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<br /> <br />. <br /> <br />. <br /> <br />included within the appendix of this document. This policy is not intended to replace <br />. either the RICD rules, or the existing RICD policy, but rather to provide additional <br />assistance to applicants for RICDs by explaining the Board's understanding of the <br />relevant statutory authority. <br /> <br />4. Adverse Flood Impacts and Permanence Criteria <br />The applicant for an RICD needs to demonstrate through appropriate technical analyses <br />that the boating course (one or more control structures) is designed and will be (is) <br />constructed in such a manner as to: <br />· Adequately pass all flows through the lOa-year (1':10 probablity) flood flow without <br />causing adverse impacts to upstream, downstream or adjacent property owners. <br />Verification of "no adverse impact" must be demonstrated through the use of a <br />CWCB approved step-backwater hydraulics model such as HEC-RAS. For <br />proposed boating facilities, the "existing conditions" (pre-facility) scenario and <br />the "proposed conditions" (with-facility) scenario must be modeled by a <br />registered Professional Engineer (Colorado Registration) having expertise in <br />surface water hydraulic modeling. Impacts that should be analyzed include, <br />increases in stage at more frequent flood events, increases in velocity or bed <br />shear stress, and decreases in sediment carrying capacity. As commonly required <br />in flood plain management, in the event that the lOa-year flood profile for the <br />proposed conditions exceeds the flood profile for the existing conditions by more <br />than 0.10 feet, or potentially detrimentally changes certain other parameters, <br />then the applicant may either 1) re-design the boating course until no adverse <br />impact is achieved, or 2) notify all affected property owners of the proposed <br />increase in the flood profile and obtain written permission from all affected <br />property owners to construct the proposed boating course in question. <br />· Adequately withstand stream forces over an identified design life of at least 100 <br />years for all flows through the lOa-year flood so that damage and failure of the <br />boating course is avoided. The boating course must consist of appropriate <br />materials and installation to endure velocities, shear stresses, and other erosive <br />conditions that would be experienced over its design life, and during flooding <br />through the lOa-year flood event. For example, a boulder drop structure must be <br />constructed with material having suitable size, hardness, shape and gradation and <br />must be installed in such a manner that it is anchored into the stream bank and <br />streambed to survive long-term operation and flood events. <br />. Boating course designs shall take into consideration potential adverse impacts <br />caused by excessive stream forces, erosion, sedimentation, and debris handling. <br /> <br />4 <br /> <br />uuuuJ <br />