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BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

BEsT MANAGEMENT PRACTICEs HANDbooK - Tahoe BMP

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• Avoid disturbing aquatic species during installation, dewatering,maintenance, or removal of clean water diverters. Maintain adequate flowdownstream to support aquatic life.• Key-in or stabilize diversion inlet sections to prevent movement.Consider installing a screen or grate on the inlet structure to reduceplugging by trash and debris.• To prevent downstream erosion, provide velocity and energy dissipationat transitions in the diversion, particularly where the stream is diverted tothe natural channel and where the diverted stream is returned to thenatural channel. Refer to Section 4.3.1.4 for more details regarding OutletProtection. If the runoff is sediment laden, install a sediment trap belowthe outlet protection.INSTALLATION CONSIDERATIONSThere are two types of clean water diversions: the diversion method involvesintercepting clean runoff water from upslope, diverting it around aconstruction area, and conveying it by various means to a stable dischargepoint down slope. The isolation method, on the other hand, uses varioustechniques to isolate and dewater a construction area that exists in a stream,lake, or other water environment.Diversion Techniques for Upland Areas:Flexible downdrain: A flexible conduit of heavy duty fabric or other flexiblematerial used to convey water from the top to the bottom of a slope, bypassingcut-and-fill. Use flexible tubing having the same diameter as the inlet pipe andwith hold-down grommets and anchor pins/stakes at 10-foot intervals. Do notplace any material on top of a flexible downdrain that may collapse it andprevent water from flowing through.Flexible downdrain diverting upstream runoff through a construction site during installationof <strong>BMP</strong>s.TRPA <strong>BMP</strong> HandbookChapter 4: <strong>BMP</strong> Toolkit2012 4.5.1.4-Clean Water DiversionPage 3

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