2009-04-20_GENERAL DOCUMENTS - M2009076 (6)

Home Browse Search

solids for the establishment of soil capable of supporting re-vegetation. A highland pasture grass seed suitable • for mountain altitudes will be sowed together with fertilization and irrigation until permanent vegetation is re- established. This method of reclamation was successfully implemented by Phelps Dodge at the Climax Mine as referenced in Appendix J. It should be further noted that the USFS is beginning a major pine beetle kill remediation project and the availability of wood chips will not only be massive, but using this material will help the local community dispose of this "waste" product. Additionally, as each 40' high terrace is completed, the surface of the terrace will be re-vegetated as described above. Rip-rap will be installed for a channel width of 6 feet at each end of the impoundment, at the intersection with the natural grade, to provide a permanent stormwater control. A worst case Maximum Exposure cost estimate has been prepared in Appendix K for a third party to perform the work. Once the impoundment has reached maximum build-out, shown in Appendix C drawing T6, all construction traffic will be diverted away from the site. The last of the reclamation will be preformed and previous reclamation measures will be inspected and any necessary repairs will be done, paying particular attention to stormwater diversion. Signage will be posted at the locked entry gates stating the impoundment has been closed and to limit traffic as to not adversely effect reclamation recovery. Emergency contact information will also be provided. Following 3.5.8, a report will be sent to the CDPHE of successful incremental, phased reclamation/closure activity. 2.6, 3.6 Post-closure care and maintenance Site will be monitored, quarterly, to ensure that re-vegetation has been established, irrigating as needed. The sedimentation collection structure will be inspected and excess sediment will be removed accordingly. The • stormwater management rip-rap channels and culverts will be inspected and repaired as needed. The groundwater monitoring wells will also be checked. Additionally, all construction traffic will be diverted from the closure area. Appendix K details a cost estimate for this work to be performed by a third party. It is estimated that after approximately 2 years from the closure date, sufficient re-vegetation will have occurred to leave this impoundment in a stable, and reclaimed state that will require no further maintenance. 9.3 Impoundment Design Criteria The disposal cell is a Class III Impoundment, pursuant to 9.2.4(A) and (B). Existing ground water quality is indicated in Appendix E (Water Handbook for Metal Minim), page 10, Table II, column entitled "Central Zone". Appendix E, page 13, Figure 1 shows the effect of raising the pH of this effluent water to 7-8. The method employed in Venture Resources' processing plant has the identical beneficial effect as shown in this Figure 1. This has also been verified by the Company and is evidenced by Appendix F, the waste stream lab sample results. 9.5 General Design Standards 9.5.1 Benchmark & Measuring A permanent bench mark will be set on the top of the concrete Leachate Collection Barrier as shown on Appendix C, Drawing T8. A gauge calibrated in 0.05 ft. increments shall be installed in the impoundment. 9.5.2 Embankments The impoundment and closure plan detailed above are designed to minimize erosion and to withstand all forces from impounded wastes. Appendix C, Drawing T7 & T8 shows the details of the tailings impoundment structure and Leachate Collection Barrier. The slope of the impoundment benches of 1:1.5 is sufficient to provide a stable impoundment embankment with the proposed tailings waste stream. E 22