Pipes

From LID SWM Planning and Design Guide
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Perforated Pipe 550x550.jpg
Pipes are available with perforations on just one side, these should be situated on the lower half of the pipe. Pipes with 360° perforations should have a strip of geotextile or membrane placed over the pipe to reduce the migration of fines from overlying media.

Pipes should have been manufactured in conformity with the latest standards by the Canadian Standards Association (CSA) or ASTM International.

  • Perforated pipes should be continuously perforated, smooth interior HDPE (or equivalent material) with a minimum inside diameter of 100 mm.
    • Smooth interior facilitates inspection and maintenance activities; internal corrugations can cause cameras or hydrojetting apparatus to become snagged.
  • Where freezing is a concern, horizontal underdrain pipes should be over-sized to a minimum 200 mm diameter.
  • Perforations should be made on all sides of the pipe and provide a ≥ 1 m2 of open area per linear meter of pipe.
    • A perforated pipe with many rectangular slots has better drainage characteristics than a pipe with similar open area provided by fewer circular holes [1].
  • Non-perforated pipes should be used for conveyance to and away from the facility, including overflow.

  1. Hazenberg, G., and U. S. Panu (1991), Theoretical analysis of flow rate into perforated drain tubes, Water Resour. Res., 27(7), 1411–1418, doi:10.1029/91WR00779.