When an old under ground pipe system (most commonly water, sanitary, and storm) is replaced or no longer needed due to an upgrade, the project engineer may wish for the existing pipe to be removed or abandoned. Because leaving old pipe in the ground causes confusion and delay for future excavating construction work in the same area, the practice of abandoning pipe is avoided if possible and the pipe is entirely removed. This is more economical if the pipe being removed is incidental to a new trench being dug for a replacement pipe, but cases where a contractor will be required to dig a dedicated trench for pipe removal are also common.
For storm or sanitary pipe it is often old vitrified clay pipe that requires removal, sometimes due to an old piping system being replaced. Sometimes the pipe is discovered during construction of a new piping system requiring the old pipe be removed. Other commonly removed underground pipe types are ductile or cast iron (water main) or plastic (water main, sewer, gas, or electrical conduit).
As with any underground pipe or structure removal, if the pipe being removed resided under or near an existing or proposed pavement, the trench must be backfilled with aggregate stone and compacted to avoid future settling issues.
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