Casey Trees' rain garden in Northeast D.C.
Group's garden provides more than shade
At the headquarters of Casey Trees, a non-profit working to preserve D.C.'s tree canopy, there's a new full time employee: nature.
As the group's executive director Mark Buscaino gives a tour of his building, he pauses by the giant garden right in front of it. This is much more than a garden. It's a filtration system, also known as a bio retention planter.
"These are all 'wet foot' species. It means they can take prolonged moisture," Buscaino says of the trees in the garden. "You typically find these on stream sides by rivers, so we’re recreating that here."
The garden is tasked with absorbing and filtering all the rainwater that hits the parking lot and the roof when it rains. This kind of stormwater is actually one of the biggest sources of urban pollution.
"In the District of Columbia, 40 percent of the surface area of the city is paved so what happens is, when the rain falls down, as opposed to hitting a forested area or a field where all that water can filter through the ground level, it flushes like it's a torrent into the Anacostia and the Potomac at a very high volume, very high rate," Buscaino says. "It scours the streams, it takes that pollutant load, the oil, et cetera, into the water."
Green features can be comprehensive
This building stops that process where it starts.
"The whole building is designed to capture rainwater, and to hold it so those peak flows that create poor water quality are really minimized," says Buscaino.
There's a carpet of plants on the roof -- known as a green roof -- that filter and store water. Even the sidewalk is green.
"You can see these curb cuts here, when it rains hard enough, the water will come hit that street, run down into these inlets here into the street tree box area, and it helps to water and keep this vegetation healthy and alive," Buscaino says.
This is what's known as green infrastructure; letting nature clean up the mess that humans create. The District is spending millions to help people retrofit their homes to include green infrastructure.
Larger developments struggle with green design
But when it comes to new development, big ideas take time to trickle down.
"The bureaucracy of a number of different agencies within Washington, D.C. you have to deal with that need a certain level of coordination," says Sean Cahill, vice president of development for the Louis Dreyfus property group. "DDOE, DC Water, DDOT, Public Space." LDPG owns several large office buildings in D.C. and is working on others.
Both building designers and green advocates say building codes need changing, adding that some of those people doing the permitting aren’t yet comfortable with green infrastructure.
Cahill says that in highly built-up D.C., one big road block is the sidewalk.
"D.C. builds to the lot line, so unless we're allowed to do these rain gardens in the public space, we're not gonna be able to achieve what they want to achieve," he says. "So there's got to be some give and take here."
For green projects, DDOE must juggle priorities
Figuring out that 'give and take' is on the shoulders of D.C.'s Department of the Environment. "There's a lot of demands on the public space, so sometimes the questions are quite reasonable," says Rebecca Stack, with the District Department of the Environment. "There are utilities, there are bicycle lanes ... so all these things have to be resolved in a process that's comfortable for the reviewers."
She says DDOE has test projects going around the city to work some out of these issues, and the agency is talking to other agencies about streamlining approval for green infrastructure. They're also making a guidebook to help designers.
Mark Buscaino with Casey Trees says this can't happen fast enough. Even his project was an uphill slog to get approved.
"This is a very natural system that any home, any commercial establishment can use to control stormwater," he says. "You can see the beauty and the greenery that it provides."
Because D.C. is among the first major cities to try and make green infrastructure work, it'll be setting a national example when it does.