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All these constituents are monitored through the combined ground and surface water monitoring programs <br />of the DRMS and CDPHE. In addition other parameters such as Sulfate (SO4) are monitored for possible <br />indication of ARD generation. There is a potential to generate ARD from pit backfill in areas such as the <br />East Cresson pit. Because of this potential, CC&V has proposed to install a low infiltration layer, consisting <br />of a minimum of 3 feet of clay compacted to 95 Procter density, over the waste rock prior to final <br />reclamation. This should minimize water percolating into the waste rock. All other pits that will either be <br />partially backfilled or backfilled to original contour, will be free draining, thus limiting the potential for <br />ponding water that could potentially contact acid generating waste rock and create the potential of ARD. <br />Numerous long term waste rock and ore analyses provided though the various amendments for the site <br />and evaluated by independent geo chemists and hydro-geologists, in addition to our in house review, <br />concluded that ARD may be produced from some of the pit backfill. However, the high Net Neutralization <br />Potential (NNP) values in the lower part of the diatreme should result in neutral ground and surface <br />waters at the first points of use. Above the water table, which in the mine area occurs at slightly above the <br />Carlton Tunnel level, there is no ground water use and no means of regulating the unsaturated zone waters. <br />Volume II Appendix 1 refers to surface and ground water discussions as it relates to AMD. <br />Detoxification and monitoring of the Valley Leach facility remains the same as what was approved in <br />Amendment # 8. It includes two pore volume rinses with water and one pore volume rinse with hydrogen <br />peroxide. The monitoring after detoxification has been increased from 2 years, when the first amendment <br />for the current operator was approved, to 4 years presently. Each rinse cycle will take approximately one <br />year to complete. The Division and the State has the most restrictive detoxification procedure for such <br />operations in the country. The 0.2 mg/1 WAD cyanide standard for decommissioning of cyanide heap leach <br />pads is an EPA, set standard. To date the Old Victory Leach pads, Carlton Mill Leach pads, #3 and # 4 and <br />the 86 pads have been successfully detoxified and released for reclamation under the same three pore <br />volume rinse procedure. In addition to monitoring for 4 years after detoxification, the site will not be <br />released until all the approved reclamation is completed and the applicant demonstrates it has met all the <br />performance standards approved for the permit. The Divisions ground water monitoring points and points <br />of compliance will be in place until the site is released from all reclamation responsibilities. Surface water <br />monitoring permits are issued by the CDPHE and only they can terminate the surface water discharge <br />permits at Arequa (AG 1.5) and the Carlton Tunnel. <br />8) Flood control, the current proposal if it works would be satisfactory, however if the drainage basins <br />fail, there could be flooding in poverty gulch. ( Dan Baader, Mayor Cripple Creek) <br />DBMS Response: <br />The storm water design for the site and drainage basins are for two 10 year 24 hour events, which is a very <br />conservative design. It utilized the same design criteria for surface water diversions and detention basins <br />set by the Office of Surface Mining (OSM) Diversion Manual and the SED-CAD program, which accounts <br />for peak flows and sedimentation. The peak rainfall events for both the 10 year 24 hours and the 100 year 24 <br />hour event were selected for the region from the U. S. National Oceanic and Atmospheric Administration s <br />Isopluvial Map. The peak runoff for the selected areas was calculated based on Soil Conservation Technical <br />Release No.55, "Procedures for determining Peak Flows in Colorado". The procedure utilized the following <br />parameters to determine peak flows or surface runoff from different watersheds: 1) precipitation, whether it <br />occurs in the form of rain or snow, 2) soil and vegetation cover, and 3) mechanical treatment on the water <br />shed along with its topography and shape. To date all detention basins designed for the facility have been <br />found to be handling the flow as deigned and the DRMS, does not expect the detention basins in Poverty <br />Gulch to be any different in terms of function.