To minimize the discharge and transport of pollutants to storm drains and prevent the deterioration of water quality, certain new developments and redevelopment projects will be required to submit for approval a stormwater management plan or a comprehensive drainage plan to control the quality, volume and rate of stormwater runoff. The City Stormwater Management Design Manual establishes standards and guidelines for implementing BMPs and stormwater management plans and is incorporated by reference and made part of this chapter.
A. Plans Required: Stormwater management plans or comprehensive drainage plans are required for industrial, commercial and institutional developments which require a building permit and multi-family residential developments that are not part of a larger subdivision project, as well as subdivision projects that have private access, which also require a building permit.
B. Redevelopment Projects: Redevelopment projects may be required to submit complete stormwater management plans or operation and maintenance plans if they meet the criteria found in the City Stormwater Design Manual.
C. Included Provisions Of Plans: Stormwater management plans and comprehensive drainage plans shall provide for the following:
1. Prevention of any direct discharge of untreated stormwater and nonstormwater, either on or off site.
2. Prevention of increased post development discharge rates.
3. Removal of a minimum amount, determined by the percentage of impervious parcel area, of annual total suspended solids generated from development or redevelopment runoff prior to any off site discharge.
4. Continuation of BMPs for appropriate periods of time.
5. Protection of groundwater from instances of development runoff infiltration.
D. Plan Development: Stormwater management plans and comprehensive drainage plans shall be developed in accordance with the City Stormwater Management Design Manual or equivalent, and shall include:
1. Site evaluation.
2. Drainage system report.
3. Peak flow rates and runoff volume calculations.
4. Safety requirements.
5. Grading plans.
6. Operation and maintenance plan.
7. All other necessary BMPs not covered in the areas listed above.
E. Certification Required: All drainage system reports, peak flow rates and runoff volume calculations, safety requirements and grading plans shall be certified by a licensed professional authorized by the State to perform such functions.
F. Conceptual Plans Not Considered: Drainage plans that are conceptual only, without engineering specifications, shall not be considered as comprehensive drainage plans.
G. Minimum Requirements For Drainage Systems: Drainage systems shall have the following minimum requirements:
1. Designed to provide primary conveyance for runoff from a 50-year frequency storm on sites with less than fifteen percent (15%) slope or a 100-year frequency storm on sites with greater than fifteen percent (15%) slope.
2. Designed to provide secondary conveyance for runoff for all flows up to the 100-year frequency storm, within defined rights-of-way or drainage easements.
3. Designed to prevent an increase of peak flows at any location for the 2-year, 10-year, 25-year and 100-year frequency storm which could cause increased inundation of any building or roadway surface.
4. Achievement of peak flow regulation by on site discharge, off site discharge with permission or participation in an approved regional stormwater management facility.
H. Amendments, Modifications: The City Council reserves the right to amend, modify and/or add requirements to the City Stormwater Management Design Manual. The design manual references in this chapter shall be to the most currently adopted version. (1952 Code § 8-15-03.01)