CLEVELAND, Tenn. - Smoke is blowing through manholes and sewer lines in the Cleveland neighborhoods between Keith Street and Interstate 75, and from the Village Center down to Tinsley Park.
As part of detection efforts to locate damage to the wastewater system, nontoxic smoke tests play a critical role in Cleveland Utilities' long-term rehabilitation plans for its wastewater system, according to officials.
The 10-year "Strategic Commitment to Protect the Environment" - also known as SCOPE-10 - recently started its second year of operations.
"This process has allowed for the identification of problem areas and the development of rehabilitation plans for these areas," said Greg Clark, manager of the SCOPE-10 program.
The project goal is to reduce unwanted water flow - known as inflow and infiltration - into the city's wastewater system, hopefully reducing the number of sewage overflows that can occur after heavy rains. Stormwater typically invades the sewer system through damaged pipes or illegal downspout connections.
Smoke-test investigations can lead technicians to sections of pipe that have cracked, ruptured or simply worn away. Smoke rising from the ground, manholes or exposed pipe is the first clue, said Bill Miller of Utility Technologies, who is performing smoke tests on behalf of Cleveland Utilities.
Clark said noted leak areas may be investigated further with video cameras. If damage is severe enough, Cleveland Utilities will step in to repair the pipes. The program is intended to maximize effort and save money by concentrating on the worst leaks instead of fixing them all, he said.
Smoke testing not only pumps smoke into the main sewer lines, it pushes it through the plumbing system of nearby homes and businesses, and that freaks out some people, Clark said.
"The tests can be a little alarming when people see smoke rising out of their plumbing vents," said Clark. "We've received a few calls from people wanting to make sure that was supposed to happen."
Cleveland Utilities sends notices to customers before crews start smoke tests in their area.
The notices instruct customers to pour a gallon of water into all sinks, showers, and floor drains; dry toilets also should be filled. This measure is intended to fill drain traps with water and prevent smoke from entering the building.
The test smoke should not enter a building unless it has defective plumbing or dry drain traps, officials said.
The smoke, which smells a little like mineral oil, is not a hazard but can cause minor throat irritation. The letter warns people who suffer from respiratory conditions to leave their residence if smoke enters it.
If that should happen, Clark said, the smoke typically dissipates within 15 or 20 minutes.
Smoke test operations also require some coordination with local emergency services.
"We notify the fire department where we will be working," Miller said. "We probably see a fire truck once a day, though."