TRANSMITTAL LETTER FOR BOARD MEETING OF FEBRUARY 15, 2024
COMMITTEE ON STORMWATER MANAGEMENT
Mr. Brian A. Perkovich, Executive Director
Title
Report on Green Infrastructure, Detention, and Compensatory Storage Volumes Required by the Watershed Management Ordinance
Body
Dear Sir:
The Watershed Management Ordinance (WMO) regulates sewer construction within the District’s service area and development within suburban Cook County. It provides uniform stormwater management regulations to prevent future development projects from exacerbating flooding and protects environmentally sensitive areas. Green infrastructure, referred to as volume control in the WMO, is installed to comply with the stormwater management requirement of capturing one inch of stormwater runoff from all impervious surfaces of the development. Detention requires stormwater runoff to be retained and controls the rate at which it is released from the site. Compensatory storage is required to mitigate development impacting the floodplain.
When a WMO permit is required, the development must comply with the stormwater management provisions of the WMO. The first of the two attached tables indicate the number of permits issued semiannually since the WMO became effective. It also summarizes the development area, green infrastructure storage provided, detention volume provided, and compensatory storage provided. The total for each year and running total are also provided.
The second table includes permits and permit revisions issued for the construction of offsite volume control or detention facilities and permits that utilize these offsite facilities. To date, six offsite volume control facilities and two offsite detention facilities have been permitted and are available for stormwater trading. Of these eight offsite facilities only two will be reported on our website. The municipalities, in which the other six facilities are located, intend to utilize them for future projects within the municipalities and do not need to broadly publicize them.
Respectfully Submitted, Catherine A. O’Connor, Director of Engineering, KMF:MD
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