Title
An Ordinance to Amend Sections 5.22.2 and 5.22.3, of Chapter 55 (Unified Development Code) of Title V of the Code of the City of Ann Arbor (Storm Water Management Systems) (ORD-23-02)
Memorandum
Two amendments to the Section 5.22 Storm Water Management and Soil Erosion are proposed.
• Subsection 5.22.3 (Storm Water Management Systems) is proposed to be substantively amended to eliminate currently offered exceptions, and to revise, simplify, and streamline the currently offered provisions for alternatives to storm water management. These amendments are proposed in response to comments from the Michigan Department of Environment, Great Lakes, and Energy during a periodic, routine review of the City’s federal permits for municipal storm sewer systems.
o The UDC references the Rules of the Washtenaw County Water Resources Commissioner for the required storm water design standards, however, some exceptions are offered to certain developments. For example, sites that propose development activity that is approved the Planning Manager which doesn’t increase the total amount of impervious surface do not need to comply current standards no matter how much impervious surface exists. This exception is proposed to be eliminated. With the proposed amendment, exceptions will be linked to the size of the site (only those less than 1 acre), not the result of the proposed activity.
o The current provisions for alternative storm water detention has only been utilized once in the 20-plus years it has been offered. The proposed changes will allow more staff flexibility when site constraints make it infeasible to meet the full storm water management volume while still maintaining the intent of the section.
• Subsections 5.22.2 (Single and Two-Family Residential Storm Water Management) and Subsection 5.22.3 are proposed to be reorganized, without any substantive changes other than what is proposed to 5.22.3, to provide tables with compliance criteria and additional headings to more easily find and understand the standards and requirements.
o Subsection 5.22.2 will clearly outline when storm water management must be provided (for both single and two-family residential and all other land uses)
o Subsection 5.22.3 will (for both single and two-family residential and all other land uses) identify the review responsibility of the required system in Paragraph A, provide the volume or level of storm water management needed in table form in Paragraph B, note the standards and procedures for designing the management system in Paragraph C, explain approval in Paragraph D, and offer alternatives in Paragraph E.
Attachments: Ordinance to Amend Chapter 55 (Storm Water Management Systems)
October 18, 2022 Planning Staff Report
October 18, 2022 Planning Commission Minutes
September 2, 2022 Memorandum from Jerry Hancock, Stormwater and Floodplains Programs Coordinator
Ordinance to Amend (Storm Water Management Systems) Annotated Strikeout
Staff
Prepared by: Alexis DiLeo, City Planner
Reviewed by: Brett Lenart, Planning Manager
Derek Delacourt, Community Services Area Administrator
Approved by: Milton Dohoney, Jr., City Administrator
Body
(See Attached Ordinance)