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.

Perforated pipes are a common component of underdrains, infiltration trenches and exfiltration trenches. 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 .
• Non-perforated pipes should be used for conveyance to and away from the facility, including overflow.

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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.