Eversource submarine cable projects in the works

Representatives of energy service provider Eversource say the company’s two proposed undersea cable installation projects are expected to be completed by 2025 — a year later than initially anticipated. 

Last year, Eversource announced plans to replace a 37-year-old faulty electrical distribution cable that provides Martha’s Vineyard with electricity, along with plans to install a new one to meet the Island’s growing energy needs.

Currently, there are four cables servicing the Island. The most recent installation was in 2013, and is the only existing buried submarine cable. The other three are direct-lay cables that sit on the ocean floor.

Back in 2021, the oldest direct lay cable, dubbed “91 cable,” which was installed in 1986, was deemed compromised after a failure caused a series of brownouts across the Island. 

The faulty, and soon to be decommissioned “91 cable,” which according to Eversource has “reached the end of its useful lifespan,” will be replaced by a 4.4-mile buried submarine cable that will connect the Falmouth station to Squantum Avenue in Tisbury. 

As part of an effort to meet the current and future electrical demand on-Island, Eversource has also outlined plans in its Martha’s Vineyard Reliability Project to install a fifth electrical cable, which will be buried beneath the seafloor and run roughly 6.24 miles from the utility’s existing Falmouth station, beneath Vineyard Sound, to Oak Bluffs’ Eastville Avenue, where it will transition to onshore cables. 

According to Eversource, both 23-kilovolt cables will be installed using similar methods, including a combination of hydroplow for burying the cables beneath the sea floor, and horizontal directional drilling. 

Additionally, the utility company plans on decommissioning and removing five diesel generators as a part of the company’s effort to decrease its carbon footprint. 

Although Eversource has already received the water quality certifications for both cables from the Department of Environmental Protection and orders of conditions from the two Island towns and Falmouth, a number of other approvals are still pending, as are determinations by the Army Corps of Engineers.

Project representatives say they expect land construction on the Falmouth side to begin this winter, along with receiving final marine construction approvals by the spring. 

Last year, Eversource hosted a “community conversation” about the company’s plans, which had been received generally favorably by attendees.