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The Division is still reviewing two of the technical reports associated with this <br /> application: "Riverside Berm Failure Analysis and Flood Control Mitigation Plan" (Flow <br /> Technologies LLC, 2020) and "Dewatering Evaluation, Varra Two Rivers Mine" (AWES <br /> LLC, 2020). Division comments and questions related to these reports will be sent <br /> under separate cover. <br /> August 05, 2022 - Additional reviews for preliminary adequacy <br /> Flood Control Mitigation Plan <br /> Raptor received additional comment on this aspect of the application November 17, <br /> 2022 and will respond separately on this issue. <br /> 1) Hydro graph Development: Paragraph 3.2.3 indicates the 10-year flow was <br /> subtracted from the inflow hydrograph because "it is estimated the earthen berm <br /> will control a 10-yr flood event". This does not seem to be a straight forward <br /> assumption. If the entire site is to be flooded, it seems the water elevation of the <br /> flood above the berm elevation would be the controlling flow parameter, much as a <br /> hydrograph routed through a reservoir controls the depth of overflow in a dam <br /> overtopping failure analysis. Please provide some background on why this <br /> assumption is reasonable. <br /> Raptor Materials First Adequacy Response <br /> Please refer to Flow Technologies Report dated August 27, 2022, now appended to <br /> the Application as an addendum to Exhibit G. <br /> 2) _Hydrograph proportionment: Paragraph 3.2.3 references FEMA, Flood Insurance <br /> Study, January 20, 2016 as validation for having two-thirds flow through the south <br /> side of the Site (Central Field) and the remaining one third flow through the north <br /> side of the site. Please: <br /> a) Elaborate on the purpose of splitting the flows, <br /> b) Explain if this is used directly in the WinDAM C berm failure analyses or n the <br /> hydrograph development for determining water elevation, or somewhere else, <br /> c) Explain how it impacts the approach and results (e.g., how sensitive is the <br /> analyses to this 2/3 ratio) <br /> Raptor Materials First Adequacy Response <br /> Please refer to Flow Technologies Report dated August 27, 2022, now appended to <br /> the Application as an addendum to Exhibit G. <br /> 3) Hard Armoring' Both paragraphs 3.2 and 4.2 reference Section V, Hard Armoring. <br /> 561Page <br /> Correspondence to the Colorado Office of Mined Land Reclamation—Reply to Rob Zuber,EPS—Adequacy Letters of 24 June and 5 <br /> August 2022;in the matter of the Two Rivers Sand,Gravel and Reservoir Project—M2022-013. <br />