(A) Evaluation according to contents of Design Manual. All stormwater control measures, also known as SCMs, required under this chapter shall be evaluated by the Stormwater Administrator according to the policies, criteria, and information, including technical specifications and standards and the specific design criteria for each stormwater practice, in the Design Manual. The Stormwater Administrator shall determine whether proposed SCMs will be adequate to meet the requirements of this chapter.
(B) Determination of adequacy; presumptions and alternatives. Stormwater treatment practices that are designed, constructed, and maintained in accordance with the criteria and specifications in the Design Manual will be presumed to meet the minimum water quality and quantity performance standards of this chapter. Whenever an applicant proposes to utilize a practice or practices not designed and constructed in accordance with the criteria and specifications in the Design Manual, the applicant shall have the burden of demonstrating that the practice(s) will satisfy the minimum water quality and quantity performance standards of this chapter. The Stormwater Administrator may require the applicant to provide the documentation, calculations, and examples necessary for the Stormwater Administrator to determine whether such an affirmative showing is made.
(C) Separation from seasonal high water table. For SCMs that require a separation from the seasonal high-water table, the separation shall be provided by at least 12 inches of naturally occurring soil above the seasonal high-water table.
(D) Required storm depth. For high density projects designed to achieve runoff treatment, the required storm depth shall be one inch. Applicants shall have the option to design projects to achieve "runoff volume match" in lieu of "runoff treatment."
(E) Stormwater outlets. Stormwater outlets shall be designed so that they do not cause erosion downslope of the discharge point during the peak flow from the ten-year storm event as shown by engineering calculations.
(Ord. 2020-11-01, passed 11-16-20)