Of Rain and Rivers
It was a dark and stormy night. Rain fell steadily on rooftops, down gutters, along streets and sidewalks. It poured into drains, where it joined the current already rushing through the pipes beneath the streets. Invisibly, the rain water became a nasty cocktail of toxins as it flowed along.
The combination of rain and pavementby themselves ubiquitous and seemingly harmlesshas replaced illegally dumped chemicals as the pollutant du jour for the nation's rivers. Rainwater carries motor oil, brake-lining residue, dog feces, and other noxious substances that collect on pavement down into drains that empty directly into rivers. Rivers also suffer from pavement's impenetrable seal over the soil. If rain can't soak in, the level of subterranean ground water (which gradually replenishes rivers and streams) decreases and the likelihood of flooding during storms increases.
But pavement is here to stay. The solution is to catch rainwater before it reaches the streets and storm drains. "Today's mantra is 'Start at the source,'" says associate professor of landscape ecology Robert France, who teaches a workshop in urban storm-water management at the Graduate School of Design. France encourages individuals, businesses, city governments, and even universities to collect storm water earlybefore it's tainted by pavement's poisonsand reuse it for irrigation, decorative fountains, or so-called "green roofs" (extensiveand not necessarily accessiblerooftop gardens with sufficient soil and plantings to absorb rain). "We need dispersed micromanagement [of storm water], starting with lawns, driveways, rooftops, and buildings," he says.
Landscape engineers, who usually focus on watersheds outside residential sites, such as suburban industrial parks, customarily design detention ponds (which collect rain from sewer pipes and gradually release it into rivers) or infiltration systems (which hold water and allow it to absorb into the soil). These methods, although widespread and effective, are costly and require plenty of space. "They're hard to do in urban settings," says France. He decries the prevailing "pipe-to-pond mentality" that views "storm water as a nuisance" and hinders engineers from considering more environmentally sound alternatives.
A year ago, however, two of France's students won a national competition aimed at changing this paradigm. Sponsored by the Environmental Protection Agency and MIT, the competition challenged landscape architects and engineers to design creative, replicable, and affordable ($10,000 or less) methods of managing storm water at a Cambridge residence located near the Charles River. The winning proposal will serve as a model that local residents can replicate.
A pipe (above) carries runoff and pollutants into the Rivanna River in Virginia. The winning stormwater design's "rain chain" of linked copper funnels (below) drips into a buried rock filter at its base. Below, a pergola has roof beams of PVC pipes, linked into a network of rain channels draining into several rain chains.
|Courtesy of Katherine Alberg Anderson and Gweneth Newman
Third-year landscape-architecture students Katherine Alberg Anderson and Gweneth Newman used gardens and rain barrels to keep storm water on the property and designed gutters and stone streambeds to direct runoff to plantings and gardens. But their proposal's most striking featurespecifically praised by one judgewas its unusual embrace of rain's aesthetic and sensory qualities. Instead of treating storm water as an annoyance to be removed swiftly and soundlessly, Anderson and Newman celebrated rain's soothing patter and appealing shine on stones and plants. They designed a "rain chain" pergola: a series of connected copper funnels that hang from gutters and over paths to direct runoff from the roof into gardens. As rain falls, it tinkles pleasantly against the funnels. "The rain chains drape on either side of the walkway, enhancing the sight and sound of cascading water on rainy days," Anderson and Newman wrote in their proposal. The stone streambeds gleam during storms, but otherwise remain dry, "drawing attention to the ephemeral nature of rain."
The design's other featuressuch as barrels to collect rain to water the gardenare popular among environmentally savvy homeowners, but professionals typically neglect them. "Sustainability is generally not in the landscape architect's toolkit," says Anderson. "It's not taught." But both students envision the completed project (construction should finish by spring) as an educational tool. Because homeowners can replicate each feature separately and cheaply, they can easily customize the design for their own yards. "The designs are very durable, very do-it-yourself," Anderson explains. "We may even get the neighbors to help with the installation."
Although pleased with the competition's objectivesand his students' designFrance remains discouraged by the community's general unwillingness to embrace storm-water management strategies even as individuals readily complain about flooding. "Walk around. How many people are using rain barrels?" he asks. "Even Harvard"with its many flat roofs and sloped lawns with drains emptying directly into the Charles"is a poor environmental citizen."