US sues Eversource over harbor cable installation

The federal government sued Eversource Energy Friday over the flawed installation of a massive electrical cable under Boston Harbor that powers the Deer Island sewage plant.

US Attorney Carmen M. Ortiz also named the Massachusetts Water Resources Authority in the civil suit, alleging the cable was not properly installed and in danger of interfering with the $300 million planned dredging of the harbor to allow for larger cargo ships.

The four-mile cable is buried at some places just 12 feet below the seabed, much shallower than it was supposed to be.

“At its current location, the cable may interfere with the dredging operations,” Ortiz’s office said in a statement.

The cable was installed by a predecessor, Boston Edison. The company was then renamed NStar, and became Eversource with the merger with Northeast Utilities.

Eversource and the MWRA have been fighting over the cost of protecting the cable during the dredging — estimated to cost up to $20 million — with the authority suing the energy company in November. The issue remains unresolved.

The federal lawsuit asks for a permanent injunction ordering Eversource and the MWRA to remove the power cable. It also asks the defendants to pay “appropriate” penalties and cover the government’s unspecified costs.

“We are disappointed that the parties were not able to finalize an agreement prior to the filing of the complaint,” Eversource spokeswoman Caroline Pretyman said. “However, we remain hopeful that the parties can reach an amicable resolution of these issues.”

The Massachusetts Water Resources Authority insisted that neither it, nor its ratepayers, “should bear the burden for NSTAR’s incorrect installation of the Boston Harbor Electric Cable, and we look forward to the timely resolution of this issue,” spokesman Sean Navin said.

In 1989, the utility was supposed to lay the cable 25 feet below the seabed, beginning from an electrical station in South Boston, along the Reserved Channel — where massive container ships access the city’s main cargo port — and then across the harbor to Deer Island. The contractor installing the cable used high-pressure water jets and a rock saw to cut a narrow trench, according to a scientific paper on the project written by a Boston Edison engineer that was published in 1991.

Most of the seabed along the route is silty or rocky deposits that can be more easily trenched. But near the outside end of the Reserved Channel, the contractors hit a long section of bedrock that was closer to the surface of the seabed than expected.

Instead of cutting into the rock, the MWRA said, the contractor simply laid the power cable above it, around 12 feet below the harbor floor in some parts. The contractor then continued the installation at its proper depth across the harbor. The MWRA paid the utility around $41 million for the line, but said it wasn’t told of the bedrock issue at the time.

The power line has been in service since. Its location under the sea floor wasn’t a problem until the Massachusetts Port Authority and the US Army Corps of Engineers adopted a dredging plan for the shipping lanes in Boston Harbor to accommodate a new generation of cargo and container ships that have deeper, wider hulls.

Boston Globe