Planning for New York after Hurricane Sandy

Hurricane Sandy hit New York City on October 22, 2012. As with Hurricane Katrina in New Orleans, the damage came from the storm surge rather than from the wind directly. Some thousands of housing units in low-lying areas of Queens, Brooklyn, and Staten Island, three of the city's five boroughs, were damaged or destroyed. But the fraction of the city's total housing stock of approximately 3.4 million affected was quite small compared with that of New Orleans. For most New Yorkers the experience was one of disruption rather than damage to their housing. The high waters flooded subway tunnels and shut down the system. Minimal service was restored in a week or so and most of the system was running normally within a month. Electric power was knocked out in the lower part of Manhattan and scattered parts of the city but was largely restored within a week or so. Many people spent some days without heat or light and in apartment buildings tenants who couldn't negotiate flights of stairs had the experience of being marooned for several days. Many businesses were shut down until utilities were restored and, in some cases, basements pumped out. But when the U.S. Department of Commerce studied the aftermath of Sandy it found the effect on the city's economy to be minimal.28

As bad as it was, Sandy's effect on New York City was vastly less than Katrina's effect on New Orleans. Nonetheless, it was not an experience that anyone in the city wanted to go through again, and it was also a portent of similar or worse events in the future. The administration of then Mayor Michael Bloomberg quickly moved into planning mode.

There were three distinct possible approaches, and many combinations thereof.

One possibility that offered almost complete protection to most of the city was to build a barrier across the mouth of New York Harbor, as shown in Figure 14-1. Most of the barrier would be rock, but there would be a movable gate across the shipping channel (Ambrose Channel) and several other gates to allow the tide to flow in and out, and thus maintain the prebarrier ecology of the harbor and the Hudson River which empties into it. It would be the city's equivalent of the Army Corps of Engineers rebuilding the levees and flood walls around New Orleans. It would offer protection to low-lying parts of Brooklyn, Staten Island, Manhattan, and parts of New Jersey along the west shore of the Hudson River, and would protect some low-lying areas of Queens. The technology for doing this was well established. Several such barriers had been built in the Netherlands. Gates were installed in the Thames River in 1982 to protect low-lying parts of London. They have been opened and closed well over 100 times and have worked as planned. The city of St. Petersburg is protected by a long barrier from storm surges in the Baltic. The idea for a barrier for New York had been discussed some years before Sandy.29

The Bloomberg administration ultimately rejected the idea. The Mayor argued that future increases in sea level and possibly storm intensity would ultimately render the barrier unworkable. Very probably, cost was also an issue.

That left two other approaches: hardening the target and a variety of green approaches. The Bloomberg plan called for both: a lot of the first and a little of the second.

Hardening the target meant a wide variety of measures both to prevent flooding and to lessen the effects when flooding occurred. For the protection of low-lying areas the plan called for dunes, wider beaches in some places, levees, and sea walls. To protect buildings when flooding did occur the plan called for revised building codes and some funding to help property owners make improvements to the building. One improvement might be structural changes to keep water out. Another might be to place electrical utilities in a sealed, watertight enclosure. Another might be to move some mechanical systems up to a higher floor. Another might be to install an auxiliary generator so that the building would have power to operate lights and elevators if there were an area-wide power loss. Much of the disruption the storm caused in Manhattan was due to flooding of electric power substations. That could be dealt with by making them watertight or elevating them. The flooding of the subway system was caused by water coming through street-level entrances and air vents. That could be addressed with fairly simple structural changes. Several vehicular tunnels flooded and had to be pumped out. That could be prevented with gates. And so on.

When it came to the question of adjusting the city's footprint to the possibility of future Sandys the Mayor was adamant:

The barrier, at the bottom center of the figure, is shown by the dashed line between Sandy Hook in New Jersey and Breezy Point in Queens

FIGURE 14-1 The barrier, at the bottom center of the figure, is shown by the dashed line between Sandy Hook in New Jersey and Breezy Point in Queens. In the New York part of the region it would offer essentially complete protection from storm surge for Brooklyn, Staten Island, and Manhattan. It would protect the Borough of Queens from flooding from Jamaica Bay but would not protect parts of Queens that front onto the ocean. The Bronx is sufficiently high that storm surge is not an issue here. On the New Jersey side it would protect the low-lying area between the west shore of the Hudson River and the Hackensack River, an area which sustained heavy damage from Sandy. At present, the plan is off the table, but a Sandy-like event in the future may well bring it back to life.

We will build back stronger. We will build back safer. We will build back more sustainably. But we will build back here.30

After the storm the question of what was to be done about destroyed housing near the shoreline arose. Many of those with green sensibilities adopted the position that the areas should not be rebuilt, but rather the city's footprint should be pulled back in these areas. This is no different than conventional planning wisdom that building on flood plains is not a good idea, and certainly should not be encouraged with public funds (e.g., below-cost flood insurance). But the overwhelming resident preference was to rebuild, and to get some public help in doing so. The reason that they lived in this vulnerable situation was that they liked to live near the ocean—a very understandable preference—and they wanted to continue doing so. The Mayor clearly stood with the homeowners. This was a very different position from that held by the state's Governor, Andrew Cuomo. He proposed to buy up property owners' land in some flooded areas at pre-Sandy values and then to keep the land undeveloped in perpetuity. The Mayor did have some proposals for expanding or creating wetland areas and for plantings that would reduce rates of water runoff but, overall, his plan was to harden the target and tough it out. In that very basic way it was not very different from the New Orleans approach.

Sandy is much closer to us than Katrina, and New York's situation in the aftermath was far less urgent than New Orleans's, so it is not possible to say at the time of writing what New York will ultimately do. Mayor Bloomberg has been succeeded by Mayor De Blasio who has different priorities, and choices between goals have to be made. Up until the time of writing he has shown no interest in major steps to protect the city against a future Sandy.

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