2013-04-12_REVISION - C1980001 - Laserfiche WebLink

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The PHC predicts a maximum level of Total Dissolved Solids (TDS) of 1186 mg /l for Trout Creek immediately downstream from the Edna Mine. Monitoring data indicate spoil leachate caused an increase to 1400 mg /l in one sample in 1995, but has since declined to less than the predicted maximum of 1186 mg /1. Completion of the Hydrologic Reclamation Plan The only ditches, ponds, and wells that remain in the bond release area are those that have been previously approved for permanent retention. Monitoring wells TR -3 and TR -4 were transferred to landowners, wells TR -1.5 and WR -1 were reclaimed in August 2009 and the sites inspected in September of 2009. The Division approved termination of the water monitoring program with the approval of Technical Revision No. 48 (TR -48) on August 20, 2009. Findings on Protection of Hydrologic Balance The observed hydrologic impacts at the Edna Mine are consistent with those predicted in the Probable Hydrologic Consequences section of the permit application and the Division's Yampa River Cumulative Hydrologic Impact Assessment. With the exception of the occasional historic dischargeof leachate from spoil springs into Trout Creek, water pollution is not occurring at the Edna Mine, and there is no potential for future water pollution. Aquifer recharge has not been diminished (infiltration of meteoric waters into the ground surface has not been reduced), and the permittee has not caused adverse impacts to ground water that impair the postmining land use. Based on the foregoing observations regarding hydrologic impacts, the Division finds the operator of the Edna Mine has minimized disturbance of the hydrologic balance in the bond release area and adjacent areas, and prevented material damage outside the permit area. It is noted that although the Division is proposing to terminate its jurisdiction of the Edna Mine and its responsibility on the protection of hydrologic balance, this finding does not terminate Chevron Mining Inc.'s responsibilities under its Colorado Water Quality Control Division's discharge permit. Summary and Conclusions Based upon a review of the mine permit, the applicant's bond release application, and site inspections, the Division finds that Chevron Mining, Inc. has replaced topsoil in accordance with the approved reclamation plan. The Division further finds that Chevron Mining, Inc. has established vegetation which supports the approved post- mining land use and meets the approved success standards for vegetative cover, production, species diversity and woody plant density. Post - mining land -use is supported by the documented wildlife use and grazing uses of the rangeland areas. Impacts to surface and ground water quality are in accordance with predictions, and in compliance with applicable standards. The bond release areas under consideration have all achieved the minimum of ten years of revegetation liability responsibility (Rule 3.02.3(1)). Edna Mine Page 25 April 12, 2013 Phase II. and III Bond Release