Flood Insurance: Rain gardens can help ease flooding

Kali Katerberg/Daily Mining Gazette A rain garden at Houghton’s Kestner Waterfront Park near the Chutes and Ladders area uses native vegetation and low spots to capture stormwater runoff from the parking lot.

HOUGHTON — Installing a rain garden to control stormwater runoff is a relatively simple process but includes crucial considerations like soil type and slope of the terrain.

Rain gardens can help control where runoff ends up, sending it back into the ground instead of into a storm sewer or down a parking lot. However, there are more benefits to this style of multi-purpose gardening.

Depending on the plants and vegetation used, they can attract wildlife and birds, as well as help with filtration and improving water quality, said John Gierke, chairman of Michigan Tech Geological and Mining Engineering and Sciences.

Gierke is also a professor of civil and environmental engineering at Tech and has been involved in low impact development methods like rain gardens, wetlands, permeable pavement and green roofs, such as the one at the Great Lakes Research Center.

“All of them have this purpose of trying to reintroduce stormwater back into the ground more to mimic natural conditions. So the rainfall that lands on the ground, a large portion of that infiltrates the ground and where plants can use it, and a lot of it keeps going and recharges groundwater and flows out and becomes streams and rivers and lakes,” Gierke said.

In areas with a lot of concrete or pavement, rain gardens can provide a natural area for water to soak in.

For avid gardeners like members of the Houghton Beautification Committee, rain gardens are beautiful and functional. The committee has begun implementing rain gardens around the city, all of which survived the June 17 flash flood with only a little lost mulch, said committee member Julie Waara.

The city’s rain gardens use native plants to provide for habitat for native wildlife and brighten the downtown with hearty flowers and vegetation.

To collect the water the gardens were dug slightly deeper than surrounding areas, providing a place for the water to gather before percolating into the soil.

Though fairly easy to set up in some areas, a successful rain garden would be difficult for some properties in the area, said MTU Civil and Environmental Engineering professor David Watkins.

The steep hills of Houghton and Hancock might make some properties poor sites, since rain gardens should be mostly flat. Landscaping could be modified, but the process could become cost-prohibitive.

Soil composition needs to be sandy or well-drained. Sites that don’t meet these qualities might also require dramatic landscaping, like digging up 12 to 24 inches of soil for replacement, he said.

Space is also a factor. Rain gardens should be at least 20 feet away from the home to prevent any basement damage or flooding, Watkins said. Overflow should also come into the design using rock paths or small ditches.

For land with a spot that is relatively flat, has permeable soil and a reasonable distance from a home, rain gardens can be a simple addition with many benefits.