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there is a possibility that water tributary to Hubbard <br />Creek will continue to be depleted until the mine workings <br />and all dewatering faults, fractures and rock strata below <br />the creek level are filled or recharged. The amount of <br />water involved in the filling of the workings and affected <br />strata will be small, given the limited area of mining <br />below the level of the creek. <br />Subsidence fractures which extend to the surface may impact <br />overland surface flow and stream flows in the small <br />ephemeral drainage above the mine workings. This impact to <br />surface water is expected to be negligible due to the small <br />total area of the mine, the steep slopes (60 percent slope, <br />or 30 degrees) and the steep stream gradients encountered <br />in the permit area. The steepness of the slopes and <br />streambeds would favor runoff over infiltration even with <br />subsidence fractures intercepting the surface. <br />Blue Ribbon Coal Company has conducted a spring survey of <br />the permit area. One spring was located within the permit <br />area. This spring is located below the mine bench and <br />discharges from rock strata which are stratigraphically <br />below the E seam. The Blue Ribbon mining operation should <br />have no effect on the quantity and quality of flow in this <br />spring. <br />Impacts from Coal Mine Waste Disposal on Surface Water <br />The primary concern with regard to the underground <br />coal mine waste is the impact on Hubbard Creek from <br />water that seeps through the pile. <br />The waste pile encompasses an area of about five <br />acres. For the purposes of determining the worst case <br />for impacts on Hubbard Creek, it was assumed that the <br />average rainfall of 16.94 inches would all percolate <br />through the pile. Therefore, seven acre-feet of <br />water, with a conductivity of 5,300 umhos/cm would <br />reach Hubbard Creek and the downstream receiving <br />waters; the North Fork of the Gunnison River. Actual <br />data from the Blue Ribbon site regarding conductivity <br />and TDS is limited. However, based on the available <br />data, the worst-case conductivity and TDS were <br />determined to be 5,300 umhos/cm and 5,300 mg/l, <br />respectively. The seven acre-feet of water would <br />percolate through the pile and would contribute <br />51 tons of salt to Hubbard Creek during the year. The <br />Colorado Department of Health considers mine <br />discharges of less than 350 tons per year (one ton per <br />day) to be no salt discharge. Therefore, the worst <br />estimate of 51 tons per year is considered to be an <br />insignificant contribution. <br />_28_ <br />