Laserfiche WebLink
fine sand to boulders. The median diameter is approximately 2 inches based on a <br />general visual evaluation" (Denison EPP page 1 -5). <br />Furthermore, <br />"In addition inclusion of cobbles and boulders in laboratory analyses of samples <br />from West Sunday and Topaz mines may affect the predicted percolation rates. <br />However available laboratory instruments do not facilitate inclusion of these <br />larger particle sizes" (Denison EPP attachment 6- Estimate of Percolation Using <br />Unsaturated Flow Modeling page 6). <br />The concern is that Denison is relying on meteoric water mobility procedure (MWMP), <br />which can not factor into the equation larger rock sizes, rather than the more rigorous <br />fortan analysis program (UNSAT -H). According to Pacific Northwest National <br />Laboratory's website (that is operated for the U.S. Department of Energy), the UNSAT -H <br />program has been effectively used with grains of different sizes. Because the EPP <br />specifically names the UNSAT -H program and the MWNP is unable to accommodate <br />cobbles (the median particle size) Denison should release the computer program data. <br />These data should be compared to MWMP and all constituents (e.g. arsenic, chloride, <br />molybdenum, nitrate, nitrite, pH, selenium, sulfate, uranium, vanadium) should be <br />evaluated using the maximum numbers. Using the upper -limit data points will better <br />illuminate the potential for leachate and possible environmental degradation. Absent <br />such data, the Division cannot effectively discharge its duty to ensure that Denison <br />minimizes all impacts to water quality.. <br />Third, there are several cases where waste rock areas will be used to capture storm water <br />run -off. For example, at the Topaz mine, "Storm water runoff from Basin 3 will be <br />captured and detained by a proposed earthen berm along the crest of the waste rock area <br />WRA" (Denison EPP attachment P page 2 -2); at the West Sunday Mine, "Storm water <br />runoff from Basin 3 will be captured and detained by an existing earthen berm along the <br />crest of the WRA" (Denison EPP attachment P page 3 -2); at the St. Jude Mine, "Storm <br />water runoff from Basin 3 will be captured and detained by an existing earthen berm <br />along the crest of the WRA" (Denison EPP attachment P page 4 -2); at the Carnation <br />Mine, "All storm water runoff from Basin 2 will be captured and detained by an existing <br />earthen berm along the crest of the WRA" (Denison EPP attachment P page 5 -2); at the <br />Sunday Mine, "All storm water runoff from Basins 2, 3, 4 and 5 will be captured and <br />detained by a berm along the crest of the WRA" (Denison EPP attachment P page 6 -2). <br />Denison bases the leachate discussion and metrics on rainfall; however, given the fact <br />that several mines will be collecting storm water runoff on waste rock areas, there must <br />either be a discussion of how this storm water runoff collection will affect leachate or of <br />the best management practices that will prevent storm water from percolating into the <br />waste rock piles. <br />Furthermore, as several of the waste rock area berms flow into the Big Gypsum Creek <br />(which flows into the Dolores River), this requires extra care and monitoring to ensure <br />that all sediment containing arsenic, chloride, molybdenum, nitrate, nitrite, selenium, <br />sulfate, uranium, and vanadium settle in the retention areas and not in Big Gypsum <br />• 3 <br />