OTISFIELD — The Board of Selectmen has received a 15-page report from a Portland consultant that says the Pleasant Lake dam in Casco is in poor condition but there are no signs of imminent failure.
The dam is on Mill Brook behind the Hancock Lumber office on Route 121. It regulates the water level of the 3.8-mile-long lake which lies in Casco and Otisfield. There are numerous homes and cottages around the lake, as well as the Seeds of Peace International Camp on the northeast shore and Camp Arcadia for Girls on the western shore, both in Otisfield.
The dam has been jointly owned, operated and maintained by Casco and Otisfield since 1994. It was previously owned by Hancock Lumber Co.
Maine Emergency Management Agency officials inspected the dam Aug. 15 and reported significant leakage and structure deterioration.
Local officials say it has been losing as much as 1,000 gallons of water per minute in at least three places.
In addition to addressing the condition of the structure, the report proposes short- and long-term operation, maintenance and remedial measures to improve its condition.
“The good news is, we’re not expecting anything catastrophic,” said Selectmen Chairman Hal Ferguson who received the report at Wednesday night’s board meeting.
Myron Petrovsky, principal of MBP Consulting in Portland and author of the report, said a review of the project information and field inspection findings indicates the overall condition of the dam is poor.
“The dam appeared stable at the time of the inspection and no signs of imminent failure of the structure were observed,” Petrovsky’s report said. “However, the existing numerous dam deficiencies, such as severe deterioration, excessive seepage and limited hydraulic capacity, may require at some point in the future to perform major repairs to improve operation and reduce a risk of its failure.”
Petrovsky’s report said the dam, which is a tributary of the Crooked River, is leaking extensively.
“Almost every component of the dam was leaking …,” he said.
He said it if fails it could drain Mill Pond and lower the lake level between the Route 121 bridge and timber crib cofferdam by about 3 feet. Other consequences could occur, he said.
Petrovsky recommended short-term solutions, including removing brush, dead trees and other debris, visually observing the water levels on a consistent basis, stockpiling sandbags near the dam and creating an emergency plan.
Long-term approaches include remedial measures to extend design life of the dam and to bring it into compliance with the current dam safety regulations and requirements. Petrovsky has suggested doing a topographic and underwater survey of the dam, Mill Pond, and the area of the Route 121 bridge, including property boundaries and developing a conceptual remedial design.
He said in his report that permanent dam repair measures may include partial or complete replacement of the north dam section; renovation of the side spillway and replacement of both training walls; replacement of the front spillway with a gated spillway and installation of reinforced concrete overlay on the waterside faces of deteriorated structures.
The cost of short-term and long-term actions are not known at this time. Petrovsky said once town officials determine what the dam repair approach will be and funding is finalized, more engineering work can be performed, including final design, construction cost update, permitting, contract documents, bidding and construction management.
Otisfield selectmen took no action at Wednesday night’s meeting except to approve an additional $300 to the consultant. Each town will pay $800 for the inspection report for a combined total cost of $1,600.
Ferguson said Otisfield selectmen and their counterparts in Casco will need to study the document before getting together to decide on an action. He said that should happen in a couple of weeks.
According to the Maine Dams Inventory, the 110-foot-long, 12-foot high dam was built in 1850, repaired in 1980 and has low-hazard classification, meaning there is nothing significant downstream that would be affected by a dam breach.
ldixon@sunjournal.com
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- The dam at Pleasant Lake in Casco is located behind the office of Hancock Lumber Co. on Route 121. Officials are concerned about the deterioration of the dam.
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