock and help keep the miner in the coal seam and avoid dilution from the roof and floor. Depth of penetration and coal recovery will vary depending on coal seam splitting, thinning or pinching, coal quality, roof and floor integrity, and machine physical limitations. Penetration depths of up to 1,600 feet are possible under optimal conditions; however with Trappers thin and steeply dipping coal seams much shorter penetrations are anticipated. Trapper is not currently aware of any abandoned or active underground mine workings in any of the pertinent coal seams in the proposed highwall mining areas. In the event abandoned or active underground mining operations are identified, no highwall mining will be conducted within 500 feet of previous workings in the applicable seams. Trapper is also not aware of any dwellings, buildings, tanks, impoundments or utilities overlying areas planned for highwall mining. ` Access to highwall miner entries will be blocked or buried within 30 days following coal extraction. Any highwall mining entry discharging water containing toxic -forming or acid-forming material will be plugged within 72 hours after completion by backfilling and compacting non-combustible and impervious material into the hole to a depth sufficient to form a water -tight seal or the discharge will be treated within 72 hours after completion to meet applicable effluent limitations and water quality standards. Revision: "r7 3-15b Approved: