Stormwater shall be conveyed from a development in an adequately designed drainage system of natural drainageways, grass swales, storm sewers, culverts, inlets, and channels. Drainage systems shall be designed, constructed, and maintained to encourage natural infiltration, control velocity, control flooding, and extend the time of concentration of stormwater runoff. The post-development runoff rate for the one-year storm event shall be attenuated to the predevelopment runoff rate for the one-year storm. The nitrogen loading contributed by new development shall be restricted to 3.6 pounds of nitrogen per acre per year. Methodologies for determining nitrogen loading are outlined in the stormwater design manual. A developer has the option of offsetting the nitrogen loading from a development by paying into the state wetlands restoration program. Procedures for offset payments are outlined in the stormwater design manual. When using the offset payment, the total nitrogen loading from a development shall not exceed six pounds per acre per year for residential development and ten pounds per acre per year for nonresidential development.
(Ord. of 7-10-2000, § 9.5; Ord. of 1-2-2001, § 9.7)