Pipes

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.

• Non-perforated pipes should be used for conveyance to and away from the facility, including overflow.
• a perforated pipe with many rectangular slots has better drainage characteristics than a pipe with similar open area provided by fewer circular holes .

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Filter fabric that is installed to separate dissimilar soils and provide runoff filtration and contaminant removal benefits while maintaining a suitable rate of flow; may be used to prevent fine-textured soil from entering a coarse granular bed, or to prevent coarse granular from being compressed into underlying finer-textured soils.

Soil particles with a diameter less than 0.050 mm.

A perforated pipe used to assist the draining of soils.