Study to examine adding flood barriers in Port Deposit
PORT DEPOSIT — A new geotechnical study funded by Exelon Generation will examine the possibility of installing new barriers to stop floodwaters from inundating the town.
Vicky Rinkerman, Port Deposit town administrator, announced Tuesday night that AECOM won the bid to conduct the study, which will determine if the Norfolk Southern railroad embankments can support a temporary barrier, when needed, to hold back the Susquehanna River.
“Anything we can do to even reduce the amount of damage is win-win 100 percent for us,” Rinkerman said.
Exelon Generation gave the town $73,000 in donations toward the study. As part of the study, AECOM will determine if the underpasses at Vannort Drive and Netter’s Alley — if equipped with some sort of damming device — will hold back the river when floodgates are opened on the Conowingo Dam.
“The Maryland State Highway Administration has done some work at Netters and Vannort,” Rinkerman said, adding those areas are also part of the stormwater remediation project launched by the state earlier this year.
That project — which was supposed to be completed by May 2018 — is now on hold to be re-designed. Engineers need to account for solid granite and other barriers to construction, along with the discovery of asbestos piping. This includes the revelation that the underpasses are one large concrete pipe instead of multiple pieces.
In the meantime, AECOM will start its investigation of the potential flood barriers, which David J. Athey, principal water resources engineer, said would include testing the rail bed.
“We will do some boring into the embankments to test strength and permeability,” Athey told the mayor and town council.
Councilman Tom Knight mentioned that SHA also conducted borings.
“Would the results of those borings be helpful?” Knight asked.
Athey said AECOM plans to test a bladder system that would be brought in and installed only when needed, to help the outfalls being upgraded by SHA.
“We’ll look more closely at these underpinnings and look at what effect these bladders could have,” Athey said. “We have to determine at what elevation these floods occur.”
The idea is in certain situations the bladders would be anchored and inflated to prevent the river from entering the town. Rinkerman said this Exelon-funded study will find out if it could work, and which system would do the best job.
“This is to determine if the town will be able to go through with installing temporary floodgates,” she said, adding these would work in concert with the SHA’s outfall project.
In the almost 22 years since an ice gorge invaded the town, a system has been devised where Port Deposit officials are notified by operators of the dam and can monitor the river at numerous points whenever crest gates are opened. With 52 gates at their disposal, dam operators can open any number to release pressure.
In Port Deposit, seasoned residents know that there is no need for concern until that number approaches 16. By then, water covers Route 222 north of town and begins to cover Marina Park at the south end. When the number of gates passes 20, residents begin to take action, depending on their location along Main Street.
“Because of the technology we have and because of the emergency plans in place, we always have enough information,” Rinkerman said.
David J. Athey, principal water resources engineer for AECOM, explains to Port Deposit council members how the engineering firm will conduct a geotechnical study to determine if the railbeds and overpasses owned by Norfolk Southern can hold up under the weight of water from the Susquehanna River during a flood event.
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