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siphoned into them. Furthermore, the permittee predicted that sediment <br /> accumulating in the cracks, and clays in the overburden would ultimately seal <br /> them off from surface inflow. <br /> Continued monitoring of Red Wash has confirmed the permittee's predictions. <br /> As projected, subsidence in Red Wash initially resulted in water ponding in the <br /> stream bottom. The high content of silt and clay carried by Red Wash rapidly <br /> fills the ponds. The silt and clay layers have sealed any cracks that formed in <br /> the alluvium as the result of subsidence. Water continues to flow in the surface <br /> channel at Red Wash while piezometric levels in the basal alluvial gravel have <br /> dropped, indicating that the basal alluvium is not recharged by surface flow <br /> infiltration. <br /> Minimal subsidence impacts are expected on Scullion Gulch, similar to those <br /> observed on Red Wash. Thickness of overburden is much less under Scullion <br /> Gulch than Red Wash. The Staley-Gordon Mine, abandoned in 1970, has only <br /> 200 to 300 feet for overburden thickness, comparable to that under Scullion <br /> Gulch in the Deserado Mine. No surface expressions of subsidence have been <br /> noted over caved areas in the Staley-Gordon Mine. Examination by Western <br /> Fuels-Utah, Inc., showed that the one known roof fall in this mine caused a <br /> collapse that extended only 16 feet above the roof line where it was halted by a <br /> massive, competent sandstone. <br /> Tension cracks probably did occur above the Staley-Gordon Mine, but have <br /> been healed by weathering. Similar tension cracks could cause several stock <br /> ponds in the Scullion Gulch basin (within Federal Coal Leases C-8424 and <br /> C-8425) to lose some impounded water. Potentially impacted stock ponds are <br /> Lincoln Reservoir, Halandras Reservoir, and Raven Park Reservoir. Lincoln <br /> Reservoir is located over a room and pillar panel and pillar dimensions and <br /> extraction ration consistent with that in the main entries will be employed <br /> directly under the reservoir to prevent subsidence. Tension cracks <br /> characteristic of longwall mining are expected to occur at Halandras Reservoir <br /> and Raven Park Reservoir. The ponds are normally dry, but if water is <br /> present, loss of water could occur as a result of damage to the dams or pond <br /> bottom that would allow seepage loss. Prior to advancement of mining that <br /> could potentially impact the ponds, monitoring will be initiated, and the ponds <br /> will be repaired or replaced by the operator if water retention capability of the <br /> ponds is diminished due to subsidence. The operator will haul in water for <br /> stock if necessary as a temporary measure during pond repair or construction. <br /> Similar monitoring has been conducted on Red Wash and will be conducted on <br /> Scullion Gulch prior to longwall panel advancement beneath the drainage, to <br /> allow for detection of subsidence features which may require repair. <br /> See the Subsidence Section of this document for further details on impacts <br /> related to subsidence. <br /> 25 <br />