BELLOWS FALLS, Vt. – On Tuesday, March 30 the Joint Board of the Bellows Falls Trustees and Rockingham Selectboard discussed updates on the replacement Depot Street Bridge with the Vermont Agency of Transportation and Vanasse Hangen Bruslin.
VTtrans Project Manager Jonathan Griffin, Senior Architectural Historian Kyle Obenaeur, and VHB Project Manager Scott Burbank presented three bridge designs and gave explanations for the higher cost projections.
The eight-month timeframe for construction of the 102-foot concrete arch would require additional costs to the bridge construction of $2.1 million for a cofferdam and $200,000 to $600,000 per month to Great River Hydro for lost revenue at a cost estimate of $1.6 to $4.8 million. In addition, Burbank explained that if ISO New England needed GRH to make more power due to a scarcity event, charges of $120,000 per hour would be added to the project cost.
Burbank presented an alternative steel truss with two design options, explaining that construction would still take eight months, but the impact to the canal would be only one month “essentially for the demolition period of the existing concrete arch.”
The cost of the steel truss would be significantly less because only one month of lost income for GRH would be charged and the cofferdam was not necessary. The scarcity event charges were still possible but greatly reduced by the shorter construction period.
Obenaeur agreed that due to the challenges of working in the canal, the concrete arch was “not feasible.” He shared a picture prior to 1909, when a truss was used, and said it could connect well with the history of the railroad.
Chair Peter Golec asked if the turning radius was greater with the steel truss alternative.
Burbank said the bridge would be 87 degrees angled north with a widened truss and an eight-foot sidewalk. He said it would improve the turning radius and drivers “should be able to maneuver a 48-foot trailer without issue.”
Trustee Stefan Golec asked about the town’s options, “What happens if we look at that consideration of the [off-alignment bridge] and make [Depot Street] a walking bridge only?”
Griffin agreed that was a viable option. “This is a town-owned structure.”
Selectboard member Bonnie North mentioned she was in favor of the off-alignment bridge but was not on the board at the time, which voted 3-2 in favor of the on-alignment option.
Stefan Golec said that most new truck trailers were now 53 foot trailers. “It’s cheaper to spend that extra money now than it would be five or ten years down the road.”
Trustee Jeff Dunbar agreed with Golec. He would like to see them “reconsider the off-alignment bridge in consideration of the impact it could have economically long-term.” He said, “I would love to see the trucks diverted in some way.”
Village President Deborah Wright agreed. “It would make sense to see your numbers aligned” for the cost comparisons of all bridge designs. The “interruption of the canal is going to have some additional financial impacts.”
Development Director Gary Fox highlighted the importance of getting new numbers, reminding the board that the off-alignment bridge did not include demolition or possible scarcity event fines. “Those are not the numbers we compared with the off-alignment.”
He said the off-alignment bridge “shouldn’t impact the canal at all.”
Fox explained, “Without having car traffic, [projections] increased the lifespan by 40 years.”
Selectboard member Rick Cowan suggested adding to the village vibe with a bridge of flowers like the one in Shelburne Falls, Mass. As a recreational pedestrian bridge, like a bridge of flowers, Fox suggested that GRH could assist with ongoing maintenance and repair of spalled concrete.
Griffin agreed it would “certainly be plausible to avoid the canal” with an off-alignment bridge but that the span would be longer and limit the type of bridge structures that were possible.
Trustee Wade Masure asked for lifespan comparisons. Griffin said code assumes 75-year design life. He said, “I think the concrete arch would probably be a little bit superior in longevity.”
Chair Golec asked about contaminants. Griffin said preliminary analysis found contaminants but they didn’t have final data. He explained, “If you can leave [contaminated soil] where it is or put it back, that’s preferred.” If soil exceed residential or urban standards, it would need to be removed. If the soil was suitable, it could be used for any urban backfill.
Griffin said that regardless of whether the town chooses to go with an on- or off-alignment bridge, VTrans would try and utilize the parking lot for the duration of construction to manage soils cost-effectively.
When asked about contaminants, Burbank could not recall if Canal Street had any, but said the island exceeded residential and urban standards. Griffin said any soils disturbed would be part of project costs and “We would limit the impact to reduce those costs.”
VTrans agreed to send the cost comparisons for Joint Board deliberation. Griffin recommended pushing construction out one year.
The Joint Board’s next meeting is June 29.