Posted on April 3, 2023
The United States Army Corps of Engineers project aiming to protect New York City against devastating storm surge is inching toward a final plan that would jumpstart a multi-billion dollar effort to bolster defenses against climate change.
The U.S. Army Corps “NY-NJ Harbor and Tributaries Coastal Storm Risk Management Feasibility Study” (HATS) report published last year outlined multiple approaches to blunting the impact of flooding when powerful weather systems roll into the area.
The agency backed one proposal — Alternative 3B — that would fundamentally change the makeup of waterways surrounding Staten Island by creating massive retractable barriers and installing coastline measures to shield communities against future storms.
WHAT IS ALTERNATIVE 3B?
The United States Army Corps “Alternative 3b” infrastructure project.
There are five proposals being considered by the Army Corps, and an interactive map details each proposal. Elements in fuchsia on the map are part of Alternative 3B, which carries a $52.7 billion price tag.
The plan would create 2.2 miles of storm surge barriers, 50.6 miles of shoreline based measures, 11.8 miles of flooding-mitigation features and 18.7 miles of risk reduction features, according to the Army Corps.
The latest Army Corps effort is separate from its years-long and delay-laden East Shore Seawall project centered on protecting borough communities devastated by Hurricane Sandy more than a decade ago. It would also join the South Shore Living Breakwaters coastal protection project that broke ground in 2021.
The public comment period for the project was extended to March 31, and will be followed by a span where the Army Corps considers the suggestions before a meeting in June. Comments can be submitted via email or mail.
A U.S. Army Corps of Engineers’ image released Sept. 22 shows an artist’s rendering of what a possible flood barrier could like near the Outerbridge Crossing.
WHAT WOULD STORM SURGE GATES LOOK LIKE?
Under Alternative 3B, two storm surge gates would be created in Staten Island waterways and would join 10 other storm surge gates in the New York City area.
These behemoth structures would close during major storms and otherwise remain open for water traffic — a critical measure as the borough’s West Shore begins to host the burgeoning offshore wind industry.
One would be placed below the Outerbridge between Staten Island and New Jersey and another between Staten Island and Bayonne, N.J.
“The navigational and auxiliary surge gate structures at these locations are currently delineated to have an estimated total length of 5,600 feet, with an associated 5,588 feet of shore-based measures comprising floodwalls and deployable flood wall barriers to tie-in to high ground,” the Army Corps wrote in its 569-page report.
The storm surge barriers would be key infrastructure pieces within the larger project and be accompanied by smaller efforts to address coastal flooding concerns.
A group of major environmentalist groups have sounded alarm over the project’s scope and effectiveness, specifically criticizing some of the major infrastructure elements of the proposal and calling for a greater infusion of nature-based solutions in place of gray construction.
Calls, for example, to “use in-water barriers only when absolutely necessary” and instead prioritize nature-based solutions, would fundamentally alter the approach of mitigating intense flooding. Additionally, it is not clear what form of nature-based solution could substitute hardened infrastructure like storm surge barriers.
Placating some of those concerns would have wide-spanning implications for a project that has taken years to even reach its planning phase.
Daniel Zarilli, the city’s former chief climate policy advisor and a Staten Islander, said the project’s importance is too vital to take steps back and instead called for continued partnership to making the project work for the city.
“What I think New Yorkers really need to see is multipurpose flood protection infrastructure that needs to go through a deep design process with communities to make sure that we get the protection we need, and that it is integrated into our dense urban environment in a smart way,” said Zarilli. “And I think the Corps can do that, and they need New Yorkers to help them do that.”
A U.S. Army Corps of Engineers’ image released Sept. 22 shows an artist’s rendering of what a possible flood barrier could like near the Kill Van Kull.
THE SOUTH SHORE
The pink and yellow structure shown in the Army Corps’ interactive map centered on Staten Island’s South Shore shows the location of the proposed storm surge gate; however, other structures would also be implemented north of that area.
The yellow highlighted areas north of Ellis Street, near the Tottenville Marina, are low flood walls that would stand near the coast. The green section is a bulkhead, which is effectively a retaining wall aimed at holding back floodwaters.
The final two sections, in purple, are revetments typically made of concrete or stone that are placed against the coast to protect against erosion
THE WEST SHORE
A flood wall would be placed above Burke Avenue in an area within the William T. Davis Wildlife Refuge in New Springville, which connects to the Arthur Kill through Main Creek.
The Army Corps indicated the flood wall is expected to have “low” impacts to the refuge’s lands, though some species may become displaced during construction. The agency said species that flee the area during that phase “are expected to return to the area when construction is completed.”
When the barriers are in the closed position in anticipation of a storm, the Army Corps said the area behind the wall would be benefited from coastal flood risk management.
THE NORTH SHORE
Outside of the major storm surge gate between Staten Island and Bayonne, a series of smaller projects would be put into place on the borough’s North Shore to help mitigate flooding.
Areas in green on the Army Corps map are bulkheads slated to be placed along the coastline north of Richmond Terrace. They would play a role in reducing the risk of flooding in areas behind storm surge barriers that could experience high frequency flooding when the barriers are not in use.
A National Oceanic and Atmospheric Administration (NOAA) tidal gauge near Mariners Harbor saw seven high-flooding days in 2020 — nearly double what the same gauge saw in 2000. By 2030, between 15 and 35 high-flood days are projected by NOAA; a range of 45 to 130 high-flood days could occur by 2050 — causing consistent and significant risks to the coastline and those that live there.
Revetments with flood walls similar to measures that would be implemented on the South Shore under Alternative 3B are labeled in green. A low flood wall, in yellow, would connect that infrastructure between Wright and Housman avenues in Elm Park.
“Alternative 3B” measures on Staten Island’s West Shore.
Meanwhile, east of the Bayonne Bridge, standard flood walls would line the coastline between Ferry Street and the mouth of the waterway extending into the northern end of Port Richmond.
