Fowler estimated dam repairs could cost upward of $15,000 to $20,000, depending on the extent of the repairs.
Work may include pressure grouting to fill other cracks and voids found in the dam. Officials can use a waterproof camera to get beneath the dam structure for additional inspection. When water flows so rapidly due to structural damage, soil and landscape can be comprised.
“You don’t know how much soil you’ve lost,” Fowler said. “We want to try to protect what’s left underneath there. We need to see how much erosion there was.”
Fowler said Derry owns another dam at Hood Pond. A lagoon near the transfer station is also considered a town-registered dam.
An inactive dam at Beaver Lake on Pond Road was removed in 2011. Dams that are no longer in use can become an expensive liability for the town. Others dams scattered around town are privately owned.
It’s always good to be prepared for any dam problems that occur, Fowler said. He said the town and residents living near the dam did a good job responding to the trouble.
“This wasn’t something we expected to happen,” Fowler said, “but we had to address it as soon as possible.”