Derry Director of Public Works Michael Fowler expects the repairs to the Beaver Meadow Dam to be complete by sometime this week. The New Hampshire Department of Environmental Services (DES) signed off on the repair plan and Derry paid $3,000 for a reconstruction permit. Fowler said his department has been working closely with the DES Dam Bureau on the repair plan for the dam.
He explained that a 5- to 6-foot hole was found under the dam.
The reconstruction and repair plan include three phases, he said. The first involved pouring a new concrete pad on the upstream side of the dam. The second phase involves construction of a 12-inch vertical wall on the upstream side to tie into a new sluiceway gate. In addition, a new plastic 16-inch pipe was to be inserted into the sluiceway, tying into the new wall on the upstream side and through to the downstream side.
This is expected to deliver the same flow for the drawdown of Beaver Lake in the fall.
The final phase is the injection of grout under pressure to fill the hole and all the potential fingers of the hole that may not be visible to the human eye.
Fowler said the three phases had to be done in sequence and by specialty contractors.
“We were fortunate to get the specialty contractors needed to come and do this now, as we see it as an emergency and want to protect the level of Beaver Lake,” he said.
Initially, Fowler said he thought the project would cost $25,000 to $50,000, but the cost of the specialty contractors, getting the repair plan designed, and doing all that is entailed in the repair will push the final price tag closer to $100,000. He said the grout process alone costs $20,000.
“We have money in the current budget,” he said, estimating he had $150,000 remaining. “I am paying close attention to what is coming in but right now I think we have enough to cover this. If something unforeseen arises and we don’t have sufficient funds, we will go to the Town Council for an emergency appropriation.”
This spring, a vigilant resident noticed the flow of water under the dam down the stream and reported it to Fowler’s office, initiating his inspection and action to address the situation. The spill was slowly emptying the meadow and keeping the level of water low in Beaver Lake.
The dam protects Beaver Lake and controls its level. It dates back to the early 1900s, when Benjamin Chase, owner of the Chase Mill, erected it to create water power, and later electric power, for his mill.
A second dam stood at the end of Beaver Lake as well, between the lake and the meadow, but it had ceased to function and the town, rather than repair it, removed it last year.