UNIVERSITY CITY — Crews are set to begin inspecting and clearing piles of concrete and debris from the River Des Peres tunnel system as soon as Monday, raising hopes that the work could help reduce risks of extreme flooding.
The effort will extend through 6 miles of sewers and tunnels and roughly 100 “connection points†that feed into it between its upstream mouth in University City and its downstream opening near Macklind Avenue and Manchester Road in ºüÀêÊÓƵ.
“I’m delighted,†said University City Councilmember Dennis Fuller. “My only hope would be that they now do this on a routine basis. ... This tunnel thing has been a thorn in everybody’s side.â€
For months, the mounds of material — some of which are 30 feet long and 5 feet high — have stoked criticism and concern along the flood-prone waterway. University City residents, stormwater commissioners, and city councilmembers have voiced alarm about the debris and its lingering presence more than a full year after devastating flash flooding swamped the region in July last year. Several have demanded that MSD remove the debris and fully inspect the tunnel.
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But the Metropolitan ºüÀêÊÓƵ Sewer District said this week that the main purpose of the work is to inspect the tunnel and its connecting sewer lines. The effort wasn’t prompted by the slabs of concrete debris piled inside, said spokeswoman Bess McCoy, and the removal of the piles is not expected to create any significant reduction in local flood risks, she said.
“The tubes behaved exactly as our models said they should behave†during the 2022 flash flooding, said McCoy — when the upper River Des Peres overran the roughly 20-foot opening to the tunnel in University City, adding to widespread flood damage.
Still, some here are ecstatic that the moment has come.
“Sixteen months after the historic floods, I fully support and am thrilled that MSD is now going to inspect and clean out their stormwater sewer infrastructure,†Councilmember Jeff Hales said in an email.
MSD said that the known debris piles near University City’s end of the tunnel are expected to be removed by the end of this year, McCoy said. She said that the work will reveal new information as it progresses, since plenty about the state of the tunnel system remains a mystery.
In recent months, for instance, the utility tried to fly a drone into the tunnel to scout it out, but McCoy said it was a “failed experiment,†as complications prevented the drone from getting a thorough look.
“It was way too dark in there,†McCoy said.
She said insights from the upcoming work could be used to better plan future sewer improvement projects, and even help the utility grasp some basic details about the structure.
“This is a very old tunnel,†said McCoy. “Our maps of it may not be accurate.â€
MSD has hired contractor Ace Pipe Cleaning to do the work.
The utility said it could take nearly a year and cost up to $2.2 million, though actual costs could be significantly lower.