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Section 4 <br />Pofenfia/forRockfo be Toxic Forming <br />parameters, node spacing or <br />information is presented in E <br />Snmmarj of Findings: The water <br />indicate that significant percolai <br />unlikely. These evaluations furt <br />by upward evaporative flux of i <br />dominant mechanisms controlli <br />development rock areas. Minor <br />magnitude of annual precipitati <br />of percolation. <br />moisture conditions. Detailed sensitivity analysis <br />neat 6. <br />lance estimates and the UNSAT-H simulations <br />i from the base of the development rock piles is <br />indicate that infiltration of precipitation followed <br />er stored within the development rock areas are <br />the volume of percolation through the <br />ferences in the physical characteristics and the <br />are less important controls on the expected volume <br />The results of these estimates correspond to the input parameters including the <br />development rock physical and ydrologic parameters, and the available climate <br />data. Site-specific climate data an not available, and differences between actual <br />climate conditions at the site and the data compiled from the Uravan and Montrose <br />weather stations could result in variations in percolation through the piles. There are <br />other site-specific variations that are not directly accounted for in the model. For <br />example, a rind of highly compacted tight soil/rock was encountered at the surface of <br />the rock piles (see photographs i. Attachment 2). This rind likely reduces infiltration <br />by allowing for increase runoff and increased surface evaporation via ponding versus <br />infiltration. This site-specific condition (which could further reduce modeled <br />percolation rates) was not accounted for in the model. <br />4.2.3 Attenuation Capacii <br />The attenuation capacity of soils <br />component of this assessment in. <br />naturally attenuate constituents <br />However, the unsaturated flow :i <br />indicate that the rock piles are n+ <br />Therefore, attenuation data is no <br />attenuation testing are presenter: <br />of Soils Underlying Rock Piles <br />underlying the rock piles was evaluated as a <br />arder to investigate the capacity of these soils to <br />hat could potentially leach from the rock piles. <br />iodeling and water balance estimates of percolation <br />t likely to produce significant quantities of leachate. <br />discussed in detail in this document. Results of the <br />in Attachment 3 of this report. <br /> <br />• <br /> <br />4-14