by John Gessner
Thisweek Newspapers

What would a curb cut channeling stormwater into the front yard do to the resale value of a home?

Probably enhance it, said Burnsville resident Moira Webster-Larranaga, the proud owner of one of 17 rain gardens along Rushmore Drive.

This spring, city crews will make curb cuts to channel water into the rain gardens, where much of it will infiltrate the soil instead of ending up in nearby Crystal Lake.

ìI actually think itís going to be a selling point,î said Webster-Larranaga, whose garden is planted with winterberry and other species. ìIt looks nice, and itís some extra landscaping that was just grass before. And if you tell the story about the reason behind it, itís got a nice ecological advantage.î

Spread across 15 yards, the rain gardens are the centerpiece of a demonstration project on reducing runoff, which impairs water quality when it reaches the lake through the sewer system.

The city received a $117,000 grant for the project in 2001 from the Metropolitan Council and is spending $30,000 in city funds, said Leslie Yetka, Burnsvilleís water-resources specialist.

The first step was finding a neighborhood, or ìwatershed,î near the lake with residents willing to plant rain gardens in their yards.

The gardens are depressions about 10 feet wide and 20 feet long, dug 12 to 10 inches below street grade.

City staff did walking tours in seven neighborhoods to explain the project. The Rushmore Drive neighborhood northeast of Crystal Lake came out on top because of willing neighbors, suitable lots and sandy soils that soak up water.

The 280-acre Crystal Lake, popular with swimmers and boaters, has marginal water quality, earning a ìCî grade under a Met Council system of measuring lakes.

Surrounding land is almost completely developed, leaving little room for traditional runoff-capturing devices such as treatment ponds.

Webster-Larranaga said she and husband Bob were willing to do their small part to improve the lake.

ìWe use the lake quite a bit, so we were very happy to see the water quality increase.î she said.

The rain gardens were dug and planted last September with the help of a consulting engineer, who worked on the design of each garden. The curb cuts are the final step in completing the gardens.

ìMost homeowners wanted a somewhat maintenance-free, or at least reduced-maintenance, garden,î Yetka explained. ìThere are a lot of shrubs and perennials ó things like dogwoods, winterberry, wild rose shrubs, day lillies, feather reed grasses, astors.î

The curb cuts are crucial to capturing street runoff, whose sediments contain phosphorous and other lake pollutants, Yetka said.

The rain gardens wonít absorb torrential rains but are expected to absorb most water from most rainfalls.

ìOur goal is that we should be capturing at least a 1-inch rainfall event,î Yetka said. ìWe should have little to no runoff for that type of event in 24 hours. The significance of that is that most rainfall events in our area, probably 80 to 85 percent, are less than an inch.

ìItís the first flush, or first half-inch of a rainfall, that carries, some say, up to 90 percent of pollutants. If we can capture at least that first flush we should capture most of the pollutants, and if we can capture a 1-inch area, we should be able to capture most of the volume leaving a watershed.î

For two summers the city has monitored the volume of stormwater runoff from Rushmore Drive and an adjacent neighborhood. That provided baseline levels of runoff from each neighborhood.

Monitoring will continue for probably another two seasons, Yetka said. The comparison between the neighborhoods will test the project hypothesis that rain gardens reduce runoff. Runoff from each neighborhood will be measured at monitoring stations in the sewer pipes.

ìI think this is probably the first study of its kind, maybe in the country,î Yetka said.

The project alone will have little or no effect on Crystal Lake water quality, she said.

ìBut the benefit is gathering the data to show that this works, educating homeowners and showing a precedent that we can actually look at ways to go into developed areas and reduce runoff,î Yetka said.

John Gessner is at burnsville.thisweek@ecm-inc.com.

Top of Page

Check out this week's newspaper for more about your community.

Thisweek Newspapers
12190 County Road 11, Burnsville, MN 55337
Telephone: 952-894-1111 Fax: 952-846-2010