What you flush down the toilet doesn’t always make it to the wastewater treatment plant

By Ralph Echtinaw

The city continues to struggle with sewer line clogs caused by unauthorized material being flushed down St. Louis toilets.

“Twice in the last few weeks the Michigan Avenue pump facility had to be unclogged,” wrote Public Services Director Keith Risdon in his monthly report. “DPW and Water Department personnel removed one pump to clear wipes and rags clogging the impellers and found that the pump (only 18 months old) has suffered scoring and damage from this clogging.”

This photo from April 2022 shows the volume of rags and wipes that accumulated in the wet well and around the pumps at the Michigan Avenue pump station.

Risdon continues: “The Union Street pump station has been tripping off regularly and recently after staff cleared the clog, the variable frequency drive (VFD) failed to start. A contractor was brought in after hours to work on the pumps and controls. Additional work has been scheduled with the contractor to reconfigure the controls then program and install the new VFD (our spare). Another spare VFD has been ordered.”

“People continue to flush items into the sewers which eventually settle into the pump station wet wells or settle in the pipes.”

Public Services Director Keith Risdon

The root cause of the problem is unauthorized material flushed down St. Louis toilets. “People continue to flush items into the sewers which eventually settle into the pump station wet wells or settle in the pipes,” Risdon wrote. “I recently assisted DPW with a blocked sewer. We were out from 9 p.m. to 1:30 a.m. trying to locate and clear a blockage which was causing backups into residences. Once the blockage was isolated, attempts to clear it failed so DPW had to try to cut through the blockage. The depth of the sewer exceeded the reach of our equipment so had we not been able to cut it loose a contractor would have been required to excavate the line. Fortunately the blockage was cut, and it was found to be an accumulation of wipes and rags. The plumber who was onsite for the resident said he was finding the same materiel when he was trying to clear the lines near the residence.”

Unauthorized material that doesn’t clog pumps and pipes is screened out at the wastewater treatment plant. “During our recent heavy storm rainfall event, our WWTP filled three dumpsters full of heavy solids and grit,” said City Manager Kurt Giles.

During that period of heavy rain a blockage formed downstream of the Michigan Avenue pump station, meaning the materials were able to be pumped through the sanitary sewer pumps and into the pipe. “It eventually settled out along the sewer line and continued to build up over a short time to cause the blockage,” Giles said. “DPW crews tried to ‘jet’ the blockage out but after they were unable to clear it, we had to try to cut it out.  That was successful, and when the cutter head was removed, it too was covered with rags and wipes.”

The best solution is to stop flushing things into the sanitary sewer system which do not belong there, Giles said. “Costs for maintenance, repair and replacement for our sewers come directly from our sewer rates. As the efforts required to maintain, repair and/or replace increases, rates too would be required to increase to cover those costs.”

So how is a person supposed to remember what can be flushed and what shouldn’t?

That’s easy. Anything that’s not fecal matter, urine or toilet paper should never be flushed.

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