2010-02-16_PERMIT FILE - M2009076

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Letter to Ryan J. McHale 7 February 16, 2010 Permit Application Adequacy Review File No. M-2009-076 a. The drainage analysis provided assumes runoff from hydrologic soil group A. The contributing basin above the proposed tailing impoundment has been surveyed by NRCS and is primarily Cathedral-Rock Outcrop Complex, hydrologic soil group D. A small percentage of the contributing basin is mapped by NRCS as Mammoth Ohman soil, hydrologic soil group B. The analyses must be redone using the correct hydrologic soil group inputs. b. Exhibit C states that diversion channels around the tailing impoundment will be constructed in phases as the impoundment expands; Exhibit E maps illustrate completed diversion ditches that intersect at the apex in the early stages, e.g. drawings E5, E6, E7, etc. If the ditches are to be installed in phases, they must intersect above the impoundment sequentially for continuous run on protection. Please clarify the sequence for installation of the diversion ditches. c. Diversion channel dimensions are provided in Exhibit C, but no analysis is provided to demonstrate the capability of the ditches to pass the peak flow. Rip rap is specified but no information on sizing or other properties is provided. As discussed in item 21 a, the drainage analysis must be redone. The flows calculated from the new analysis must be used to produce a detailed ditch sizing and armoring design. d. The Exhibit E drawings illustrate the tailing impoundment diversion ditches discharging into the sedimentation collection pond. These does not correlate with some of the narrative description of the diversion ditches and sedimentation pond provided in Exhibit C, nor is it sound storm water control practice. As much runoff as feasibly possible from undisturbed upland should be routed around the tailing impoundment and discharged back to the natural drainage below the sedimentation pond. e. There are drawings and some narrative description of the proposed sedimentation collection pond in the permit application, but no detailed design information. Design information must be provided including foundation preparation, fill specification, compaction specification, and spillway rip rap specification considering peak flow rate and velocity. f. DRMS believes that a WQCD storm water permit for the proposed operation will be required. A requirement of a storm water permit will be the preparation of a storm water management plan (SWMP). In accordance with Rule 6.4.20(10)(b), provide DRMS a copy of the SWMP, or, alternatively provide a written finding from WQCD that a SWMP is not required for this operation. 22. The Environmental Protection Plan at section 6.4.20(13)(a) states that no liquid containment systems are proposed. The DRMS views the tailing impoundment, the water holding pond, and the crusher feed pad as liquid containment systems subject to Rule 6.4.20(13)(a). See items 4, 11 a, 17, and 21 for further discussion of the water balance issue. 23. In accordance with Rule 6.4.20(15) a detailed schedule for installation of the tailing impoundment liner is required. The schedule is primarily needed for the DRMS to schedule inspections of the construction. Therefore, a commitment at this time to provide a detailed schedule well in advance of commencement of construction will suffice. 24. Reclamation of the tailing impoundment cannot be considered complete until termination of leachate collection. Provide an infiltration evaluation for the reclaimed surface to demonstrate that evapotranspiration will be sufficient to terminate leachate generation, or provide a cover design, with estimated installation costs, that will sufficiently limit infiltration. 25. Tailing and water return pipelines are environmental protection facilities subject to Rule 8 reporting requirements. The permit application indicates that these lines are to be laid across the natural ground surface