The City of Berkeley recently began a 10-year program of smoke testing the sanitary sewer system. The testing reveals places where there are defects or improper connections in the sewer system, and is particularly intended to find places where the separate stormwater drainage system may infiltrate into the sewers. Excess water into the sanitary sewers can overload the system, pump stations and treatment plants, and could cause overflow of untreated wastewater during storms.

“Berkeley has been pretty efficient in rehabbing its main lines,” said Jeff Blum of E2 Consulting Engineers, who are conducting the smoke testing throughout the EBMUD area. “Now we’re looking at lines they may have missed.”

In the smoke test, a fan pushes smoke down from a manhole opening into the sewer system. If the sewers and home plumbing systems are in good shape, smoke appears from the roof vent. If there is a crack or a poor connection, smoke will seep out through the ground, or in cracks in the sidewalk or from a storm drain.

The smoke is noticeable, although not very dramatic. “It’s 15 minutes of inconvenience for a neighborhood,” Blum said. Signs are posted near testing so passersby or drivers don’t mistakenly think there’s a fire.

The smoke used in the testing has been approved by the EPA and is non-toxic and non-staining. However according to a FAQ on the Berkeley city website, residents with pre-existing conditions such as emphysema or heart/lung problems should either vacate the area during testing, or keep doors and windows open so the smoke dissipates rapidly.

Homes in areas being tested (see map below) are notified two weeks before testing begins and then again at the beginning of the week of the testing.

Where problems are discovered with sewer laterals, storm drain connections or sewer leaks within structures, staff from the city’s Public Works department will notify property owners and make recommendations on how the problems can be resolved.

Lance Knobel (Berkeleyside co-founder) has been a journalist for nearly 40 years. Much of his career was in business journalism. He was editor-in-chief of both Management Today, the leading business magazine...