By SCOTT JACKSON
Residents of the Post Island neighborhood want the city to further investigate the installation of pump stations in the area before committing to a new seawall height.
About 30 residents, many from Post Island Road and nearby streets, attended a community meeting on the new seawall Tuesday in the Coddington Building. Residents spent more than two hours discussing the seawall design with city officials and engineers from Tighe & Bond.
Tighe & Bond is working with the city to design a new seawall that would stretch along Quincy Bay from Chickatabot Road to Babcock Street, covering some 8,000 linear feet of coastline in total. The replacement of the seawall will require various federal, state and local permits, including approval from the Quincy Conservation Commission. The commission will hold a public hearing on the proposal Nov. 7.
The seawall currently in place along Quincy Bay sits, on average, 11 feet above mean sea level, according to Dave Murphy of Tighe & Bond. Tighe & Bond had initially planned to raise the height of the entire seawall to 15 feet above mean sea level, Murphy said, using the same design as the seawall that stands there now.
Based on feedback from some residents worried the four-foot increase in the seawall height would impact their view of the waterfront, Murphy said the plan, which is not yet set in stone, now calls for a two-foot increase in the seawall height with the option of adding an extension up to two feet tall to the top of the wall in the future.
“It’s a compromise between going too high and blocking people’s visual view. It allows us to go back to the standard block, which the city has used all along…that block design will be modified so that we can properly dowel into an extension block above,” Murphy said.
Thirteen feet above mean sea level is equal to the height of the storm surge and wave action seen during the Jan. 4 nor’easter, which brought the highest high tide Boston has ever seen, according city engineer Paul Costello said.
As part of the project, the city will also replace the 14 outfall pipes that drain stormwater from the areas behind the seawall into Quincy Bay. Ken Mavrogeorge, an engineer with Tighe & Bond, said the new outfalls would be placed at the proper grade to allow stormwater to flush any sediment out of the pipe. The new outfalls will also have one-way valves inside to stop seawater from surging up the pipe onto land.
The outfall pipes will be wide enough to handle the rainfall from a 100-year storm event, which is about 8 inches of rain in 24 hours.
The seawall itself would have drainpipes, with one-way valves, to allow water to drain back to the ocean.
City officials and Tighe & Bond are also eyeing pump stations for the Post Island neighborhood, Murphy said, separately from the seawall and outfall project.
“Even by raising the seawall, even by adding the drain-back pipes through the seawall, even by increasing all the outfall pipes to a much, much larger size to handle one-year storm events – even with all that there will be conditions of flooding,” he said.
“That therefore concludes that the city needs to work towards having in this particular area…some sort of an intake structure that is designed for emergencies only.”
The permitting process for a new pumping station is less stringent than the process for a seawall, Murphy added.
When residents were asked towards the end of the meeting if they would prefer the new seawall be built two or four feet higher than the existing barrier, they said their answer depends on whether or not the pumping station were built.
“The pump station is tied to the height of the wall,” said Post Island resident Bill Bowen. “We can’t come to a decision on the height of the wall until we figure out can we do the pump station.”
“Our decision is not aesthetic,” said Ann Donovan. “Our decision is if we want to have a house in 10 years.”
Another resident, who declined to give her name, compared asking residents what size seawall they would like to see built without knowing more about the pump station to answering a marriage proposal without knowing if the other person was already married to someone else.
The city received a $441,000 state grant in 2016 for design and engineering costs related to the new seawall and outfall pipes, which are estimated to cost between $15 and $20 million. Murphy said the city would apply for state and federal grants for the seawall project, and the pumping station project, later this year or early next year.
Ward 1 Councillor David McCarthy said he planned to meet again with residents to discuss their concerns. Mayor Thomas Koch, McCarthy, is committed to seeing the project through.
“I’m sure we’ll have another powwow as we talk to the mayor and others about the funding and our options, and I’m sure he’s going to fix the problem,” McCarthy said. “He knows what the problem is and he’s going to fix the problem.”
The meeting for Post Island residents is the second of three seawall meetings McCarthy will host. The third and final meeting, for those living in Adams Shore, will be held Nov. 1 at 6 p.m. at the Coddington Building.