HYANNIS — Toxic transformer fluids could pollute drinking water if leaks occur at a substation where an offshore wind energy developer plans to connect to the region’s electric grid, according to an attorney for the town of Barnstable.
“We haven’t seen the plans,” Charles McLaughlin said of Vineyard Wind’s plan to connect an underground transmission cable to an Eversource substation in Independence Park.
But it’s not the first time McLaughlin and others have raised concerns about how energy from offshore wind turbines would be plugged into the electric grid.
Vineyard Wind was one of three companies to submit bids last week to sell up to 800 megawatts of offshore wind energy to electric distribution companies, part of a package of renewable energy incentives in 2016 state legislation. The companies, each with undeveloped federal land under lease south of Martha’s Vineyard, will hear in April whether their bids have been selected for negotiations.
The other two companies, Revolution Wind and Bay State Wind, plan to bring their transmission cables aground west of Cape Cod.
In a Nov. 17 letter to Vineyard Wind Chief Development Officer Erich Stephens, Barnstable Town Manager Mark Ells emphasized that the company’s project “will need to demonstrate to the town’s satisfaction that it will not pose a danger to the town’s groundwater and fragile public water supply.”
In turn, Stephens said the company would build a system to handle any spills as part of the upgrades that would be needed at the substation.
“We’ve said all along that we will be building containment into the substation so that in the very unlikely case there is leakage it would be fully contained to protect the watershed,” Stephens said.
The cable would be solid, with no fluid, but there would be fluid in the transformers at the substation, Stephens said.
The town, though, has learned a thing or two from its experience with Cape Wind, McLaughlin said.
The long-debated 130-turbine wind farm planned for Horseshoe Shoal in Nantucket Sound came to a quiet end this month when Cape Wind officials gave up their federal lease after a 16-year permitting and legal effort.
New equipment that was to be added to the substation in the Cape Wind plan included two harmonic filter capacitors and an expanded compensator, according to 2014 materials in the Cape Wind and NStar — now Eversource — petition before the state’s Energy Facilities Siting Board.
With the help of consultants during the Cape Wind permitting process, the town learned about two fluids for the new equipment with the proprietary names of Edisol, for the harmonic filter capacitors, and Faradol, for the compensator, that were to be used, McLaughlin said.
Edisol, manufactured by a company in Wisconsin, should not enter storm sewers, ditches or drains that lead to waterways, according to the 2014 siting board materials. Faradol, supplied by a company in France, should not be released into the environment, and should not be allowed to enter drains.
Although the specific names of Edisol and Faradol are not on the state’s oil and hazardous material list, they possibly could be listed generically as transformer oil, said Edmund Coletta, spokesman for the state Department of Environmental Protection. The state’s cleanup rules require that certain spills or contaminated soil and groundwater be reported to the state agency so that an assessment and cleanup can begin. The reportable spill quantity for transformer oil is 10 gallons.
Town officials are concerned that under certain conditions, a leak of fluids could end up in the groundwater “within a couple days time” and into the town’s drinking water well system within about seven days, McLaughlin said.
The switching station is located in groundwater protection and well protection districts approximately 2,500 feet north of two municipal water supply wells, one of which is owned by the Barnstable Fire District and one by the Hyannis Water Department, according to the 2014 siting board materials. The groundwater is 50 to 75 feet below the surface.
Cape Wind and NStar had proposed an alarm system, an on-site response within four hours and a concrete containment system as part of updated spill prevention, control and countermeasure plans that would include fire, health department and other officials. The release of 5 to 8 gallons of insulating fluid would reach a depth of only 4 feet before it would be cleaned up by the hazardous material contractor, according to the two companies.
But Cape Wind’s intended offshore wind generation capacity of 468 megawatts — an estimated 170 megawatts of production on average — is substantially less than the 1,600 megawatts that could ultimately be generated by 2027 under the 2016 legislation, McLaughlin said.
The Hyannis water supply extends to the entire commercial downtown and Cape Cod Hospital and has already been the focus of pollution concerns.
Barnstable town officials have issued public health advisories for the Hyannis water system twice since 2015. In both instances, levels of the perfluorinated chemicals PFOS and PFOA above the Environmental Protection Agency’s health advisory limits were found in wells serving 18,000 residents and businesses in Hyannis, Hyannisport and West Hyannisport.
The chemicals are typically found in the types of firefighting foams that have been used in the past at the Barnstable County Fire and Rescue Training Academy and Barnstable Municipal Airport. The contamination has sparked lawsuits over who is responsible for the pollution.
“The importance of getting this right can’t be ignored,” McLaughlin said of the latest proposed offshore wind energy connection.
Vineyard Wind intends to run its cable directly north, underwater, to Lewis Bay to a bulkhead at the end of New Hampshire Avenue in West Yarmouth, Stephens said at a public meeting in November at the Yarmouth Senior Center. From the bulkhead, the cable would run roughly 2 miles along Berry Avenue to Higgins Crowell Road and end up at the Eversource substation across the town line.
If the project moves forward, the laying of the cable is at least three years away, Stephens said.
A second cable route under consideration makes landfall in Barnstable, but the route to the substation is considered more densely developed and industrial than the Yarmouth route, Stephens said.
Towns also could levy a personal property tax on Vineyard Wind for the transmission cable snaking through their towns, estimated at hundreds of thousands of dollars each year.