In its ongoing efforts to reduce the reliance on constructed infrastructure to manage stormwater flow, the City of Chicago enacted new guidelines early this year.  The overall goals are to increase Best Management Practices (BMPs) to reduce runoff, prevent polluted water from discharging directly into Lake Michigan, the Chicago and Calumet Rivers, and reduce sewer overflows and basement flooding.  Primarily, the City is focusing on stormwater control that relies on separate storm sewer systems and riparian areas to allow stormwater to infiltrate into the ground or be detained before flowing directly into water bodies.
 
The ordinance incorporates the following major changes:
· Instead of receiving a maximum allowable release rate from the Department of Water Management (DWM), developers and their consultants now must calculate the total allowable release rate.  Based on the capacity of the downstream sewers from the project site to the outlet, the most restrictive downstream capacity governs the release rate.  This change results in developers facing a longer, more costly process to determine maximum release rates.

· Projects with significant Dry Weather Flows (DWF) shall consider the average DWF as stormwater for the purpose of calculating stormwater detention.  A project is considered to have a significant DWF if the average DWF is greater than 10% of the calculated total allowable release rate.  This has the effect of increasing required detention volumes on affected sites.
· Buildings with multi-level roofs and sidewalls tributary to an internal drainage/gutter system now are required to consider 25% of the "most significant" sidewall to be a part of the drainage area.  This area is not applied to the allowable release rate.  The DWM considers the sidewall as part of the tributary area because rain that strikes the sidewall is captured on a lower roof level.  This also has the effect of significantly increasing detention volumes.

· Volume control is required for runoff from a site.  Although a variety of options are available, the City encourages options that focus on stormwater reuse or percolation.  These methods include reducing the amount of impervious surfaces, utilizing BMPs or installing rainwater harvesting systems.  In most cases, sites must capture ½-inch of runoff from all impervious surfaces to provide adequate volume control.

· Operations & Maintenance Schedules are now required.  The basic O&M requirements include frequency of inspections, responsible parties and documentation of inspections.
 
Please direct questions or concerns regarding how this ordinance may affect your City of Chicago project to Laura Shafer at lshafer@v3co.com.

 

 

 

 

 

 

 

New Federal Wetland Mitigation Rule Revises Standards
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On April 10, 2008, the US Army Corps of Engineers and the US Environmental Protection Agency jointly issued regulations on "Compensatory Mitigation for Losses of Aquatic Resources."  This new rule regulates actions taken to offset unavoidable adverse impacts to wetlands, streams and other aquatic resources authorized by Corps of Engineers permits.  The new rule, which becomes effective June 9 and is generally known as the "Mitigation Rule," replaces three previously issued documents. 
 
Compensatory mitigation can be carried out through four methods:
· Restoration of previously existing wetland or other aquatic resources;
· Enhancement of an existing wetland or aquatic site's functions;
· Establishment or creation of a new wetland or aquatic resource;
· Preservation of an existing wetland or aquatic resource.
 
The new rule establishes equivalent standards for the three compensatory mitigation mechanisms (i.e., permittee-responsible mitigation, mitigation banks, and in-lieu fee programs).  It also sets standards to improve the success of compensatory mitigation; increases the efficiency and predictability of the compensatory mitigation proposal process used to approve new mitigation banks and in-lieu fee programs; and increases public involvement in the mitigation decision-making process.
 
Rule highlights include:
· A stated preference to utilize mitigation banks and in-lieu fee programs as the primary mechanisms for implementing compensatory mitigation instead of permittee-responsible on-site or off-site mitigation. 
· The identification of a new mitigation hierarchy (listed in order of preference from most  to least preferential) as avoidance of impacts; minimization of impacts; mitigation banks/in-lieu fee programs; on-site and in-kind mitigation; and off-site and out-of-kind mitigation.
· A stated preference for approaches that encourage a watershed-based approach for site selection and implementation of mitigation banks, in-lieu fee programs, and permittee-responsible mitigation. 
· A policy that ensures mitigation credit is provided for the establishment of buffers even if buffers are non-aquatic resources such as prairie buffers or riparian set-backs.
 
Please direct questions or concerns regarding how this rule may affect your project to Tom Slowinski at tslowinski@v3co.com.