2012-08-21_REVISION - M1980244 (32)

Home Browse Search

developed based on an overall 2.5H.•1 V slope criterion. " Thus, CC &V is uncertain why the same language is being questioned by the Division, however, for clarification purposes, a minimum criterion for intrabench slopes should benches created during operations that may need to be retained, as appropriate, for geotechnical and erosional stability would generally be at in a range from 1.6HJ: V to 2.0HJV, if not at 2.5H. 1 V. Additional comments on elements related to Exhibit U are presented in a memorandum from Berhan Keffelew are to be submitted under separate cover. 6.5 GEOTECHNICAL STABILITY EXHIBIT 54. Given the DCF sloughing event that occurred in April 2012, please comment on the stability of the DCF on the SGVLF liner system prior to ore placement. RESPONSE: In order to improve the stability of the DCF on the liner, the geomembrane has been changed from an 80 -mil smooth LLDPE geomembrane to an 80 -mil double -sided textured LLDPE geomembrane. AMEC is currently testing the 80 -mil double -sided LLDPE geomembrane with the DCF to determine a revisedfriction angle. Once the tests are completed, AMEC will re- evaluate the slope stabilities in the areas of 2H.•1 V to verb an improved safety factor of the unloaded VLF. Secondly, CC &V is proposing to phase the installation of the DCF based on the schedule of the advancement of the ore. This will minimize the time the DCF is exposed to the elements and reducing the risk offuture sloughing. OBJECTOR COMMENTS 55. Kirby Hughes Comment No. 3 — Please provide some background discussion on the rationale to puncture the VLF liner after rinsing the VLF for the purpose of reclamation. RESPONSE. As an initial matter, CC &V disagrees that the comments submitted by Mr. Hughes on behalf of Sierra Club /Rocky Mountain Chapter (Colorado) are "objections ". Rather, Mr. Hughes seeks clarification on seven matters for which some are within the jurisdiction of the Division. With respect to puncturing the VLF liner, as the Division well knows from prior amendment applications reviewed and approved for the Cresson Project included discussion of puncturing the VLF liner after rinsing the VLF for the purpose of reclamation. Thus, CC &V is uncertain why the same language is being questioned The detoxification process of the current approved AGVLF and proposed for the new SG VLF consists of two pore volumes of water and one pore volume of hydrogen peroxide. The numeric limit for the decommissioning of the VLFs remains at 0.2 mg11 wad CN (weak acid dissociable cyanide). Once this is achieved, the liners are to be punctured so they will free drain. The puncturing of the liners serves three general purposes: ])it will allow the Division to detect any metal releases from the VLF by monitoring the ground water compliance points during reclamation, 2) it will allow root zones to properly establish below the liners and 3) it will help eliminate build up of hydrostatic head. 56. Letter from Janet A. Kunz — Please respond to Ms. Kunz's concerns regarding the remains of her son, Wayne B. Tease. RESPONSE: As an initial matter, CC &V disagrees that the comments submitted by Ms. Kunz are "objections". Indeed, Ms. Kunz's was very clear in stating in her letter that "My goodness, I am not interested in work being stopped at the mine, I am interested in CC &V digging down and retrieving what remains maybe left of my son". In response to the Division's request, please reference Attachment 12 for a copy of the most recent correspondence submitted from CC& V to Ms. Kunz. 57. State Historic Preservation Office — Please provide an update on the status of the "previously agreed to documentation of five (5) sites located within the Cripple Creek & Victor Gold Mine (CC &V), Cresson Project, Amendment (AM) #9 area ". (reference March 26, 2012 letter signed by Edward C. Nichols). RESPONSE. As an initial matter, CC &V disagrees that the comments submitted by Mr. Nichols as the State Historic Preservation Officer are "objections ". Rather, Mr. Nichols mainly seeks documentation related to five features associated with Mine Life Extension (Amendment No. 9). With respect to that matter, please reference Attachment 13 for copies of correspondence. Included within the attachment is a copy of the letter submitted to Mr. Corson, dated May 4, 2012, that went out with the data, as well as, correspondence from Mr. Corson to CC &V acknowledging SHPO's receipt of historic resources reports and site forms.