Pleasantville Seeks to Control Nannahagan Pond Floods, Protect Pool Facility
Construction of a new Pleasantville village pool will begin at the end of the 2022 summer season, driving a concern to prevent flooding from the adjacent Nannahagan Pond that has previously damaged the existing facility.
At last week’s Pleasantville Village Board meeting, Bob DeBruin of DeBruin Engineering in Westbury, N.Y., presented a detailed report on how to mitigate and offset future flooding from the pond.
Damage was sustained to the pool and pool house as a result of Hurricane Ida near the end of last summer. The hurricane, categorized as a highly-destructive 100-year storm, forced the village to end the pool season just before Labor Day weekend. A previous major storm saw the pond overflow, dumping mud and silt into the pumps and pool building, which damaged the piping, filtration, treatment and electrical systems.
DeBruin told village officials that the dam over Nannahagan Brook was built in 1908 and caused the formation of Nannahagan Pond.
“The source of all the water contributing to the pond is from a watershed that is some 854 acres,” DeBruin explained, showing an image of the watershed covering a vast area surrounding the pond.
Currently, water flowing over the dam discharges over two weirs, or walls, and into an open channel between the lake and the walkway adjacent to the pool building. There are also two bypass pipes that, during a storm, carry the water from the lake and discharge it into the channel.
At the walkway, the channel flows into a seven-foot-wide by six-foot-high box culvert that runs under the pool building and parking lot before emptying into Nannahagan Brook, which then flows through the village and eventually empties into the Saw Mill River.
“The problem with a big storm, when the flooding starts, the water level rises and goes over the wall between the walkway and the building, seriously flooding the pool area,” DeBruin said.
He presented the village with a series of mitigation options that would protect the new pool and be able to withstand the flow of what has been considered a 100-year storm, now a more frequent event as predicted by scientists. The five options are estimated to cost from $100,000 to $1.1 million.
Mitigation includes dredging the pond to increase the pond’s detention capacity, raising the walls and constructing a new culvert. DeBruin recommended raising the walls around the channel and constructing a new culvert around the south side of the pool building.
He proposed that the work be done in tandem with the new pool project, and suggested the culvert be constructed in place using a poured-in-place concrete floor, gunite walls and pre-cast concrete top slabs. The culvert would be adjusted to measure eight feet wide by five-and-a-half feet high. The weirs at the pond would not be modified but could be at some point in the future.
The plan would cost about $1 million, DeBruin said.
The village is planning to put the pool project out to bid by early May and award the bid in June. An estimate of 90 percent of the project’s total cost is expected by early next month. Officials are planning to move forward with a bond resolution that gives them authority to borrow up to a specific amount.
The new pool will mostly be funded by the bond, which would be subject to a permissive referendum. A modest increase in pool membership fees is expected to contribute toward the project’s cost. Construction would begin in the fall soon after the swim season ends on Labor Day.
Mayor Peter Scherer said a decision on which mitigation option to pursue must be made relatively soon.
“It’s going to be expensive whatever we do but we have no choice but to do it now,” Scherer said. “One would hate to spend a lot of money on a new pool and have this (flooding) damage happen and affect the new pool and pool house.”
Scherer said the cost of the flooding mitigation would likely be added to the bond.
“There may also be some infrastructure money floating around; whether we could compete for it is another question,” he said.
Abby is a local journalist who has reported on breaking news for more than 20 years. She currently covers community issues in The Examiner as a full-time reporter and has written for the paper since its inception in 2007. Read more from Abby’s editor-author bio here. Read Abbys’s archived work here: https://www.theexaminernews.com/author/ab-lub2019/
