State plans to implement pollution collection system for I-294

I-294 brings up images of collecting tolls but, as of 2010, the tollway authority plans to start collecting pollution.

The ongoing $6.3 billion lane-widening project will culminate with the installation of bioswales, depressed patches of land planted with native grasses that help control pollution and flooding from highway runoff.

The bioswales will be installed by the Illinois Tollway along the roadside stretch of tollway running north from O'Hare International Airport to the state line after the existing road is rebuilt.

"When you lift up the entire road, a new drainage system is being put into place and these bioswales are integrated into that," said Joelle McGinnis, spokeswoman for the Illinois State Toll Highway Authority.

The tollway authority worked with the Forest Preserve District of Cook County to gain access to about 13 different strips of land ranging in widths up to 75 feet along the length of the highway between Touhy and Milwaukee Avenues with an additional piece just south of Lake-Cook Road. Altogether, the areas make up about 16 acres.

While the total area sounds small, "nothing has ever been done on this large of a scale before," said Angela LaPorte, an environmental planner with the Toll Highway Authority.

This is the largest project of this kind to be completed in the U.S., LaPorte explained. Bioswales have been frequently used in commercial and some residential developments.

But this use for a roadway is fairly unique, said Patrick Kelsey, vice president of the natural sciences division of Christopher B. Burke Engineering West, a natural environmental engineering business.

The bioswales are expected to help filter out pollutants, including lead, zinc and iron, from the roadway runoff.

"It will have an impact on metals and there are plenty of metals in roadside runoff," Kelsey said. "Where the tollway will get the biggest bang for their buck is in control of metals."

On the surface, a bioswale looks simply like grass or other vegetation but, below the ground, is a complex layering of sand, soil and drainage system that mimics the natural ground and its filtering capabilities.

Bioswales have three main functions, said Jenny Molloy, of the U.S. Environmental Protection Agency. They control water flow and flooding, pollution and soil erosion. They work by trapping suspended solids, like metals, on the vegetation and in the soil.

"[Bioswales] are designed to essentially trap the total suspended solids and some of those sediments that are coming off of the roadway," LaPorte said. "The pollutants tend to get attached to some of those sediments."

In addition to trapping pollutants, the swales help reduce flooding and slow water flow from the road, which will reduce soil erosion. In addition, the patches of native grasses will add an aesthetic element to the roadside.

But the bioswales won’t help with the worst component of highway pollution – deicing salt.

"[Bioswales] won't help with chloride," Kelsey said. "”In any region that needs to use deicing salt, and highway safety has to come first, we just don't have good mechanisms to deal with chlorides."

Unfortunately, chloride doesn't accumulate anywhere but in the lowest areas because it remains dissolved in water. This saltwater can have a dire influence on local environments accustomed to fresh water. "It's not good for fresh water systems. It's not good for fresh water wetlands. It's not good for terrestrial systems, typically, that aren't adapted to salty environments," Kelsey said.

The bioswales won't be installed until the tail end of the construction project, which is planned for 2010. Until then, the tollway will be conducting the Tollway Runoff Monitoring Project to look at the characteristics of the runoff.

“It fluctuates seasonally as you could imagine, so what we're trying to do is study that," LaPorte said.

The decision to install the bioswales came about after a number of discussions between the tollway, several state and federal environmental agencies and advocacy groups.

As part of each roadway project the tollway submits permits to the federal and state environmental agencies, LaPorte said. "Sometimes, as part of those initial discussions or as a result of a permit application, we look for ways to try new things, to incorporate demonstration projects, to really address the concerns of those agencies."

"This may be an opportunity on large scale to address large infrastructure like the tollway to try something new,” Laporte said.