1992-11-19_REVISION - M1980244 - Laserfiche WebLink

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5! Mr. Edgar Hunter 15 November 19. 1992 the structural fill, maximum thicknesses for the lifts to be placed, degree of compaction which will 6e attained for each lift, upstream and downstream slopes and slope stability analyses, primary and emergency spill-way details, etc. 7. Pit Wall Stability The operator should submit details regarding pit design and pit wall stability. This submittal should include the basis for designed overall slope angles, bench-face angles, bench width and bench height. The analyses must consider whether you are dealing with wet or dry slope conditions, the relationship between remaining intact rock bridges and the possibility of severe blast damage, the orientation and continuity of adverse joint including trace length and spacing, rock types and material strength parameters for individual lithologic units including uniaxial, triaxial, and shear strength testing of intact rock as well as direct shear testing of sawed and surface ground samples, and evaluation of all potential failure geometries including, at a minimum, plane shear down the dip direction of a single joint set and wedge shear down the plunge bearing of the intersection formed by multiple joint sets. S. Lack of Specific Commitments There are numerous places within the application submittals where the operator is vague or makes unsubstantiated assumptions. For example, the application gives two possible sources far the material to be used for the compacted soil liner. CC&V has indicated verbally that the amended tails are to be used, but there is no documentation in the application to this effect. An example of an unsubstantiated assumption is found in the section on water balance, where it is assumed that porosity of the heaped ore will be 30 percent. Porosity of the ore is a critical factor in calculating water balance in a valley fill heap leach, and the value Heads to be determined from direct testing of the crushed and run of mine ore. The Division recognizes that assumptions need to be made in design work, and are often acceptable; however, we need as much as possible to receive commitments regarding design and design criteria. The operator can remain flexible within the criteria through submittal of as-built documentation which will describe and justify any variation from approved designs. ;f. Monitoring. Verification and Reoortina Program In order to avoid misunderstanding, the applicant should submit a brief but comprehensive description of a "Monitoring, Verification and Reporting Program." This program should clearly state the purpose of the program. It should include consideration of all forms of monitoring; geotechnical, hydrological, water quality, air quality, revegetation, etc. It should summarize the monitoring facilities to be installed and observations to be performed, including a schedule or frequency of monitoring. It should commit to the periodic reduction of the monitoring data and the comparison with project design properties and performance standards. Appropriate reporting frequencies should be proposed, with no less frequent than annual report submittals. Exhibit L, "Reclamation Costs" should be amended to include bonding necessary to complete the monitoring and verification program in the event of default or premature termination of the project. Finally, the applicant's proposal should clearly state the applicant's commitment to have responsible professionals in charge of site operations and the conduct of the monitoring program. If you have additional questions or concerns please call.