Updated: RBL dam Remediation Project
This post was originally posted on May 30, 2021. It has been updated to include the video of the meeting.
At a Zoom meeting on Saturday, June 12 at 9:30 am Hans Hasnay, the Chief Engineer on the dam project, and Town Supervisor Sam Oliverio answered questions about the RBL Dam Remediation Project.
Hans Hasnay, Chief Engineer of the RBL Dam Remediation Project
Town Supervisor, Sam Oliverio
Last year, at our 2020 budget meeting, Sam Oliverio informed us that the NY State Department of Environmental Conservation required remediation work on the RBL dam. Since then, we have had a full engineering analysis and recommendations from WSP, an environmental consulting firm. What have we learned? What are our plans? How will it affect properties near the dam? And…what is it going to cost?
Some background from RBLPOA president Ina Cholst:
The RBL Dam is classified as a High Hazard dam. About 400 of NY State’s 5,000 dams are considered High Hazard. High Hazard does not refer to the condition of the dam; it indicates that a dam failure might result in loss of human life. In December 2014, an engineering assessment of the RBL dam found the construction of the dam to be sound, but identified two deficiencies in meeting the safety requirements for a High Hazard dam:
The spillway is inadequate for an extreme weather event.
In an emergency, the low level outlet at the valve is not sufficient to drain 90% of the lake in 14 days.
On August 4, 2020, Putnam Valley received notice from the NY State Department of Environmental Conservation (DEC) that the Roaring Brook Lake Dam was in violation of NYS dam safety laws. The DEC rated the RBL Dam as “Unsound-Fair,” meaning that although it was expected to perform well under normal conditions, it would be unsafe under rare or extreme conditions.
Until the deficiencies are remediated, the RBL dam is considered unsafe, in violation of NY State Safety laws, and is subject to fines.
Without remediation, in an extreme weather event, the dam could overtop, with as much as 1.7 feet of water coming over the top of the dam. The force of that much water coming over the top of the dam could scour and rapidly erode the RBL earthen dam. The rapid erosion could cause a break or breach of the dam, with a potentially catastrophic failure. Overtopping could destroy homes, possibly cause loss of life, and possibly cause failure of the dam. For more information, read the May 7, 2021 Engineering Analysis and Recommendations for the Roaring Brook Lake Dam here.
To quote Sam Oliverio “Without the lake, we are just another development.” And without a safe, well-maintained, dam, there is no lake. The RBL District property owners are the owners and the guardians of the RBL dam. Come to this meeting. Take a look at the reports. The more we all understand the dam and its issues, the safer the dam — and the lake — will be.
