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Letter to Ryan J. McHale 2 February 16, 2010 <br />Permit Application Adequacy Review File No M-2009-076 <br />year/24-hour storm inflows. Containment for the 100-year event is required (Rules 6.3.3(2)(c), 6.4.20(7)(f), <br />and 7.3.1(3)). If containment is predicated on accumulation of rainfall limited to the dimensions of the pad, <br />slopes and diversions must be described that will prevent other inflows to the pad during heavy downpours. <br />Describe how water accumulations within the pad will be disposed including timing of disposal against the <br />potential for multiple storms over a short period. <br />5. In Exhibit C, the water holding pond is described as already constructed with an asphalt emulsion applied to <br />a shot-crete lining. The mineral processing described in the permit application includes recirculation of process <br />solutions through the water holding pond, processing of rock containing reactive minerals, and maintenance of <br />an alkaline pH. This system of processing will result in deposition of mineral residue in the water holding <br />pond. DRMS requires disposal of the residue into a controlled, reclaimed repository; the obvious disposal <br />location in this case is the tailing impoundment. Provide a plan and estimated costs to collect and dispose of <br />the residue. DRMS suggests that installation of a flexible membrane liner would facilitate both collection and <br />disposal, and would limit the potential for seepage through cracks in shot-crete. <br />6. To establish the amount of required reclamation bond, it must be assumed that at the time of bond forfeiture <br />fluids will have filled the water holding pond, crusher feed pad, tailing impoundment, and sediment pond to <br />capacity, and that the fluids cannot be released to the environment. Provide a plan and estimated cost to <br />dispose of the fluids. <br />7. Exhibit C states that a three hundred gallon diesel tank will be installed. DRMS requires secondary <br />containment for fuel tanks. Describe the tank, secondary containment, and management of fluids collected by <br />secondary containment. <br />8. Exhibit C states that the tailing impoundment out slope will be 1.5H:1 V and that the shell of the <br />impoundment will be constructed of hydraulically classified and hydraulically placed tailing, coarse fraction. <br />No mechanism or process control for classification or placement is described. In Exhibit D Venture Resources <br />states that the angle of repose for the coarse tailing is forty to forty five degrees, six to eleven degrees greater <br />than the proposed impoundment out slope angle, and points to this physical property as sufficient <br />demonstration of impoundment slope stability. No testing or analysis was provided as the basis for the angle of <br />repose figure. The tailing impoundment cross section provided as drawing EI I does not illustrate boundaries <br />between hydraulically placed course fraction tailing and impounded fine fraction. Drawing E11 illustrates each <br />of the five proposed steps of tailing impoundment following the filling of the barrier impoundment as having a <br />back slope forming the toe foundation for the subsequent step, whereas the narrative description provided in <br />the permit application indicates that the sequential impoundment shells will be founded on near horizontal <br />deposited tailing, fine fraction. Exhibit C states that a network of perforated pipes will be installed at the base <br />of the tailing and at each twenty vertical foot level of impoundment elevation. The DRMS has identified the <br />following issues to be addressed for the tailing impoundment plan. <br />a. Provide a detailed description of the construction of the impoundment shell, including specifications, <br />mechanisms, and process control for grain size, moisture content, and density. <br />b. The discussion in the application of impoundment stability based on angle of repose is inadequate. A <br />rigorous slope stability analysis must be provided that considers the shear strength, density, and pore <br />pressures of the impoundment shell and the impounded tailings, fine fraction. <br />c. A cross section must be provided that shows the zoning of fine and course fraction tailing within the tailing <br />impoundment. A description of process controls to distribute the fine and coarse fractions according to plan