The Massachusetts Energy Facilities Siting Board (EFSB), in a Feb. 24 tentative decision, said that it approves NSTAR Electric’s d/b/a Eversource Energy (NYSE:ES) project involving a new 115-kV underground transmission line, using the company’s primary route, subject to certain conditions.
As noted in the tentative decision, the company has proposed to build the new approximately 7.7-mile line between the company’s Woburn substation in Woburn, Mass., and its Mystic substation in Everett, Mass.
The new line would operate in parallel with, and supplement the capacity of, the company’s existing 211-514 line, which is a 115-kV underground transmission line that runs between the Woburn and Mystic substations. According to Eversource, the EFSB added, the two parallel lines would operate as a single circuit, and would effectively be a single larger-capacity transmission line.
The company has also proposed to install a new air-core series reactor at the Woburn substation to balance power flows between the existing line and the new line, as well as to modify the connection arrangement of the existing line and the 115-kV 488-518 transmission line within the Mystic substation to accommodate connection of the new line.
The EFSB also said that the company’s most recent estimate for the project’s cost is $81.5m, which is expected to be in service by December 2018.
The company’s primary route for the new line exits the Woburn substation at the Winchester town line and travels primarily under streets for about 7.2 miles, parallel to the existing line, through Winchester, Medford, Somerville, and the Charlestown section of Boston, and then an additional 0.5 miles within an existing pipe under the Mystic River to the Mystic substation fence line in Everett, the EFSB said.
In addition to traveling within an existing pipe under the Mystic River, the primary route crosses the Aberjona River in Winchester and the Mystic River in Medford.
The EFSB said that it concludes that the primary route is superior to the company’s “noticed alternative route” – which is about 9.1 miles long and traverses Winchester, Medford, Everett, and a short distance within Boston city limits – with respect to providing a reliable energy supply for the state with a minimum impact on the environment at the lowest possible cost.
The EFSB also noted that ISO New England (ISO-NE) recently issued a periodic needs assessment, the “Greater Boston Area Updated Transmission Needs Assessment,” and that the company’s assertion of need for the project is based extensively on that assessment, including the planning criteria and standards, as well as demand forecast contained within.
The EFSB noted that a working group, which was established by ISO-NE in 2008 and includes members from ISO-NE and local electric utilities, completed its initial assessment of the reliability needs of the Greater Boston area in July 2009, and that a number of subsequent updates to that assessment were required in order to reflect significant changes on the transmission system. The most recent needs assessment was issued in January 2015, the EFSB said, adding that according to the company, that “2015 Needs Assessment” identified numerous reliability concerns throughout the area, including a number of thermal and voltage violations following certain N-1 and N-1-1 contingencies.
Eversource said that by 2023, post-contingency overloads were observed across the 69-kV, 115-kV, and 345-kV transmission facilities within the Greater Boston area. The working group identified “Sub-Area B” as one of the areas of concern, the EFSB said, adding that Sub-Area B contains five 345-kV transmission lines and eight 115-kV transmission lines that connect a number of company-owned substations. Eversource identified two key substations in Sub-Area B: the Woburn substation and the Mystic substation.
The EFSB added that the company presented evidence that if proposed transmission system reinforcements elsewhere in the Greater Boston area were built with the exception of the project, then the regional transmission system would still be vulnerable to thermal overloads.
“The company has provided enough information to permit a general understanding of its forecasting method, and the siting board finds that the company’s forecast is reviewable, appropriate and reliable for use in this proceeding to evaluate the company’s assertion of need,” the EFSB said.
Noting that Eversource explored non-transmission alternatives, including generation, energy efficiency, demand response, and energy storage, as well as alternative transmission and substation facilities, the EFSB said that it “finds that the project is superior to the other alternatives identified with respect to providing a reliable energy supply for the commonwealth with minimum impact on the environment at the lowest possible cost.”
The EFSB also said that the record shows that the primary and noticed alternative routes each cross park lands and roadways subject to “Article 97” jurisdiction and are comparable with regard to Project Article 97 impacts. Accordingly, the EFSB said that it finds that the primary route is preferable to the noticed alternative route with respect to land use impacts. In order to mitigate impacts of the project on recreational parklands, the company committed to limiting construction to non-peak use months – for example, November through April, the EFSB said.
According to the company, Article 97 of the Amendments of the Constitution of Massachusetts provides that state-owned lands and easements originally taken or acquired as natural resource land cannot be used or disposed of for other purposes except by a law enacted by a two-thirds vote of each branch of the Legislature.
The EFSB also noted that the primary and noticed alternative routes would involve two new river crossings and work in 100-foot buffer of Winter Pond, and are both comparable in terms of potential project wetland impacts. The company has proposed project impact mitigation on wetland resources along the primary route, including implementation of erosion and sedimentation controls, the EFSB said, adding that with implementation of the company’s proposed mitigation and conformance with certain conditions, it finds that impacts to wetlands and waterways along the primary route would be minimized.
The EFSB also said that it grants the company’s request for certain individual zoning exemptions, including “Groundwater Protection District Section 15.” According to the company, a substation use is not permitted in the “R-1” zoning district, and therefore, the company’s proposed use is prohibited in the Groundwater Protection District. The granting of a use variance is not authorized under the zoning ordinance, according to the company.
Among other conditions, the EFSB said that it directs the company to continue to work with local conservation commissions, MassDEP and DCR to implement preferred restoration and mitigation plans that are consistent with applicable rules and regulations of the state. Also, the company is to develop – in consultation with Woburn, Winchester, Medford, Somerville, Everett and Boston – a comprehensive outreach plan for the project, describing the procedures to be used to notify the public about the scheduled start, duration and hours of construction in particular areas, for instance.
The EFSB also said that the company is submit to the board an updated and certified cost estimate for the project prior to the start of construction.
According to the Executive Office of Energy and Environmental Affairs’ website, written comments concerning the tentative decision should be filed with the EFSB by March 3.