December 14, 2011, 10:00 PM
ABERDEEN, SD -
When a city's sanitary sewer has a problem, a lot of other people can lso have problems including sewer back-up in homes and sewage being pumped into rivers or creeks.
Aberdeen has been working to correct trouble spots in its aging system. Sometimes, there's more water passing through the wastewater treatment plant than it can handle.
"We never know exactly from spring to spring what's going to happen, what's going to come," Superintendent Pete Hesla said.
This past spring there was so much extra water passing through the plant, some of it had to be pumped directly into nearby Moccasin Creek.
"We don't have a permit that allows us to do that so obviously we don't want to do that if we don't have to," Hesla said.
Water flows are below the max the plant can handle now, so it's in good shape. But in the recent past when there's been flooding, the plant has seen more than 20 million gallons come in a day when it can only handle nine million.
Under the streets of Aberdeen lie aging sanitary sewer pipes that eventually lead to the plant. They've developed leaks over time. So, when there's more water around, there's more getting into the system.
"I can recall a time some 20 years ago when we were amazed at ten-million-gallon flows. And now we're seeing flows in excess of 20. And I think that speaks to how the system is degrading," Hesla said.
City engineer Robin Bobzien agrees. His department has been looking for solutions.
"It's a huge problem, a lot of feet of pipe throughout the whole town," Bobzien said.
Kline Street is one area that has a pipe under it that may be causing a lot of problems. The city suspects water is leaking from the storm sewer pipes into the sanitary sewer. So, plans are in the works to replace them.
But that is just one place. The city's been working with a consultant to figure out other potential problem spots. It's been sending cameras through the aging pipes and is still reviewing video from that. It's using other methods as well.
But finding the problem is just the beginning. The city has to pay to fix it as well. The repair work that would happen on Kline Street comes in at about $1,000 per foot.
"When you're getting into that kind of money, you don't want to spend it in the wrong spots," Bobzien said.
So, the city is trying prioritize problem spots. Bobzien figures the city could afford a couple million dollars of repairs per year for the next few years.
"I think over the next couple years, you'll see a dramatic improvement in what the wastewater treatment plant is seeing," Bobzien said.
Hesla hopes that's true. In his decades at the plant, he's seen the problem getting worse with water getting into the system from sources including Moccasin Creek.
"We've taken hundreds of fish off our bar screen in previous springs," Hesla said.
For now, he has holding ponds ready to take excess if flooding hits this spring again. The city hopes efforts will prevent flooding from leading to an automatic overload south of the city at the treatment plant.
"The problem is only going to get worse as our infrastructure ages so we need to keep looking for those problem spots and not become complacent because we've gotten a few million dollars of pipe replaced," Bobzien said.
The city is also applying for grant money so it can afford to make more progress in a year.
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