Going Green On The Cheap: Low Impact Development
When most people hear of "green development" they think of big and splashy projects like wind farms, solar panels, LEED certification - the sort of thing that takes a lot of money and a whole new way of thinking to implement.
But something as beautifully simple as a flower garden in a parking lot can be a green project. An increasingly popular approach to storm water management called Low Impact Development, or LID for short, encourages rain gardens, bioswales, and porous pavement as a way to improve the health of the watershed here in Southeast Michigan and ultimately, the Great Lakes themselves.
That's because even a routine summer rainstorm causes water laden with pollutants and sediment to run off roofs, roads, and parking lots into the sewer system, and from there into streams, rivers, and the Great Lakes. Runoff also tends to be considerably warmer than water that flows naturally into a stream – sometimes up to 150 degrees during a summer rainfall. That double whammy delivers a whopping dose of trouble to the aquatic life that makes the waterways its home, while contributing to stream bed erosion.
Replacing some of those hard surfaces with plantings on a green roof, or slowing down the flow of water before it gets into the streams with a bioswale or rain garden, brings the impact of storm water almost back to what it would be if an area was undeveloped.
"Urban areas do a great job of destroying our watershed," says Don Carpenter, a professor of civil engineering at Lawrence Technological University. Carpenter has been instrumental in building Lawrence Tech's role as a leading research institution on the effectiveness of LID.
One study done by LTU students found that green roofs retain 65 to 70 percent of water, and at least a quarter inch of rain must fall before any water comes off the roof at all. Around 85 to 90 percent of all "rainfall events" fall below that threshold.
In a traditional hard-surface environment, 90 percent of rainfall goes into the waterways, while rain gardens and a flat roof allow only 10 to 30 percent to escape. And a turf grass field that's been mowed for 30 years is similar to a parking lot in terms of the water runoff it absorbs.
Carpenter has compiled an interactive map of all the LID projects in the Metro area, complete with pictures, so interested people can get a sense of what these projects look like. There are also several demonstration projects on Lawrence Tech's Southfield campus.
The beauty of Low Impact Development goes beyond efficiency – it does in fact create beauty in a grim concrete environment. Native plants and wildflowers capture and filter rainwater before it gets into waterways. These plants have deeper root systems than turf grass, which means they absorb more water more readily.
Several projects around the Metro area have incorporated LID techniques. The Southeast Michigan Council of Governments (SEMCOG) has created a LID manual for Southeastern Michigan and has been presenting workshops on LID to local communities.
Local officials are generally receptive to the idea, says Amy Mangus, coordinator of environmental programs for SEMCOG. "I would say the response is interested yet cautious, because they don't have extra money. We need to show how using certain practices can save them time and money."
Most commonly, communities will demonstrate LID techniques in a municipal project rather than mandate them for local developments through ordinances, she says.
Macomb County used LID to great effect in a parking lot project at its municipal complex in downtown Mount Clemens. To create the parking lot, it tore down a vacant auto dealership and muffler shop. Although the land was contaminated with heavy metals and petroleum, it was fine for parking. However, the county wanted to lessen the impact of those pollutants on the waterways and minimize storm water runoff, said Gerry Santoro, senior environmental planner for Macomb County.
Four rain gardens are connected by 500 linear feet of bioswales, which are essentially shallow ditches planted with grasses. To the untrained eye, the general effect is of an attractive and well-designed parking lot beautifying downtown Mount Clemens, but in fact it's kept virtually all of the rainfall for the last three years out of the Clinton River.
Interestingly, Santoro says, designing and planting the rain gardens and bioswales added only $2,000 to the $411,000 project cost and paid for itself within one and a half seasons. Savings come from not mowing and watering grass, and the depressions created by the rain gardens and bioswales allow a place for plowed snow, meaning it doesn't have to be moved all the way off site.
Wayne County Parks have implemented "Grow Zones" in Hines Park – spots where native plants have been established and no mowing is done. To prevent more stream bank erosion along the Rouge River, they've also planted native trees like dogwoods. Both were funded by part of a state grant totaling close to a million dollars.
Noel Mullet, technical projects coordinator for the Wayne County Department of Public Service, says people have been pretty receptive to the Grow Zones, although it has taken some education. "Those folks who are into the environment and nature certainly appreciate it," he says. "To those who really like the ‘green carpet' look, it looks like neglect." To that end, the areas are marked with signage explaining their purpose.
Both projects have saved the county about $4,000 in mowing costs this summer alone and provided about $85,000 worth of storm water management, Mullet says.
Beyond municipal cost savings, there are economic benefits to using LID techniques. Saving the Great Lakes is a pretty crucial one, and some studies even show that people are more willing to buy upscale goods on a tree-lined street. LID projects can also create a better sense of place and a far more pleasant environment, Carpenter says.
"Would you rather be in a place with landscaping, or in a concrete desert?" says Carpenter. "It makes a subtle difference in the quality of life you associate with that area."
Kuras is a Detroit-based freelance writer whose grandparents owned a grocery store in Detroit's Warrendale neighborhood. Her previous article for Metromode
was Upscale Markets In A Downsized Economy
Bioswales at Lawrence Technical University
Don Carpenter, professor of civil engineering at Lawrence Technical University
University of Michigan students at the Nature Interpretive Center
Macomb municipal parking lot
Grow Zone at Hines park
Photographs by Detroit Photographer Marvin Shaouni Marvin Shaouni is the Managing Photographer for Metromode & Model D
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