MIDDLETOWN – The town’s 10-year-old wastewater treatment plant is failing, and the cost to repair or upgrade it will be in the millions.
Mayor Charles Harbaugh said the town was told it would last 25 years.
“I did not know how bad it was until tonight,” Harbaugh said after a Monday night work session.
At that session, town officials and council members heard from Keith E. Lane, a professional engineer with Peed & Bortz LLC, about the plant’s overall condition and its bio-wheel treatment process.
“It appears the bio-wheels are at significant risk of failing,” Lane said. “There are six of these. One of the six is not functional. The other five appear to be getting ready to fall apart. It is truly a matter of when and not if.”
The bio-wheels are large rotating drums where attached microorganisms are grown to consume pollutants and treat wastewater. They work as the main biological treatment portion of the overall treatment plan of the plant, Lane explained.
That is the most significant risk to the plant, but it is not the only issue, he said. Town officials may want to consider increasing its 400,000-gallon capacity.
“You are seeing monthly peaks of 350,000,” Lane said.
Those monthly average flows are approaching the plant capacity, with five months in the last two years that were over 70 percent, he said.
The town has to consider future growth and the demand it would place on the plant, including The Village of Middletown, which is a development of 180 units under construction on about 60 acres near Lord Fairfax Community College.
The plant would also need to be upgraded to handle potential regulatory changes, including a pending change expected to occur to ammonia-nitrogen levels.
“There is a very real risk that the town’s existing permitted discharge ammonia limits will be lowered due to these pending rule changes, and the existing plant will not likely be able to achieve more stringent limits without upgrade,” Lane noted after the meeting
Lane presented town officials with four alternatives to consider:
No action, which means there could be a high risk of major mechanical failure and of future violations.
Rehabbing the existing plant at an estimated total cost of $2.3 million. That would replace or repair the existing bio-wheels, replace existing influent pumps and controls, new mechanical screens and other work. Lane and town officials expressed concern they would have to repair the bio-wheels again in another 10 years.
A retrofit process change of the plant at an estimated total cost of $3.2 million. This would remove the bio-wheels and replace them with a modern system, such as one that uses diffused aeration. Other improvements would be done as well. This would likely improve performance and provide a potential for limited capacity increase.
A major upgrade of the plant at an estimated total cost of $4.8 million. This would remove the bio-wheels and replace them with a modern system, and a new, larger basin would be constructed for increased capacity. This option provides the highest potential for increased treatment performance and future capacity increase if needed.
The town is in its 10th year of paying on a 25-year zero-interest loan taken out to pay for the existing plant. The town pays $180,000 a year on the loan, Harbaugh said.
He did not know how much the loan was for or how much the town still owed. Emails and phone messages on Tuesday left with Town Manager Rebecca Layman seeking that information were not returned before press deadline.
Harbaugh and Layman are discussing the possibility of looking into whether they can add the cost of whatever option is chosen onto the existing loan and making payments as large as possible, he said.
“This is frustrating,” Harbaugh said, adding the town has spent money to maintain the plant — more than $500,000 in the last and current fiscal year, he said. That money could have been spent on other much-needed projects or saved for these improvements, he said.
Town officials are working on scheduling a Public Works Committee meeting to discuss the matter.
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