Title
City of Ann Arbor Environmental Commission Resolution in Support of a revised Public Street Stormwater Management Guidelines Policy
Memorandum
On February 18, 2014, City Council passed Resolution R-14-051 adopting a Green Streets Statement consisting of Stormwater Guidelines for Public Street construction and reconstruction. The resolution and policy were the result of work by the Environmental Commission Water Committee with assistance from City Staff (Systems Planning, Engineering, and Public Works units of Public Services).
During the drafting of the original policy the Water Committee and City Staff came to the conclusion that the most common denominator in green infrastructure is infiltration of stormwater on-site where it is generated. As such, a policy statement regarding stormwater management guidelines for public street construction and reconstruction was developed to set infiltration standards based on the ability of the project site to infiltrate stormwater.
In 2023, the Systems Planning Unit, Water Group was requested by the Environmental Commission to provide data regarding some of the Green Streets projects that the City has successfully completed. That data was provided in a September 29, 2023 memo titled “Green Streets Policy - Implementation Update”.
As a result, City Staff have reviewed and are proposing revisions to the Green Streets Policy based on almost 10 years of implementation experience. Over the past several years, staff has encountered challenges to applying the Policy successfully. A change in preventative road maintenance changed the way that the City maintains and rebuilds roads. Because of this change in practice, there were fewer opportunities to implement the Policy. Thus, City Staff have been working to determine a more effective method to work with road projects to increase infiltration.
Staff now recommends revisions to the Green Streets Policy. Here is a summary of the proposed revisions:
• Change policy title to Public Street Stormwater Management Guidelines
• Rewrite to calculate volume for the full right-of-way within the project limits.
• Clarify that the policy does not apply to preventative maintenance and resurfacing where the subsoil/full road base is not disturbed.
• Apply policy to underground utility projects that disturb at least half of the road width base at the CIP level.
• Add guidance on soil borings (where, depth (20 ft), ect.)
• Allow multiple infiltration standards on one project to be used for different soil zones.
• Move note about following the “County stormwater Rules” to the first paragraph of the policy.
• Update Chapter 63 to UDC 5.22.3
• Describe the process for a PSAA waiver.
• Describe the maintenance plans, who develops (project designer), who reviews (Water Quality Manager).
• Describe the design/review process as a collaboration with Public Works, Systems Planning Staff, Engineering (Project Designer)
Staff
Prepared By: Systems Planning Staff
Body
WHEREAS, impervious surfaces are major contributors to stormwater runoff pollution and volume;
WHEREAS, in Ann Arbor, rights-of-way include the public streets and the stormwater pipes. Public streets are actually part of the stormwater management system since they receive runoff from adjacent parcels and convey the stormwater to the piped system;
WHEREAS, the City of Ann Arbor’s NPDES permit requires action related to stormwater management;
WHEREAS, the City is subject to a Total Maximum Daily Load (TMDL) restriction by the State of Michigan for biota (total suspended solids), E. coli and phosphorus from storm water;
WHEREAS, weather models are predicting increased frequency and intensity of intense stormwater events;
WHEREAS, Infiltration is the stormwater management goal for green infrastructure;
WHERAS, On February 18, 2014, City Council passed Resolution R-14-051 adopting a Green Streets Statement consisting of Stormwater Guidelines for Public Street construction and reconstruction;
WHERAS, City Staff are proposing revisions to the Green Streets Policy based on almost 10 years of implementation experience with the policy;
RESOLVED, that the Ann Arbor Environmental Commission is fully supportive of the original Green Streets Initiative and recognizes the necessity to update the policy, and hereby recommends Ann Arbor City Council direct City Staff to implement the attached revisions to the Policy Statement regarding Public Street Stormwater Management Guidelines.