Aerial view of the Boston Harbor HEEC Cable Project

Boston Harbor HEEC Cable

At a Glance Client


Epsilon led the environmental permitting for the New HEEC Cable Project – a key project for the Boston Harbor.


The Harbor Electric Energy Company (HEEC), a wholly-owned subsidiary of Eversource Energy, provides the sole electrical power supply to the Massachusetts Water Resources Authority (MWRA) Deer Island Wastewater Treatment Plant. HEEC owns and operates the 115-kV submarine distribution line that extends 4 miles under Boston Harbor from the South Boston K Street substation to Deer Island.

During the installation of the submarine cable in 1990, proximity to bedrock and other factors led to the cable’s installation at a shallower submarine depth in an approximately 2000-foot long section in the Reserved Channel. This 2000-foot long section of cable was potentially vulnerable to damage from planned improvement dredging of the Reserved Channel as part of the Boston Harbor Deep Draft Navigation Improvement Project by the U.S. Army Corps of Engineers (USACE).


Epsilon led four phases of permitting for this effort. The first two phases involved permitting two different surveys of the cable. It was exposed by a combination of mechanical and diver-assisted dredging techniques in four discrete locations in the first survey and three discrete locations in the second survey. This allowed for its location (horizontal and vertical) to be precisely surveyed. The third phase involved permitting an effort to dredge a 200-foot wide, 2080-foot long corridor centered on the cable. This dredging was proposed to install a cable protection system. The cable protection system would have been concrete mats or steel plates installed directly over the cable. Dredged sediments (over 100,000 cubic yards) were proposed to be disposed of at the Massachusetts Bay Disposal Site, or in CAD cells. A fourth permitting phase was initiated after input from the USACE that they planned future dredging of the Reserved Channel which would extend below the existing cable. To accommodate this future dredging, Eversource decided that it was necessary to install a new cable to Deer Island.

Based on standard cable installation construction techniques, Epsilon prepared and secured all necessary approvals for the New HEEC Cable which included: a USACE Section 10/404 Individual Permit, MEPA Certificate, Chapter 91 License, Section 401 Water Quality Certification, and an Order of Conditions. Work was located in Essential Fish Habitat due to the presence of winter flounder and the selected route included an unavoidable crossing of an eelgrass meadow. These sensitive resources required involvement by the Mass. Division of Marine Fisheries and Office of Coastal Zone Management. Epsilon negotiated reasonable mitigation to potential impacts on the winter flounder habitat in the form of a reduced in-lieu fee (ILF) based on site-specific conditions as compared to applying the standard ILF fee formula.

The selected marine contractor proposed some unique construction methodologies that required Epsilon to secure permit amendments to all issued permits. Because this change occurred after contractor procurement, Epsilon needed to manage this process to meet the aggressive construction schedule to ensure the new cable was installed prior to the planned dredging of Boston Harbor, and by federal court-mandated deadlines. This was achieved.

During construction, Epsilon was on-hand to secure permit modifications and approvals for field changes because of changed bottom conditions, such as shallow lens of cobble that interfered with horizontal directional drilling, and other field changes that required some deviation from permit conditions.


New HEEC Cable construction was completed on schedule in May 2019. Epsilon is currently working to secure all the permit closeouts for the cable installation project. The Boston Harbor Deep Draft Navigation Improvement Project has moved forward as planned. The significant impact of this project is that the Boston Harbor can now safely accommodate additional dredging, creating more space for larger ships to enter the harbor; and ensures a stable and long-term power supply to the MWRA Deer Island Wastewater Treatment Plant – the key element to cleaning Boston Harbor.

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