The Main Street bridge will be closed for roughly a month while repairs are made to erosion discovered under the bridge abutment at the Center Falls Dam project site.
The bridge closure and repairs, both of which were unanimously approved by the Board of Selectmen on Thursday, is expected to begin by May 9.
The reconstruction work, which is being handled by Hudson, Mass.-based New England Infrastructure, is Project III of the town's Flood Mitigation Program. Work got underway at the site on March 25.
Sometime between late March and early April, Howard said the contractor visited the site and discovered additional problem areas.
"At that time we found that there had been some erosion with the (cascading) steps," Howard said, "and we have since amended the contract to include work to repair the step activity behind the dam wall."
Howard said additional underwater work was done around the bridge abutment, and "that work has revealed additional erosion under the bridge abutment itself."
Howard said he has been advised and thought it was an appropriate step to take to close down the Main Street bridge while repair work was being conducted to address the erosion under the bridge abutment. The work is expected to take 3-4 weeks to complete, he added.
The town manager said town center business owners, Lincoln Elementary and McCall Middle Schools and the community at-large would be notified about the bridge closure.
The estimate to do the work is $425,000 to $450,000, according to Howard. The estimate includes engineer, design and repair work, and the costs would be a qualified expense through the chapter 90 program, he added.
The Massachusetts Department of Transportation's Highway Division corroborated the degradation under the bridge abutment, according to Howard.
"The bridge is safe to travel over," Howard said. "The concern is for the degradation of the bridge foundation by virtue of vibration that would occur by having truck and (vehicle traffic) traveling over the bridge structure while the erosion is still apparent so it is really a cost consideration."
A meeting was expected to be held Friday with school, police and fire departments to discuss the traffic plan at the site while the bridge is closed, according to Howard.