The Saco River embankment is shown here in the fall of 2021 after workers temporarily shored up a section that had collapsed after heavy rains. There is now a roadway cofferdam in the river that allowed examination of the issues and a recommendation has been made on how to repair the damage. Tammy Wells Photo
BIDDEFORD — On Oct. 30, heavy rain washed out a portion of the embankment along the Saco River at the North Dam Mill in Biddeford.
It was temporarily shored up soon after the mishap, while Biddeford and York County emergency management officials worked with their state counterparts to put together an application for an emergency declaration that could see federal funds pay for the vast majority of repairs.
Not long ago, FEMA approved the declaration.
While that was ongoing, the city engaged an engineering firm, Weston & Sampson, to assess the situation and provide repair alternatives.
In a memo to the City Council, City Manager James Bennett said the engineering firm has recommended a soldier pile and lagging wall design.
“It happens that this design is also the lowest cost alternative,” said Bennett. According to figures provided by the city, that design will cost $2.2 million to $2.8 million — with the higher figure still about $700,000 less than the next lowest cost alternative.
Biddeford Chief Operating Officer Brian Phinney said the soldier wall and lagging alternative met the criteria for longevity and the least amount of compacted soil.
According to the Weston & Sampson report, “soldier pile and lagging walls are comprised of vertical steel piles (H-piles) with horizontal lagging between the piles. The H-piles are driven through overburden soil and/or drilled into bedrock at regular intervals along the wall alignment. The lagging would consist of precast concrete panels.”
Bennett said to ensure selection of the most appropriate alternative, the James W. Sewall Company was asked to review the recommended alternative and has confirmed Weston & Sampson’s findings.
Following the temporary shoring up of the collapsed wall section, a roadway was constructed in the river to facilitate examination of the area, and found erosion damage in another area, at the wall around Mechanics Park near the CSO tank outfall, Bennett said. He said moving ahead with permitting for that section as well will allow repair and reduced overall costs.
“The City’s EMA director is actively pursuing separate federal funding to assist with repair of the wall at Mechanics Park while the roadway exists,” Bennett said in the council memo. “Delaying repair until a later date would increase costs due to reinstallation of the roadway.”
He said the next steps for the wall collapse near North Dam include moving forward with permitting, final design once FEMA sign-off is received, and construction bidding.
Bennett told the council on April 5 that there is encouraging news on funding. FEMA usually picks up 75 percent of the cost of repairs for an approved remedy, with the state picking up 15 percent and a municipality paying 10 percent. During COVID, FEMA is paying 90 percent, he said, and the city is looking to the state for funds, which could lessen the municipal contribution.
“It’s looking like (the city’s cost) will be less than originally anticipated,” said Bennett.
The council unanimously agreed to extend the Weston & Sampson contract and to seek permits for the Mechanics Park wall repair as well.
“That makes a ton of sense,” said City Councilor Amy Clearwater. “I’m glad we can do this cheaply. Let’s get ‘er done.”
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