Tanya Blanchard: The Northern Maine Transmission Route

CMP released a route map today for the proposed Haynesville-to-Pittsfield transmission line during an informational meeting held this morning. For the first time, we can see the route CMP is proposing in considerably more detail.

The map also confirms that a significant portion of this project would be new transmission development rather than construction within an existing transmission corridor.

transmission corridor.

The areas highlighted below show (approximately) where there are no existing transmission lines. This will be new development.

The Haynesville-to-Pittsfield transmission line is approximately 108 miles long. Of that, approximately 40 miles is in areas where there is no existing transmission line.

That means roughly 37% of the route would create a new transmission corridor.

That is 40 miles of new clearing and construction, new transmission structures and access roads, and land that will have to be maintained over the life of the project. The towers are expected to be approximately 150 feet tall (that part of the design has not yet been released).

Rail Trail Crossings

The route may also cross one or more rail trails, including rail trails in Lagrange and Corinna.

The rail trails are important to note because Maine law requires a high-impact electric transmission line crossing or utilizing certain state-designated public lands - including state-owned former railroad rights-of-way used as recreational trails - to receive approval by two-thirds of all members elected to each house of the Legislature. Maine law also created a process for the Bureau of Parks and Lands to establish criteria under which a transmission line crossing certain designated lands would not constitute a reduction or substantial alteration of those lands.

That rulemaking has not been completed.

I have sent several emails to the Bureau of Parks and Lands asking where the rulemaking stands. Their response was essentially that they will let me know when they have something to tell me.

I’m not holding my breath.

From LD 2087, passed in April, 2024:

Until that rulemaking is completed, the statutory requirements remain important for any portion of the proposed route that crosses the affected public lands. And now that CMP has released a route map, we can begin to see exactly where that issue may arise.

And then there is the Haynesville substation

The map released today shows the location of the Haynesville substation only as a square. It does not provide a site plan or indicate how much land the new substation will occupy. We don’t yet have the current design details.

However, a Haynesville resident recently showed me a copy of a substation design from 2014 that indicates a footprint of approximately 15 acres. To be clear, this is not a design for the current project and I have not seen a current site plan for the Haynesville substation. (For comparison, CMP’s Coopers Mills Substation in Windsor occupies approximately 17 acres. Coopers Mills has the largest single-voltage source converter (STATCOM) of its kind in North America, so a 15-acre substation is substantial.)

I took a photograph of the 2014 Haynesville substation design. The quality isn’t great, but it gives some perspective on just how large the substation might be.

Is a facility of approximately this size required for a 1,200 MW, 345-kV transmission line?

I don’t know. I’m not an engineer.

But now that CMP has released the route, I think it is reasonable to start asking questions about not just where the line will go, but what will actually be built along it, how much land will be required, and how much will Maine ratepayers actually benefit, including those who will never receive their electricity from this project?