Sinkholes on Long Island caused by aging infrastructure, extreme weather, experts say

In May, a 20-foot deep sinkhole swallowed part of a Lido Beach road. In June, another one opened in Baldwin. In late July, a third appeared in Oceanside, its dimensions less impressive than its predecessors but big enough “that cars can’t drive safely over it,” a Nassau County police spokesman, Officer Kenneth Palmieri, said at the time. 

In Suffolk County in January, a sinkhole opened in the front lawn of a home in Huntington Station, and three people had to be hauled out.

So far, the consequences have been manageable — the Lido Beach hole forced temporary evacuation of a critical firehouse, the Baldwin hole caused sewage to leak into neighbors’ yards and a nearby creek, and all three Nassau holes snarled traffic — but lawmakers and experts say the holes have highlighted the need to invest in infrastructure, with some water and sewer pipes nearly a century old. 

Lauren Sternberg, a spokeswoman for Veolia North America, the company that manages Nassau’s wastewater treatment plants and 3,000 miles of sewer pipes, wrote in an email that the Lido Beach sinkhole was caused by a maintenance hole failure and the Baldwin sinkhole caused by a pipe failure. “The common factors are that the system is aging and requires investment,” she said. The Oceanside sinkhole was related to a water main issue, she said. 

Wei Li, an assistant professor in Stony Brook University’s Civil Engineering Department, said that many of Long Island’s sinkholes are created when groundwater runs through the mix of gravel, sand and soil deposited 11,000 years ago by the Wisconsin glaciation. “Groundwater, especially if the velocity is high, moves particles with it — these particles are constantly taken away.” 

Construction of underground infrastructure like tunnels and sewers also loosens soil, increasing the scouring; over time, underground cavities can develop, resulting in depressions that may slowly deepen or suddenly collapse, he said. 

While changes in record keeping make it hard to say if more or fewer sinkholes are occurring than in the past, it’s “not surprising” to see a spate of collapses in the summer because of heavy rainstorms and changing groundwater conditions, Li said. Climate change may also play a role, he said. “With more extreme weather events, more rainfall, this water goes underground, and it will increase the flow rate, making it more likely to take particles away.” 

Reducing the number of sinkholes is difficult but possible, he said, and involves design and monitoring. Veolia, which the county pays $57.4 million annually, is contractually obligated to clean the entire sewer system on a three-year cycle and inspect it on a seven-year cycle. Sternberg said that Veolia inspected the pipes in Baldwin using closed-circuit television in 2020; the company inspected the pipes in Lido Beach using an acoustic device in 2017, and with a pole camera in 2018. 

Other monitoring strategies being developed but not yet commonly used are satellite images of roads and cellphone accelerometers to detect depressions, Li said.

Some elected officials have reacted with alarm to this summer’s spate of sinkholes.

“There is an urgent need to repair our aging infrastructure,” Legis. Debra Mulé (D-Freeport), whose district includes Baldwin, said at a Monday news conference in county offices. There is “no doubt this will happen again here and in all parts of Nassau County.” 

Mulé has asked for local investment through the county’s capital spending plan and for federal investment through the $1 trillion 2021 Infrastructure Investment and Jobs Act.

Also on Monday, the Nassau legislature approved $15 million for sewer repairs in Lido Beach and Baldwin; the Nassau Interim Finance Authority must approve it as well.

Adrienne Esposito, executive director of Citizens Campaign for the Environment, said that the county already had a detailed list of about 600 badly needed infrastructure projects but must be more aggressive in seeking outside funding. Those include "suggested priorities for the county to consider," Sternberg said. 

In a statement, Nassau County Executive Bruce Blakeman said the county had not yet received “one dime” of the money from the federal Bipartisan Infrastructure Law that provides $550 billion for infrastructure from 2022 to 2026. The county’s fair share, “coupled with the millions of dollars in county funds my administration has already committed for these projects, would allow us to immediately update our aging infrastructure that has been neglected for decades,” he said.

According to the U.S. Department of Transportation, New York State can expect to receive about $13.6 billion over five years in federal highway formula funding for highways and bridges, and $480,000 in federal grant money awarded to Nassau in fiscal 2022 to develop a safe streets action plan.

Angelo Roefaro, a spokesman for Sen. Chuck Schumer (D-N.Y.), the Senate majority leader, said in an email that the bipartisan infrastructure law "provides record amounts of funding to NY for road and sewer projects, and we have engaged with Nassau County on potential funding."