2007-05-31_REVISION - M1980055HR

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requirements and which are designed to provide adequate protection to the environment, the public, and the mine work force. Surface Drainage Control Structures -Disturbances to existing drainage systems were avoided to the extent possible during the design of [he surface facilities layout. Two permanent diversion channels curtently exist uphill of the portal area to direct stormwater runoff around the surface facilities to the east and west sides of the portal area. These diversions direct surface water runoff into two ephemeral drainages located on the east and west sides of the surface facilities area. The channels are intended to minimize the volume of runoff that will flow down the WRA slopes during both active mine operations and the post-reclamation period. A 100-year, 6-hour storm event was used to evaluate the sizing of these existing channels and ensure that they will be of sufficient size to permanently divert water around the mining area following mining activities and reclamation. These diversion ditches are large enough to contain a 100-year, 6-hour storm event; however, minor modifications in slope and alignment will be made to lower the flow velocity in the channels. Sediment control measures including an earthen berm and a catchment basin will be located along the base of the expanded WRA. A second berm will be located at the top of the WRA to prevent surface water from flowing into the WRA From the mine surface facilities area. The berms and catchment basin were designed to dischazge a 100-year, 24-hour storm event via an emergency overflow spillway located on the west side of the catchment basin. An emergency overflow for a 100-year storm is included for the catchment basin and discharges during a 100-year storm to the ephemeral channel located west of the catchment. The catchment basin and berms will be reclaimed after the mine is closed. Other sediment control devices, such as earthen berms and straw bale barriers, will be placed downgradient from disturbed areas as necessary to minimize the volume of sediment impacting the drainage system. Solid Waste Disposal -Aseptic system is located west of the maintenance shop and it has been determined that the system is relatively new. Currently the mine sanitary waste is disposed of in portable toilets that are serviced by a mine contractor; however, the septic system may be revitalized and used in [he future at the site. Small quantities of inert solid waste (rubble and debris), as defined by the Colorado Mined Land Reclamation Act, will be disposed of in the WRA during mine operations. Debris will be buried in parts of the WRA that will not be subject 5-23-2007 Ezhibit D Mining Plan D-9