With coffee cup in hand, Dan Oldham calmly watched a thick stream of white smoke rising from a pipe on the roof of his Folsom home Tuesday morning – a sight that normally would have sent him hurrying to call the Fire Department.
Oldham had been warned by the city of Folsom that his house would be included in a program that uses smoke to test the soundness of the sewers. The smoke testing reveals where cracks exist in sewer lines, or where a homeowner has illegally hooked up gutters into the sewer system.
“When people take their downspouts and connect those directly to the sewer, rainwater goes directly to the sewer, and we don’t want that,” said Todd Eising, environmental and water resources manager with the city of Folsom.
Stormwater flowing into the sewer system eats up valuable capacity and can potentially lead to raw sewage spills. It also costs money to treat and convey that extra water.
The smoke testing is simple. Workers open a manhole and attach a lawnmower-sized engine. It powers a fan that blows vaporized water into the sewer system. The water is harmless, more condensation than smoke.
The most noxious part of the process stays at the street, in the form of the smoke that sputters out of the engine at the manhole cover.
In order not to alarm residents, the city alerted homeowners two weeks prior to testing, said Eising.
Some of the homeowners spilled into the street Tuesday to watch smoke trail out of their pipes. “I’m glad they’re doing it,” said Oldham. “I just don’t want any smoke inside my house.”
It takes less than half a minute for the smoke to travel underground from the manhole cover and emerge from a home’s vent pipe. The vents, located on roofs, are part of standard home design. They work with the sewage system to make sure changes in water pressure in the house don’t suck in sewer gases or smells, Eising said.
Smoke rarely enters the home, unless there is a leak – or the homeowner has tied into the system illegally.
Folsom’s sewage collection system consists of more than 267 miles of sewer pipe and nine pump stations. The smoke testing costs the city between $2,000 and $2,500 for each mile of pipe.
The entire system was smoke-tested between 2002 and 2006, said Eising. This year, the city is testing in phases. It’s the kind of testing that feels like it never ends, he said. Once all the 17 basins have been tested, it’s not long until the city needs to start testing again.
Smoke testing also has been employed by such cities as Berkeley and Santa Rosa.
Eising said the testing is part of Folsom’s commitment to water quality – an issue that dogged the city in the past. Between 1995 and 2000, the city had several overflows of raw sewage into the American River and the Folsom South Canal.
The largest overflow occurred in 2000, when the Central Valley Regional Water Quality Control Board fined the city $700,000 after a spill sent 700,000 gallons of sewage into the American River.