2023-02-02_PERMIT FILE - M2022013 (6)

Home Browse Search

Page 13 6.4.7 EXHIBIT G - Water Information will be made in cooperation with the Colorado Division of Water Resources, and any resulting submittals and approvals made available to the OMLR at the time of the Annual Report, or by separate cover. No measurable impacts to the prevailing hydrologic balance are foreseen. ii. The Flow Technologies Report of 22 January 2020, provides a plan of modified basin design to be incorporated into this submittal as a means to minimize erosion of the basin berms while optimizing the integrity of the basin from the South Platte and Big Thompson Rivers during a 100-year flood event. The DRMS in a supplemental adequacy response dated November 17, 2022 challenged the validity of the engineered design approach taken by Flow Technologies despite having accepted it as valid in the past. Raptor Materials believes the approach is valid and is in the process of performing an analysis by alternate methods incorporated in HEC-RAS. This, however, will take time. Raptor has per DRMS suggestion decided to adopt the 400-foot setback from the top of the riverbanks to the top of the pit-side slope based on guidance developed using generic and non-site-specific empirical methods as adopted by the Mile High Flood District whose jurisdiction does not include the proposed operation. Raptor Materials intends after permit approval to present the results of the ongoing engineering evaluation as a Technical Revision to obtain relief from what we are confident are extreme setbacks. (2) (a) Please refer to Exhibit C-1: Existing Conditions Map. 5Wells are also shown on Exhibit G: Water Information Map and a table providing well details is included as an addendum to this Exhibit G. (b) The known aquifer under the site is the stream alluvium. (c) Discharge water will be dissipated with hard surface riprap or established grassed waterways. Other waters are retained by internal pit drainage, directed by vegetated berms or established waterways or through the maintenance or establishment of a stabilizing cover of vegetation, or as otherwise established under an approved Colorado Department of Health stormwater permit and/or stormwater discharge permit. 6Stockpiling of soil, overburden, or product above the existing ground elevation will not occur in a manner understood to obstruct flood waters where they might occur within the existing floodplain. It is understood and agreed here-in that their longitudinal dimensions if they occur there should extend parallel to anticipated flood flows where they exceed a cone or other shape that might find its existence contrary to intent by volume beyond that which could be understood to be temporary, or transitory; especially outside of seasonality where flooding might be more reasonably anticipated. s Supplemental Groundwater Adequacy Item 4 6 Adequacy Item 45:Floodplain management,including conveyor crossing discussion VARRA COMPANIES, INC. TWO RIVERS SAND GRAVEL AND RESERVOIR PROJECT MARCH 2O22 A REGULAR IMPACT[1121 CONSTRUCTION PERMIT APPLICATION-COLORADO DIVISION OF RECLAMATION MINING&SAFETY OFFICE OF MINED LAND RECLAMATION