Proposed dam repair could save Litchfield approximately $ 150,000


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

LITCHFIELD – Litchfield officials are currently exploring a long-term solution for the Woodbury Pond Dam that could cost around $ 150,000 less than the initial repair plans.

The problems started to show up this spring, when the dam keeper Terry avill Witness the sagging of the rockfill next to the right side of the upstream drive wall. He also noted seepage along this wall, starting at around 7 feet and intensifying to 7.5 feet.

Since then, Topsham-based engineering firm Wright-Pierce has inspected the site and presented Litchfield with a report, along with an estimate of repair costs. The company was also assisted by geotechnical engineering consultants from Haley & Aldrich.

Testing confirmed that water was passing through that wall and out under the downstream drive wall, and engineers also noted that the rip-rap deposited between their visits in May. They found that the problem was caused by a loss of material to the backfill in an area of ​​10 feet and recommended that the elevation of the pond not exceed 7 feet until action was taken against the leak. .

They proposed a two-phase approach to tackle the problem. The first phase would stabilize the situation and consist of installing sandbags along the affected area as well as pressure injecting this area to temporarily stabilize the dam. This part of the plan also involves regularly monitoring the dam and dike and noting any changes in infiltration or settlement.

The first phase was estimated to keep the area stable for up to two years.

In June, residents approved an addition of $ 55,000 to the municipal budget to help with the first phase of the dam repair.

Phase two would be a long term remedial strategy. The engineers suggested three options: the installation of a concrete core in the backfill of the existing dam, the installation of a steel sheet pile separation wall on the upstream face of the dam or the installation of a secant concrete pile wall on the upstream face of the dam.

Litchfield coaches discussed the approval of the first phase in a meeting on Monday, but chose not to approve until engineers could provide a more precise financial estimate. In total, the costs of this phase were initially estimated between $ 79,500 and $ 142,000.

The dam at the east end of Woodbury Pond recently in Litchfield. Joe Phelan / Journal Kennebec

City manager Kelly weissenfels said on Wednesday that the city’s director of public works Larry Nadeau suggested to go ahead with the steel sheet pile partition wall option for phase two. He said this option would allow the city to skip the pressure grouting step and install sandbags only as part of the first phase.

“Grouting costs up to $ 150,000,” Weissenfels said, “so rather than investing money in this procedure, which would give us about two years, we hope to go straight to the sheet steel wall instead. , and that way it would save us $ 150,000, that’s our hope.

Looking ahead, he said the next step would be to allow engineers to conduct a geotechnical survey and determine if the sheet steel option would work.

In the meantime, the city will continue to research the permits and monitoring necessary to install sandbags at the site. Once the permit was obtained and the sandbags installed, Weissenfels said the dam’s problems would be kept at bay for about seven months, by which time the engineering work would ideally be completed and authorities could secure permits for the solution. long-term.

Nothing has been finalized at this point, he said, but said he would be presented to the selection committee on July 12.

Weissenfels said they are still exploring the costs of the long-term solution, and initial estimates were around $ 300,000. To help fund this solution, he said the city will explore grants as well as the Maine Municipal Bond Bank Dam Repair and Reconstruction Fund.

“This is great news in terms of the economy,” Weissenfels said. “There is a bit of a risk if the leak increases, and that’s why monitoring the dam is important. “

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