NORTH LIBERTY — Think of them as large-scale rain gardens.

Bioswales, which manage stormwater and mitigate flooding by capturing and soaking up runoff, are gradually growing mainstream in Iowa.

Gene Schmickle of North Liberty, with Forever Green, plants vegetation in a rain garden at Penn Meadows Park in North Liberty. The rain gardens as well as bioretention basins, infiltration trenches and pervious concrete in a parking lot on the south end of the park will enhance the water runoff quality in the area. (SourceMedia Group News/Jim Slosiarek)

North Liberty is one of the leaders, with a prime example in its Penn Meadows Park.

The city of more than 13,000 residents not only used pervious concrete for the park’s new 63-stall parking lot, but installed a series of bioretention basins, rain gardens and infiltration trenches to improve water quality for nearby Muddy Creek.

The creek flows to the Iowa River, one of Iowa City’s drinking water sources and the primary source for the University of Iowa.

“Here in Iowa we’ve got plenty of rain,” said Larry Trout, who directs construction inspection and stormwater control for North Liberty. “It’s just a matter of where that rain goes.”

Bioswales and rain gardens, which capture water from roofs and parking lots, are planted in shallow depressions, typically with native grasses and plants, such as blazing star and purple coneflower that have deep root systems to soak up and filter rainwater.

The plants remove pollutants carried in runoff, including pesticides from yards and oil from parking lots.

Matt Klein, civil engineer with Shive-Hattery in Iowa City, which is working on the Penn Meadows project, noted that an acre of Iowa land receives 760,000 to 977,500 gallons of rain in a typical year.

The pervious concrete and rain gardens collect water from over six acres of the park, he said.

Rather than having rainfall rush into storm sewers and on to streams and rivers, pervious, or permeable, paving allows water to percolate into the soil.

The $313,000 project was funded, in part, with a $100,000 I-JOBS grant.

Larry Trout

Trout said businesses and homeowners are joining the effort.

North Liberty offers a cost-share grant program so residents can receive half the cost of a rain barrel, for example, or up to $750 for larger projects.

Trout said one homeowner is installing a $15,000 cistern that will capture all of the rain from the home’s roof.

Efforts also are under way elsewhere in Eastern Iowa.

A bioswale was installed last year at the former Siegel Jewelry site in downtown Cedar Rapids. Marion is working to offer businesses incentives to reduce stormwater runoff as it develops its new stormwater utility ordinance.

As Eastern Iowa program manager for the Iowa Stormwater Education Program, Stacie Johnson is keeping tabs on bioswale projects to assemble a tour for city engineers and other program members.

Stacie Johnson, Cedar Rapids Stormwater Commission chairwoman and Eastern Iowa program manager for the Iowa Stormwater Education Program looks over a public improvement project at Penn Meadows Park. (SourceMedia Group News/Jim Slosiarek)

Johnson examined  nearly a dozen sites in the Iowa City area earlier this month, checking out bioswales at the UI Athletics Hall of Fame; Johnson County Administration Building; East Side Recycling Center; homes and a 1916 apartment complex.

The tour’s goal is to showcase best practices of stormwater control.

“We can’t say it can’t be done anymore,” said Johnson, who is also chairwoman of the Cedar Rapids Stormwater Commission. “What we’re discussing in Cedar Rapids, they’ve already done.”

Cedar Rapids is updating its stormwater management ordinance with hopes to include at least some type of a “zero runoff” concept proposed by Rich Patterson, director of the Indian Creek Nature Center, 6665 Otis Rd. SE.

Johnson said the idea would be to require 100 percent infiltration of a 1-inch rain in 24-hours in new construction and major reconstruction to assist in both flood control and water quality.

Flow meters can measure incoming and outgoing runoff from bioswales to determine the effectiveness, she noted.

Patterson wants the Nature Center to lead by example, with permeable pavement installed in recent years and a new bioswale this year in its parking lot, shared by the Cedar Rapids Parks Department.

Parks Superintendent Daniel Gibbons worked with Patterson and the Nature Center’s land steward, Jean Wiedenheft, on redesigning the parking lot to dig in the bioswale, capturing water before it rushes into Indian Creek.

Another “retrofit” of an existing parking lot is taking place at Hall & Hall Engineers, 1860 Boyson Rd., Hiawatha.

Andrea Blaha and Michael Sharp, Hall & Hall landscape designers working on the bioswale, said it was important that the company set an example for work it does on other projects.

Bioswales, like other landscaping, can enhance and beautify a site, in addition to controlling runoff, they said.

Both said bioswales, like other practices, are slower to be integrated in Iowa than they are on the coasts and in larger metropolitan areas.

“It’s not second nature to everyone quite yet,” Sharp said. “Sometimes it just comes down to what the client or developer can afford.”

FYI

The Cedar Rapids Stormwater Commission has general meetings the first Monday of every month at 5 p.m. on the second floor of the Public Works Building, 1201 Sixth Street SW. Meetings on updating the stormwater ordinance are in the same location at 4:30 p.m. the third Tuesday of every month. The next meeting is July 19.