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Section 13 <br />Geochemical Data and Analysis <br />Exhibit 13-3 summarizes the results of the modeling effort for on an annual basis. <br />Additional detail, including daily percolation estimates are included in Attachment <br />H. The estimate was completed for the West Sunday and Topaz Mines and for <br />average annual precipitation and the wettest year on record. <br />Exhibit 13-3. Summary of UNSAT-H Modelina Results <br />• <br />Model Run Annual Annual Annual Annual Annual Annual <br /> Potential Precipitation Actual Runoff (in.) Infiltration Percolation <br /> ET (in.) (in.) Evap. (in.) (in.) (in.) <br />West 67.0 12.8 12.7 0.0527 12.7 0.0103 <br />Sunday- <br />Average <br />Precipitation <br /> <br />West 67.0 19.9 18.07 0.190 19.7 0.0106 <br />Sunday- <br />Wettest year <br />on Record <br />Topaz- 67.0 12.8 12.7 0.0185 12.7 0.00822 <br />Average <br />Precipitation <br />Topaz- 67.0 19.9 18.1 0.0619 19.8 0.00849 <br />Wettest year <br />on Record <br />Based on the UNSAT-H simulations, the estimated percolation through the rock piles <br />is estimated to range from 0.008 to 0.011 in. per year. The simulations show the <br />importance of evaluating upward movement of water from the rock piles caused by <br />evaporation because the majority of water that infiltrates the surface of the <br />development rock piles evaporates in the semi-arid environment present at the Van 4 <br />Mine. <br />The UNSAT-H simulations suggest that significant percolation from the base of the <br />development rock piles is unlikely. However, a small amount of percolation is <br />estimated for all simulations. The simulations further suggest that infiltration of <br />precipitation followed by upward evaporative flux of water stored within the <br />development rock areas are dominant mechanisms controlling the volume of <br />percolation through the development rock areas. Minor differences in the physical <br />characteristics of the development rock from West Sunday and Topaz mines as well <br />as the magnitude of annual precipitation are less important controls on the expected <br />volume of percolation. Additional sensitivity analyses were also conducted and <br />indicate that the model is not particularly sensitive to modifications in convergence <br />parameters, node spacing or initial moisture conditions. Detailed sensitivity analysis <br />• information is presented in Attachment H. <br />13-8 <br />7:164986-Denison Mines7ask Order 4 - EPP Sunday Mines Group-Van41Van4TINAL Report\FINAL - Environmental Protection Plan Van4.doc