The Conservation Commission voted 5-0 to recommend with no objections the issuance of a Conditional Use Permit to Eversource for geotechnical boring in emergent wetlands.
The work will provide information on the physical properties of soil and rock at the proposed sites of towers being installed in Londonderry as part of the Merrimack Reliability project, a transmission line project from the Scobie Pond substation to Tewksbury, Mass.
The Conditional Use Permit (CUP) was filed on May 14 with the Planning Board.
The transmission line project is to be approved through the New Hampshire Site Evaluation Committee (SEC), but Eversource is pursuing local and state wetlands permits for the geotechnical boring work, which must be completed to finalize design of the project, according to Sherrie Trefry, director of energy services for VHB engineering consultants in Bedford.
Trefry said at the Commission’s Tuesday, May 26 meeting that they don’t anticipate any of the towers will require foundations, but the boring work is required to support that design.
“Not all the transmission projects require borings,” she said. “In this case, some of the structures are quite large and designing the foundation will be based on the condition of the wetlands. Given the size of this project and level of design they need to finalize the application, the borings need to be completed. The project needs to be in service by 2017. If they wait to do the geotechnical borings and don’t get the bid out for the foundation and steel, they won’t make this end date.”
Trefry noted Eversource is working to notify abutters of the boring that is to be conducted to ensure they understand it’s not work to install new towers.
“We tried to be liberal with the notifications – particularly being sensitive this has been described as a long process, so people are aware that there will be equipment on the right-of-way separate from the overall project,” she said. “Once the engineering work is done, the SEC filing will be completed at the end of June. Once that’s filed, they will come back for another round of open houses. They will use the open houses to get feedback from local communities as to their concerns related to the project.”
Impacts to wetlands resulting from the boring are expected to be minimal. The probe used to investigate the locations is about 4 inches in diameter, according to Trefry.
There will be one boring, or probe, at each structure location, and crews will use existing access as much as possible, she said, adding, “There are some locations that are in forested areas, where there may be some minimal clearing of vegetation to get in among the trees and get the borings in. We will do our best to not disturb as much as possible.”
Swamp matting is to be used where necessary, and equipment will be brought in on tracks to avoid impacts to the wetlands as they enter the emergent wetland areas.
In terms of restoration, the matting won’t be in the wetlands for longer than a day in most cases, according to Trefry.
“Usually, when we lay swamp mats down, emergent marsh vegetation pops back up,” she said. “They will not be creating any rutting because the matting disperses the weight enough.”
In planning the location of new towers, Trefry said pole sites have been shifted, in some cases, to reduce impacts that would affect rare species.
“At one site we learned there was a vernal pool where a rare turtle appeared to be living. In some places the poles are in wetlands because they have to be,” she said.
Commissioner Mike Considine asked if the towers will look different from what’s already in the wetlands.
Eversource spokesman Elizabeth LaRocca said the towers will look similar to existing structures, with the tallest structures proposed to reach 106 feet.
Work in Londonderry is expected to include the construction of about 75 new structures, with the average height anticipated to be 88 feet above ground.
The new, 24-mile, overhead transmission line will pass through Londonderry, Hudson, Windham and Pelham. A total of 18.1 miles of the transmission line will run through New Hampshire, with 8.1 miles to run through Londonderry.
LaRocca told the Commission the purpose of the proposed transmission line is to address a growing demand for electricity in the region, preventing potential overloads on existing transmission lines.
Commissioner Mike Speltz said the Commission has discussed installing a parking lot at the end of Hickory Hill, on Eversource’s easement, near the location of proposed construction for the new transmission line.
“What’s Eversource’s position on that?” he asked.
“As the underlying landowner, you could do what you wanted as long as the parking lot meets clearance requirements,” LaRocca said. “We realize the Musquash is an important resource for the Town of Londonderry. If there’s any way we can accommodate what you’re trying to do, we’d like to facilitate that.”
LaRocca told the Commission she would take their comments to the team working on the project in Londonderry and see if they can help.
“I’d be happy to move this forward for you,” she said.
Eversource held a public information session May 6 as part of its application process with the SEC and the company must hold a joint public information session with National Grid in each county affected by the project within 45 days after their application is filed. The SEC will hold additional public hearings within 90 days of its application’s being accepted.
Residents may contact Eversource with questions and concerns related to the project by phone at (844) 646-8427 or by email at info@MA-NHSolutions.org. For more information, visit the project’s website at www.MA-NHSolution.com.