DIXFIELD – Selectmen learned Monday night that an elusive sewer pipe leak might just be the harbinger of a much-needed but costly wastewater pump station overhaul.

According to a Wright-Pierce engineering report, several problems were found at the station that was designed in 1977 and has been operated continuously since the early 1980s.

After having E.L. Vining, a Farmington contractor, excavate a large hole on Hall Hill Road at the suspected leak site on Aug. 12, Public Works Director David Orr now believes the system’s air and vacuum release valves may be the culprits behind the leak.

“We dug up 80 feet of road and went 14 to 16 feet deep and didn’t find anything,” Orr said Monday night. “Then it leaked again and I talked to an engineer who said the system is 25 years old.”

Orr said that air and vacuum release valves on the town’s sewer system piping are suspect now after the Wright-Pierce engineer told him the valves are supposed to be looked at every three to four months.

“But nothing’s ever been done to them,” Orr added.

According to Stephen A. Broadbent, an environmental services engineer with Wright-Pierce, the valves are an integral part of many pumping systems. “The valves are particularly important in systems with long force mains, relative high points and high-head conditions,” Broadbent wrote in an Aug. 14 letter to Orr. “If air or other gases become trapped in the piping system, the pumping rate can be reduced and water hammer can occur.”

Broadbent said water hammer can cause movement in the piping system and, under the worst conditions, it can cause catastrophic failures in the piping system.

“We could have an air bubble in the line, but we can’t release it because the valves are so rusted. If we fix the leak, but not the valves, we run the risk of it all blowing back out,” Orr added after telling selectmen that it would cost $5,000 to replace each valve.

Selectmen Chairman Hugh Daley said the board had no choice but to replace two of the three valves and rebuild the third, which had rusted out completely.

With only three of the town’s five selectmen present, a unanimous vote gave Orr the right to take $10,000 from the sewer budget and buy two new valves. After all three valves are fixed, however, the leak must still be located and repaired, Town Manager Nanci Allard said.

Orr also recommended that selectmen take a hard look at Broadbent’s report and decide when to retrofit the pumping station, something that could cost upward of $400,000 or more.

“Given the age of the system, there are a number of code, worker safety, and hydraulic issues that should be addressed as part of any improvements you make to the station,” Broadbent wrote.

Although the town has rebuilt the station’s pumps, he recommended that replacement pumps be considered in the near future.

Broadbent also said that the station’s ventilation systems are not in compliance with current code requirements. And, a new supply-air source is needed for both spaces.

Additionally, access into the wet well side’s confined space must be improved for worker safety.

“This area is a confined space and by today’s standards, entry into this type of space is to be avoided as much as possible. We are smarter today than we were 30 years ago and we would certainly do things differently in this area given the current worker safety regulations,” Broadbent added.

Before the board decides what to do about the aging facility, Orr suggested they take Broadbent up on his offer to do a more detailed evaluation of the pump station for between $2,500 and $4,000.

tkarkos@sunjournal.com

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