Ordinance & Administrative Rules
The Wayne County Stormwater Control Ordinance (Enrolled Ordinance No. 2021-526a) and Administrative Rules (Resolution No. 2021-526b) assist in compliance with the mutual requirements of the County, local government, and other public agencies under the federal NPDES stormwater regulations. These requirements include the development, implementation, and enforcement of programs to manage stormwater from new development and re-development projects. Implementation of measures for long-term control of stormwater from development projects helps to minimize flooding, streambank erosion, loss of or damage to natural resources, and water quality impacts for the protection of the public health and safety. Partnerships between the County, local government, and other agencies that influence development and stormwater controls help ensure that the stormwater management programs are effective.
The Wayne County stormwater regulations, adopted on October 19, 2000 by the Wayne County Commission, and subsequently amended in August 2003, December 2006, and August 2021 consist of the following documents:
- Stormwater Control Ordinance
Provides the legal authority for the County to require that stormwater control systems are implemented by development projects subject to the Wayne County stormwater control regulations.
- Stormwater Control Administrative Rules
Provides quantification of the requirements to comply with the Stormwater Ordinance.
- Stormwater Standards Manual
Provides standards and guidance for design of different types of stormwater control measures that can be used to comply with the requirements established by the Stormwater Administrative Rules. The Standards Manual also provides other useful information including example calculations for design of various types of stormwater measures, a listing of contacts for different types of permits necessary for construction projects, and a "plain English" explanation of the Stormwater Control Ordinance and Administrative Rules.
Which Types of Development Projects Do the Ordinance and Rules Apply To?
The Wayne County Stormwater Ordinance and Administrative Rules apply to development activities as described below:
- Residential, commercial and industrial subdivisions
- Mobile and manufactured home parks
- Projects that impact stormwater runoff into or around new or existing:
- Wayne County Road rights-of-way
- County Road drainage facilities
- Storm sewer systems owned, operated or controlled by the County
- Projects that impact stormwater into or around a Wayne County Drain
- Projects that impact stormwater into, on, or through properties owned by Wayne County (e.g., County parks)
- Projects developed, designed or constructed by Wayne County
- Multi-unit residential development (e.g., condominium) projects that impact stormwater runoff in, around, or to watersheds that are included in the County's Michigan Stormwater Permit for municipal stormwater discharges.
Persons intending to engage in these activities are required to apply for and obtain a stormwater construction approval from the County prior to commencing onsite work.
What Do the Rules Generally Require for Development Projects?
Under the Wayne County Stormwater Management Program, stormwater control systems must be selected and designed with two main objectives: flood control and water resources protection. Minimum performance standards that stormwater systems must achieve to meet these objectives are:
- Stormwater control systems with drainage areas greater than or equal to 100 acres, the peak flow rate of stormwater runoff
leaving the development site must not exceed 0.15 cfs/acre for a 100-year recurrence interval storm.
- Stormwater control systems with drainage areas less than 100 acres, the peak flow rate of stormwater runoff leaving the
development will be determined based on a variable release rate curve for the 100-year recurrence interval storm, equal to 0.15
cfs/acre for 100-acre developments, gradually increasing to 1.0 cfs/acre for developments 2 acres and smaller.
Water Resources Protection
- Stormwater control systems must be designed and constructed to remove 80 percent or more of the total suspended solids (TSS) load from the development site or limit the peak TSS concentration to 80 mg/L for the first one (1) inch of rainfall (First Flush Treatment/Water Quality Control, WQC).
- Stormwater control systems must be designed, where soil/groundwater conditions permit, to infiltrate the first one (1) inch of rainfall over the site development (Channel Protection Volume Control, CPVC).
- Stormwater control systems must be designed and constructed to store and release the volume generated by a 1.9 inch storm event for a minimum discharge duration of 48 hours (Channel Protection Rate Control, CPRC).
Wayne County has established general design standards to be met by all stormwater systems, and specific design standards to be met by certain components of stormwater systems. These standards help ensure that each component is designed, operated and maintained such that the performance standards are met. Chapters 6, 7, and 8 of the Standards Manual provide detailed information about standards and guidance for designing stormwater system components to satisfy the performance standards.
The Wayne County Stormwater Control Ordinance and Administrative Rules were deliberately written as a performance-based program in order to provide developers with flexibility to design stormwater systems to best fit the situation at each site. Developers and designers of stormwater systems in Wayne County may select any combination of stormwater control elements which meet the performance standards provided that the designer's selection: (1) complies with other requirements of the Ordinance, Administrative Rules, and Standards, (2) complies with other applicable local, state, and federal requirements, and (3) does not conflict with existing local stormwater management plans. Wayne County has published our "Stormwater Standards" manual to provide developers/designers with information on the variety of control practices available to meet the performance standards of the Wayne County Stormwater Control Ordinance and Administrative Rules.
How are Stormwater Systems Maintained?
Long-term maintenance generally begins when construction of the stormwater system has been completed and the stormwater construction approval is released. The Property Owner is responsible for the long-term maintenance of stormwater control systems and shall be the Permit Holder under the long-term maintenance permit (M-permit). The local unit of government in which the stormwater control system is located, or other public entity approved by the County, must also execute the M-Permit and guarantee it will assume jurisdiction over and accept responsibility for the long-term maintenance of stormwater control systems that require a County stormwater construction approval. The long-term maintenance must be conducted in accordance with a long-term maintenance plan and schedule approved by the County if the Property Owner fails to maintain the stormwater control system. This perpetual maintenance guarantee by the local unit of government or other approved public entity shall be made by a resolution or equivalent instrument, the form of which resolution or equivalent instrument shall be as provided by the County and issued without change, unless otherwise agreed to and approved by the County.
Ordinance Implementation and Additional Information
The Wayne County Stormwater Control Ordinance and Administrative Rules are implemented through the existing review and permit processes of the Permit Office of the Wayne County Department of Public Services, Engineering Division. Copies of the ordinance, rules, and standards manual are also available through the Permit Office (33809 Michigan Avenue, Wayne MI 48184, (734) 858-2757).