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should not occur because there is approximately 600 to 1200 feet of overburden <br />above the coal seam in that area. Furthermore, the swelling of shales and <br />overburden from the caved roof should effectively fill the open mine cavity. An <br />ongoing monitoring program was implemented to detect subsidence on the first <br />longwall panel and first room - and - pillar section to be mined during the initial <br />years of production. Predictions of probable disruption of the hydrologic regime <br />from subsidence were based on an analysis of those data. The permittee <br />originally predicted that tension cracks from subsidence may develop in <br />formations directly underlying Red Wash and that these cracks may extend <br />upward for several tens of feet. These cracks were predicted to be of limited <br />extent; therefore, a minimal amount of surface water was predicted to be <br />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 the <br />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. The overburden is much less under Scullion Gulch than <br />Red Wash. Tension cracks could cause several stock ponds in Scullion Gulch <br />basin to lose impounded water. Although the stock ponds are normally dry, a loss <br />of water could occur where water is present as a result of damage to the dams or <br />pond bottom that would allow seepage loss. Prior to the advancement of mining <br />that could potentially impact the ponds, monitoring is required to be initiated, and <br />the ponds repaired or replaced by the operator if water retention capability of the <br />ponds is diminished due to subsidence. The operator will haul water for stock in <br />the event of pond repair or construction. <br />2. Groundwater Impacts <br />The impact of the proposed mine on ground water will be very localized, with no <br />significant impact expected on a regional basis. This is due primarily to the <br />small quantity of ground water in the area. <br />Water encountered within the mine will be utilized underground for dust <br />suppression. As a result, only those inflows that temporarily exceed storage <br />capacities and mine use requirements would potentially be discharged to the <br />surface and lost from the ground water system. Pumping from approved mine <br />water discharge locations ceased upon sealing of the "D" seam northern longwall <br />30 <br />