A report commissioned by the town of Harpswell to address the impact of sea-level rise on two low-lying roads offers solutions ranging from $300,000 worth of temporary flood barriers to a $5 million bridge.
The report, by South Portland engineering firm Gorrill Palmer, examined two locations prone to flooding: Abner Point Road at Lubee Lane, near Mackerel Cove on Bailey Island; and Bethel Point Road at the bridge over Hen Cove, on Great Island. It was funded by a $50,000 grant from the Governor’s Office of Policy Innovation and the Future’s Community Resilience Partnership.
Harpswell has used grants to commission recent studies of several locations vulnerable to future flooding from sea level rise. Others include Basin Point Road and the Lookout Point causeway and boat launch, both on Harpswell Neck; and Garrison Cove Town Landing, on Bailey Island.
The town plans to have Gorrill Palmer write a similar report on two additional locations: the Dingley Island bridge and Lowell’s Cove Road on Orr’s Island. Those studies are already in progress.
The latest report proposes two possible solutions for Abner Point Road. One would be to raise the road by just over 2 feet. Gorrill Palmer estimated about 530 feet of road would need to be raised, at a cost of about $1.6 million.
“The upper portion of the (adjacent) boat launch would be reconstructed at a steeper slope to match the new roadway grade as well,” the report says.
The engineering firm’s other proposed solution would be far less expensive. It would involve buying temporary flood barriers at a cost of about $300,000.
Such products are made of interlocking pieces that can be quickly assembled as needed, making them ideal for areas where permanent flood defenses aren’t feasible or cost-effective. Still, Gorrill Palmer said it would require a crew of up to five people to deploy the barriers before a flooding event and then take down, clean and store them afterward.
“These barriers are not a perfect solution,” the report says, adding that it would take about two hours to set them up along Abner Point Road prior to each storm.
Gorrill Palmer’s proposed fixes for Bethel Point Road would be far more expensive, and the firm said temporary flood barriers aren’t a viable option.
The least expensive choice would be to raise the road by about 2.3 feet and widen the box culvert underneath, at a total estimated cost of just under $3 million. The road could be raised higher to prolong its resilience to sea-level rise for an additional $700,000.
Another option would be to raise the road and replace the box culvert – a concrete structure that allows water to flow underneath – with a 50-foot bridge, according to the report. The bridge would reduce flooding even further, but would cost an estimated $5.2 million.
One additional option was explored but ultimately abandoned. It would involve rerouting Bethel Point Road around the westerly side of Hen Cove/Mill Pond, which would require purchasing private land, including a portion of Harpswell Heritage Land Trust’s Little Ponds Preserve. The option was deemed too costly and disruptive.
There are no plans to fund construction of any of the proposed projects, town officials have said. Since 2016, Harpswell has used state grant money to fund engineering studies on roads deemed most vulnerable to climate change. The town hopes to secure additional grants to implement the recommended fixes.
Nancy West, who serves on Harpswell’s Conservation Commission and its Resiliency and Sustainability Committee, said in an interview that all of the town’s major flood-prone public roadways have either been studied or are being studied.
West said the next priority is to facilitate similar studies of vulnerable private roads. About two-thirds of Harpswell’s roads are private, she said, and the town isn’t responsible for climate-proofing them.
Grants are regularly available to study the effects of sea-level rise on private roads, West said, but residents must first form a private road association and register it with the state.
“It behooves people in Harpswell to form a statutory road association, because they might have opportunities for grant proposals,” she said. “Secondly, the Conservation Commission would love to know about those road associations, because we can provide information when requests for proposals cross (our) radar screen.”
West said the commission can help neighborhood groups form their own road associations. While the town can’t help pay for private road studies or projects, she said, it has an interest in helping residents assess their roads’ vulnerability to future sea-level rise.
“We want to translate this into something people can do for themselves,” West said.
