NSTAR Electric, in a Nov. 15 petition filed with Massachusetts state regulators, requested approval of the installation of two new transmission lines and to be granted individual and comprehensive zoning exemptions from the operation of the “Boston Zoning Code” in relation to its project.
The authorizations are needed in connection with the company’s proposal to build and operate a new 115/14-kV substation on a 28,357-square-foot parcel of land owned by the company on Seafood Way in South Boston, Mass., and to loop two of its existing 115-kV transmission lines from Northern Avenue to the new substation.
The company also said that the proposed Seafood Way substation will improve the reliability of the current electricity supply to that portion of the city, which is served by the company’s K Street substation, and establish a foundation to reliably supply the anticipated increased load requirements as development in the South Boston Waterfront area continues to grow.
Load growth for that area is expected to continue and is forecast to grow by 45 MVA through 2015, and by 50 MVA to 60 MVA as of 2020.
The new substation’s firm capacity will be 135 MVA, the company said, adding that the substation has a planned in-service date of June 1, 2016, which will relieve the heavily loaded Andrews Square and K Street substations.
The estimated cost of the project, including distribution costs, is about $112m, and the estimated time to complete the construction work is about 24 months, but the exact duration will depend upon when the required approvals are received. Certain parts of the construction can occur only during off-peak times, or during the fall and spring “shoulder season,” the company added.
NSTAR Electric also said that the project is designed to meet immediate capacity and reliability needs of its electric system while accommodating future expansion and promoting improvement in system performance and reliability.
“In 2003 and 2004, NSTAR Electric developed a new 115/14-kV substation at K Street, which improved the reliability of service to customers in South Boston and six additional customers in the area totaling 16 MVA of non-network load within the area of South Station and Back Bay,” the company said, noting that the K Street substation’s firm capacity is 212 MVA.
“In the past decade, however, the South Boston Waterfront has experienced extraordinary load growth associated with the redevelopment of the area for new economic uses,” the company said, adding that the area now hosts a highly mixed set of uses, including office buildings, hotels, residential condominiums, retail shops, restaurants and entertainment venues.
The area’s location in proximity to Boston’s Financial District, the downtown waterfront and new transportation infrastructure is expected to be the impetus for strong future load growth in the coming years, the company said.
The Boston Zoning Code prohibits the construction and operation of public utility uses such as an electrical substation on the site, NSTAR Electric added, noting that the construction and operation of the substation and related equipment may be inconsistent with several additional provisions of the code.
NSTAR Electric noted that the DPU has recognized that comprehensive zoning relief is appropriate in circumstances where, as in this case, numerous individual exemptions are required and the issuance of a blanket exemption could avoid substantial public harm by serving to prevent delay in the construction and operation of needed electric utility infrastructure.
To interconnect the new Seafood Way substation with its existing transmission system, NSTAR Electric said it must loop two of its existing 115-kV lines by about 1,095 feet each, from the Northern Avenue traffic circle to the new substation.
The substation will include bulk power system design in which each element of the protection and control design consists of two independent systems; control and protection equipment for 12 115-kV circuit breakers, four 115-kV lines, three 115/14-kV transformers and two 115-kV end buses; digital fault recorder and annunciator; and a remote terminal unit to transmit indications, alarms control and measurements to the company’s dispatch center.
NSTAR Electric also said that it has carefully considered making the substation as “green” as possible in terms of its adaptation to climate change, facilitation of distributed generation (DG), demand response (DR) and renewables, and qualifying for related certification.
The major components of the substation will be built at a 15-foot elevation above grade so as to be resistant to storm surges, should such major storms strike the waterfront area in South Boston.
Regarding DG, NSTAR Electric added that the substation will not be a direct part of the network system serving downtown Boston, so it will not be subject to the restrictions otherwise in effect concerning the interconnection of DG facilities to the downtown low voltage networks. As a result, and subject to the normal interconnection review conducted for all such facilities under DPU standards, DG units, such as wind, solar and combined heat and power, will be able to connect to the 14-kV distribution facilities that are a part of the substation’s development.
Of the substation’s required transmission line connections, NSTAR Electric said it proposes to open the Mystic-to-K-Street 115-kV Lines #250-516 and #250-517 and install extensions from Northern Avenue to Seafood Way, and along FID Kennedy Avenue over the Ted Williams Tunnel to Northern Avenue.
The company said it met with Boston, state and other officials on numerous occasions over the past decade. It also noted that it has met and consulted with the city’s Inspectional Services Department (ISD) to discuss plans for the development and design of the Seafood Way substation and the potential application of the Boston Zoning Code to the substation.
NSTAR Electric said that during planning and construction of the project, it will continue to cooperate and work with the city, including the ISD and Boston Redevelopment Authority, to address any zoning and non-zoning permit and construction-related issues that may arise.
The company also said that the project will also address ongoing distribution reliability concerns, noting that the Summer Street tunnel that houses the existing distribution circuits – seven 14-kV lines and three 4-kV lines – was placed into service in 1917 and will require extensive repairs in the future.
“The proposed Seafood Way distribution getaway duct bank eliminates the need to construct the K Street to East First Street to Summer Street duct bank and cables, thereby avoiding a $16m expenditure that would otherwise be incurred,” NSTAR Electric said.
Among other things, NSTAR Electric noted that it identified potential alternatives for addressing the need and reliability issues. For instance, it considered whether energy efficiency (EE) or DR programs would be effective in meeting the identified need.
“While passive DR or EE, over the last five years, has reduced the cumulative peak load within the South Boston Waterfront region by approximately 3 MW, load growth has exceeded the load relief observed through EE installations,” the company said. “As such, overloading of equipment in the vicinity of the proposed Seafood Way substation cannot be effectively resolved through such measures.
NSTAR Electric is a Northeast Utilities (NYSE:NU) company.