Laserfiche WebLink
Section 4 <br />Potential for Rock to be Toxic-Forming <br />flux of water stored within the development rock areas are dominant mechanisms controlling • <br />the volume of percolation through the development rock areas. Minor differences in the <br />physical characteristics and the magnitude of annual precipitation are less important controls <br />on the expected volume of percolation. - The results of these estimates correspond to the input parameters including the development <br />rock physical and hydrologic parameters, and the available climate data. Site-specific climate <br />data are not available for the West Sunday and Topaz mines, and differences between actual <br />climate conditions at the site and the data compiled from the Uravan and Montrose weather <br />stations could result in variations in percolation through the piles. There are other site-specific <br />variations that are not directly accounted for in the model. For example, a rind of highly <br />compacted tight soil/rock was encountered at the surface of the rock piles (see photographs in <br />Attachment 2). This rind likely reduces infiltration by allowing for increase runoff and <br />increased surface evaporation via ponding versus infiltration. This site-specific condition <br />(which could further reduce modeled percolation rates) was not accounted for in the model. <br />4.2.3 Attenuation Capacity of Soils Underlying Rock Piles <br />The attenuation capacity of soils underlying the rock piles was evaluated as a component of this <br />assessment in order to investigate the capacity of these soils to naturally attenuate constituents <br />that could potentially leach from the rock piles. However, the unsaturated flow modeling and <br />water balance estimates of percolation indicate that the rock piles are not likely to produce <br />significant quantities of leachate. Therefore, attenuation data is not discussed in detail in this <br />document. Results of the attenuation testing are presented in Attachment 3 of this report. • <br />• <br />cm 4-14 <br />7164986-Denison Mines\Task Order 3 - DMO Sampling and Analysis PIeMT88k 3.12 - Soil, Ore, Rock Data Assessment Reporl\Sunday Rock Report\8nal reportRepor9Final Sunday Mnes Group Soil Ore Rock <br />Data Assessment Report_061609.doc