1. Installation of Facilities. Each applicant who is required to have coverage under General Permit No. 2 for a site shall install post-construction stormwater management facilities as set forth herein and as approved by the City during site plan, platting, or construction plans.
2. Maintenance of Facilities. Each applicant or its successor person(s) or entity shall be responsible for maintaining all stormwater management facilities or BMPs as approved by the City.
3. Proof of Construction of Stormwater Facilities.
A. For sites equal to or greater than one acre, each applicant must provide to the City as-built plans detailing dimensions and elevations as well as a certification that stormwater management facilities or BMPs were built as part of the approved development that includes the site.
B. For sites less than one acre that are part of a common plan of development and for which the applicant establishes that stormwater management facilities or BMPs were or will be built to address all properties (either collectively or individually) within the development, each applicant must provide to the City a copy of the notice of discontinuation for General Permit No. 2 applicable to the property.
4. Adoption of Specifications. In 2024, the Iowa Legislature passed new regulations that limit how cities and counties can enforce local stormwater post construction requirements. The City hereby acknowledges the new Section 364.3(18) of the Code of Iowa relating to the regulation of topsoil and storm water at construction sites and incorporates limits into the Waukee Standard Specifications for Public Improvements for management of stormwater.
5. Adoption of Preferred Specifications. The City hereby adopts the Iowa Stormwater Management Manual (ISWMM) and the Waukee Standard Specifications for Public Improvements for management of stormwater. The ISWMM is written as a guideline recommending certain techniques and advising against others in order to accomplish goals related to managing water volume and quality. Therefore, where the ISWMM states a design element or technique is “essential” it is required by the City. Where ISWMM states a design element or technique is “target” such design element or technique is desired by the City and every effort shall be made to accomplish. Where ISWMM states a given design element or technique is “advisory” this design element or technique shall not be used within the City.
6. Alternative Specifications. In cases where Section 364.3(18) of the Code of Iowa does not speak to a stormwater issue, such as sizing or installation of pipes, the City follows the Iowa Statewide Urban Design and Specifications (SUDAS), the Waukee Standard Specifications for Public Improvements or the Iowa River Restoration Toolbox Streambank Stabilization Guide as applicable.
7. Drainage and Detention of Treatment Areas. Each applicant must include in the site design those stormwater management facilities of BMP that will convey drainage through the property to one or more detention or treatment areas such that no development shall cause downstream property owners, watercourses, channels, or conduits to receive stormwater runoff from the proposed development site at a peak flow rate greater than that allowed by the policy or standard in effect at the time of approval of the development unless such requirements are waived by the City. Nothing contained herein shall prohibit the City from changing the policies or standards in the future, or from requiring the site to comply with the new requirements.
8. Compliance with City, State, and Federal Permit Requirements. Each applicant shall comply with all other applicable City, State, or federal permit requirements as they apply to the City or to the property.
9. Regional Detention Facilities. At the discretion of the City, the applicant may satisfy the post-construction stormwater management requirements by ensuring the conveyance of the stormwater discharge from the property to a regional detention facility. For purposes of this chapter, a “regional detention facility” shall be wet or dry detention basins, which are designed to accept stormwater runoff from two or more sites that are required to obtain a State NPDES General Permit No. 2 and that otherwise complies with all City, State, or federal permit requirements as they apply to stormwater management requirements for those sites.
10. New Development. Any new development of land adding more than 10,000 square feet of new impervious surface shall provide stormwater management as outlined in Section 364.3(18) of the Code of Iowa and the Waukee Standard Specifications for Public Improvements. This threshold is a cumulative amount of new square footage and may be reached over time in increments. At such time that a development site exceeds 10,000 cumulative square feet of new impervious surface the site will be required to come into compliance with this chapter.
11. Redevelopment.
A. Any redevelopment of land adding more than 10,000 square feet of new impervious surface but disturbing less than 50 percent of the site shall provide stormwater management as outlined in Section 364.3(18) of the Code of Iowa and the Waukee Standard Specifications for Public Improvements. This threshold is a cumulative amount of new square footage and may be reached over time in increments. At such time that a development site exceeds 10,000 cumulative square feet of new impervious surface the site will be required to come into compliance with this chapter.
B. Any redevelopment of land disturbing more than 50 percent or more of the site shall provide stormwater management as outlined in Section 364.3(18) of the Code of Iowa and the Waukee Standard Specifications for Public Improvements.
12. City Projects. Stormwater management standards per the ISWMM guidelines for water quality and channel protection shall apply to all City projects including new City parks and buildings.
13. Exemptions. The following activities shall be exempted from meeting the stormwater management standards of this chapter:
A. New development or redevelopment adding less than 10,000 square feet of new impervious surface and if in compliance with a previously approved stormwater management plan.
B. Removal and replacement of impervious surface exactly matching location and area of existing impervious surface.
C. Logging or agricultural activity that is consistent with an approved soil conservation plan or timber management plan prepared or approved by the appropriate agency, as applicable.
D. Additions or modifications to single family structures.
E. Repairs to any stormwater management BMP deemed necessary by the City.
F. Linear reconstruction projects, such as road construction, that are not associated with a larger planned development.
(Section 103.02 – Ord. 3115 – Jul. 24 Supp.)