CHARLESTOWN — The section of Route 12 between Charlestown and Walpole will be closed for the foreseeable future as the project is more in-depth that first believed.
“There is a deep layer of silty soil and it’s thick,” said New Hampshire Department of Transportation (NHDOT) project engineer Jason Ayotte in an interview with the Eagle Times. “That’s was caused the road to shift.”
The project was tentatively set to begin mid-September but results uncovered from test bores revealed that the condition beneath the pavement is worse than anticipated.
“The road will need to be excavated and with the railroad so close, there is an issue with supporting the railroad bed,” Ayotte said.
Contractors with soil nail wall experience from areas as far away as the mid-Atlandic area are being sought for this project. This type of construction involves running rods under the rail bed and filling the area with grout that once hardened will tie into the excavation of the road.
“The rail bed cannot be compromised,” Ayotte said. Once the rail bed is stabilized, the road can be excavated to a safe depth to rebuild the base.
At least 10 feet must be excavated from the road to install a stable base and the work can be done after the ground freezes if needed.
“We are moving as fast as possible but it must be done right,” said Ayotte with no timeframe yet set. “It’s been a very busy season for construction and we’re looking at all possibilities to get the project done as quickly as possible.”
Slope failures are not uncommon along rivers, recently a section of Route 12 south of West Lebanon had the issue and involved shoring up the bank of the Connecticut River before stabilizing the road itself.
There will be no alternating traffic pattern because of the worry about further slippage with traffic loads. The road will be closed until repairs are completed, according to Ayotte.
While this section of road must be repaired first, it is on the 10-year plan for a complete reconstruction much like the southern section of Route 12 that was recently completed after a two-year project. But these two sections are separate projects.
No cost estimate was available but there will be federal funds to help mitigate costs, according to Ayotte.