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SALT LAKE CITY — People living in downtown Salt Lake City have reported hearing music amid the construction.
Musician Rosemary Olsen lives downtown, one block east of State Street. She said she heard a B augmented chord repeatedly outside of her window.
"Just really kind of eerie, but it was beautiful," Olsen said.
She posted about the strange sounds on Nextdoor, a social media platform for neighbors to interact with each other.
"A lot of people said, ‘It’s aliens!’" she said. "Someone else said, ‘Oh, that was my band practicing, it was supposed to be a minor 7th. I guess we blew it.’"
Salt Lake City’s Department of Public Utilities said the noise is coming from sewer technology that’s been used since 2015.
"We deploy tones to the sewer line in order to identify whether there are any blockages in the system we can clean out," director Laura Briefer said.
The technology is called the Sewer Line Rapid Assessment Tool, or Sewer Rat. A transmitter is placed on one maintenance hole and a receiver on another several feet away.
"One will emit the tone and the receiver will listen for the tone," wastewater collections manager Steve Terry said. "The receiver, as it listens for this tone to come through, then it will assign it a score as far as how open and unobstructed the pipe is."
A change in volume indicates there’s some sort of blockage or cleaning to be done. The Sewer Rat gives each sewer line a rating and number score.
"Things like flushable wipes can clog our sewer lines along with things like fats, oil, and grease," Briefer said.
She said the technology keeps the workers out of confined spaces, away from waste and is environmentally friendly.
"We greatly reduce the amount of water and energy needed in order to do a traditional water line assessment," Briefer said.
Olsen said she finds the notes pleasing to the ear.
"I thought, that’s very earthy work and they’ve made it into something ethereal and beautiful," she said.
She has a question for the developers of the technology.
"Why did they choose an augmented chord? Does it have more push, does it have more power?" Olsen said.
Briefer said residents are welcome to report what they hear to the department.
"Often times the work we do is out of sight and out of mind, and I don’t think people really realize how much is going on behind the scenes and underground," she said.