The City of Chicago’s Department of Water Management has made updates to its Sewer and Stormwater Requirements. A link to the full list of revisions can be found here. A few impacts to highlight from the ordinance update include:

Rainfall Intensity – Effective February 2025

The most significant change in stormwater requirements is the transition from Bulletin 70 to Bulletin 75 rainfall intensities. This change will result in an increase in required stormwater storage. Our engineers estimate the storage requirements will increase by approximately 15%. The City of Chicago has set February 1, 2025, as the effective date of transition. To maintain the current Bulletin 70 stormwater design standard, projects must be submitted to the City for stormwater review before February of next year.

Reduction in Code Compliance Triggers – Effective Immediately

• Grease basins are no longer needed for residential buildings with more than six units.
• Regulations are revised to clarify that pavement resurfacing is considered maintenance. Therefore, operations on existing facilities, like asphalt mill and overlays, are no longer considered ground disturbance and will not trigger detention requirements.  However, full-depth pavement reconstruction is still considered disturbance and reconstruction larger than 7,500 sq. ft. will still be subject to stormwater regulations.

As always, EEA is here to make sure your projects run smoothly while meeting all necessary stormwater and sewer requirements. If you have any questions, please reach out to your EEA Project Manager or Engineer.