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The Staten Island Seawall: A Formidable Defense

When Hurricane Sandy smashed into the East Coast in 2012, New York City’s Staten Island was overwhelmed by massive waves that swept away properties and killed 24 of the dozens of people who eventually died in the storm. With a population of almost half a million, low-lying Staten Island was no match for the waves whipped up in New York Harbor, one of which reached a record 32.5 ft. high.

Forget about that wall at the Southern border. By 2025, Staten Island will be fortified by a towering seawall running 5.3 miles along the coast, an engineering feat designed to ward off the future threat of extreme flooding.

The plan calls for a series of dams, earthworks and concrete barriers culminating in a pedestrian promenade, which will gird the shoreline of the neighborhoods between Great Kills and Fort Wadsworth.

A recent report by the Center for Climate Integrity estimated it could cost the United States more than $400 billion over the next 20 years to protect coastal communities. More than $615 million in funding has been secured for the Staten Island project, which includes a levee, buried seawall and vertical floodwall reaching 20 ft. above sea level.

Topped with a public walkway, it’s officially being called the “Staten Island Multi-Use Elevated Promenade.”

The design also includes wetlands, and is part of the New York Mayor Bill de Blasio’s $10 billion scheme to “climate-proof” New York City, an investment he said is needed to tackle a “national emergency.”

The boardwalk will be big enough to host concerts, carnivals, marathons and cultural events, the governor’s office says. But the new promenade’s true public value will only be measured by how well it succeeds in shielding people from natural disaster.

The first seawalls were built centuries ago, though there are now, arguably, greater assets to protect and more people living along vulnerable coastlines than ever before.

Seawalls are not only expensive to install but need regular maintenance if they are to withstand the prolonged barrage of pounding waves. But in many places, they are considered vital to protect land and property that would otherwise be swept out to sea.

Techniques used centuries ago are being refined and reinvented, and the latest designs have found new ways of encouraging marine life to coexist with man-made structures.

This seawall will be built to withstand a 300-year flood event – a water height 2 ft. above the highest levels recorded during Hurricane Sandy, said Frank Verga, a project manager at the New York District of the United States Army Corps of Engineers (USACE).

According to the final feasibility study, the wall is estimated to reduce damages, including risk management, by $30 million each year. But it won’t prevent all flooding, and in the case of severe storms, residents will still need to follow orders to evacuate.

In New York, the first contracts for the Staten Island seawall are expected to be awarded next summer, with work to begin soon after, according to the USACE.