The project came together recently, and rather quickly as the result of work and agreement from several campus areas. Involved are the Department of Biology and the College of Arts and Sciences, and the College of Built Environments and its Department of Landscape Architecture. Apprentices with the Seattle local of the Roofers and Waterproofers Union did much of the manual work.
"I'm really excited about this, and I'm struck by how beautifully these different departments and sectors on campus integrate on this type of project," says Doug Ewing, manager of the Botany Greenhouse, who also thanked Facilities Services for its assistance and permission.
The shed has a corrugated steel roof on which was added a protective plywood deck and a layer of water-resistant EPDM (ethylene propylene dilene monomer) rubber as a sealant. Concrete squares are used as borders and a railing has been added for safety.
On top of the protective layer are plastic trays, 4 inches and 8 inches deep in different parts, that host the plants to make the green roof. "They drain slowly so they retain rainwater for a certain period of time and keep it around so the plants can use it, and then it slowly drips away," explains Pierce.
The trays are filled with three types of plantings: one section is filled with sedum, a leaf succulent often used as ground cover; another with various edible plants and vegetables planted and maintained by the UW Farm program; and the third featuring plants native to the region. "We're putting in native plants as a sort of experiment," Pierce says. "We're going to grid it off and map out where each one grows, so we know who's alive and who's dead."
Many of the materials for the project were donated by Snyder Roofing of Snohomish, which has a similar experimental green roof over one of its materials sheds and is studying different technologies and how they interact with stormwater runoff and water quality.
"Right now there's just a tremendous amount of interest in this whole idea of green roofs and green walls," says Ewing. He's particularly interested in the educational element of the green roof, and the notion that school children here on campus tours will see it as an example of what can be done.
"What motivates me is getting people interested in plants—growing plants and noticing plants and sort of recognizing that plants are important," he says. "It's... what we've been doing here with this botany greenhouse for decades. And having the chance to put a little display green roof up is just another little component of all this."