Pipes

From LID SWM Planning and Design Guide
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  • Perforated pipes should be continuously perforated, smooth interior HDPE (or equivalent material) with a minimum inside diameter of 100 mm. **Where freezing is a concern, horizontal underdrain pipes should be over-sized to a minimum 200 mm diameter.
    • Perforations should be 10 mm in diameter and distributed at least every 90 deg around the pipe.
  • All underdrains should be capped on the upstream end.
  • At least one vertical well per BMP is recommended, for inspection and monitoring water level.
    • Well(s), of 100 - 150 mm diameter perforated pipe, should extend to the bottom of the facility.
    • Where a horizontal underdrain is being installed, an upstream and a downstream well should be coupled to the underdrain pipe. The pair of wells can then be used to flush out the length of underdrain if required.
    • The exposed tops of all wells should be fitted with lockable caps.
  • Non-perforated pipes should be used for conveyance to and away from the facility, including overflow.
    • To function correctly, overflow pipes must be larger in diameter than inlet pipes.