2012-02-29_REVISION - M1977285 (3)

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Page 4 of 9 The issues raised by the Objectors are summarized below. The Division's responses are also summarized, along with citations to the applicable sections of the Mined Land Reclamation Act, C.R.S. § 34 -32 -101, et. seq. ( "Act ") and/or the Mineral Rules and Regulations of the Colorado Mined Land Reclamation Board for Hard Rock, Metal, and Designated Mining Operations, 2 C.C.R. 407 -1, et. seq. ( "Rules "). The Division has listed the issues it believes are within the jurisdiction of the Board first and the issues it believes are outside of the jurisdiction of the Board last. A. ISSUES WITHIN THE JURISDICTION OF THE BOARD Possible Adverse Impact to Water Quality (C.R.S. § 34- 32- 116(7)(g); Rules 3.1.5(11), 3.1.6, and 6.4.21) 1. Objection: All water (both ground and surface) from the Denison mine sites should be presumed to flow into the Dolores River. Since water quality samples taken from the development rock and ore stockpiles detected constituents at levels greater than Colorado groundwater standards, leachate migration and testing and water infiltrating the mine must be fully examined. See August 2009 Letter, 1. The Division should require additional testing and monitoring and should monitor all discharges into ephemeral streams or any drainage that flows into Big Gypsum Creek. Id. at 2. The Division should take a cautious approach that protects against a "worst case scenario." Id. at 5. The Division's Response: The Division has required the Operator to address the Objectors' concerns. The EPP includes a thorough groundwater monitoring plan. As explained in detail below, the Division believes that previous water quality testing of the development rock and ore stockpiles produced very conservative results that do not directly correlate to potential negative impacts to the prevailing hydrologic balance. Prior to further mining, the Operator will be required to establish ambient water quality levels based on five to ten quarters of groundwater quality samples taken from a background well located up- gradient from the mine workings, development rock areas, and ore stockpiles. The ambient water quality data will allow the Division to establish a monitoring protocol that ensures disturbances to the prevailing hydrologic balance are minimized. The Objectors are correct that the hydrologic gradient is generally westerly towards the Dolores River (either via the Big Gypsum Valley or the Disappointment Valley). Because the hydrologic gradient in the proximity of the ore deposit is southwesterly, the Division has established two points of compliance along the South and Southwest boundary of the permit area to ensure that negative offsite impacts will not occur. The Division has required three additional monitoring wells at strategic locations between the location of the mine workings, development rock areas, and ore stockpiles and the compliance wells. The monitoring wells are located in a manner that will provide multiple levels of early warning in the event that adverse impacts to groundwater quality occur. There is currently no evidence of any discharge of mine- related pollutants into ephemeral streams or any drainage that flows into Big Gypsum Creek. Finally, it should be noted that groundwater flow rates in this area are extremely low. Furthermore, the area's low precipitation limits the amount and depth of subsurface percolation. The arid climate and storm water control structures limit the ability of runoff to carry leachate to offsite surface waters. The Division anticipates that the slow rate of groundwater flow will leave ample opportunity for the monitoring wells to flag unforeseen problems and for mitigation measures to be developed and implemented.