Laserfiche WebLink
- " '' <br />i~ <br />that may be exacerbated due to mining related disturbed slopes. At a minitnum, the assessment <br />will need to include the following information: <br />a. predicted Flood elevation or "stage" above disturbed slopes <br />b. predicted flood flow velocities in the disturbed pit areas & in-pit stockpile areas <br />c. extent of pit disturbance during a "worst case" flooding event, ie: pit slopes, slope heights, size <br />or diameter of pit wall materials, size or diameter of s[ockpiled/processed materials <br />d. potential for headcutting of pi[ walls and movement/saltation of stockpiled materials <br />e. extent of potential headcutting and/or erosion, ie: will headcutting/erosion be contained within <br />the permit azea or will headcutting/erosion extent beyond the permit boundazies? <br />f. mitigation measures to be employed to minimize potential for predicted impacts such as <br />headcutting, channel scour &/or downcutting, bank erosion, etc. <br />4. The applicant states that the depth of mining in the RRA will be related to market demand and <br />has requested that the previously submitted plan and mining depth for the RRA be approved as <br />submitted. The Division will not approve such a plan because the terms of the suggested plan are <br />unenforceable, and are based on the subjective judgement of the applicant rather than scientific <br />and/or empirical evidence such as estimated bedload volumes. It should be noted that this <br />information has been requested by the Division in previous adequacy reviews. Under the terms <br />of this application, the Division will allow excavation in the RRA up to but no more than 5 feet, <br />ie: the maximum depth of excavation at any location within the RRA may be 5 feet. The <br />Division will consider the operator's request for a greater maximum depth of excavation in the <br />RRA at any time, provided the operator can provide adequate monitoring data, estimated bedload <br />volumes, and/or a detailed assessment to justify a greater depth of excavation. Such request will <br />need to predict possible impacts to the channel of the Colorado River both within the RRA, the <br />surrounding affected land, and the immediate upstream and downstream areas. <br />RULE 6.4.7 EXHIBIT G -Water Information <br />5. The applicant states that a Spill Containment & Countermeasures Plan is being prepared. ws (- <br />Such plan, if not available prior to the Division's recommended decision date, wino be <br />submitted ~ ''' ~ ~ o i,~ ~c~rior to site disturbance. Please address. <br />6. The applicant has stated [hat detention ponds will be created in the surface facility area to treat <br />stormwater until [he pit can be used for this purpose, and that a drainage study is being prepared <br />with recommendations on detention pond location and sizing for the surface facilities area. Such <br />infonna[ion, if not available by the time of the Division's recommended decision date, will need <br />to be submitted as a technical revision to the permit prior to any site disturbance. Please address. <br />