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refuse stockpiles, other water quality monitoring stations on <br />Sylvester Gulch, and sites above and below the mine on [he <br />North Fork of the Gunnison, provide water quality information <br />to allow evaluation the changes in water quality that could result <br />from the impacts of this refuse stockpile. An additional <br />groundwater monitoring well is scheduled for installation in the <br />alluvial deposits downgradient of the RPE area. Conductivity <br />and TDS from samples of monitoring well GP-1 showed slightly <br />higher levels in 1986. However, this does not appear to be a <br />continuing problem. Concentrations of iron during 1991 were <br />higher than the baseline monitoring data, which the operator <br />believes may be associated with B development waste. <br />Concentrations of iron will be monitored to see if the elevated <br />levels continue. <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 <br />of B Seam refuse on leachate were also evaluated and can be <br />found in Exhibit 56. The permeability contrast found in [he pile <br />will cause most of the leachate water to perch within the refuse <br />pile and above [he native soils. A shallow water mound will <br />build within the pile and cause the water to migrate laterally to a <br />small seepage area at the edge of the site. <br />Upper Refuse Disposal Area -The upper waste rock pile was <br />approved, with stipulations on June 14, 1986. This pile has not <br />been constructed and construction is not proposed for this permit <br />term. The final pile will cover approximately 40 acres and <br />contain five million tons of coal reject and developmental waste <br />rock. The primary predicted impact to groundwater is the <br />development of leachate from precipitation infiltration through <br />the pile. The approved plan calls for the installation of five <br />lateral subdrains to collect this leachate. The drains will help <br />prevent the formation of a large perched leachate aquifer that <br />may effect the stability of the pile. Additionally, the drains will <br />intercept most of the leachate and prevent it from entering the <br />shallow colluvial aquifers. The subdrains will daylight into <br />surface channels where the leachate will flow to a sediment <br />pond. As this pile is constructed, spoil wells will be installed. <br />There are a number of stipulations which must be addressed <br />prior to beginning the construction of the upper refuse pile. <br />39 <br />