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<br />45 <br /> <br />in the North Fork alluvium and would be attenuated where the alluvium <br />significantly widens upgradient from Somerset. North Fork alluvial <br />ground water is monitored upgradient from Somerset at the Bear No. 3 <br />Mine. <br /> <br />Low permeability of bedrock units in and near the West Elk Mine <br />(Rollins Sandstone, B through F seams, and the Barren Member) will <br />prevent any significant seepage of gob leachate into these units. <br /> <br />MCC has submitted two plans for sealing the portals upon closure of the <br />mine. One plan calls for perpetual gravity discharge of mine water to the <br />surface through a four-inch PVC pipe that will be installed in a block <br />wall at the portal. An alternate plan (to be constructed if water is toxic) <br />is to construct water-tight seals within the mine that will withstand the <br />expected hydraulic pressures. Samples taken in the adjacent Oliver Mine <br />indicate mine waters will not be toxic. <br /> <br />Subsidence fractures that develop over mine workings have the potential <br />to dewater natural springs and wetlands in the West Elk permit area. The <br />permit application explains that the risk of such depletion is significantly <br />reduced by the overburden thickness of greater than 280 ft. and the <br />resistance to fracturing of interbedded fine-grained units that would <br />deform ductiley (bending), rather than brittley (fracturing). Monitoring <br />of springs since before the mine was developed has not detected impacts <br />from mining. This monitoring will continue. <br /> <br />The operator predicts overall ground water/surface water balance will not <br />be significantly affected if mine inflows are much greater than predicted <br />because mine inflows will ultimately be discharged back to the North <br />Fork of the Gunnison. <br /> <br />i. Refuse Material Disposal Impacts on Groundwater - <br /> <br />Lower Refuse Disposal Area – Coal mine waste will be disposed <br />in the Lower Refuse Disposal and Refuse Pile Expansion sites. <br />The lower refuse pile is permitted for permanent disposal of 1.09 <br />million cubic yards of mine development waste and sediment <br />pond cleanout material. The refuse pile expansion is designed to <br />hold 1.38 million tons of material over a life of 9.4 years. The <br />Refuse Pile Expansion is discussed in Permit volume 10B. An <br />Upper Refuse Disposal Area has also been approved for <br />construction, and has not been built. MCC has verbally indicated <br />this pile will not be needed. Stipulation #7 requires MCC to <br />complete a geotechnical investigation prior to constructing Upper <br />Refuse Pile. <br /> <br />To date, refuse piles have not impacted the groundwater zone <br />near Sylvester Gulch. Because of the low permeability of the