Design for Troubled Waters
A New York City worker clears a sewer drain in Lower Manhattan after Superstorm Sandy.
Two large buildings stand about a quarter mile apart in Red Hook, on the Brooklyn waterfront. One is a 19th-century brick warehouse handsomely renovated to house apartments and Fairway Market, a much-beloved gourmet grocery; the other is the local outpost of IKEA in a sprawling yellow-and-blue shed whose ground floor is mostly parking. The storm surge from Superstorm Sandy wrecked Fairway, which will take months to rebuild. IKEA, by contrast, with its merchandise mostly off the ground floor, was scarcely damaged and reopened a few days later; FEMA even housed a temporary office there.
There’s a lesson to be learned there, but Stephen Cassell, a principal in New York’s Architecture Research Office, thinks we’re in danger of learning the wrong one. “The one surefire way to deal with flooding is to raise buildings off the ground,” says Cassell, who spoke at a symposium November 16 on post-Sandy urban design organized by the American Institute of Architects’ New York Chapter (AIANY). “But that doesn’t make for good urbanism.” Every disaster leaves its mark on the built environment, not necessarily for the better, as the rows of bollards and concrete planters lining the sidewalks of New York and Washington testify. The challenge will be to design buildings, public space, and infrastructure that can resist flooding without compromising other values, such as aesthetics, urbanism, and accessibility. Or inadvertently making things worse in other ways. Building owners in Lower Manhattan are drawing up plans to relocate backup generators from flooded basements to roofs—from which some were moved down as a security measure after 9/11.
Even before Sandy, the prospect of bigger storms and the certainty of rising sea levels were influencing architects and planners, even in a city like New York, whose civic motto might well be “We make our own reality.” In the wake of a summer deluge that shut parts of the subway system in 2007, the Metropolitan Transportation Authority had begun a project to replace flush ventilation grates with undulating stainless-steel louvers-cum-benches, in an award-winning design by the New York firm Rogers Marvel Architects. The city’s design guidelines for the development of Willets Point, 62 low-lying acres just east of the Mets’ baseball stadium, call for raising the entire site to 14 feet above mean sea level, incorporating a terraced public space at the water’s edge on the model of Hamburg’s HafenCity on the banks of the Elbe. If planners had been thinking that way in the 1970s, when Battery Park City was being designed on Hudson River landfill, it would have saved a lot of trouble last fall.
Building by building, the architectural and engineering solutions to flood resistance aren’t necessarily esoteric or even expensive. But they have been applied inconsistently at best, says structural engineer Guy Nordenson (see page 48). Building codes have been slow to catch up to the increased risk, lagging several decades behind, say, seismic protection. “The general attitude for a long time was, you build a levee and forget about it. They found out in New Orleans that wasn’t the case,” says Nordenson. Now the areas of New Orleans that flooded in 2005 during Hurricane Katrina are being recolonized by houses raised on pilings above the flood line, many of them built under the auspices of the Make It Right foundation. The flood line varies from place to place, obviously, and calls for different approaches. There’s a perfectly good Southern vernacular for bungalows or shotgun houses raised a few feet above the ground, but to build a house in midair demands a certain structural imagination, and some of the best examples have a touch of futuristic whimsy. The less successful examples are where the architect has plopped a turreted, gabled Spanish provincial atop a slab and then lifted it straight up off the ground. And, of course, almost none of them are accessible to the disabled, nor do they lend themselves to what Brandon Welling of Morphosis Architects describes as the porch-sitting, street-oriented working-class culture of the Lower Ninth Ward.
In its submission to Make It Right, Morphosis designed a house that sits at ground level on a base of concrete-encased foam but can rise as much as 12 feet in high water, sliding on two anchored posts that keep it from floating away. “It’s not meant to be habitable while it’s floating,” Welling clarifies, “but if it does float, you can come back to it and live in it once it’s settled.” It was built, and is occupied, but so far no one else has opted for that particular solution.
But flood resistance can’t be achieved one building at a time, says Donald Watson, former chair of the Environmental Design program at the Yale School of Architecture; it’s a zoning and planning problem as well as an architectural one. Zoning in residential areas often imposes height restrictions; raising a building above grade might mean sacrificing a floor, says architect Mark Ginsberg of Curtis + Ginsberg, a prominent advocate for better urban housing. If Manhattan office buildings are built out to their full allowable floor area, locating mechanical rooms above the basement (where they don’t count against the floor-area ratio) will reduce rentable space. These issues can be addressed by local zoning, but putting a building entrance above street level requires a ramp for wheelchair access, which not many development sites in crowded downtown neighborhoods can accommodate—and changing that requires, as they say, an act of Congress.
In the long run, planners argue, we need a new way to think about flooding. “We’ve approached this as a binary question until now—either you’re too low and you get flooded, or you’re high enough and you don’t,” says Cassell. “We’re going to have to build in resiliency. Probably 20 percent of Manhattan is landfill, and that’s always going to be vulnerable.” That might mean, for instance, designing streets for water management, rather than letting rain and storm surges drain into the same sewers that handle waste. At the AIANY symposium, Cassell presented a plan for streets paved with pervious materials above a deep base of synthetic, water-absorbent soil, with embedded discharge channels isolated from sanitary sewers. It might also mean accepting that certain places and buildings will flood, but minimizing the resultant damage by a careful selection of materials (stone, concrete block, water-resistant drywall, and foam insulation instead of fiberglass) and uses (an occasional flood might be an acceptable risk for a newsstand or a sandwich kiosk, but not a jeweler or a BMW showroom). The goal, says Rob Rogers of Rogers Marvel, is “to make it more like a bad snowstorm than an atomic bomb—you shut down for a day, you clean it up, and life goes on.”
Jonathan Rose, the developer, avoids building in areas subject to flooding but recognizes that it’s going to happen anyway, and identifies some strategies to minimize the dangers. We have to design for the possibility that buildings could be without power for extended periods, he says. Thermal insulation should be treated not just as an environmental benefit but as a life-safety issue; residential buildings should be designed to maintain a minimum temperature of 45 degrees for extended periods without heat. Similarly, apartments should allow cross-ventilation, in case power goes out in the summer, and stairwells should have access to daylight.
Rose, as it happens, is a member of the New York State 2100 Commission, which is concerned with infrastructure resilience. It’s sobering, if not downright scary, to hear him contemplate a future in which large numbers of citizens will be relying on sunlight to keep from freezing or falling to their deaths—a return to an era not just before electricity but even before fire. It’s worth remembering, as we confront an uncertain and increasingly dangerous future, that even the most advanced civilization on earth cannot escape the fate of the planet it inhabits.