Engineers designing projects with exterior changes in Chicago need to be aware of a city ordinance before beginning the project. As a general requirement disturbing more than 7,500 square feet puts your project under the control of the Chicago Stormwater Management Ordinance. This holds true even if a parking lot is just being repaved or resurfaced for maintenance. The ordinance requires many items that might not fit into the budget, and could potentially reduce the useable amount of property.
Understanding the stormwater ordinance
The Stormwater Management Ordinance regulates the stormwater discharge rate, discharge quantity and discharge quality during construction and of the ongoing operation and maintenance of the stormwater management infrastructure for the entire area that is being disturbed. If there is an existing large parking lot that didn’t require stormwater detention when it was built that needs to be resurfaced, all of these stormwater components will be required if the area is more than 7,500 square feet, as most parking lots are. For many development sites, there isn’t space to provide water detention on the surface, which means that it would have to be put underground. This is an extremely expensive endeavor that could greatly exceed the project budget.
The problem is a simple parking lot maintenance project, repairing pot holes or repaving, becomes a much more costly project if the engineer is unaware of the ordinance ahead of time. And it’s important to note that this requirement is cumulative since adoption of the ordinance, so once 7,500 square feet of disturbance is met, the stormwater requirements then must be adhered to, regardless of the timeframe, whether the project is completed all at once or divided into phases.
RTM’s innovative solutions
RTM’s team of engineers is well aware of this city ordinance, which proves useful when working on various projects around Chicago. In one situation, a failing sidewalk in front of a large multi-tenant building was becoming dangerous and did not provide handicap accessibility. To fix the sidewalk problem, RTM also had to disturb the adjacent pavement. A typical design would have disturbed more than 7,500 square feet, so an innovative solution was needed to keep costs low and avoid extra stormwater management expenses. RTM designed the limits of the disturbance in the adjacent parking lot to be less than 7,500 square feet. This resulted in some areas of steeper-than-typical parking pavement slopes, but still within maximum slope requirements, while correcting the deficient sidewalk. This was worth it to the client to avoid the added expenses.
For another project, RTM needed to reconfigure the entrance approach throat for a Target store to install a traffic signal. With the ordinance in mind, RTM was able to develop a design that disturbed less than 7,500 square feet, saving the client from having to pay those additional costs to provide upgrades to the stormwater management system at the site.
Engineers need experience and local expertise
It’s imperative that engineers have experience and local expertise and do their due diligence before performing design work that takes this ordinance into account to develop the most cost-efficient solutions to save clients substantial amounts of time and money.