cover, use of sediment flocculants, and use of enhanced ground cover practices.
iv. Grade . Newly constructed open channels in HQW zones shall be designed and constructed with side slopes no steeper than two (2) horizontal to one (1) vertical if a vegetative cover is used for stabilization unless soil conditions permit a steeper slope or where the slopes are stabilized by using mechanical devices, structural devices or other acceptable ditch liners. In any event, the angle for side slopes shall be sufficient to restrain accelerated erosion. (4) Stormwater Outlet Protection. If condition (i) or (ii) of this paragraph cannot be met, then the receiving watercourse to and including the discharge point shall be designed and constructed to withstand the expected velocity anywhere the velocity exceeds the “prior to development” velocity by 10 perc ent (10%). A. Intent . Stream banks and channels downstream from any land disturbing activity shall be protected from increased degradation by accelerated erosion caused by increased velocity of runoff from the land disturbing activity. B. Performance standard . Persons shall conduct land disturbing activity so that the post construction velocity of the 10-year storm runoff in the receiving watercourse to the discharge point does not exceed the greater of:
i. The velocity established by the Table – Maximum Permissible Velocities set out within this subsection; or
ii. The velocity of the 10-year storm runoff in the receiving watercourse prior to development.
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