Managing Infiltration

Infiltration: Line Inspection / I&I Reduction Program

Infiltration is groundwater that enters sanitary sewer systems through cracks and/or leaks in the sanitary sewer pipes.  Cracks or leaks in sanitary sewer pipes or manholes may be caused by age related deterioration, loose joints, poor design, installation or maintenance errors, damage or root infiltration.  Groundwater can enter these cracks or leaks wherever sanitary sewer systems lie beneath water tables or the soil above the sewer systems becomes saturated.  Often sewer pipes are installed beneath creeks or streams because they are the lowest point in the area and it is more expensive to install the pipe systems beneath a roadway.  These sewer pipes are especially susceptible to infiltration when they crack or break and have been known to drain entire streams into sanitary sewer systems.  Average sewer pipes are designed to last about 20-50 years, depending on what type of material is used.  Often sanitary sewer system pipes along with the lateral pipes attached to households and businesses have gone much longer without inspection or repair and are likely to be cracked or damaged.

In 2007, PAWSD began a sewer line televising program.  Each year, approximately 10 miles of the District's 100 miles of sewer line are televised and cleaned, and point repairs made or portions of sewer line replaced to eliminate infiltration of groundwater.

In 2008:

  • Amount of line televised: 12.8 miles
  • Amount of line cleaned: 13.2 miles
  • Number of point repairs made: 13
  • Feet of sewer pipe replaced: 298
  • Amount spent: $133,588

Hi-tech camera and other testing equipment like those shown below will be used again this year to locate problems and identify sources. 


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