Posted on November 17, 2021
On the southern tip of Staten Island, New York City’s latest project to address climate change is now slowly rising from the sea. This September, the Governor’s Office of Storm Recovery began work on the Living Breakwaters, a series of eight enormous rock piles that are being installed off the coast of Tottenville. When complete, this $107 million project will stretch along a mile of shoreline, blunting the impacts of waves, erosion, storm surges and sea level rise — while also providing an important habitat for marine species.
From a 250-foot-long barge moored in the shallows of Raritan Bay, workers are now slowly and methodically placing more than 1,100 stone-filled mattresses into the water, creating a foundation for the first two breakwaters. Each 22-foot-long marine mattress, held together by a geosynthetic mesh and weighing roughly seven tons, is gently lowered into the bay by an equilibrium crane and guided into place by underwater divers.
“They get installed in kind of a jigsaw puzzle, Tetris formation, where they are all side-by-side, up against each other,” said Kevin Robinson, the project manager for Weeks Marine, which is constructing the breakwaters. “That provides scour protection and a structural foundation for the stone, so it doesn’t settle into the bay and collapse over time.”
The landscape architecture studio SCAPE designed the Living Breakwaters after winning funds from the Rebuild By Design competition, an initiative created by the U.S. Department of Housing and Urban Development in the aftermath of Hurricane Sandy. SCAPE is coordinating the entire construction process, which is expected to be completed in 2024.
The breakwaters will include hundreds of specially designed concrete features that mimic tide pools and marine habitats. The four largest breakwaters will also create reef ridges extending out into the bay, providing shelter for fish and other marine life, including an oyster colony installed by the Billion Oyster Project. The final step will be a beach replenishment, spreading 21,000 tons of newly dredged sand across the Tottenville shoreline.
Walking along the coast of Tottenville, it is easy to see why this neighborhood is in dire need of protection. The shoreline here has badly eroded over the last few decades, and waves now crash just a few feet away from the lawns of waterfront homes. A barrier of sand-filled TrapBags was installed along the coast after Hurricane Sandy made landfall in 2012, but hundreds have since split open, emptying their contents back onto the ocean. Where this barrier ends, homes are protected by little more than loose piles of rubble.
During Hurricane Sandy, Tottenville was inundated by a storm surge that destroyed homes, cars and businesses.
“There were a number of houses that were just obliterated. The first line of houses was the wave break,” said Pippa Brashear, the planning principal at SCAPE and project manager for the Living Breakwaters. “The aim here is to take that offshore. The breakwaters are designed to be high enough, but also strong enough, that those big waves are breaking out there on the breakwaters, and not reaching shore.”
Starting in January, the breakwaters will begin to emerge from the water, as workers start to place larger stones onto the completed mattress layers. These materials are being quarried in Johnstown, New York, where each stone is inspected by the construction team’s geologist, before being floated down the Hudson River in barges.
When construction is finished, the top 7.5 feet of the largest breakwaters will be visible at mean tide. Navigational lights will be placed on top to prevent accidents with boats and jet skis.
“It’s about 120,000 tons of stone that we are going to be placing out there in the bay,” said Robinson. “The largest stone we will set on this project is about five tons, which is roughly a five foot diameter boulder. It’s big!”
The Living Breakwaters is part of a collection of major infrastructure projects that are now underway in New York to mitigate the impacts of climate change and sea level rise.
A few miles up the coast in Staten Island, the United States Army Corp of Engineers is now designing a massive 5.3 mile long seawall, which will cost $615 million to construct. Along the East River shorefront in Manhattan, the city has begun construction on the East Side Coastal Resiliency project, a contentious $1.45 billion project which will create 2.4 miles of coastal barriers. And the Metropolitan Transportation Authority is now wrapping up $7.7 billion in resilience and rebuilding projects around the city, which it began in the aftermath of Hurricane Sandy.
Unlike the walls, levees and berms created by these other projects, the Living Breakwaters is explicitly designed with the secondary goal of restoring marine habitats and ecosystems off the city’s coast and will not be an impermeable barrier.
Staten Island’s coast was once home to extensive wetlands and oyster beds, which helped protect it from waves and erosion. Over the last century, that habitat was largely erased by pollution and overdevelopment.
“The harbor is still a rich estuary, but if you look at Raritan Bay, it is a shallow, sandy bottom with a giant navigation channel dredged through it,” said Brashear. “We said if we are going to put something in the water, we need to create something that is going to bring back that ecosystem function, and really serve the diverse species that are there… There is no excuse for having a hardened shoreline that is sterile.”
The Living Breakwaters have a functional lifespan of 50 years, after which they will slowly become less effective. They are designed to fight up to 18 inches (1.5 feet) of sea level rise, which may occur as soon as the 2050s, according to projections from the New York City Panel on Climate Change. But by the end of this century, sea levels could rise by up to 9.5 feet, according to the panel, which would completely submerge the breakwaters and the coast of Tottenville.
“They are probably already going to have to elevate homes and adapt over time, and understand that periodic flooding is going to happen,” said Brashear. “Living with water is going to be a part of that adaptation.”
In three nearby Staten Island neighborhoods, the Governor’s Office of Storm Recovery has already facilitated a managed retreat from the waterfront, buying and demolishing hundreds of low-lying homes in Oakwood Beach, Graham Beach and Ocean Breeze.
These former neighborhoods are now being left permanently undeveloped, as a buffer against future storm surges. Even with its new breakwaters, Tottenville will eventually need to decide whether to undertake a retreat of its own.