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Wetland Restored as Part of Oak Creek's Main Street Development

S Bence
Detention pond west of Oak Creek development slowly feeds storm water into natural wetland.

Oak Creek’s new civic center abounds with sustainable features – natural light pouring into the buildings, LED lights and geothermal heating and cooling. But what has most excited city’s environmental engineer, Susan Winnen, about the new Drexel Town Square development is the wetland.

Located next to the former industrial site, this parcel of land survived decades of intense activity. The 18 acres have now been christened Emerald Preserve.

Credit S Bence
Walker enjoys Oak Creek's new preserve trail.

It includes a paved path and boardwalks, called Dale Richards Trail – named for a former mayor. Winnen says teams added at least 80,000 native plants throughout the preserve.

“One of the things we tried to emphasize is habitat for pollinators, because a lot of people aren’t yet aware, but for instance Monarch butterflies are becoming extremely rare. Their populations have crashed. Part of that is because they don’t have access to milkweed, which is the only plant that caterpillars will eat,” she says.

When spring comes, Winnen says a sea of caterpillar food and inviting plants will sway and attract honey bees and other native pollinators.

Credit GRAEF

As the vision of Oak Creek’s new city centerhub began to crystallize, inspiration struck because of the area’s spongy nature, she says.

Winnen's specialty is storm water management, so she knew Oak Creek had a chance to raise its innovation bar.

“I thought of what this should be; and when I bounced it off of management and elected officials, they also saw the potential and it just went from there,” Winnen says.

When rain used to fall, about 80 percent of the massive industrial site drained into a large storm sewer. Today the parcel seeps into the wetland, which cleanses the water.

Credit Fred Hampe
Preparing the former industrial site for its new life required removal of more than 2,000,000 sq feet of concrete, asphalt and exposed foundations, much was repurposed. "We also uncovered an additional 10,000 cy in buried slabs, caissons, piles, and foundations which was also crushed and recycled," Fred Hampe, KM Development Corp.

Winnen admits, it took heaps of human-induced hydrology to redirect the storm water.

“On the northeast corner there are three bioswales. We have the pervious pavement and there’s a lot of pervious pavement in the roads. So between all of those we get enough treatment to remove what they called the suspended solids,” Winnen says. Those are pollutants.

“The water from the entire site comes to this pond, or this pond to the north and from here, it discharges into the wetland,” Winnen says.

Oak Creek’s wetland can now handle more than 11 million gallons of rain.

Credit S Bence
The civic center parking lot is made with pervious pavers. "The rain water goes into the pavers and through some stone, and to the extent it can soak into the subsurface. Then it goes into a rain garden on the west end of the parking lot where it is further stored in some engineered soil. The plants and roots uptake the moisture and use it to grow," Susan Winnen says. Water eventually makes its way into a detention pond if storms are heavier.

Winnen says among the partners pivotal to the project was the U.S. Fish and Wildlife Service. The agency helped streamline the permitting process.

"Additionally, and perhaps as importantly, all agreed that showing the water holding capacity of a large natural wetland was important and would benefit the public recognizing how important wetland function is to flood prevention," she says.

Credit S Bence
Posts like the one far right are designed to support an Eagle Scout project. "My plan is to build and install 18 various types of bird houses, duck and bat houses. Several ... will include wireless pinhole cameras inside as well as wireless surveillance cameras to capture what is happening on the outside. The cameras will feed to TVs inside the new public library. I hope this will encourage our residents to explore both the wetlands and the library." Oak Creek scout Steven Raymus.

Everything from frogs and turtles to a green heron and mink have been spotted on the preserve.

“And when you come in here, especially during autumn there are just tons of birds, eating all the seeds,” Winnen says.

Credit Midwest Floating Island

Another attraction coming in spring are three floating islands. A team will anchor them in the largest storm water detention pond.

Winnen says they’re meant to do more than provide attractive habitat. “One of the challenges of an urban environment is fertilizer. If you get too much nutrients into wetlands you get algae. So the floating wetland islands, they have vegetation and as the roots grow down, they’ll actually will take nutrients out of the water and use them to grow the plants,” she says.

No matter how the islands fare, Winnen calls the project a success.

She says city leaders and developers alike embraced the environmental and monetary value of restoring a wetland in a community that's re-imagining itself.

Susan is WUWM's environmental reporter.
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