ELLSWORTH — The Branch Lake Dam is in need of repair and further analysis is required to determine the best course of action.
That is the message civil engineer Gillian Williams, from GEI, delivered to the City Council during its regular monthly meeting on July 18. And the council agreed.
In a 4-1 vote, with Councilor Steve O’Halloran the only “no” vote, councilors approved up to $175,000 for the next phase of the rehabilitation of the dam. The funds would come from bond proceeds.
“It’s been noted here tonight that for 10 years we’ve been getting reports that the dam is worsening and seeping more and more and more, which tells me that for 10 years we’ve kicked the can down the road,” said Councilor Marc Blanchette. “I think it’s time to stop kicking and repair it.”
The dam, located on the northeast tip of Mill Pond, was initially constructed in 1911 by the Bangor Hydro-Electric Co. to be used for water control and downstream power generation. It was then purchased by the city in 1994. While it no longer helps generate power, it does control the water levels for Branch Lake, the sole public water supply for the city.
The Maine Emergency Management Agency has classified the structure as a “significant hazard potential dam,” which means failure or misoperation could result in major economic loss and environmental damage but would most likely not result in the loss of human life.
A rehabilitation project was completed in 2000, so parts of the dam are still in good condition, according to Williams’ review. But the troublesome left embankment wall through which seepage is occurring was not included in that work. Williams also noted that the fence and the gate to access the spillway had been vandalized or damaged and that there was no guardrail or fall protection on the upstream side of the spillway, making it treacherous for city staff who have to access that portion of the dam.
The review also found several issues involving the dam’s sluice gates, which are used to control the flow of water through the dam.
“There is no documentation that mentions the discharge capacity of four sluice gates, which makes it difficult to gauge what category of flood the dam is able to handle,” Williams explained. “The gates are also corroded and difficult to open, so they might not even be able to open them if needed for a flood.”
Discharge from the dam travels down Branch Lake Stream and into Leonard Lake, a fact that concerned City Manager Glenn Moshier.
“Obviously the Leonard Lake Dam is much more significant, but if this dam were to fail then that’s likely to cause catastrophic failure further down,” Moshier noted during the presentation.
Williams assured councilors that the dam was not at risk of immediate failure, but intimated that it was better to deal with the issues now as opposed to finding out what the dam can handle during a catastrophic event.
“Infrastructure doesn’t get better over time,” Williams said. “Things will continue to deteriorate if it’s not addressed. I’m not saying it’s going to fail tomorrow or anything like that, but it’s getting worse.”
“And with larger and larger storm events I think it’s critical,” added Public Works Director Lisa Sekulich. “We’re going to need to know what this piece of infrastructure can handle.”
The plan, approved by the council, prioritizes addressing the left embankment wall to better control the seepage. Williams recommended the next phase be boring into the left embankment’s crest to determine the state of the foundation. With that knowledge in hand, the team could then determine whether the wall could be rehabilitated or would need to be replaced.
She also recommended pursuing gate and fencing replacement options to make it safer on the spillway and a diving inspection of the sluice gates to determine why they are so difficult to open. Conducting hydrologic and hydraulic analyses also would help the city better understand what kind of flood events the dam is able to handle going forward.
Council Chairman Dale Hamilton also recommended that the city pursue short-term safety measures such as harnesses for city staff who regularly travel the spillway.
All told, Williams estimated the cost of this phase of the project to be $101,600. Once this information is collected, the next phase will be assembling a construction plan based on the findings.