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COLORADO DEPARTMENT OF HEnLTH, Water Quality Control Division <br />Rationale -Page 2, Permit No. CO-0043648 <br />The main features of this project are rite Cresson Mine Pit, t/te Va[lev Lencit Facility (VLF), which has been <br />constructed on top of dte Arequa Guld: drainage channel, the Minernls Beneflcintion Facility, the Arequa Gulch <br />Waste Rock Storage Aren which has been constrtcted ttpstrennt of the VLF on top of springs which supply flow <br />to Arequa Gulclt, and rite Ironclad Waste Rock Storage Aren, located at the /teadtvaters ojSquaw Gulch. <br />While the Cripple Creek and Victor Gold Mining Company (CC&V) ltns designed the VLF with the intention of <br />avoiding any discharge of the type that rite State would normally require to be permitted through the CDPS <br />progratn, it is possible for there to be some leaknge t/trough the solution liner, or for t)te solution distribution <br />system to frail, resulting in such a discharge. A rnarimunt of 3 layers of liners and a ntirtimurn oJ2 layers of <br />liners exist under all areas of the VLF. Also, d:e bottom soil layer of the liner system that lies under dte VLF <br />bras been constructed utilizing previously leached !airings wltic/t contain low levels of cyanide. It is possible that <br />any water flowing under the VLF that comes in contact with these tailings will be contaminated and thereby be <br />subject ro permitting requirements if it later enters surface waters. <br />Also, seepage may emanate from either [he Arequa Gulch or Ironclad Waste Rock Storage Areas. The quality of <br />such seepage may be affected by geochernical reactions at either storage site. At the Arequa Gulch site, there is <br />the additional potential for seepage from the relocated Carlton Tailings, which have not been !orally isolated <br />from rite hydrologic system. <br />Otter po[er:(ial sources of pollutants wit/lira t/te Cresson project area include seepage or runoff from areas where <br />pre-existing cyanide-contaminated tailings (Carlton Tailings) !rave been removed, allowing increased <br />ntobiliza[ion of cyanide; mine haul roads which have been constructed using pre-existing leached material; and <br />pre-existing mine water that ltas been used for dust suppression. <br />The intent of this permit is to address all potential point source discharges of "mine drainage" that originate <br />froth within tl:e Cresson Project mining permit area, including those listed above, which either directly or <br />indirectly enter surface waters oflhe State. <br />Taking the above fnctors into consideration, detailed descriptions bf rite discharge points that will be included in <br />the permit are provided below: <br />OOIA This point is located at rite outfal[ froth the sediment pond drat is located downstream of the Valley <br />Leach Facility, and w/tics: discharges to Arequa Gulclt. Ti:is point is located upstream of the outjall <br />from rite diversion ditch that intercepts uncontaminated surface runoff from areas upgradient of rite VLF <br />and rv/rich may carry treated runoff discharged from point 002A, which is associated with a sediment <br />pond located at the crusher area. CC&V's instream monitoring point AG 1.5 is located downstreat of <br />point OOIA. <br />The sources of wastewater going ro the sediment pond for outfall OOIA include flows from the leach <br />facility underdrain, flows from tl:e face of the leach facility toe berm, and any flow from the area above <br />or to the sides of the leach facility which are not intercepted by diversion canals. <br />The leach facility underdrain has been isolated from the leaching solution through lire use of a multi- <br />tayer linersystem. The underdrain consists of a constructed 5 jeer deep, 10D feet wide channel, filled <br />with broken rock, which surrounds rite following pipes, which are listed in order, going from left to <br />right when looking upstream towards the face of the toe berm: <br />a) one perforated 24-inch pipe which collects ground water flowing underneath the western portion of <br />the leach facility. <br />b) one 24-inch solid pipe, which is currently blinded at t/te upper end, but which is intended to carry <br />stormwater flows front the Arequa Gulch Waste Rock Area after the leaching operation is <br />completed. <br />