Flood-Resistant Neighborhood Would Be 80 Years in the Making

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A team of architects and consultants is proposing to build a new neighborhood of residential towers and office buildings on landfill in the East River as part of a counter-intuitive plan to make the city more flood resistant.

The idea, called Seaport City, was hatched last year by the Bloomberg administration. It would be constructed high enough to block major storm surges from flooding the Financial District and also generate enough money to pay for itself and potentially another $900 million worth of resiliency projects around the city by selling the development rights, according to the study expected to be released today by the city’s Economic Development Corporation.

The recommended option in the Seaport City feasibility study calls for a two-block wide landfill to be constructed in the East River. Buildings shown for demonstration purposes only.

The recommended option in the Seaport City feasibility study calls for a two-block wide landfill to be constructed in the East River. Buildings shown for demonstration purposes only. (Thomas Schaller and FXFOWLE)

The $4 billion levee would, however, take an enormous commitment by City Hall and at least eight years’ worth of approvals and additional studies before ground is broken. The neighborhood would take an astounding 80 years to fully build out after that. The city, or a city authority, would issue the bonds and then pay them back by the sale or lease of development rights.

"We need to be asking ourselves difficult questions about ambitious plans where traditional solutions will be unlikely to be effective," said Daniel Zarrilli, the director of the city's Office of Recovery and Resiliency.

Mayor Bill de Blasio has spoken favorably of the Seaport City's idea, also called a "multi-purpose levee." But he did not include any money to pursue further studies of the idea in the budget plan he presented earlier this month. Zarrilli said the next step would be to bring the study — and the city's other resiliency plans — to community boards and other groups in the coming months to get their input.

"We got this study and it showed the multi-purpose levee is certainly a world-class solution," Zarrilli said. "It would work. It’s feasible. But it’s clearly a long-term endeavor that would continue to develop in partnership with stakeholders and community residents over time."

The study’s legal team, Sive Paget & Riesel, determined that the project could pass legal muster. However, some environmental groups oppose the project because it would fill in a waterway that serves as habitat for fish and other sea life.

“If we put our eggs in a basket of an infill practice like this, and litigation and controversy ensue, it may end up taking far longer than other solutions would,” said Roland Lewis, president and chief executive of the Metropolitan Waterfront Alliance. “Is this the best way to spend economic and political capital? Probably not.” 

But Seaport City supporters argue that there are few clear sources of revenue to make New York City more resilient other than building into the river. Revenues from the project would also pay for interim solutions, like a ring of seawalls and levees around the southern end of Manhattan that would be constructed in the near term, well before Seaport City is completed. It would be similar to the “Big U” proposal put forth under a design competition sponsored by the federal Hurricane Sandy Rebuilding Task Force and the Rockefeller Foundation.

The study team for the East River project, which cost $950,000 to conduct and was led by the Dutch engineering firm Arcadis, looked at 20 options for the 1.3 mile stretch from the Battery Maritime Building to just north of the Manhattan Bridge. The recommended design calls for concentrating the development at the south end near the financial district on landfill that would extend 500 feet, or two blocks, into the East River. Office buildings there would rise 40 to 60 stories, roughly the height of other buildings in the Financial District. A gentle rising slope would bring pedestrians from South Street, below the low FDR Drive, to a mound about 19 feet above low tide.

The levee would narrow further north, to allow the South Street Seaport to continue operating on piers, at least for the short-term. Closer to the Brooklyn and Manhattan bridges, it would turn into a narrow strip of parkland to provide open space for nearby public housing. The levee would bulge out again just north of the Manhattan Bridge for another apartment complex. An esplanade for biking and walking would stretch the entire length of the levee.

The preferred option calls for about 11.1 million gross square feet of residential space — roughly enough for 20,000 residents — and 7.7 million square feet of commercial office space. The amount of money the project would generate for other resiliency projects depends largely on how much affordable housing it would provide. A traditional 80/20 model (80 percent market rate, 20 percent subsidized housing for low-income families) would yield $900 million in today’s dollars over the life of the project, but only $70 million if developed on the 50/30/20 model that is increasingly coming into vogue (50 percent market, 30 percent for moderate-income families and 20 percent low-income). 

The levee is modeled on similar projects in Europe and Asia, but it would have a lower level of protection. Hamburg’s HafenCity, for example, is designed to withstand flood levels that only have a 0.1 percent chance of occurring in any given year. The feasibility study assumed Seaport City would be constructed to withstand a 1-percent-a-year event — commonly known as a 100-year-flood – and then added 6 feet to allow for sea level rise. The 100-year standard has become the norm for the United States, but Klaus Jacob, a senior research scientist at Columbia University, said that if the city is taking such big risks by building in a waterway, it should make sure to protect the new area sufficiently.

“That is not sustainable resilience. That is only short-term resilience,” said Jacobs, who is also a member of the New York City Panel on Climate Change. “When a Katrina comes along and things are not entirely maintained to that 100-year storm level, then bad things can happen. And I hope that we never have a Katrina in Manhattan.”