2012-08-21_REVISION - M1980244 (32)

Home Browse Search

12.2 Growth Medium Materials The availability of growth medium has been updated in this section based on information from the proposed MLE2 development areas. Soil types were mapped based on existing data available from the NRCS, as confirmed by field reviews. The results of this mapping are discussed in summary in Section 4.8 of this Project Description and included in Appendix 3, Volume III of this document. Growth medium removal and salvaging is addressed in Section 5.4.2 of this Project Description. CC &V calculated approximately 1.9 million yds3 of growth medium in areas approved under MLE and not yet developed and areas planned to be developed by the activities of MLE2. This volume was determined from: (1) the mapped soil types in the areas that will be developed under MLE2, (2) the average thicknesses of each soil type, (3) drilling information available from geotechnical studies in Squaw Gulch, (4) field observations during construction of sediment ponds in Grassy Valley in 2010 and 2011, and (5) specific knowledge of the past disturbances, which may limit available soils. The amounts of growth medium already removed, stored, or reused to date are not included in that total; however, the amount already salvaged and stored in stockpiles under previously approved activities is approximately 1.5 million yds3. As was noted in previous applications and earlier in this document, an extensive amount of the Cresson Project area has been historically disturbed by previous underground mining and related activities of the past and, as a result, the soils that may have been suitable have been previously removed or substantially disturbed by those activities. The District has been disturbed by these previous mining related activities for more than 110 years. Thus, there may be limited amounts of high quality (defined as dark, typical A- horizon materials) growth medium available for salvaging prior to full development of MLE2 in many areas and the total volume salvaged for MLE2 may differ from the estimated 1.9 million yds3 outlined above. The reclamation and closure plan incorporates about six inches of growth medium replacement on OSAs, select haul roads into the surface mines, certain surface mine backfills, the re- contoured SGVLF and AGVLF, support facility sites and other ancillary disturbance areas to be reclaimed. In order to accomplish this reclamation, approximately 2.4 million yd of growth medium will be required. It is estimated that approximately 3.2 million yds3 of growth medium are available from the existing and future development areas of MLE2 for the completion of reclamation, indicating that there is a more than sufficient volume of suitable growth medium available to accomplish the proposed reclamation as part of MLE2. Cripple Creek & Victor Gold Mining Company Cresson Project Mine Life Extension 2 12 -2