Who says you can’t teach an old dog new tricks?
Angie Hong
Who says you can’t teach an old dog new tricks?
People passing by the Cottage Grove Park and Ride on Wednesday, Oct. 17 probably wondered why that huge group of people was standing in the middle of a parking lot. One woman called her bus to a stop and hopped out to see if we were offering complimentary coffee to all Park and Riders, while another older gentleman asked how much we were charging for the doughnuts. (I offered him one for free.) In retrospect, we must have looked quite odd standing there on a chilly, cloud-filled day, especially considering our ample use of duct tape to anchor things in place. It turns out, though, that the Park and Ride was the perfect location for the latest East Metro Water Resource Education Program workshop – Raingarden Maintenance 101.
When the Park and Ride was built a few years back, the MN Department of Transportation was faced with a challenge. How would they prevent stormwater runoff from polluting the Mississippi River and other local water bodies? With acres of pavement in the parking lot, there would be nowhere for rainwater or melting snow to soak in, and the majority of it would wash off into the storm sewer system and eventually the river, carrying with it leaked engine oil, salt, sand and other debris.
Faced with a similar problem, many businesses choose to build large stormwater ponds alongside their parking lots to capture stormwater runoff. This only solves part of the problem, however. While ponds are able to delay the release of water to storm sewer systems, thereby reducing the potential for flooding, they can only remove some of the pollutants and do nothing to decrease the volume of stormwater runoff. In contrast, almost all of the rainwater in a natural setting is absorbed by trees and plants or soaks into the ground to refill groundwater aquifers.
Recognizing the shortfalls of stormwater ponds, MNDOT decided instead to build a series of raingardens at the Cottage Grove Park and Ride. Most likely, the majority of people who use the Park and Ride have never noticed that the parking lot islands are actually sophisticated stormwater management machines. Featuring shallow depressions with deep-rooted plants, the raingardens collect stormwater from the parking lot and soak it into the ground where it is filtered by layers of sand before eventually reaching the groundwater table. In fact, the raingardens at the Park and Ride are so effective, that they have almost completely eliminated stormwater runoff from the parking lot.
Wednesday’s Raingarden Maintenance 101 workshop was an opportunity for more than 80 people from local city and county public works and parks departments, landscaping firms and stormwater management agencies to get hands-on experience with how raingardens work and what steps are needed to ensure that they continue to function well. Many cities, including Stillwater, Woodbury, St. Paul Park and Lakeland are including raingardens as part of their building remodeling and street repair projects. While some city staff are initially reluctant to switch to raingardens from traditional stormwater ponds, they often change their mind when they discover that raingardens have both aesthetic and functional value and are no harder to maintain than storm ponds.
With a group of workshop participants huddled around a parking lot island that Wednesday, presenter Rusty Schmidt of the Washington Conservation District looked into one of the storm sewer inlets and announced, “Looks like there are cobwebs in this one. I guess it’s never had runoff.”
Angie Hong is an educator with the East Metro Water Resource Education Program. She can be reached at (651) 275-1136 x. 35 angie.hong@mnwcd.org
Posted: October 17, 2007