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SALT LAKE CITY — Residents of downtown Salt Lake City said they heard music amid construction.
Musician Rosemary Olsen lives downtown, one block east of State Street. She said she heard a raised B chord repeatedly outside her window.
“It’s really weird, 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, ‘They’re aliens! ‘” she said. “Someone else said, ‘Oh, that was my group practicing, that was supposed to be a minor 7th. I guess we screwed it up. “”
The Salt Lake City Department of Utilities said the noise came from sewer technology that has been in use since 2015.
“We are deploying tones in the sewer line to identify if there are any blockages in the system that we can clear out,” Director Laura Briefer said.
The technology is called Sewer Line Rapid Assessment Tool, or Sewer Rat. A transmitter is placed on a maintenance hole and a receiver on another several meters away.
“One will emit the tone and the receiver will listen for the tone,” said sewage collection manager Steve Terry. “The receiver, as it listens to this tone, will rate it based on how open and unobstructed the pipe is.”
A change in volume indicates that there is some sort of blockage or cleanup to be done. The Sewer Rat gives each sewer pipe a grade and a numerical score.
“Things like flushable wipes can clog our sewer lines with things like grease, oil, and grease,” Briefer said.
She said the technology keeps workers out of confined spaces, away from waste and is environmentally friendly.
“We’re dramatically reducing the amount of water and energy required to perform a traditional waterline assessment,” Briefer said.
Olsen said she found the notes pleasing to the ear.
“I thought it was very down to earth work and they made it into something ethereal and beautiful,” she said.
She has a question for the technology developers.
“Why did they choose an increased chord? Does it have more thrust, does it have more power?” Olsen said.
Briefer said residents are encouraged to report what they hear to the department.
“A lot of times the work we do is out of sight and out of mind, and I don’t think people really realize all that goes on behind the scenes and underground,” she said.