Using rain gardens to educate the community about rainwater runoff is serious business at the 12 mgd (design) activated sludge wastewater treatment plant in Superior, Wis. Since 2003, the staff has built six rain gardens covering nearly 5,500 square feet, each with a different strategy to demonstrate versatility in location and size to citizens interested in building such gardens on their own property.

“The main purpose of a rain garden is to control rainwater runoff,” says Environmental Services Division research assistant Carrie Sanda, the plant’s community outreach and education coordinator. “They are much more effective in soaking up water than regular turf grass.”

The gardens are named to reflect their locations or other special features. For instance, the 900-square-foot garden built to handle runoff from the grit building is called Nitty-Gritty. Native wildflowers grow along the streetside perimeter and chokeberry shrubs went near the building. Between the two is a showcase of blue flag iris with a mixture of sedge and wildflowers.

Another larger garden built on a steep slope is called Prairie Hillside. Deep-rooted prairie grass grows here because it holds significantly more water than ordinary turf, like Kentucky bluegrass. “It’s about 1,800 square feet and shows that a garden can be built on steep hills like those of nearby Duluth, Minnesota,” says Sanda.

She says it is important for people to know that the more rainwater that stays on their property, the less goes into storm drains. “All the runoff from roofs, parking lots and other impervious surfaces can carry along pollutants that end up in the streams and rivers and finally Lake Superior,” she says. “The more rainwater that stays on the property, whether it’s homes or businesses, the better it is.”

Stormwater coordinator Diane Nelson was involved in the rain garden project from its inception. “We were awarded a grant from the Great Lakes Commission for Erosion Control and built the first three gardens in large areas of runoff,” she says. “Then we realized that most people wouldn’t need such large gardens, so we built smaller ones in more difficult areas, like the 1,088-square-foot Queen’s Greens garden which gets only brief morning sun, then rests in the shade for the rest of the day.”

Excavating and amending the soil to overcome the poor infiltration rate of the predominantly clay soil in the area was the biggest cost in building the gardens. The treatment plant staff did that work. Local contractor Leaning Pine Native Landscapes developed the designs, provided the plants, and did the initial planting.

“Since then, a lot of the work was done with volunteers from our plant and the community,” Nelson says. For instance, the 300-square-foot Neighborhood Nook garden got its name because community members helped with layout and planning. Bluebell Dell garden was planted by community volunteers taking part in a rain garden workshop hosted by the plant.

As head of the plant’s Public Education, Involvement and Relations initiative, or PEIR program, Sanda takes her message about the benefits of rain gardens directly to the community, attending local events with displays and giving out information. She explains how to design and build a rain garden using native plants that require no mowing and a minimum of maintenance.

A yearly rain barrel and compost bin sale provides another opportunity for Sanda to deliver her message. In 2010, nearly 200 barrels and half as many bins were sold throughout this community of nearly 28,000. An upcoming native tree sale and a stormwater newsletter will also promote interest in rain gardens.

A separate grant from the Wisconsin Coastal Management Project in 2005 was used to partner with the Superior Middle School to create five rain gardens at the school, each designed and built by students from two sixth grade science classes. “The seeds were harvested from rain gardens at the wastewater plant and grown under lamps over the winter so students could observe their growth,” Sanda says.

Tours of the treatment plant also serve as an opportunity to educate. In addition to city officials and the general public, each year Sanda leads ten classes of fifth graders through the treatment plant and gardens. “That’s about 350 fifth graders,” she says with enthusiasm.

“The rain gardens have been one of the things we were able to do to improve our rainwater management and education,” says plant operations manager John Shamla. “They are not only aesthetically pleasing, but practical as well.”