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<br />e <br /> <br />e <br /> <br />e <br /> <br />SUMMARY OF SIGNIFICANT CHANGES <br />2001 Version Versus 1969 Version of the <br />URBAN STORM DRA/NAGE CR/TER/A MANUAL <br /> <br />GENERAL <br />. All chapters edited; some totally rewritten, <br />. Many design aids added, including figures, nomographs, spreadsheets, etc. <br />. New chapters on Revegetation and Design Examples added, <br />. Emphasis on maintenance, public safety, aesthetics and multidisciplinary design approaches. <br />. Design checklists added to many chapters, <br />. Stronger emphasis on "designing with nature" principles such as "bioengineering." <br /> <br />POLiCY CHAPTER <br />. Provides increased emphasis on staying out of the 1 OO-year floodplain. <br />. Recommends reducing runoff rates, volumes and pOllutants to the maximum extent practicable. <br />. Recommends reserving sufficient rights-of-way for lateral movement of incised floodplains, <br />. Clarifies the role of irrigation ditches in urban drainage, <br />. Revises street inundation criteria for the 1 DO-year flood. <br /> <br />DRAINAGE LAW CHAPTER <br />. Contents totally updated, <br /> <br />PLANNING CHAPTER <br />. Also addresses the areas now being emphasized in the Policy chapter. <br /> <br />RAINFALL CHAPTER <br />. Adds a 25-year design storm and Its distribution. <br />. Provides spreadsheets for calculations of design storms and IDF curves. <br />. Expands rainfall maps to Include new areas of District added since 1969. <br /> <br />RUNOFF CHAPTER <br />. Clarifies the use of flows published in District's master plans and other reports. <br />. Also clarifies the use and applicability of statistical analysis. <br />. Provides spreadsheets for the Rational Method and CUHP calculations. <br />. Describes the use of CUHP and UDSWM software. <br />. Includes new procedure for calculating the runoff coefficient "C" in the Rational Formula, <br />. Clarifies which hydrologic methods to use as a function of watershed size. <br /> <br />STREETS/INLETS/STORM SEWERS CHAPTER <br />. Combines three separate chapters on design of streets, inlets and storm sewers. <br />. Uses protocols from the Federal Highway Administration Engineering Circular Nos. 12 and 22. <br />. Includes reduction factors for allowable gutter/street flow. <br />. Provides an inlet capacity reduction protocol that accounts for Inlet clogging. <br />. Also provides spreadsheets for calculations and design examples. <br /> <br />MAJOR DRAINAGE CHAPTER <br />. Includes expanded and updated design guidance and criteria for each channel type. <br />. Provides guidance for protection of natural channels from effects of urbanization. <br />. Adds new section on bioengineered channel design. <br />. Includes new guidance on use and design of composite channels. <br />. Adds text on the fundamentals of open channel hydraulics and stream stability. <br />. Updates text on 404 permitting. <br />. Revises guidance for sizing trickle channels and low-flow channels. <br />. Includes new criteria for design of boulders and grouted boulders, <br />. Provides spreadsheets as design aids. <br />