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Section 4 <br />PofenAa/for Rock /o be Toxic Forming <br />for the rock piles to generate <br />climate of the area and the p <br />used in this analysis: <br />:e in significant volumes. This is a factor of the <br />characteristics of the piles. Two methods were <br /> <br />¦ A water balance approach; <br />¦ Unsaturated flow modeling. <br />This evaluation is based on devellopment rock samples collected from Denison 's West <br />Sunday and Topaz mines, which are located 10 miles south of the Van 4 mine. These <br />development rock piles are composed of similar geological materials as the Van 4 <br />mine, the physical characteristics of the piles are expected to be similar (e.g. particle <br />size distribution, moisture holding capacity etc.), and the mines are located in similar <br />climates. Therefore, the following evaluation of potential leachate production from <br />the West Sunday and Topaz Mims is thought to be generally representative of <br />potential leachate production at the Van 4 Mine development rock pile. <br />Water Balance Estimation of Perco <br />the development rock areas usii <br />1994). To clarify water balance t <br />discharges from the base of the <br />square inches of rock pile footpi <br />that infiltrates the surface of the <br />square inches of rock pile footpi <br />may be subsequently removed f <br />water may move downward in <br />tion: This calculation estimates percolation through <br />a water balance approach (adapted from Guymon <br />ms, percolation is the volume of water that <br />ck pile measured as cubic inches percolation per <br />it (i.e., inches). Infiltration is the volume of water <br />ock pile measured as cubic inches percolation per <br />it (i.e., inches). Water that infiltrates into the pile <br />)m the pile by evaporation or transpiration or the <br />pile and become percolation. <br />Empirical information such as temperature and precipitation data and development <br />rock characteristics are used for t e water balance evaluation. The procedure included <br />the following activities: <br />¦ Compile temperature and pre <br />the site; <br />¦ Estimate runoff and <br />¦ Estimate moisture holding <br />capillary moisture data ob <br />testing; and <br />¦ Estimate percolation through <br />approach. <br />Details of the estimation method <br />discussed previously, developmf <br />analyses including SWCC testin€ <br />rock samples, including SWCC b <br />data from a location as close as possible to <br />piration (ET) for the rock pile; <br />.ty of development rock based on site specific <br />from soil water characteristic curve (SWCC) <br />development rock pile using a water balance <br />re included in Attachment 5 of this report. As <br />it rock samples were collected for physical property <br />Geotechnical laboratory data for the development <br />ting data, are also provided in Attachment 5. <br />C: <br />0 <br />4-10