The top of the St. Louis County motor pool in downtown Duluth was not the kind of place people wanted to spend much time.
The leaking asphalt roof did have some green -- weeds sprouting in cracks -- but was mostly used as a graveyard for abandoned impounded cars.
Starting this week, the roof is being transformed into a lush garden that county officials hope will help cut the building's energy use, reduce rainfall runoff and help keep downtown a little cooler and greener on hot summer days and even warmer on cold winter nights.
It's all part of the county's official plan to cut energy use and reduce carbon emissions.
Roofers were busy Thursday laying trays of sedum -- seven different varieties designed to withstand Minnesota winters and long periods of drought.
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"It's essentially a no-
maintenance roof once they take hold. We won't even have to water them,'' said Tom Romundstad, project manager for the St. Louis County property management division. "This kind of roof costs a little bit more to start. But it will last three times longer than a traditional asphalt roof. And it's going to save us money in energy costs.''
The idea sprouted in 2005 when Tony Mancuso, St. Louis County property management director, first raised the plan with the County Board.
Engineers said the building -- which houses a workshop and the county's fleet of cars and light trucks -- probably shouldn't take the stress of parking many cars on the roof any longer, so the green roof became a viable option, Romundstad said
Eventually, most of the 18,000 square foot roof will be covered with native sedum plants. The first phase of the project will cover about two-thirds of the roof at a cost of $174,450. A $50,000 grant from the Lake Superior Coastal Program helped cover the cost.
It's the largest green roof worked on by Twin Cities-based Bachman's, which earned the contract to provide the stock. Trays of plants are being placed on a double layer of waterproof membrane on top of new insulation. It is the first green roof job for Duluth-based roofers A.W. Kuettel & Sons.
Paver blocks placed in between rows of plants will allow people to walk through the rooftop garden.
"We want it open for educational purposes. And we were thinking of a picnic table up there for people to spend their lunch,'' Romundstad said.
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Other county government changes include electricity-generating wind turbines on the government services building, solar panels on a parking garage, new windows and lighting and energy assessments for old county buildings. Even electricity-gobbling vending machines and coffee pots have been replaced.
Many of the projects have been funded by grants, rebates or cost savings. They have saved taxpayers tens of thousands of dollars in energy costs. And the county is reducing its carbon footprint -- the amount of greenhouse gasses emitted by county actions.
There are a few private homes and garages with partial green roofs in the region, and the new Unitarian Church in Duluth has a partial green roof. The Zeppa Foundation also plans a green roof on its downtown building. But the concept still is novel here.
Mindy Granley, coastal nonpoint source pollution specialist for the Minnesota Department of Natural Resources in Two Harbors, said the county motor pool project is perfect for the Coast Program's goal of reducing runoff from urban areas.
"This is the biggest green roof I know of anywhere in the area,'' Granley said. "It's going to be a great demonstration project for our area. Not only does it store storm water, which is a huge issue in a city like that, but it's adding insulation and cutting energy use.''
