The Harbor Electric Energy Company (HEEC), a wholly owned subsidiary of Eversource Energy, provides electrical service to the Massachusetts Water Resources Authority (MWRA) Deer Island Wastewater Treatment Plant, in fact it is the primary power supply to the Deer Island Wastewater Treatment Plant. The HEEC cable is an electric submarine cable that extends under Boston Harbor for approximately 4 miles from the South Boston K Street substation to Deer Island.

To accommodate larger ships, Congress approved funding for Boston Harbor Deep Draft Navigation Improvement Project to deepen the Boston Harbor Federal Navigational Channel so the port can accommodate larger ships. To ensure a reliable and uninterrupted power supply to the MWRA's Deer Island Treatment Plant and protect it from damage during dredging operations and for the long-term, HEEC needed to consider either protecting the existing cable from damage or replacing it.

Epsilon facilitated cable investigative surveys and marine surveys by sub-consultants and self-performed environmental permitting services for this project. The project required several phases of investigations (cable surveys, bathymetric surveys and marine archaeological investigation) and securing permits to implement those studies. In addition, Epsilon conducted a comprehensive routing alternatives assessment to identify the least environmentally damaging practicable alternative (LEDPA). Replacing the cable was selected over armoring the cable, thus the LEDPA route was needed. The shortest route would have been to install the New HEEC Cable parallel to the existing cable. However, eelgrass had been planted over and adjacent to the existing cable such that now a well-established eelgrass meadow was flourishing above the cable. Routes to avoid the eelgrass were examined, including a terrestrial route from the north to avoid the harbor completely. The preferred route was selected through the harbor, and the New HEEC Cable route avoided the Reserved Channel and entered the harbor along the easterly margin of the Massachusetts Port Authority Conley Terminal and crossed the harbor with a route to the south of the eelgrass meadow. The extensive permitting effort required additional marine surveys to support the following approvals: U.S. Army Corps of Engineers Section 10/404 Individual Permit, MEPA Certificate, Chapter 91 License and Dredge permit, Section 401 Water Quality Certification, and an Order of Conditions from the Boston Conservation Commission. Additionally, the proximity to Logan Airport required extensive coordination with MassPort and the FAA. Epsilon carefully managed the project's aggressive permitting schedule to ensure that approvals were obtained so that the New HEEC Cable would be installed prior to the planned improvement dredging. The New HEEC Cable is located in Essential Fish Habitat established for winter flounder and the selected route included a short unavoidable eelgrass meadow crossing. These sensitive resources required scrutiny by the Mass. Division of Marine Fisheries and Office of Coastal Zone Management. Epsilon negotiated reasonable mitigation in the form of a time based in lieu fee ("ILF") based on site-specific conditions as compared to applying the straight ILF fee formula, and an eelgrass mitigation/monitoring plan.  

 

The initial permits and approvals were secured assuming standard cable installation construction techniques would be employed. The selected marine contractor proposed some unique construction methodologies that required Epsilon to secure permit amendments to all issued permits. Whereas 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 improvement dredging, and regulatory deadlines. This was achieved.

 

During construction Epsilon was on-hand to secure permit modifications and approvals for field changes because the contractor encountered unavoidable shallow cobble layers and other changed conditions which required some deviation from permit conditions. The New HEEC Cable construction was completed in May 2019, on schedule. Epsilon is now in the process of securing permit closeouts.

 

For more information on this project or about Epsilon's coastal and marine services contact Dwight Dunk who is managing the New HEEC Cable Project for Epsilon.