1. Use a surface withdrawal mechanism, except when the basin drainage area is less than 1.0 acre;
2. Have a minimum of 1800 cubic feet of storage area per acre of disturbed area;
3. Have a minimum surface area of 325 square feet per cfs of the Twenty-five Year Storm (Q25) peak flow;
4. Have a minimum dewatering time of 48 hours;
5. Incorporate 3 baffles, unless the basin is less than 20 feet in length, in which case 2 baffles shall be sufficient.
6. Upon a written request of the applicant, the Director may allow alternative design and control measures in lieu of meeting the conditions required in this Section if the applicant demonstrates that meeting all of those conditions will result in design or operational hardships and that the alternative measures will provide an equal or more effective level of erosion and sediment control on the site. Alternative measures may include quicker application of ground 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 percent (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
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