In 1927 at the confluence of the Detroit and Rouge Rivers, Henry Ford began to mass produce the famous Model A, the latest in his legendary line of mass produced cars. Today, a newly renovated Ford Truck Assembly Plant now sits on that 243-hectare site. It is the company's largest single industrial complex. The plant also has the world's largest "living roof."
The roof of the Ford Truck Assembly Plant is as big as eight football fields, some four hectares big, and right now, it is all in bloom. It is a sea of yellow flowering sedum. The succulent and drought resistant plant attracts birds, bees and butterflies. Ford Vice President for Communications Tim O'Brian says the company believes the project makes good environmental and economic sense.
"It keeps our building cooler in the hot summer than it would otherwise be, and warmer in the cold winter, reducing our heat and electric bills," he said. "It extends the useful life of this flat roof by protecting it from the sun. On a very hot sunny day like today we think that our green roof on the Dearborn Truck Plant is going to last twice as long as a roof would ordinarily last in this area, and that is going to save us millions of dollars." At its peak in the 1930s, the plant site had ore docks, steel furnaces, coke ovens, glass furnaces and plate glass rollers. It employed over 100,000 people. Little thought was given then to toxic waste disposal or to soil contamination around the plant site. Today the unwanted soil could be trucked to a landfill, an environmentally unsustainable and expensive proposition, says Ford's Tim O'Brian.
"Rather than do just that, we have started a really interesting experiment with the University of Michigan, Dearborn and Michigan State University using natural plants to essentially break-down the chemical contamination that is there and restore the soil to a healthy condition on the site," he said. "Once again, it saves us money. It doesn't require us to fill up a landfill somewhere. We've got an acre and one half [about a half hectare] plot that we are following very closely with the EPA [Environmental Protection Agency] and our state regulatory authorities."
Clayton Rugh with Michigan State University's Department of Crop and Soil Sciences works on that project with Ford Motor Company. Beside soil remediation, Michigan State is evaluating growing conditions, rainwater retention and temperature at the plant. It also has 48 other test platforms on the university campus. Mr. Rugh says one of the major documented advantages of a green roof over traditional roofing is its capacity to absorb rainwater.
"Green roof systems can capture that rainfall that comes in and allow it to slowly percolate through that growing soil or soil type material and then the plants will pick up a lot of that and re-evaporate that into the air, retaining at times up to 90 to 95 percent of the rainfall that comes down on the roof," said Mr. Rugh. "So you can imagine they greatly reduce the amount of water that discharges off these rooftops."
And that, says Ford's Tim O'Brian, helps improve water quality not just around the plant but throughout the entire region.
"The Ford Rough Center is right on a river which empties into the Great Lakes system. This green roof captures rainwater and absorbs it in the roof, this is rainwater that in a typical manufacturing site would hit the hard roof, pick up what ever surface contamination is there and go directly into the river," he added.
Steven Peck wants green roofs to cover North America. He heads an industry group called "Green Roofs for Healthy Cities" to promote the idea. He says it will take training, education and public policy support for the idea to catch on. He suggests several initiatives to make that happen.
"One is to have governments in their own buildings to put green roofs on," said Mr. Peck. "Another is to provide some kind of a grant or tax incentive or something like a density bonus, which allows building owners to add a few more floors in exchange for a green roof, which already exists in Chicago and Portland. There is a range of policy instruments that can be used to provide some incentives for private building owners to implement green roofs because the costs are higher."
Steven Peck adds that in the long run, the public benefits greatly outweigh the initial costs. Citizens can make their own judgements from the 25-meter high observation tower at the Truck Assembly Plant in Dearborn, Michigan, or from other green roof buildings that are beginning to sprout all across America.