B. Stormwater Runoff Rate . The measures shall control and treat the difference in stormwater runoff rate leaving the project site between the pre-and post-development conditions for, at a minimum, the 1-year, 24-hour storm, the 2-year, 24-hour storm, and the 10-year, 24-hour storm. Runoff volume drawdown time shall be a minimum of 48 hours, but not more than 120 hours.
(3) Standards for Stormwater Control Measures . The following standards shall apply for the implementation of stormwater control measures:
A. Evaluation According to Contents of Design Manual . All engineered stormwater controls and stormwater systems (also referred to as Stormwater Control Measures, or SCM) required under this section 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 engineered stormwater controls will be adequate to meet the requirements of this section. B. Determination of Adequacy of Alternatives . Engineered stormwater controls 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 ordinance. 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 ordinance. 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. (4) Completion of Engineered Stormwater Controls . The developer of any nonresidential development will be expected to have installed and stabilized the final SCMs supporting their development prior to issuance of a Certificate of Occupancy, unless otherwise specified in §9-1808 Common Application Procedures, z. Site Plan, (3) Site Plan Components, N. Phasing, iv. Stormwater Control Measures. For residential development, the final stormwater device must be installed at such point that 75% of the residential lots are completed and sold. (5) On-Site Wastewater . On-site systems for domestic wastewater covered by the Phase II Requirements shall be operated and maintained so as to avoid adverse effects on surface water and groundwater, including eutrophication of surface water and microbial or nitrate
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