A $32 million project to protect dams from flood damage along the Mohawk River would preserve the Erie Canal’s historic nature and avoid the need for massive overhauls that could cost as much as $800 million.
The Federal Emergency Management Agency on Feb. 22 issued a letter responding to public comment on the Erie Canal Mitigation Project, a post-flood disaster effort aimed at minimizing flood damage to the movable gates that form dams along part of the canal.
According to the notice, people filing comment on the plans sought a more widespread, flood-prevention study of the Schoharie Creek — the biggest tributary to the Mohawk River — and the non-movable dam at Lock E-7 in Niskayuna.
But the post-disaster project is confined to minimizing flood damage to the state Canal Corp.’s facilities, so FEMA is referring the comments on the Schoharie Creek and the Niskayuna dam to other agencies.
Full FEMA response
To view the full FEMA response letter to public comments on the Erie Canal Mitigation Project, click here.
The unique, century-old movable dams that have sustained millions of dollars in damage from 2006 and 2011 flooding would get beefed up under the proposals.
FEMA spokesman Donald Caetano said engineers are drafting plans to internally overhaul the electric winches, or “mules,” used to raise and lower dam components.
The project will also include replacing chains, strengthening uprights with steel plates on their downstream face, replacing bushings for rollers that the panels move on and replacing lights on the dams.
Real-time gauges will also be installed both upstream and downstream of each of the dams, replacing the current method of gauging water levels — painted lines viewed by eye.
Canal Corp. spokesman Shane Mahar, in an email Monday, said the new gauges will provide real-time river flow data that will be remotely accessible to weather service and emergency management personnel as well as to the public.
“The more data points which can be factored into their modeling, the more accurate and timely their predictions can be,” he said.
“This information will give local communities the ability to appropriately prepare for forecasted flood conditions in advance of severe events. It will also guide the Canal Corporation in operational decision-making at each location as to the most appropriate conditions, both upstream and downstream, to initiate removal of the gates and uprights under higher water-level conditions,” Mahar said.
The dams consist of panels lowered down steel arms, which themselves can be raised out of the river using the mule. When the panels and arms are up, the river flows freely. When they are down, they create reservoirs between the locks with water deep enough for navigation.
Changes in the way the system is operated are also part of plans aimed at reducing damage caused by debris that slams into the dams, according to FEMA.
Trees, fuel tanks and parts of people’s homes battered the canal system when the flooded Schoharie Creek and Mohawk River scoured populated areas and landscapes after tropical storms Irene and Lee dropped massive rainfall in 2011.
$40M in damage
Canal Corp. damages from Irene and Lee alone exceeded $40 million, not including damage to other lands and infrastructure in and around the canal system’s series of dams and locks.
Working with staff from the Canal Corp., FEMA engineers reviewed a variety of options aimed at minimizing this recurring damage.
Several entities — including the New York City Department of Environmental Protection, the New York Power Authority and the state Canal Corp. — were able to reduce the amount of water in the system that affects the Mohawk Valley as Superstorm Sandy bore down on the region last fall.
The DEP reduced some water from the Schoharie Reservoir, held back by the Gilboa Dam, and NYPA emptied water from its lower reservoir.
The Canal Corp. was able to open up the movable dams in less than a week, providing additional room for flood water and fewer obstructions to catch floating debris.
With the goal of making it easier and faster to release water that the Canal’s dams hold back to create reservoirs, engineers reviewed several other options that would have amounted to $800 million overhauls of the movable dams themselves.
The other systems considered include taintor gates, such as those used at the New York Power Authority’s Blenheim-Gilboa dam, hinged crest gates, vertical lift gates, roller gates, wicket gates, drum gates, inflatable rubber dams and Obermeyer dams, according to FEMA.
The Obermeyer dam idea would cost about $800 million and the other designs are estimated to cost within 20 percent of that price tag.
The benefit to the less expensive project, however, is it would “modify the function of the movable dams to increase water conveyance, but retain as many characteristics and features to maintain its historic integrity,” according to the FEMA notice.
Draft plans for the work were reviewed by the state Historic Preservation Office, which determined the work “will have no adverse effect on the qualities of the dams that make them eligible for listing in the National Register of Historic Places.”
The Erie Canalway National Heritage Corridor is conducting research toward nominating the state’s barge canal for historic listing, and the movable dams themselves are important aspects of what makes them special, said Duncan Hay, a historian at the Erie Canalway National Heritage Corridor.
He said the movable dam system sprung from a period of engineering activity on both sides of the Atlantic during the 1800s and 1900s.
“People were trying to grapple with ‘how do we make rivers navigable.’ ”
The French were leading the way on designs by the 1870s and the Mohawk dams are believed to be an adaptation of two French designs, Hay said.
One of them was built on the Moldow River in what is now the Czech Republic.
The Mohawk dams were built on the Mohawk River between 1905 and 1918 as part of the Erie Canal’s transformation from a ditch that floated boats pulled by mules to the river itself being used as a canal.
Around the same time, the U.S. Army Corps of Engineers was eyeing methods to canalize other rivers, Hay said. They used a different design on canals in Ohio and Illinois — and all of those structures have been replaced at least twice, he said.
“I think it probably is a tribute to a good design to begin with. The engineers did their research and the one they picked they thought, at the time, was the best combination of available technologies,” Hay said.
The Canal Corp. is planning to share a new report detailing studies of the flow of water from Lock E-7 to E-16. Mahar said the report is expected to be posted on the Canal Corp. website Friday.