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June 9, 2021



  • Mona City will use an acoustic inspection to check sewer lines

By Myrna Trauntvein
TN Correspondent

Mona will pay $17,889 to have the entire sewer system in the city evaluated and the dirty areas cleaned.

Brent Arns, sewer plant operator and biosolids coordinator for the Mona Wastewater Treatment facility, presented a sewer system update to the Mona City Council.

Arns is also a review engineer with the Utah Division of Drinking Water.

“First we need to decide on how we want to do the sewer line testing for this year,” said Arns. “The company that has been working for us has cleaned one third of the city lines annually but they have a new proposal.”

They are proposing to use an acoustic inspection to check the whole city once a year. That system uses sound to locate and characterize pipes based on the sound of flowing water.

It is called the SL-RAT (Sewer Line Rapid Assessment Tool) and can provide a blockage assessment faster and cheaper than the traditional methods.

“Nephi City and Santaquin City are using the acoustic inspection,” said Jay Mecham, city council member.

Mecham made the motion to use the SL-RAT system to check on all city sewer lines, select the dirty areas, clean them and inspect all the manholes for $17,889. Randy Christensen, council member, seconded the motion and all voted in favor.

“This method can help prioritize maintenance needs by avoiding needless cleaning of relatively clean pipes,” said Arns. “They will concentrate on cleaning just the dirty areas.”

Arns said that the city council was given three options to select from but the RAT system was proposed to check all the city lines, clean only the trouble areas and the trunk lines needing cleaning.

“They will inspect all the manholes,” he said. “That adds $2,500 to the RAT inspection of $15,389.”

“In 2019,” said Mecham, “we did one-third of the town and that cost us $10,000.”

Arns said, the cost of doing the town piecemeal will go up every year, because, as the city grows, it adds more lines.

“The second option,” said Mecham, “is that they would do half the town.”

That would cost $10,938 for half the city, said Mayor Bill Mills. The price also included the $2,500 for the manhole inspection.

Arns said that the third option was to clean and TV 25 percent of the system, 25 percent of the trunk lines and 25 percent of the manholes.

The total cost for that project would be $15,394 and that included $625 for the manhole covers.

“We are one year behind because of COVID, we didn’t do it last year,” said Mecham.

RAT technology relies on the fact that sound traveling trough through air mimics the flow of water through a pipe.

It will measure obstructions within the pipe such as roots, grease, debris, joint offsets and hammer tap lateral connections. The device measures the energy gap and develops a blockage assessment.

Arns said that it was a good thing to have the sewer manholes cleaned although the council could opt out of that portion.

“It is your choice,” he said.

Vandals would put all sorts of things inside manholes like rags, sticks, tires and plastic toys.

“You are required, by insurance, to clean the main line,” said Arns.

Grease was a big problem in the sewer line. Gobs and gobs of grease that clog sewer lines and bind debris together are causing problems at the plant.

“If they find a big spot of grease, they could follow it back to where it came from,” said Arns.

He said that sewer plants have a life of approximately 20 years and the plant was now 10 years old. The membrane has a longer life and cleans itself.

Membrane Bioreactor systems, like the one used in Mona, are widely used in municipal and industrial wastewater treatment plants.