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XIV. Protection of Underground Mining <br /> Highwall mining occurs concurrently with surface mining operation at the Trapper Mine in <br /> compliance with Rule 4.19. <br /> XV. Subsidence Control <br /> No specific approvals are granted to the applicant under this section. <br /> XVI. Concurrent Surface and Underground Mining <br /> No specific approvals are granted to the applicant under this section (Rule 4.22). <br /> XVII. Auger Mining -Rule 4.23 <br /> Auger of highwall mining is planned in the C, I, J, L and N pits. Subsidence is not anticipated with <br /> any highwall mining activities at the site. Trapper is not currently aware of any abandoned or active <br /> underground mine workings in any of the pertinent coal seams in the proposed highwall mining <br /> areas. In the event abandoned or active underground mining operations are identified,no highwall <br /> mining will be conducted within 500 feet of previous workings in the applicable seams. Trapper is <br /> also not aware of any dwellings,buildings,tanks, impoundments or utilities overlying areas planned <br /> for highwall mining. Design criteria established by Agapito Associates Inc. will be utilized to ensure <br /> long-term stability of highwalls and mining areas based on seam and overburden thickness. Access <br /> to highwall miner entries will be blocked or buried within 30 days following coal extraction. <br /> XVIII. Operations on Alluvial Valley Floors <br /> Operations on alluvial valley floors (AVFs)are discussed in Section 4.8.4 of Vol. IV of the permit <br /> application. <br /> 1. Yampa River 2. Williams Fork River <br /> 3. No Name Gulch 4. Johnson Gulch <br /> 5. Pyeatt Gulch 6. Flume Gulch <br /> The above alluvial valleys would meet the regulatory definition of an alluvial valley floor(AVF) if <br /> the valleys had water availability sufficient for flood-irrigated agricultural activities [Section <br /> 1.04(10)], or availability of water sufficient for sub-irrigated agricultural activities [Section <br /> 1.04(10)]. Flood irrigation is practiced on the valley floors of the Yampa River in the Big Bottom <br /> area and the Williams Fork River near its confluence with the Yampa. Based on the presence of <br /> unconsolidated stream-laid holding streams with water availability sufficient for flood-irrigated <br /> agricultural activities,the following two alluvial valleys have been determined to be alluvial valley <br /> floors: <br /> 1. the Yampa River in the Big Bottom area <br /> 2. the Williams Fork River near its confluence with the Yampa River. <br /> Map 35A and Map 52 indicate the locations of AVF well sites and the location of alluvial valley <br /> floors. The Coy well drilled into the alluvium of Flume drainage functions as a point of compliance <br /> well. Four wells are drilled into the Pyeatt alluvium,well J1 is located in the Johnson drainage <br /> alluvium and one of the three GLEV wells in the Deacon drainage reached the alluvium at the very <br /> northeast corner of the permit. This GLEV well is located downgradient of any mining to the east <br /> that may occur in the future. These wells constitute an environmental monitoring system during <br /> surface coal mining and reclamation operations continuing until release of all bonds in accordance <br /> with Rule 3 (4.24.4). <br /> 18 <br />