BELLOWS FALLS, Vt. — Rockingham Selectboard members admitted to having “sticker shock” this week when seeing the latest cost estimations to repair and repurpose the historic Depot Street Bridge as a pedestrian walk, whose total project — including the construction of an off-alignment vehicle bridge — could cost between $8 million and $9.2 million, with the town responsible for 10% of that share.
Project managers Scott Burbank from Vanasse Hangen Brustlin, Inc. (VHB) and Peter Griffin from the Vermont Agency of Transportation (VTrans) noted the projected cost to build a new angled bridge to replace the Depot Street Bridge on Wednesday but stated that repairing the historic concrete arch bridge for pedestrian use would be significantly higher than previously proposed in 2019.
Burbank said this project option, whose projected construction cost was $3.9 million two years ago, would now cost $6.3 million.
Additionally, the project managers estimated between $2 million and $3 million in potential costs to reimburse Great River Hydro for lost revenue during the time the canal would need to be closed to work directly in the canal.
If choosing this project, Rockingham’s estimated share of the project cost would be between $1.2 million and $3.8 million, with VTrans covering the remaining cost.
In 2019 Rockingham’s projected share was estimated around $353,000, though that did not include potential reimbursements to Great River Hydro.
Selectman Bonnie North, who has advocated for this project option, said she had “sticker shock” when first seeing the number.
“The cost of that off-alignment bridge is terrifying,” North said. “But it’s what we need.”
A previous selectboard rejected this off-alignment proposal, voting 3-2 in 2019 to instead remove the existing bridge and replace it with a similar concrete arch replica.
But in March the project managers said this concrete arch design will not be economically viable, due to the engineering challenges and related cost impacts to shutdown the canal for construction and excavation.
According to Burbank, supporting an arch design would require the construction of a “cofferdam,” an watertight enclosure pumped dry to allow workers to build safely below the water level. Project managers learned from the owners of Great River Hydro, who operate a hydroelectric plant on the canal, the dam requires a constant water level of three feet.
The extensive engineering would also require an eight month dam shutdown, requiring the project to reimburse Great River Hydro for its lost revenues, which would total an additional $1.6 million to $4.8 million, according to Burban.
Burbank and Griffin are instead recommending a steel truss design, which will not require underwater construction and would reduce the closure time of Great River Hydro to only one month.
The March discussion led several selectmen, including North, to renew consideration of the off-alignment proposal.
The off-alignment proposal, according to its proponents, would reduce the number of commercial trucks that drive through the village square and create a needed connector to The Island, a high-density industrial area that Rockingham officials hope will attract new business start-ups.
Many residents and officials have also supported keeping Depot Street Bridge as a pedestrian walkway to further enhance the downtown village experience. After repairs, which would be part of the off-alignment project, the bridge could serve up to another 40 years if relieved from the weight of vehicles, according to the project managers.
“[A business owner told me] we should be basing the decisions we make on the next 60 to 100 years, not 20 years,” North said.
But even selectmen who previously supported the off-alignment project expressed worry about assuming liability of the existing Depot Street Bridge once the project is complete.
According to Griffin, VTrans would move its maintenance and inspection obligations from Depot Street Bridge to the new bridge. Rockingham would assume full ownership and liability of Depot Street Bridge if the town elects to keep it.
“I love the idea of the off-alignment in a lot of ways, but we cannot leave that bridge there and be responsible for it,” said Selectman Susan Hammond. “If it crashes into the canal then we will have a huge liability with the power company. And they will be shut down for a very long time while we deal with that.”
Burbank could not answer the town’s cost would be to maintain the existing bridge in the future, though it would be significantly less expensive to maintain if serving as a pedestrian-only bridge.
“If we repair it, it would be in better condition than it is today,” Burbank said. “And with a reduced traffic impact it would not need maintenance for a long time.”
Selectman Chair Peter Golec said there will be two more meetings with Burbank and Griffin about the bridge before the board needs to make a decision.