Oxford wants more info to address dam danger

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Welchville Dam

OXFORD — The Board of Selectmen has decided it needs more information before a decision can be made about the future of the Welchville Dam.

Selectmen agreed at its Oct. 5 meeting to continue investigating what to do with the Welchville Dam – a structure on Route 26 in the Welchville section of town that Myron Petrovsky of MBP Consulting in Portland said last May was in “imminent danger” of collapsing.

Petrovsky told the Advertiser Democrat earlier this month that a dam – such as the Welchville Dam – is considered in “imminent danger” when the structure is unraveling, leaking and deteriorating to the point that it cannot hold the impounded water at the specified level (the dam crest).

“I expect the dam will continue unraveling when the river flow exceeds the gate capacity and water goes over the dam, which was the case in the past few years,” Petrovsky told the Advertiser Democrat.

Petrovsky said if nothing is done to repair the structure, he expects the next major flood could breach the dam, releasing the impoundment of water and sediment (possibly contaminated) downstream.

In June, residents were warned to stay off the dam when selectmen followed Petrovsky’s recommendation to install “danger” signs at the Welchville Dam, a  popular fishing area.

The board was also told that it would cost about about $1.4 million to repair the dam or about $900,000 to build a new dam. Former Interim Town Manager Becky Lippincott recommended to the board that the dam be replaced.

At that time, selectmen voted to hire Petrovsky to develop specs that would allow the dam replacement project to go out to bid in order to get a truer cost estimate for the project, but Petrovsky said he never got the go-ahead to do that work.

Residents concerned

Although the Welchville Dam is considered a “low-hazard” structure, Petrovsky has said if the dam fails he expects the water levels of Whitney and Hogan ponds to drop at least five to six feet and could also send buried, old toxic materials downstream and pose a threat to recreational users in the river at the time of the failure.

Whitney and Hogan ponds, which are popular summer destinations and home to several campgrounds, lie parallel to each other and are interconnected at the northern end. The outlet leads to the Little Androscoggin River and on to the Welchville Dam.

The 170-acre Whitney Pond has a maximum depth of 24 feet, while the 177-acre Hogan Pond has a depth of 34 feet.

According to information from the Hogan-Whitney Ponds Association, more than three-quarters of the land surrounding the two ponds is residential and about 15 percent is vacant. The number of property owners who live on their land year-round is less than 25 percent. The Hogan and Whitney ponds watershed covers about 2.6 square miles.

Chris Glassman, who is a summer resident on Hogan Pond and has been coming to the selectboard meetings to ask about the dam, told the Advertiser Democrat that he believes it is important to keep the topic fresh in the minds of selectmen.

“It’s a long process. I would love to see them do something,” he said of concerns he and his neighbors have over potential property damage should the dam fail.

Glassman said many families would be affected if the structure collapsed and offered to serve on a committee to determine the outcome of the dam.

Petrovsky said the Little Androscoggin River watershed has not experienced significant floods in the last four or five years, which has helped prolong the dam’s life.

“The records show the last 2011 and 2012 floods have had major damaging effect on the dam,” he said.

In 2012, Petrovsky said he inspected the dam and recommended, as a temporary measure, to fully open, year-round, both sluice gates to reduce the frequency of the dam over topping and subsequent impact on the wooden structure.

“The gates are designed for maintenance, not for flood protection, and their ability to control the flood flow is limited,” he said.

As long as the gates are still in operation, it will reduce the risk of dam failure, he said.

Gates on dams help water levels in a lake, but during the summer when there is recreational use and “summer people” on the lakes, towns often try to keep the gates closed to ensure the water levels are conducive to recreational needs.

Last week selectmen opened the Welchville Dam gates.

ldixon@sunmediagroup.net