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The depth of overburden where the B or the E seams in the area of the <br />springs ranges from 400 to in excess of 1,000 feet. Based on experience <br />in the F Seam and geotechnica[ work, the springs will not be affected <br />significantly by mining in the B seam under these overburden depths. <br />The water balance will not be significantly affected even if the maximum <br />estimated inflows occur, since any mine inflows will ultimately be <br />discharged back to the North Fork of the Gunnison. <br />i. Refuse Material Disposal Impacts on Groundwater - <br />Lower Refuse Disposal Area -Refuse is generated through the <br />mining process and will be disposed of on the Lower Refuse <br />Disposal and Refuse Pile Expansion sites. The lower refuse pile <br />is permitted for permanent disposal of 1.09 million cubic yazds of <br />mine development waste, and sediment pond cleanout material. <br />The refuse pile expansion is designed to hold 1.38 million tons of <br />material over a life of 9.4 years. (The Refuse Pile Expansion is <br />discussed in Permit volume IOB.) <br />To date refuse piles have not impacted the groundwater zone near <br />Sylvester Gulch. Because of the low permeability of the colluvial <br />soils and the lack of a groundwater table near the surface in the <br />colluvium, no impacts on groundwater aze anticipated. Water <br />monitoring near the site of the soil stockpiles and waste piles, <br />other water quality monitoring stations on Sylvester Gulch, and <br />sites above and below the mine on the North Fork of the <br />Gunnison, provide data on impacts of this refuse stockpile. The <br />wells in the alluvium in the vicinity of the refuse piles have been <br />mostly dry for the last four years or yielded insufficient water to <br />provide an analysis. <br />A leachate study of the F Seam refuse was conducted and <br />included in the application for the permanent refuse disposal site <br />in Exhibit 51 of the permit application. In addition, the effects of <br />B Seam refuse on leachate were also evaluated and can be found <br />in Exhibit 56. The permeability contrast found in the pile will <br />cause most of the leachate water to perch within the refuse pile <br />and above the native soils. A shallow water mound will probably <br />build within the pile and cause the water to migrate laterally to a <br />small seepage azea at the edge of the site. There have been no <br />visible flows from the pile toe and midsection underdrain. <br />ii. Mitigation of Groundwater Impacts - <br />The applicant anticipates no degradation of groundwater quality <br />during mining. The applicant will treat any mine water effluent <br />55 <br />