Industrial N Illinois

Stormwater detention: The new convention

Stormwater detention: The new convention,ph1
2080 Lunt Avenue in Elk Grove Village, Illinois features a 30,000-cubic-foot, underground stormwater detention system.

There is one unifying concern on every industrial project that goes up in Chicago, whether it be a redeveloped infill warehouse or a new million-square-foot logistics center: water. Every site must include stormwater mitigation into the design to meet strict environmental regulations.

In Chicago, we average the same amount of annual precipitation as infamously rainy Seattle. But with fewer actual days with rain events, Chicago is essentially more prone to storms and flooding. Over the past few years, municipalities have integrated ever-stronger language into their ordinances, requiring developers to consider how their site will handle the rain that falls on it.

Out in the country

For new warehouses on greenfield sites, such as those in the I-80 or I-55 corridors, land is still relatively plentiful and cheap enough that the most economic strategy for handling stormwater runoff, a surface detention pond, is the way to go. That said, property owners and developers may be surprised upon hearing how much land they’ll have to set aside.

“The traditional rule of thumb used to be about 15 percent of your greenfield site would be dedicated to the detention basin,” said Mark Augustyn, co-founder and chief operating officer, Principle Construction Corp. “Today we’re using an additional 5 percent, so I like to advise our customers that about 20 percent of that site will need to be devoted to the stormwater detention system.”

Every square inch of impervious surface on a site, either roof or pavement, is a barrier slowing down the passage of rain to the water table. The more impervious the surface area, the higher the likelihood of flooding. And the requirements vary depending on where a site is located, as Cook, DuPage, Kane, Lake and Will Counties each have their own stormwater ordinances.

“It’s more than just holding the water back these days. There is also a stormwater quality mandate from all of these locales that is driving the size and nature of these detention ponds,” Augustyn said. “Civil engineers will really drive you crazy with this.”

Depending on the use, most ordinances require a bioswale on certain properties. These are gently sloping areas filled with a variety of vegetation specifically chosen to remove contaminants out of the stormwater runoff, cutting down not only on flooding but pollution.

“The design of these systems is more than how much impervious area do we have or how much stormwater volume we need to deal with,” said Augustyn. “We have to address water quality and filtration and the native plants we’re using to soak up the water and filter out these pollutants. It’s a much more challenging design effort to accommodate the needs of the new stormwater ordinances that are in place now.”

Back to the city

A detention pond is pretty straightforward; dig out a depression, line it with some combination of soil, sand, concrete and riprap and maybe plant some native vegetation. It’s also a cheap solution to a ubiquitous problem—until you get to an infill property, that is. In older, denser industrial areas, land prices preclude setting aside 20 percent of a site to a non-revenue-generating use.

“When you get to jobs near O’Hare, for example, where you’re knocking down buildings and putting up new ones, the developer’s cost of that property to put the new building on is such a premium that they can’t afford to have a detention pond,” Augustyn said. “They need to take that land area and turn it into some form of asset that can generate rent.”

Whether it’s a truck court, car parking or building area, every part of an infill industrial site needs to be elevated to a higher use to offset the underlying land prices. In these cases, almost universally, the solution is an underground stormwater detention system. Although these are costlier and take longer to install, the economics just don’t work out doing it another way.

“That’s what we’ve been doing in almost every single asset in the O’Hare submarket where we’re doing second- or third-generation redevelopments,” Augustyn said. “We don’t even have to worry about doing a financial model. Everybody already knows it makes sense because the land is such a premium.”

Seefried Industrial Properties recently tapped Principle Construction to build a 107,000-square-foot speculative warehouse at 2080 Lunt Avenue in Elk Grove Village. The project has all the features of a modern warehouse: 32-foot clear height, 16 dock positions, two drive-in doors and parking for 134 vehicles.

It also includes a 30,000-cubic-foot, underground stormwater detention system. When installing a system such as this one, there are a variety to choose from. Some work in lightly loaded areas such as a car parking lot, while a heavily loaded truck court will require something more robust.

At 2001 Arthur Avenue, another Elk Grove Village project that Principle Construction completed for Seefried, a complete underground storm water detention system went in to maximize the building’s footprint. While these systems make financial sense in the long run, they add to both the budget and time frame for a new build or redevelopment.

“The amount of time spent installing these is a consideration for many of our projects,” Augustyn said. “These infill sites are very tight and there are a lot of improvements jammed all into the same spot. If we take too long in one area devoted to just one trade, it really can hold up the construction of the remaining portions of the building. Speed of installation is an important element.”

According to Augustyn, stormwater requirements are a larger part of the development of new projects these days than it used to be. It also adds to the permitting process. But as our building standards grow ever more responsible to the environment, it’s evident that measures to reduce stormwater runoff are paramount at any build site.

“The old days when you didn’t do any stormwater detention at all are long gone,” said Augustyn. “Even when we go back to the second- or third-generation sites like we’re doing in Elk Grove Village, stormwater detention and stormwater quality issues all have to be met on those new sites.”