Black and Veatch helps install new transmission line under Boston Harbor
Black & Veatch provided design and engineering services for a project to install a new submarine transmission line in Boston Harbor.
This transmission line supplies power to the second largest water treatment plant in the United States.
Construction was provided by Harbor Electric Energy Company (HEEC), a subsidiary of NSTAR Electric Company. The job involved removing and replacing an existing 4.1-mile electric cable that extends from the South Boston K-Street Substation to the Massachusetts Water Resources Authority’s (MWRA) Deer Island Treatment Plant.
It is part of a $123-million dredging project and expansion of the Conley Terminal. The new line will be embedded deeper in the ocean floor to allow the U.S. Army Corps of Engineers to perform a massive dredging operation known as the Boston Harbor Deep Draft Navigation Improvement Project (BHDDNIP).
The BHDDNIP will deepen four shipping channels to allow larger, deeper draft vessels and container ships access, allowing for the export of iron and steel scrap and supplying New England with goods, including sugar, salt, lumber, home heating oil, jet fuel, and gasoline.
“The HEEC project began in July 2017, with Black & Veatch providing the design from concept to execution,” Bradford von Thaden, Black & Veatch project manager, said. “The timeline was incredibly tight and working underground and underwater in a busy metropolitan area and shipping port is inherently complex. It was critical that the project team remained flexible, viable and abreast of changing requirements.”
The project took place both underground and underwater. The land portion of the project involved installing approximately 8,700 circuit feet (5 miles cable) of 115 kV single core XLPE cable under the City of Boston from the K-Street Substation, installing in Butler Freight Corridor Bridge to a point approximately 500 feet west of the channel. The submarine work involved installing 16,500 circuit feet of 115 kV 3-core XLPE under Boston Harbor running eastward to Deer Island, providing power to the MWRA facility.
Black & Veatch used a horizontal directional drill (HDD) to drill the water entry points and under the shipping channel, and a barge-mounted cable hydro plow to embed the line across the shallow section of Boston Harbor.
“The Black & Veatch team carefully considered every option before optimizing the design, which really helped ensure the successful execution of a complicated project,” Kristen Trudell, Eversource project manager, said. “It really demonstrated their skill and understanding when it comes to the proper installation and operation of submarine cable, as well as industry best practices.”
