The debate on the role of the Gilboa Dam in the devastating flood of August 28 raged on Friday.
Representatives from the New York City Department of Environmental Protection told Schoharie County Supervisors Friday morning that the dam held up remarkably well and the failure of a temporary bulkhead, which the county did not know about when it was installed, had little effect on the flooding.
Dam Concerned Citizens members and some supervisors had a different perspective on the dam and the failure of the wooden bulkhead.
DEP engineer John Vickers said the improvements made to the dam since 2006 "were put into good use" during the flood.
Despite its age, the dam held back 19.5 billion gallons of water during the flood, he said.
During the peak flow, water was coming about eight feet over the top of the dam, Mr. Vickers said. It was predicted that the maximum flow was to be 1.8 feet over the top.
The existing dam "performed exceptionally well," Mr. Vickers told supervisors and about 20 people in the audience at the MOSA facility in Howes Cave.
There have been concerns about the age of the dam but Mr. Vickers said, "The concrete gets better with age," and well exceeds the stress put on it.
The dam, DEP officials said, did not move downstream during the flood but did flex under the heavy load.
A temporary bulkhead built at the dam to allow for construction work, failed early in the flood, as predicted, Mr. Vickers said. The failure of the bulkhead had a negligible effect on the amount of water released downstream.
He apologized to the county for not informing officials of the bulkhead before it was put in.
The bulkhead, which was 200 feet long and failed in 100-foot sections, failed when the water was at 1.75 feet over the top of the dam at about 9:30am on August 28.
"There was no jump in the (water) flow," he said.
Members of the DCC and supervisors disputed the effects of the failure of the bulkhead as well as other contentions by Mr. Vickers.
DCC member Sherrie Bartholomew said that while the dam did not cause the flood, there was a surge when the bulkhead failed.
"There has to be a surge," she said. "It was like a wall."
Mr. Vickers defended the action by the City.
"I stand by the actions of myself and my staff during this event," he said.
If there is an inquiry, he added, it will show that the dam is safe and the actions of the City were appropriate.
There were problems with communications. Information from the monitoring devices was lost and Mr. Vickers said phone lines were down to the NYPA downstream.
After questioning, he said he did not know if the DEP had radio communication with the NYPA.
Later in the meeting, supervisors passed a resolution supporting the call by Assemblyman Peter Lopez for a joint legislative hearing by the state houses to review the safety of the dam and the actions of the DEP before, during and after Hurricane Irene.
In part, the resolution stated, "For nearly a century, the Gilboa Dam, this sleeping and crumbling giant, has stood as an imposing and ominous shadow at the head of the Schoharie County Valley, holding back billions of gallons of water which solely benefit New York City, and which during flood or other casualty, such as we have just experienced during Hurricane Irene, holds in check the lives and property of so many, as well as the actual vitality and future of our communities."
Mr. Vickers said the DEP drained down the reservoir to 12 feet below the top in anticipation of Hurricane Irene.
Even if the reservoir was drained down to 60 feet below the top, it would not have prevented a flood, he said.
It would have taken 45 days to drain the reservoir down to that height and the rains still would have caused the reservoir to fill up and water to come 6.1 feet over the top of the dam. The maximum water flow would have peaked at 85,000 cubic feet per second. The flow peaked at 110,000 on August 28.
"This storm was massive and even if the reservoir was empty, it still would have been massive," Mr. Vickers said.
Draining the reservoir too quickly could have caused slope instability, Mr. Vickers said.
DCC member Howard Bartholomew chastised him for this explanation.
"It fills up faster than it goes down and you're worried about slope stability."
Supervisor Tom Murray was not impressed with the explanations saying, "The people in this county are getting sick of fancy talk and no numbers."
There have been improvements, Middleburgh Supervisor Dennis Richards said.
If not for the DCC, the county board and officials working with the DEP to put in additional anchors, the results of the flood "could have been a much different story."
Mr. Richards said when there is an investigation; the role of the New York Power Authority should also be scrutinized.
In addition to debating the effect of the bulkhead, DCC officials called for additional flood mitigation measures by the DEP including a second notch and enlarging or adding a second low level outlet.
Ms. Bartholomew also called for the sediment in front of the dam to be removed.
It was also noted that the tunnel to the Esopus Creek was closed before the storm hit.