The city of Waterloo has hired consultants to help find a big leak in its sanitary sewer lines.
Waste Management Services Director Steve Hoambrecker said foot-long carp are showing up at the waste water treatment plant when the Cedar River level surges above 16 feet.
“When the river goes up our flows go up at the plant,” Hoambrecker said. “When the river gets to a certain height, we have fish showing up.”
He said the most likely source of river water entering the sanitary sewer system would be connections or leakage in the large interceptor sewer lines running along both sides of the Cedar River from downtown to the Easton Avenue treatment plant.
Those 48- to 60-inch diameter sewer pipes parallel the river, with the east-side interceptor routes at times along the west side of the flood levee system.
Sanitary sewer infiltration drives up the city’s expense to treat the additional water entering the system.
City Council members have approved a $19,995 contract with RJN Group Inc., which has an office in Des Moines, to inspect 65 manholes along the east- and west-side interceptors and another 47 manholes in the 100-year flood plain.
They also approved a $117,615 contract with RedZone Robitics Inc., of Pittsburgh, to evaluate approximately 20,660 feet of the interceptor sewer pipes.
“We did a pilot test (with RedZone) in October and found out there were a lot of problems,” Hoambrecker said. “Now we want to do the whole thing. This is just one of those crucial things that need to be done.”
Information collected by the manhole and sewer line inspections will be evaluated. The results will be evaluated by engineers to determine how to fix the problems.
A long-term capital improvement programme for the city’s sanitary sewer collection system and treatment plant was developed as part of a consent decree the city signed with the U.S. Department of Justice. The decree avoided legal action the federal government was prepared to bring against Waterloo for sanitary sewer overflows.
The capital improvement plan includes more than $16 million to rehabilitate the east-side interceptor sewer. But Hoambrecker said the manhole and sewer line evaluations might identify a much cheaper solution.