Working the rain Saturday, crews finished building a new rock dam and tore down the 173-year-old wooden one that had buckled after a week of heavy downpours and forced the evacuation of more than 2,000 residents.
The construction started Friday and was done Saturday evening.
“We prefer not to work this fast,” said Michael Nisslin, deputy chief engineer with the state Department of Conservation and Recreation.
But with more rain in the forecast, officials worried the Mill River could rise again to a dangerous level, Nisslin said.
The wooden Whittenton Pond dam started breaking apart Monday after several days of rain. Fearing a breach would send a wall of water up to 6 feet high crashing through the city, Mayor Robert Nunes evacuated residents and closed downtown businesses for several days.
The new dam spans 100 feet across the Mill River and is 25 feet thick. It connects to the concrete base of the old wooden structure, and is designed to slow the flow of water down the river.
The scare prompted Gov. Mitt Romney to order emergency inspections of 186 dams in the state that were deemed most likely to be dangerous. No serious deficiencies were found by inspectors, said Joe O’Keefe, chief of staff at the Executive Office of Environmental Affairs.