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<br /> <br />CHAPTER 2 <br />cweB PRINCIPLES <br /> <br />SECTION 2 <br />CWCB OPERA liNG <br />PRINCIPLES <br /> <br />COLORADO <br />FLOODPLAIN AND STORMWATER CRITERIA MANUAL <br /> <br />designated floodway is prohibited unless it can be demonstrated using appropriate <br />detailed engineering analyses that the proposed encroachment will not cause any <br />rise in the 1 DO-year water surlace elevation <br /> <br />HOwe'o'er some local jUrisdictions In Colorado have determIned that the FEMA's 1- <br />loot rise floodway Crlleria IS Inadequate to protect the existing and future <br />developments within their communities, and have adopted a stricter floodway <br />delineation criteria (Le. UDFCD's 0.5-foot rise criteria) in addition to the FEMA <br />cnteria <br /> <br />OPERATING PRINCIPLE <br /> <br />THE CWCB RECOGNIZES THAT DESIGNATED FLOODWAYS ARE <br />ADMINISTRATIVE LIMITS AND TOOLS USED BY COMMUNITIES TO <br />REGULATE EXISTING AND FUTURE FLOODPLAIN DEVELOPMENTS WITHIN <br />THEIR JURISDICTIONS. THEREFORE, COMMUNITIES MAY CHOOSE TO <br />DELINEATE FLOODWAYS BASED ON FEMA'S 1-FOOT RISE CRITERIA OR <br />BASED ON MORE STRICT CRITERIA BY ALLOWING A LESSER AMOUNT OF <br />RISE ABOVE THE BASE FLOOD ELEVATIONS. THE CWCB FLOODWAY <br />OPERATING PRINCIPLE IS SYNONYMOUS WITH COMMUNITIES' ADOPTED <br />FLOODWAY CRITERIA. WHERE NO LOCAL FLOODWAY CRITERIA EXIST, THE <br />CWCB RECOMMENDS THE USE OF THE MINIMUM FEMA STANDARD. <br /> <br />2.5 HYDRAULIC STRUCTURES <br /> <br />A drainage system may be <br />comprised of natural open <br />channel sections, <br />manmade channels. <br />culverts and bridges. <br />levees. dams and <br />reservoirs. detention <br />basins. drop structures. <br />and other related facilities. <br />Hydraulic structures are <br />defined as the drainage <br />facilities that are designed <br />to convey stonn or <br />floodwater to a <br />downstream receIvIng <br />water body. <br /> <br />J < <br />1. <br /> <br />"" <br /> <br />- <br />- <br />;!, " <br />.e................_... .' <br /> <br />.i.: or <br />If " <br />!i'I"" <br />"!I, <br />~'. <br />, <br />, "~,,,, N <br />I~- ~~~ <br /> <br />~ <br /> <br />c <br /> <br />~ <br /> <br />A <br />4- -'\,.~ <br />:\-rh- <br />.'( r '----.c..:~ <br />~.-".~~ ~ <br />\.. <br /> <br />--. <br />~.,;;.....,,,~:-:..... <br />"./ ~..--- <br />:- 'f"j ~ <br />""". <br />~ <br /> <br />~ <br /> <br />.... <br /> <br />"" ,., <br /> <br />The recommended design and technical standards for some of the most commonly <br />encountered hydraulic structures are provided in the Statewide Manual. The <br />Infonnation presented in the Statewide Manual should be considered to be the <br />minimum hydraulic design standards. Additional analyses may be necessal)' for <br />unique or unusual site conditions. <br /> <br />Establishment of the minImum engineering standards will help to produce <br />consistency in lhe design of the hydraulic structures and provide integrated drainage <br />systems that actlogether to protect the pubhc health, safety. comfort. convenience. <br />welfare. property and commerce. The minimum design standards for the following <br />hydraulic structures are presented in the Statewide Manual: <br /> <br />CWeB OPERATING <br />PRINCIPLES <br /> <br />APRIL 2004 <br /> <br />CH2-205 <br />