Litchfield expects to receive finalized design for Woodbury Dam work by late April

The dam at the east end of Woodbury Pond on June 15 in Litchfield. Joe Phelan/Kennebec Journal file

LITCHFIELD — Officials hope to receive a finalized design from Calderwood Engineering for a permanent fix for the Woodbury Pond Dam, which began to show signs of seepage last spring, by the end of the month.

Once dam keeper Terry Averill discovered the seepage last year, the town began work with Topsham-based engineering firm Wright-Pierce and geotechnical consultants from Haley & Aldrich, who identified a loss of materials within a 10-foot area of the embankment.

Residents then approved a $55,000 warrant item to repair the dam during last June’s Town Meeting.

The dam’s issues, if left unchecked, could cause the road across the dam to become impassible and lower the water level in some of the five Tacoma lakes, negatively impacting animals, plant life and surrounding property values.

At first, town officials considered installing sandbags and pressure grouting, which would stabilize the area for two years while they figured out a permanent fix. The town later opted to just install the sandbags, without pressure grouting, a move that was estimated to save the town roughly $150,000.

The sandbags were placed along the east wall of the dam last October, but in December Averill said that some seepage was still occurring.

Town Manager Kelly Weissenfels said on Tuesday that a small amount of leakage is currently occurring at the dam.

“The sandbags are not perfect,” he said, “but it is stable, and we are monitoring it to make sure that it remains so.”

In January, the select board unanimously approved a $22,500 agreement with Calderwood Engineering for the final design and work oversight.

Weissenfels said engineers are working on addressing a few questions from the Select Board about the sheet pile’s connection to the dam and expect to deliver the updated plan ahead of the board’s next meeting on April 25. Sheet piles are structural sections that provide earth retention.

“The tricky part of engineering with the sheet pile is the connection of the sheet pile to the concrete wall of the dam, and that’s the part they wanted to provide a little more detail about,” he said. “They want to make sure they get that final attachment concept done properly, and that’s the last piece remaining.”

Once the design is finalized, the town will put the project out to bid. Contractors will have until the fall of 2023 to complete the project, instead of the end of this year, Weissenfels said.

“That’s to allow bidders to mitigate more risks by allowing more time to acquire materials if they need to do that,” he said. “Our hope is that if somebody is able to get the materials more quickly then they’ll get the job done sooner, but we want to give them the opportunity to have that length of time to get those materials at a cheaper price.”