power lines
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Critics, including the U.S. EPA, say alternatives such as burying all or part of the line have not been fully explored.

The developer of a controversial transmission line through western Maine is resisting calls to bury part or all of it, saying that doing so is technically infeasible and would make the project too expensive.

Central Maine Power told Maine regulators the project cost would increase from $950 million to $1.6 billion if it were required to bury the line. Environmental review of the project is now before the state’s Department of Environmental Protection and its Land Use Planning Commission.

The proposal to bury the first section of the New England Clean Energy Connect (NECEC) gained momentum in April when the U.S. Environmental Protection Agency wrote that Central Maine Power’s application was incomplete and should be resubmitted, in part because the undergrounding option was not fully explored. The EPA wrote to the U.S. Army Corps of Engineers, the lead federal agency in that part of the review.

Burying the line was also the primary focus of a daylong hearing in early May by the Maine regulators, who are expected to issue a ruling on the project this summer. The Army Corps permit is expected after the state permits.

The 145-mile NECEC project would import Canadian hydropower through Maine on its way to Massachusetts. The project of Central Maine Power and Hydro-Québec won a competitive bid to supply clean energy to Massachusetts.

As planned, it would require cutting a new corridor of 53.5 miles through Maine woods before connecting to existing Central Maine Power lines, which would also require widening of the right-of-way to accommodate 1,200 megawatts of electricity bound for a substation in Lewiston.

Central Maine Power says the project would effectively be killed if regulators required significant changes to the line, which is slated to be in service in 2022. CMP said it has limited money for “contingencies” in the project’s development, such as its commitment to ban the use of herbicides in the transmission corridor.

The Maine Public Utilities Commission approved the NECEC in April. The project has also won the backing of Gov. Janet Mills. The project has signed power contracts with three Massachusetts electric distribution utilities, but those contracts are still pending before state regulators there. The 20-year contracts are for 9.45 million megawatt-hours per year at a levelized price of 5.9 cents per kilowatt-hour.

Environmentalists say the proposed route would disturb or destroy hundreds of wetland area and vernal pools, and break apart natural ecosystems while disrupting wildlife habitats during construction and routine maintenance. Outdoorsmen and those involved in recreation say the transmission poles ruin natural scenery and change the character of rural Maine.

The developer says NECEC was sited as an overhead line to minimize environmental and community impacts.

“Underground lines require an open, vegetated corridor similar to overhead transmission lines, but the construction would have much more significant impacts,” said Thorn Dickinson, vice president of business development for Avangrid, Central Maine Power’s parent company. A 12-foot-wide, 6-foot-deep trench would go through streams and wetlands, he added, and heavy equipment would be needed to install concrete slice vaults to install cable.

“Building underground cable costs five to seven times more per mile compared to building overhead,” Dickinson said. “For example, building the 53.5-mile segment through northern Somerset and Franklin counties would add $650 million to the cost of the project. At that point, the project would not be economically viable.”

That’s CMP’s problem, not Maine’s, a project opponent testified before the joint agency hearing.

“It is not part of Maine [Department of Environmental Protection and Land Use Planning Commission’s] assessment to review whether CMP is or will be awarded contracts or permits for being the low bidder in a process to deliver energy to another state, particularly when it is clear that CMP was the low bidder because they chose not to consider burying the [high voltage direct current] lines,” said Garnett Robinson, a property appraiser.

Environmental advocates argued the transmission corridor would harm natural sites and resources.

“The corridor would cause serious harm to Maine’s clean water, fisheries, and wildlife” said Nick Bennett, staff scientist at the Natural Resources Council of Maine. “CMP failed to look at less damaging alternatives, such as burying the corridor along Route 201, and its proposed compensation for the corridor’s environmental damage is woefully inadequate.”

The route proposed by CMP runs west to east from the Canadian border to an area along Route 201 called The Forks. The Nature Conservancy advocates instead for using existing roads, including a north-south highway and an old logging road.

“The most effective approach to mitigating habitat fragmentation would be rerouting the 53.5-mile Segment 1 [greenfield] section to be co-located with Route 201, including undergrounding,” said Rob Wood, the Nature Conservancy of Maine’s director of government relations and climate policy. “Adjusting Segment 1 of the proposed corridor to be co-located with the nearby Spencer logging road, including undergrounding all or portions of the line, would also minimize new habitat fragmentation impacts.”

The Nature Conservancy says even burying the line in forestland would cause environmental damage because trenching would disturb habitat during construction and would still require forest clearing in the right-of-way.

The EPA also recommended examining transmission routes along existing roadways or corridors like logging roads. “Alternatives to the proposed action that would cause less impact to the aquatic ecosystem have not been fully explored,” wrote Beth Alafat, the EPA's acting chief of wetlands protection.

Burying the line along a highway is impractical, according to testimony made on behalf of CMP.

“Underground construction requires substantially more time and has increased impacts to the public during construction due to more heavy equipment, longer construction time and disruption to traffic,” said Justin Bardwell, the underground transmission manager for CMP consultant Black and Veatch. “This is particularly significant when the construction is in roadways.”

He added that Maine highway regulations prohibit the construction of manhole entries in the travel lanes on roads like Route 201 and there is not enough room in the right-of-way for line construction in the highway shoulders.

CMP did bow to public pressure last fall when it agreed to bury part of the line at Kennebec River Gorge, a popular whitewater rafting destination. However, the company said it will employ horizontal drilling for a 1-mile section so the line would not be visible. CMP said this adds $31 million to the project’s cost. Line redesign in other locations added another $11 million.

Hydro-Québec had initially partnered with Eversource Energy to win the solicitation to deliver the electricity to Massachusetts through a transmission line in New Hampshire. State siting officials rejected that project and Massachusetts chose NECEC as an alternative.

Bill is a freelance journalist based outside Albany, New York. As a former New England correspondent for RTO Insider, he has written about energy for newspapers, magazines and other publications for more than 20 years. He has an extensive career in trade publications and newspapers, mostly focused on the utility sector, covering such issues as restructuring, renewable energy and consumer affairs. Bill covers Maine, Vermont and New Hampshire and also compiles the Northeast Energy News daily email digest.