When a manufacturer closes its hydro plant in New England, it may not spend the rest of its life collecting dust. Swift River Hydro Operations Co. (SRHOCO) can step in to rehabilitate the hydro, President Davis Hobbs says.

“What I’ve found is when industries have left the region, they no longer want to operate their hydro facilities,” he explains. “We buy it to refurbish, rebuild and replace old equipment, modernizing it to raise the plant efficiency.”

Hobbs joined Peter Clark, an experienced natural resource manager and energy project developer. They founded SRHOCO in 2001 as the operating company for Swift River Company, which had initially focused on building renewable energy projects throughout New England, including wood-fired cogeneration projects and designed wood-fired power plants to divert waste wood away from landfills. 

Today, as SRHOCO, it focuses on rehabbing older hydroelectric projects in Massachusetts. Usually, Clark looks for dams and hydro plants built to power paper mills and textile factories built at the start of the industrial revolution.

“Manufacturers generated their own power to turn furniture laths, textile machinery, pulverize fibers to make paper, and to power other factories that put whole mill towns to work fabricating goods for the U.S. markets,” he explains. “SRHOCO upgrades the original turbines with new, more efficient equipment and sells the renewable power to the Reading Municipal Light Department, a local electric distribution company.”

Improving Pepperell Project

SRHOCO’s projects include the rehabilitation of a hydro plant in Pepperell, Mass., built by the Pepperell Paper Company in 1919. SRHOCO rewound two of the plant’s original Westinghouse generators to increase capacity for larger turbines, Clark says.

SRHOCO installed a Dong Fang generator that matched the speed of the original Leffel turbine, which last year SRHOCO replaced with a new Kiser Hydro propeller turbine to increase capacity by 15 percent. “Also, Kiser built another turbine replacement, raising its capacity from 640 kW [kilowatt] to 850 kW,” Clark said.

The plant’s efficiency was increased by the unique design of the Kiser wicket gatecase. “These changes helped [qualify] all the improvements for production tax credits, which helped Pepperell to win a treasury grant to fund 30 percent of the investment,” Clark says.

New England Infrastructure installed a fish passage system into the Pepperell dam. “This same structure will serve as an intake for the minimum-flow turbine that will share the bypass flows during the fish passage season,” Clark explains.

SRHOCO will generate power from flow discharged below the dam by installing a 67.5 kW min-flow turbine built by HeCong in China. “[It will] efficiently extract kinetic energy from the flow that will also be used to attract fish and eels up to the dam through the bypass reach,” he says. 

“We built a downstream fish passage system but won’t build an upstream passage system until shad and alewife migrate up to the Pepperell dam,” Director of Regulatory Affairs Martha Brennan adds.

Coping with Mother Nature

One challenge SRHOCO must face during projects is the unpredictable weather, Brennan says. 

“Recently, there’s been higher highs and lower lows in both temperature and water flows,” she continues. “That makes predicting long-term patterns more difficult.”

Although summer 2014 was busy for SRHOCO, “The 2015 summer did not turn out to be that way,” Brennan says, noting that the company endured the driest May in many years, but saw partial recovery in June-July as the summer progressed. 

“This did not prevent a 1936 turbine at Woronoco [Hydro] from breaking its shaft in June of 2014,” Clark comments. After contracting, it took 10 months for NORCAN Hydraulic Turbine Inc., a Canadian turbine designer, to manufacture the replacement for Woronoco’s largest turbine. Bancroft Contracting installed the replacement.

“Yet we could not test the new turbine in August or September of 2015 because there was too little water flowing in the Westfield River,” he says.