The Massachusetts Energy Facilities Siting Board, in a Dec. 2 tentative decision, said that it approves — subject to certain conditions — the petition of NSTAR Electric d/b/a Eversource Energy to build a new approximately nine-mile, 115-kV, underground transmission line in Sudbury, Hudson, Stow, and Marlborough in Massachusetts.
The siting board said that it approves — subject to the conditions — Eversource’s petition for a determination that the line is necessary, serves the public interest, and is consistent with the public interest. Furthermore, the siting board said that it approves — subject to the conditions — Eversource’s petition for individual and comprehensive zoning exemptions from Sudbury, Hudson, and Stow zoning bylaws in connection with the transmission facilities, including improvements to the Sudbury substation.
As noted in the tentative decision, the line would run between the company’s Sudbury substation in Sudbury and the Hudson Light & Power Department’s (HLPD) Hudson substation in Hudson. Eversource’s estimate for the cost of the project is about $95.8m.
The siting board also noted that according to Eversource, the project is needed to maintain a reliable supply of electricity to customers in the municipalities of Marlborough, Hudson, Stow, Berlin, Northborough, Westborough, Southborough, Framingham, Grafton, and Shrewsbury in Massachusetts — referred to as the Marlborough Subarea.
The siting board said that Eversource’s assertion of need for the project is based largely on ISO New England’s (ISO-NE) 2015 “Greater Boston Area Updated Transmission Needs Assessment,” which identified numerous reliability concerns throughout the Greater Boston Area. Eversource described the Marlborough Subarea as a “load pocket,” where electricity demand exceeds any local generation and, as such, power flows into the area on the five high-voltage transmission lines from elsewhere on the transmission grid.
The siting board also noted that the 2015 Needs Assessment identified numerous post-contingency thermal overloads and low-voltage violations in the Marlborough Subarea following certain N-1 and N-1-1 contingencies. According to Eversource, the siting board said, while the N-1 violations identified in the area would be addressed by other planned transmission system investments, N-1-1 post-contingency thermal overloads and low voltage violations would remain unresolved.
The siting board said that it finds that the company’s use of an N-1-1 planning criterion is reasonable, that the methods used to assess system reliability are reviewable and appropriate, and that Eversource’s existing transmission system does not currently meet the established reliability criteria.
Discussing the identification of alternative approaches for analysis, the siting board said, for instance, that the Town of Sudbury proposed a distributed solar-and-storage non-transmission alternative (NTA) consisting of about 250 MW of distributed solar photovoltaic (PV) and 160 MW of energy storage capacity within the Marlborough Subarea. Protect Sudbury, Inc., argued, for instance, that Eversource’s Transmission Alternative 2 — which would upgrade existing transmission lines in the area — poses no risk to groundwater or public water supplies, wildlife habitat, rare species, conservation land uses, nor to abutting historic or archaeological resources.
The siting board said that Eversource argued that Sudbury’s proposed NTAs are unrealistic and conceptual, and that all technically feasible NTAs are more costly than the project. The siting board also noted that Eversource argued that it has provided ample information showing that, on balance, the proposed project is superior to alternative approaches, including Transmission Alternative 2.
The siting board said that overall, the record shows that the NTA alternatives identified in the record are inferior to the project with respect to reliability and cost. The siting board also said that Eversource’s best estimate of the cost of Transmission Alternative 2 is higher than its best estimate of the proposed project, and thus, the proposed project would provide a more reliable and cost-effective solution than Transmission Alternative 2.
Discussing the route selection process, the siting board said that it finds that Eversource has developed and applied a reasonable set of criteria for identifying and evaluating alternative routes in a manner that ensures that it has not overlooked or eliminated any routes that are on balance clearly superior to the proposed project.
Among other things, the siting board said that it approves Eversource’s petition to build the project using the Massachusetts Bay Transportation Authority (MBTA) Underground Route, subject to certain conditions, with that route starting at the Sudbury substation, located off of Route 20 in Sudbury, and traveling northwest within an existing MBTA right of way (ROW) for about 7.6 miles through the municipalities of Sudbury, Stow, Marlborough, and Hudson. At the intersection of the MBTA ROW and Wilkins Street (Route 62) in Hudson, the MBTA Underground Route leaves the MBTA ROW and proceeds southwest beneath Wilkins Street and Forest Avenue for about 1.4 miles before terminating at the Hudson substation on Forest Avenue.
The siting board also said that the conditions include that:
- Eversource is to file, prior to construction, an executed MOU between DCR that outlines vegetation management along the MBTA ROW
- Eversource is to, in consultation with the owners/managers of bordering conservation land — Sudbury, Hudson, Marlborough, Sudbury Valley Trustees, DCR, and the U.S. Department of the Interior — develop an access plan that details, for instance, the time of year that access would be limited along the MBTA ROW
- Eversource is to limit construction of the new line in residential areas to Monday through Friday from 7 a.m., to 6 p.m., with the exception of in-street work as requested by the Town of Hudson
As noted in a cover email accompanying the tentative decision, comments on the tentative decision are due by Dec. 10. The EFSB will conduct a public meeting to consider the tentative decision on Dec. 17 in Boston, Mass., the email noted.