Undersea cable project presents host of challenges

LET THERE BE LIGHT: The new, National Grid PLC-owned bidirectional electric cable runs roughly 20 miles undersea from Scarborough Beach in Narragansett to a new substation on Block Island. Once on-land installation work is finished this year, the cable will be able to bring electricity and high-speed internet to and from New Shoreham. / COURTESY NATIONAL GRID PLC
LET THERE BE LIGHT: The new, National Grid PLC-owned bidirectional electric cable runs roughly 20 miles undersea from Scarborough Beach in Narragansett to a new substation on Block Island. Once on-land installation work is finished this year, the cable will be able to bring electricity and high-speed internet to and from New Shoreham. / COURTESY NATIONAL GRID PLC

In the eleventh hour of planning for the much-anticipated, 20-mile undersea cable-installation project that will bring electricity and high-speed internet to and from Block Island, National Grid PLC project manager David M. Campilii was informed that a portion of the seabed where the cable would lie about 6 feet down was once a hotbed for World War II underwater warfare activity.

“The [area] had seen active warfare and there was also maybe a torpedo test range with unexploded devices,” Campilii explained. “We had to deliberately avoid the Navy’s torpedo area, but the problem with warfare is that people don’t always put things in a designated spot.”

Luckily, the vessel carrying the undersea cable was able to safely traverse and successfully install the cable that now runs from Scarborough Beach in Narragansett to Block Island, known formally as New Shoreham.

Unexploded devices were among a number of hurdles Campilii and his team of engineers has had to clear in its attempt to complete the infrastructure project, which has an estimated price tag of $110 million.

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National Grid, the state’s largest utility company, is continuing with the installation of the cable on land to connect the nation’s first-ever operational offshore wind farm to the mainland electric grid. Deepwater Wind LLC’s five-turbine, 30-megawatt offshore wind project is currently under construction and is scheduled to come online later this year. At peak performance, the project would provide about 90 percent of Block Island’s electric demand and 1 percent of Rhode Island’s.

But ensuring power will be able to get back to the mainland has been no simple task.

“I think anytime you do a project underwater, it has a much higher level of complexity,” Campilii added. “One of the differences here is that the permitting arena was perhaps different because it was tied to an offshore wind generator, so it had a higher level of permitting requirements.”

Campilii, consulting engineer of transmission asset management and underground transmission engineering at National Grid, has some experience in this area of cable installation, as he’s helped the company put in two similar cables that connect Nantucket and Martha’s Vineyard to the mainland in Massachusetts. But the Rhode Island project has proven more difficult, he says, because of its many roadblocks.

To start, on Jan. 3, the construction team began drilling on Scarborough Beach to create a hole for the cable to run beneath the beach and out 2,250 feet into the sea. The technique requires a highly specific piece of equipment called a “horizontal directional drill,” which enters the ground at an angle and can steer underground. The team quickly discovered, however, that instead of soft sand they were drilling directly into granite. The unexpected granite slowed the project down from the get-go.

“What was supposed to be a month to a month-and-a-half [drilling] project ended up taking about four months,” Campilii said. “That put the rest of the schedule into a much tighter window.”

The drilling-induced delay forced National Grid to request an extension of time from New Shoreham officials, as the utility would need to work on about 75 feet of beach on the island when it arrived with the cable. But the request was met with a rejection from the town, and members of the council asked for what National Grid described as “large sum” of money in exchange for granting the extension of time. National Grid rejected the council’s request for money.

National Grid decided it would try to complete its work before July, which is one of Block Island’s busiest economic months of the year, but was later granted extra time on the condition it rented some space in the beach parking lot. The cable came ashore June 22 and National Grid was able to get off the beach, completing the offshore cable section of the project. But issues on Block Island continued.

While digging onshore to connect the undersea cable to a power substation in the middle of the island, National Grid came across a plethora of Native American artifacts. Typical of any archeological finding, the Army Corps of Engineers was called in to monitor the excavation process, which also caused delays.

Despite all of the unforeseen barriers, however, a spokesman said the company plans to maintain its completion date of this fall, leaving enough time for Deepwater Wind to finalize its construction and tie into the new undersea cable. The project will ultimately reduce Block Island energy costs, connect island consumers to the mainland grid for the first time and provide a fiber-optic wire that will give island residents and businesses high-speed internet. •

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