MERIDEN — Six months after it was drawn down to allow for construction of a hydroelectric generator, Hanover Pond has been restored.
The pond was lowered in September so workers could construct an Archimedes screw generator at the dam. The screw was installed in late December and is undergoing testing, said Chris Conover, spokesman for Massachusetts-based New England Hydropower.
“We’re going through the final phases of testing and approval to generate,” he said.
With construction complete, the company began refilling the pond around March 1. Refilling can be unpredictable due to weather, Conover said, but “in this case, we actually were able to do it in a pretty controlled fashion.”
“The pond is running naturally” as of Monday, he added.
While work is on schedule, it’s unclear when New England Hydropower will start generating electricity. Conover said the company is “running through the barrage of tests” and couldn’t provide an estimate.
The technology was invented over 2,000 years ago by ancient Greek scientist Archimedes and has been used in Europe for the past decade. Conover said Meriden is the first city in the United States to use the technology. Electricity will be generated when water at the top of the dam is sent through the screw, causing it to rotate at about 30 revolutions a minute.
The 20-ton, 35-foot-long steel screw, lifted by crane into the pond in December, will generate about 900,000 kilowatts of electricity annually and could save the city $20,000 a year.
The electricity will be fed into the Eversource Energy power grid. The city would then buy the electricity back with vouchers. Over the next 20 years, the property taxes are expected to total $110,000.
Fish and other aquatic animals can travel safely through the dam.
“The fish are going in at the same speed and going out at the same speed without pressure and without pinch points, just moving down in big tanks of water,” New England Hydropower CEO Michael Kerr said previously. Kerr estimated in December that the screw would be generating power by spring.
Roger Kemp, vice president of the Quinnipiac River Watershed Association, said the pond “is pretty much back to normal.”
“My only concern was, are they going to drain it again?” he said.
Conover said there is no reason to drain the pond again. It was originally drawn down so that construction crews could build coffer dams allowing the screw to be installed.
“It’s done and they don’t need to drain it again, so that’s good news,” Kemp said.