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City Sewers
MAINTENANCE:
How We Keep Sewers Working
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 Operations and maintenance activities are 'round-the-clock, 365-days-a-year. Major activities focus on operations, preventive and corrective maintenance, and emergency response.
Many maintenance activities focus on tree roots and fats, oil and grease (FOG) that clog the sewers.
The number of sewer spills (overflows) in the City has significantly decreased over the past five years as a result of these efforts. These include:
- sewer and maintenance hole inspection – over
2,600 miles of sewers are inspected annually; over 600 miles
are inspected by closed circuit television each year.
- sewer cleaning – more than 2,600 miles are cleaned annually.
- hot spot sewer cleaning – at least 1,500 miles are cleaned annually.
- root control – chemicals are applied to a minimum of 150 miles annually.
More details about sewer maintenance activities are available in the Collection System Settlement Agreement Annual Reports. |
FOG-Related Sanitary Sewer Overflows - by Fiscal Year
Root-Caused Sanitary Sewer Overflows - by Fiscal Year
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Interceptor sewers
These lines are relatively small, designed to collect sewage from properties along individual streets. Like small creeks that feed larger streams that turn into rivers, sewers become larger and larger as the sewage flows further and further “downstream”. The largest pipes in the City’s system are over ___ feet in diameter and can carry ______ gallons per minute (hour or day?). They are called interceptor sewers. |
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Pumping Plants
Most sewers are designed so that gravity alone carries wastewater to the treatment plants. Low-lying areas such as some beach communities or valley locations need pumping plants to push wastewater through pipes that are under pressure (force main sewers) so that the sewage can reach a gravity sewer. The City operates 48 pumping plants and __ force mains. |
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Drop structures
Drop structures are like waterfalls. They quickly move sewage from a higher to a lower elevation. In the past they have been used in hilly parts of the City. However, the falling wastewater causes turbulence at the bottom of the structures and this can produce sewer odors. The odors are being treated by a number of methods inlcuding air treatment facilities. (link here to air treatmetn facilities). |
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Sewer siphons
Sewer siphons are used to move sewage underneath freeways, rivers, or other potnetial obstructions that could obstruct the sewer’s route. The sewer dips under the obstuciton and then comes up on the other side and ties back into the sewer at about same elevation where it began the dip. Like a siphon used to take gasoloine from a car, the sewer siphon is powered by the pull of wastewater on its downstream side. |
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Maintenance covers
Most everyone has seen the metal plates that cover maintenance holes (formerly called amn holes). (photo of cover). The maintenacnce holes give the City access to the sewers for periodic inspection and repairs. (photo of remote TV inspection and person getting into sewer). The City’s system contains __ mainteneacne holes. |
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Report Sewer ODORS
