Dubuque smoke-testing its sanitary sewer system - KWWL - Eastern Iowa Breaking News, Weather, Closings

Dubuque smoke-testing its sanitary sewer system

Smoke pours out of a pipe atop the roof of a Dubuque home Smoke pours out of a pipe atop the roof of a Dubuque home

The city of Dubuque has taken up smoking - at least until Wednesday.

It's part of a test of the sanitary sewer system, to see where storm water is seeping in during rain events, which can lead to overflow and an overloaded system.

Dubuque, like most cities, wants to keep its waste water and its storm water separate, but aging infrastructure has allowed storm run-off to leak into the sanitary sewer system in places. City engineers call that an improper connection.

To test for leaks, work crew members light a smoke bomb, which is attached to a blower. They set that down snugly on top of an open manhole. The blower then forces the smoke through the cracks and leaks in the sanitary sewer.

"The smoke bomb only takes about three minutes to go off, and we can walk up and down the street within that range," Dubuque engineering technician Nate Steffen said while conducting smoke testing Monday.

Crews look for smoke leaks in the area.

"That shows us that would be improperly connected to the sanitary sewer, so the rainfall water would be getting into the sewer system," Steffen said.

Dubuque environmental engineer Todd Shoemaker said the smoke is, "a non-toxic, non-staining smoke."

Engineers say too much water in the sanitary sewer inundates the system and can bog down the Water Pollution Control Plant.

"The pipe system just isn't designed to carry water like this, so that's when you get the overflows and the backups," Steffen said.

Shoemaker gave an example.

He said on one particular day this past summer, there were about five million gallons of water going through the Water Pollution Control Plant in the morning. After just a two- to three-inch rainfall later in the day, "that spiked up to 25 million gallons."

"The end result is, we still have too much water that gets down to the wastewater plant," Shoemaker said.

This week, the city will test about 12 miles of Dubuque's sanitary sewer system. Shoemaker said the ground needs to be dry in order to conduct the smoke test, so August and September are ideal months for it.

This week, crews are testing just one of five problem areas the city says contribute large amounts of storm water to the sewer system. This test is the last one for the year. Other problem areas will be tested in August and September of coming years.

On Monday, crews found smoke coming out of storm drains, drain pipes on houses' roofs and even a retaining wall.

Shoemaker said, "either the private homeowners or else as the city, we ask those improper connections to be fixed and disconnected."

During this week's testing, some homeowners might see smoke come into their homes. Shoemaker urges people to not worry, that the smoke is non-toxic and doesn't stain. He said it is good, however, to report those leaks to the crews. That number to call is 563.582.5481.

For more information about the smoke testing, a list of frequently asked questions provided by the city and a map of the five problem areas outlined by the city, see Dubuque's Website by clicking HERE.

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