Sewer Cleaning Facts

Sewer overflows can cause contaminated ground water.

Most U.S. cities maintain separate rain and wastewater sewer systems. New York City joins 800 other U.S. cities that depend on combined sewer systems--merged storm and wastewater systems--that direct the mingled sewage to joint water treatment plants. When it's not raining, this setup performs nicely, but high rainfall causes problems; and when sewage lines become clogged, it's a nightmare waiting to happen.

Identification

In most cities, residential wastewater treks down sanitary sewer lines to sewage treatment plants. Older cities, such as NYC, are allowed mixed systems--combining sanitary sewage and storm runoff--to carry both forms of sewage to the treatment plants. The problem is that periods of considerable rainfall exaggerate the runoff amounts, which overwhelm treatment plant capacities, resulting in contaminated back siphonage in residences and streets. Contaminated discharge also spills into lakes, rivers and oceans, creating enormous hazards to marine life.

Function

Residential and commercial drains and toilets are piped into the sanitary sewers beneath the street. Sewage pipes are generally buried 10 feet or more below clean water pipes to prevent cross-contamination. When a single section of plumbing doesn't work, it indicates plumbing problems inside the house. If none of the plumbing works, it suggests problems outside the home. Routine maintenance keeps sanitary sewers flowing and minimizes service calls. Routine sewer cleaning removes the accumulated debris blocking pipes and reducing sewage pipe capacity.

Types

Sewer cleaning methods include the following:
1) High pressure flushing forces stone, sediment and other debris out with water pressure.
2) Sewer jet trucks cut roots by forcing high-powered water through a hydraulic motor with an attached root cutting blade.
3) Trailer-mounted bucket machines clear debris from larger sewer lines by situating two trailers over alternating manholes and dragging the bucket through the sewer line.
4) Vacuum trucks evacuate sediment and other rubbish from the sewer pipes, sometimes working together with the sewer jet system.

Prevention/Solution

Sewer repairs take place when damage has occurred somewhere along the line. First, the main sewer lines need to be repaired, followed by the smaller lateral sewers that stem from residences and businesses. Storm-water and wastewater systems are separated to decrease the water flow through the pipes and to lower water treatment costs. Culverts are restored to better redirect runoff and reduce erosion.

Effects

Sewer cleaning and repairs do two things. They reduce overflows in combined sewers by reducing the amount of water in the system and clearing out rocks, roots and other debris that may be clogging the pipes. They also improve the quality of the water in our rivers, lakes and oceans.

Considerations

Homeowners can do their part to keep sewer lines clear. Don't flush objects such as disposable diapers, feminine products or rags. Don't dump contaminants such as gasoline, oil or antifreeze. Don't send large amounts of food down the garbage disposal. Finally, let the city know whether private sewer lines are being cleared or whether sewer backups have occurred.

References

• Sewer Information. "City of Stillwater."
• Facts About Combined Sewers. "Division of Water."
• Sanitary Sewer Cleaning. "Amherst, New York Engineering Department."
• Sewer Cleaning and Repair. "City of Portland, Office of Transportation." 2010.
• The Works: Anatomy of a City. Kate Ascher. 2005.

Resources

• Sewer Cleaning and Inspection Program. "City of Winnipeg."
• Non-Conforming Sewer Program. "Portland Bureau of Environmental Services." 2010.