Laserfiche WebLink
pit, across the existing lower staging azea and southwazds towazds Taylor <br />Gulch will be left excavated in bedrock from the south pit edge to leave a <br />stable path for potential flow with no maintenance demands after mining. <br />b. The statement made regarding mitigation of "potentially" impacted water <br />stemming from historic mining areas above the highwall zone was made <br />!~o support the long standing practice as added insurance that the surface <br />water management plan as under consideration has merit regazding quality <br />of water as well as quantity of water discharged directly to Taylor Gulch. <br />However, there is no data available to confirm that low quality water (low <br />pH or elevated metal content water) presently drains from the historic <br />mining azea above the highwall . There aze no designated CERCLA <br />properties in the azea and no history of water quality issues. There is no <br />plan for partial clean-up of historic mine drainage and no data of violation <br />of stream standards within the present Taylor Gulch drainage. It is the <br />intent of Colorado Mazble to continue mining operations with the least <br />amount of change to present mine site and downstream watershed <br />systems, both from a quality and quantity perspective. The potential for <br />liability exposure due to lazge fluctuations of downstream water volume <br />dischazge appears to be much greater than violation of water quality <br />standazds. Neverkheless, should some other site management in future <br />years, including the State of Colorado, determine that diversion of old <br />mine drainage into the lower pit azea is not in their best interest, drainage <br />patterns can easily be modified to dischazge directly into Taylor Gulch. <br />Colorado Mazble feels that historic mine clean-up liability potential issue <br />is a very low risk compazed to uncontrolled release of storm related and <br />snow melt diversion <br />3. Concurrent (with mining) dump grading will utilize angle of repose waste rock faces <br />constructed via dump truck or FEL placement along the edge of rock dumps and pushed <br />off with a bulldozer. Waste dump lifts will be constructed no higher than 60 feet per lift. <br />Given the azea available down gradient from the present lower staging azea, three (3) <br />waste rock faces may be constructed during life of mine including the existing lower <br />staging area and southern boundary of the permit azea, These waste rock piles may have <br />dimensions approaching 400 feet wide, 300 feet long, and no higher than 60 feet tall prior <br />to final grading. Prior to waste rock placement, all trees, stumps, roots, and topsoil will <br />be removed from azeas to be backfilled and will be placed in designated piles for <br />processing or handling. Surface soils and organic materials will not be buried by waste <br />rock placement. Waste dump toe azeas will be cleaned of all organics and a berm (5') <br />constructed with course waste rock will be left along the lowest mazgin of the final dump <br />footprint to minimize sediment loss from the waste dump slopes during active mining <br />operations. A five foot minimum berm, constructed with coarse waste rock will be left <br />along all waste dump edges and the top of the waste rock pile will be graded to drain <br />westwazd towazd the mazble bedrock contact with the surface and final flow path to <br />Taylor Gulch along bedrock contact where ever possible. <br />