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April 7, 2012

 

Little York Lake Dam poses higher risk

DEC change to its hazard classification will make replacement project more expensive

By CATHERINE WILDE
Staff Reporter
cwilde@cortlandstandard.net

As the Cortland County Highway Committee next week considers a plan to borrow $1 million to replace the Little York Lake dam, the county is considering how the state’s recent change in the dam’s hazard level will affect the project.
Highway Superintendent Don Chambers said the state Department of Environmental Conservation informed him March 21 of the shift in classification. Previously it was deemed a low to moderate hazard, said Chambers.
Now it is considered an intermediate risk, Chambers said.
The hazard level is not related to structural safety of the 52-foot wide dam on the lake’s south end, he said, but rather the impact of water elevations on homes in the area.
“It has to do with the floodwater elevations and the impacts to the surrounding properties. And also if it does have a failure... it deals with the potential impacts to property and people,” Chambers said.
Chambers said a detailed study of the water elevations and flood analysis conducted as part of dam replacement preparations caused the DEC to change its classification. Chambers said the updated information and perhaps new development since the last time the classification was made were the reasons for the change.
Highway Committee Chair Dave Fuller (R-Cincinnatus, Taylor, Freetown and Willet) said two residences near the dam were determined to be at risk of flooding. Chambers said he “fully expects” the project will cost more than anticipated because additional engineering studies will have to be done because of the change in the designation of the dam. He could not predict how much more.
Chambers also cannot predict how the new classification will affect the dam replacement but said he hopes it does not significantly change the overall project cost: $917,000.
“There may be some issues we may have to address in regard to these change in classifications but I am not sure what those will be at this point,” Chambers said.
The county settled on the least expensive of three dam replacement scenarios in 2010. Construction is expected to take place next year.
The new dam would be a two-section structure. It would replace the existing main dam with a structure having two sluice gates, each 4 feet wide by 6 feet high.
The existing east gate structure would also be replaced. It allows water to flow over the dam and has two gates, one of which is in need of repair.
The new east gate section would have three sluice gates each 4 feet wide by 4 feet high, allowing more flow to be directed down the east channel rather than the main stream where the water currently is directed.
The water levels would be controlled by chain hoists on the gates that the county workers would pull to let more water through as needed. The new structure would also include railings and a walkway across the top of the dam, as opposed to a narrow plank the workers now walk on when adjusting water levels.
Chambers said he will be meeting with the county’s consultant for the project, Utica-based engineering firm Gomez and Sullivan, and the DEC to determine the ramifications of the changed hazard level.
The Legislature will have to decide how to change the planned replacement, said Chambers.
The dam replacement was included in the county’s bond schedule, which legislators authorized in November last year. The county will bond for up to $17 million in culvert and bridge repairs, scheduled to be done over the next 10 years and paid off over the next 40 years.
The dam is about 80 years old.

 

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