Upgraded hydropower facility recommissioned
Over the past year, developer Bill Scully's Hoosic River Hydro LLC, has installed new, more powerful generating equipment and made numerous other upgrades to the facility, which once served the former Pownal Tanning Co.
The rambling brick mill began life as a textile factory in the 19th century and stood beside the hydro dam on the Hoosic River in North Pownal village. It closed for good in the late 1980s and was razed during a multi-year, federally funded cleanup effort that ended in the early 2000s.
But the impressive 153-foot wide, 18-foot high concrete dam — technically, a concrete ogee spillway, over which the Hoosic flows and sometimes thunders — remained in place, attracting the attention of Scully.
Three years ago, the North Bennington resident brought the former Vermont Tissue Paper mill facility on the Walloomsac River in that village back online — one of the first two hydro sites to be restored in nearly three decades in the state.
He first met with the Pownal Select Board in 2012 to begin discussing a lease for the Hoosic hydro site.
On Saturday, Scully led a tour of the hydro powerplant for local officials and supporters of the $4 million project, explaining the restoration effort and the process by which the powerful waterflow generates electricity.
"I was very pleased seeing the hydro up and running, and want to thank Bill Scully for not giving up on us when things got complicated due to EPA and other issues with the site," said Select Board Chairman Nelson Brownell.
"Bill worked hard and never gave up on his project," said Select Board member Suzanne Caraman. "Pownal should be proud of this project and all the work that went into it. Everyone should drive by and see how nice it is."
"Electricity generation equipment was installed in the early 1900s and produced in the range of 250 kilowatts at peak level," Scully said in an interview. "Hoosic River Hydro replaced the old equipment with a 491-kilowatt Wasserkraft Kaplan turbine and [Hitzinger] generator set."
The concrete spillway was constructed in 1955 by the tanning company, but waterpower dam structures had stood at the site dating back to the 1800s.
The facility now is capable of generating 3.5 million kilowatts per year, Scully said, with net-metering electricity credits being provided to Southern Vermont College and Southwestern Vermont
Medical Center in Bennington and to the town of Pownal.
Adjustable Obermeyer Hydro Inc. crest gates were installed atop the spillway to divert water in a controlled flow toward the powerhouse, where the vertically mounted turbine and generator are housed.
Scully said there is an 8-foot diameter, concrete lined, steel penstock that carries water to the powerhouse and the generating equipment below. The operating range is 110 to 350 cubic feet of flow per second.
What is called the forebay — just upstream from the powerhouse — has a trash rack to filter out leaves and river debris. It includes a hydraulic trash rake to remove the material that collects at the intake.
Helping to control the exit flow at the river level below the dam, the tailrace has a cement training wall on the upstream edge.
Complicated licensing and permitting aside, the project also had to overcome deposits of polychlorinated biphenyls (PCB) that had flowed down the river — likely from former mills in nearby Massachusetts — and settled behind the concrete dam. The earliest work on the facility involved setting up a temporary cofferdam behind the concrete dam to allow approximately 1,500 cubic yards of contaminated soil to be first de-watered and then removed for trucking to a hazardous waste disposal site.
Permitting for the project involved mounds of paperwork and dealing with the federal Environmental Protection Agency, the U.S. Army Corps of Engineers, the Federal Energy Regulatory Commission, the Vermont Agency of Natural Resources, the state's brownfields redevelopment program and other entities, as well as the task of working out an agreement with Green Mountain Power to purchase the electricity generated.
"This project shows how local, state, federal and private interests can come together, revitalize infrastructure, and contribute to important environmental goals," said state Rep. Bill Botzow, D-Pownal/Woodford. "My thanks and appreciation to all who worked so hard for this success."
Jim Therrien writes for New England Newspapers in Southern Vermont and VTDigger.org.
@BB_therrien on Twitter.
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