If life gives you rain…
Between subsidence and rainstorms, both of which we have in abundance here, rain gardens make great sense.
Every time it rains, a lake springs up in front of our house. And every rainstorm seems to bend the house just a little bit closer, Narcissus-style, to its own reflection in that lake. In the past year, we’ve subsided so much that the side garage door won’t open. It swings a crack and then catches on a new fault in the concrete floor. To get to my bike, I have to take the door handle in both hands and hoist.
Our lake is a public lake, arguably. A good storm will submerge the sidewalk and reduce the parkway in front of our house from two lanes down to one. It’s an experience that draws us closer to both drivers, who slow to a crawl, and pedestrians, who climb high onto our lawn to avoid wading. Despite the communal nature of the problem, though, I don’t hope for the city to fix it. The city is busy with other things, among them maniacally pumping the water that hits the streets out to the drainage canals.
Which, in turn, dries out the subsoil. Which, in a former swamp, causes subsidence.
Into this conundrum comes Zach Youngerman, program director of Groundwork New Orleans. Youngerman is more than a believer in rain gardens; he’s a rain garden pusher. Talk to him for 10 minutes, and you’ll believe, as he does, that rain gardens can firm the earth under our houses and reduce street flooding –– and recycle petroleum-filled street runoff, reduce greenhouse gases and foster a citywide network of really cool gardens.
I’d settle for a passable sidewalk, but a green revolution would work.
“The subsoil under the city is like a sponge; it expands and contracts with water,” Youngerman explains. “Only with powerful modern pumping, it’s like a sponge that’s really dry all the time.” He squishes his fingers together to illustrate.
We’re walking down Oretha Castle Haley Boulevard, where Groundwork put in a series of curbside rain gardens in 2006. As we walk, Youngerman spouts figures: Nearly two-thirds of the city’s greenhouse gas emissions currently come from the Sewerage and Water Board’s treatment and pumping stations. It costs millions to pump water against gravity, while building gardens that let water seep back into the soil is relatively cheap.
“Obviously, we can’t just let the streets flood every time it rains,” he says. “But modern pumping keeps the water table so artificially low that it’s creating subsidence problems.”
The gardens along O.C. Haley, frankly, don’t work as well as they should. The idea of curbside rain gardens is to capture what’s in the gutter before it hits the drainage system. City rules, however, prevent existing curbs from being cut, so most of the runoff flows on past these gardens and down the street. This is a New Orleans thing. Other cities, such as Kansas City, Mo., and Portland, Ore., actually redesign curbs to divert runoff into rain gardens.
Another kind of garden awaits us in Holy Cross, where there are no curbs. On the corner of Royal and Deslonde streets, a block from the river, Sarah DeBacher and Simon Hand used to have a river of their own. “Simon had to roll up his pants and carry me piggyback to the car,” says DeBacher. With Groundwork’s help, they turned their moat into a deep trench and lined it with oyster shells. On top of this were laid, in turn, burlap sacks (used to deliver the oysters), pea stone, sand and nearly 2 feet of native soil mixed with compost and more sand. Today, it’s a wildish display of iris, papyrus, cattails and cypress. The cypress, Hand comments, put on 6 to 10 inches in their first six months.
Essentially, that’s all a water garden is: a ditch with a bunch of rubble at the bottom to allow water to percolate slowly back into a location’s subsoil. The key to building it correctly is to go down deep enough and dig wide enough to handle a volume of water. Of course, you have to situate it in a place where water is an issue. The bottom of the downspout or the boggy depression in the backyard (or the sometime-lake in the front) are good places to start.
For a fee, Groundwork New Orleans will map, plan, build and plant a customized rain garden. Youngerman, though, is always eager to educate –– and he’ll do that for free.
For further information, visit www.groundworknola.org or call Zach Youngerman at (401) 935-2113. Parkway Partners will make rain gardens the subject of its Second Saturday program on Dec. 12; for more information, visit www.parkwaypartnersnola.org or call (504) 620-2224.