PERMFILE47342 - Laserfiche WebLink

Home Browse Search

respond. Drainage Designs -The applicant indicates on page 8 that a drainage diversion will be placed as shown on Exhibit C2-B to divert water around this site and back to the original drainage course; and that surface water from disturbed areas will be diverted on the south to a settling basin prior to being released back into the natural drainage system. The applicant further indicates on page 13 that several drainages will be recreated during the grading process to drain water from the affected azea. Review of Exhibits CZ-B & C2-C indicates that diverted waters from undisturbed areas will be merged with heated waters from affected lands prior to being discharged offsite towazd North Cleaz Creek; that there is no definitive treatment system for stormwater passing over the quarry area; and that there is insufficient information to verify that all waters dischazged offsite will be dischazged safely in a controlled manner so as to m;nim;ze the potential for otfsite erosion Further, there is no supporting watershed information and/or hydraulic computations to verify the adequate sizing of sediment pond structures, culverts, or drainage channels treating or conveying runoff waters from the contributing watershed. (In most cases, it is desirable that runoff waters from upland, undisturbed areas be diverted around the affected lands and not merged with heated or process waters from the affected land. Further, Best Management Practices should be employed in treating stormwater runoff passing over affected lands prior to release downstream andlor offsite). Please address. Drainage Design Inputs -Consideration should be given to the size and capacity of natural drainage features in the design of shttctures used to convey runoff waters from an undisturbed, contributing watershed. Stroctures used to treat ar convey runoff waters from a disturbed, affected azea will need to be sized to handle the peak velocity and volume from a design storm event in a controlled utanner. Permanent structures to be left in place during final reclamation will need to be designed based on a 100-year storm event Temporary structures to be removed during final reclamation will need to be designed based on a 10-yeaz, 24-hour storm event, or a 2-yeaz, 6 hour storm event, whichever is greater. Please address. Blasting Plan -Allen Sorenson of the Division will provide review comments regazding the applicant's proposed blasting plan and documentation of blasting procedures, per Rute 6.4.4(i). Mr. Sorenson's comments will be forwazded to the applicant as soon as they become available. Uranium Mineralization - A number of objectors have expressed concert over potential impacts from uranium that maybe exposed via drilling and blasting at the MMRR Quarry. Such impacts may result from uranium from airborne dust or stormwater runoff. The Division requests that the applicant address 'the poti5ntial~foF adveisi53fiipacts to fiuman Fiealfb,-andtfie env7ronmenT indludingvegetatibn, m7d]ife, and surface water quality of North Clear Creek. The Division requests that the applicant address the potential for mineralization of uranium by implementing one of the following options: Option I -Detailed Geologic Assessment : Prior to drilling and blasting as specified in the mine plan, the applicant will submit for Division review and approval a detailed geologic assessment of the presence, extent, and concentration of uranium within the affected land to be removed and/or exposed during mining activities. Such assessment should assess the toxicology of uranium to the human and envirottmental receptors, identifying in particular the level above which uranium and radiation regulations would require dust control, and/or the l evel above which water quality regulations would require dust control to minimize impacts to surface water quality. If needed, the assessment should propose uranium monitoring, and a containment and control plan to be employed during mining and reclamation. Such monitoring, containment, and control should include mitigation measures to minimize potential impacts to human health and the environment, and containment and control measures to ensure compliance with all applicable Federal, State, and local regulations for dust emissions and surface water contamination.