Prepping for Sandy 2.0

Army Corps of Engineers will erect miles of seawalls along Staten Island

A rendering of the seawall that will zig-zag across Staten Island's coast. (Courtesy Office of Governor Andrew M. Cuomo)

The United States Army Corps of Engineers is slated to begin construction on a $616 million seawall in the New York City borough of Staten Island, one of the areas hit hardest by Superstorm Sandy in 2012. The storm, which wreaked havoc on much of the mid-Atlantic coast between New Jersey and New York, exposed and exacerbated Staten Island’s vulnerability to storm surges and flash flooding. In light of predictions by the National Oceanic and Atmospheric Administration (NOAA) and other climate-monitoring agencies that the frequency of Atlantic hurricanes will increase as global warming progresses through the 21st century, local and federal officials hope that the seawall will prevent higher levels of physical damage in the future.

When Sandy struck the New York metropolitan region in October 2012, floodwater depth in certain parts of Staten Island hit 12.5 feet above sea level. Within the area protected by the proposed seawall, depths exceeded previous records by four feet and damaged 80 percent of all structures, including critical infrastructure like schools. The storm killed 43 people in the city, including 24 in Staten Island alone.

According to the U.S. Army Corps of Engineers and the office of Governor Andrew Cuomo, the seawall system will include several components, known collectively as the Staten Island Multi-Use Elevated Promenade. About 4.5 miles of buried seawall, which will be topped by a walkable promenade, will protect the area against up to 21.4 feet of seawater rise. In addition to the 0.6-mile gate in the levee, there will also be 0.35 miles of floodwalls, 300 acres of natural water storage to manage surge, and over 226 acres of tidal wetlands and ponding areas. The latter two components will have the capacity to absorb an immense amount of floodwater, forming a robust natural barrier against major storms. One priority of the project is to protect vital infrastructure on the island, including senior centers, schools, hospitals, a wastewater plant, and police and fire stations.

Rendering of a seawall with people bike riding on top

The seawall will pull double duty as public infrastructure. (Courtesy Office of Governor Andrew M. Cuomo)

While Sandy served as a catalyst to mobilize resources and agencies to officially begin the project, research that led to the ultimate seawall system proposal actually began after a pair of severe storms in 1992 and 1993. Hurricanes, Nor-easters, and superstorms present a major threat to the borough, but the low-lying parts of Staten Island also face flooding damage in the face of regular rainfall. In addition to protecting the coastline from such stress, state officials have promised that the seawall system will enhance waterfront access for members of the public. The boardwalk will be open to cyclists, pedestrians, and other hobbyists, allowing users to experience both the shoreline and the coastal wetlands. Governor Cuomo’s office also suggested that the seawall might one day serve as a tourist attraction, bringing in visitors from across the region and country.

Signing on to a Project Partnership Agreement (PPA), New York State and the Army Corps have committed to reducing the costs of flood damage in the area by about $30 million per year. The PPA opens the project up to $400 million in federal contributions, which will be added to the existing budget of $216 million—$65 million from the city and $151 million from the state. Construction is set to begin in 2020 and will hopefully be completed before the next major weather event.

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