The winter storms over the past month punched through the coastal bluff in front of Nantucket’s sewer beds along the south shore, sending waves through the chain link fence at the edge of the wastewater treatment facility’s property line as more than 40 feet worth of dunes was eroded.
This week the Nantucket Sewer Department began its initial response to the significant erosion by starting to fill in and close the southernmost bed. A bulldozer was spotted at the site Monday morning starting to spread out what is expected to be at least 10,000 cubic yards of dirt necessary to fill the bed.
“Because the level of this bed is almost the same elevation as the beach, filling in this bed will prevent or slow the ocean from any further progression inland to other beds,” Nantucket Sewer Department director David Gray told the Current. “This by no means is a permanent solution. This is just an emergency stopgap to try and prevent a breach. This is only step one of what’s sure to be a multi-piece solution.”
Gray said the state Department of Environmental Protection had authorized the decision to fill in the bed. The late December storm just before Christmas claimed more than 40 feet of the dune in front of the sewer beds, and the three successive storms in January caused additional erosion. A beach access road in front of the sewer beds that had been accessible as recently as the winter of 2022 is now completely gone.
While the one bed being filled was not actively being used, the concern is that if it got infiltrated with salt water, it could affect the other 14 beds at the treatment plant property. Filling the bed will not impact operations or capacity at the sewer facility.
Looking ahead, both Gray and the members of the town’s Coastal Resilience Advisory Committee (CRAC) will both be watching the area of the shoreline south of the sewer beds closely. Members of the committee visited the treatment facility property last week to view the erosion hotspot and discussed the situation during their meeting on Tuesday.
“If you haven’t been out there or had a tour, you’ll get a great sense of what’s at stake if we lose that, if it’s damaged, and what happens if the water comes in even more,” said CRAC chair Peter Brace.
Among other options, Brace said that the Sewer Department is looking at investing in steel sheeting to install and protect the sewer beds in the future. For now, though, the strategy is simply to buy time.
“If you fill in the beds, that can become like new frontage and hopefully that also buys you a little time,” said CRAC member Christy Kickham. “There are a few more bed expansion areas on that site, if needed.”
The town’s Coastal Resilience Plan, which was finalized and approved by the Select Board in 2021, identifies the Surfside Wastewater Treatment Facility among the island’s critical infrastructure at risk due to erosion and prioritized it for protection.
The plan recommends “dune restoration and construction to reduce risk of erosion to critical infrastructure. Hard core dunes are appropriate given risk to critical facilities.” Such a project in front of the sewer beds would cost an estimated $33 million to $38 million with contingencies, along with annual operations and maintenance costs of $310,000, according to the town's plan.