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→Backfill Granular and Pipes (JC)
'''Impermeable liner'''<br>
'''Impermeable liner'''<br>
Underdrains are pipes that can be included to collect subsurface water. Their design is determined by the drainage requirements of the feature.
Underdrains are pipes that can be included to collect subsurface water. Their design is determined by the drainage requirements of the feature.
'''Overflow or Overflow Drain'''<br>
'''Overflow or Overflow Drain'''<br>
Overflows are features of inline facilities and convey larger storm events out of the LID feature.
Construction Steps:
*Connect the overflow drain to the under-drain
*Install overflow pit to grade at the location specified in the contract documents
*Fit a metal, domed grate to the overflow
Key Inspection Points:
*Overflow drain matches design specifications
*Overflow pit is positioned at the maximum water surface elevation of the practice, as per the contract documents
*Sufficient freeboard is provided between the overflow and inlet such that the inlet is not inundated by design storm flows
*Overflow grate matches design specifications
*Overflow grates that are located in high-traffic areas are screwed on or equipped with locks
Mistakes to Avoid:
*Backflows – ensure that backflows are avoided by confirming that inlet and overflow elevations match design specifications with surveys
*Incorrect sequencing – install overflow drain prior to backfilling with granular material and engineered soil
*Incorrect grate material – avoid using plastic overflow grates due to breakages and UV degradation
For more information on overflow drains, see the page on overflows.
'''Monitoring well'''<br>
'''Monitoring well'''<br>
Monitoring wells are important for sampling procedures and ensuring that bioretention features are performing as intended.
Construction Steps:
*Anchor the perforated pipe to the bottom of the LID feature
*Install a lockable cap to the top of the standpipe to protect against vandalism
Key Inspection Points:
*Pipe is perforated, rigid, and matches design specifications
*Well is installed according to contract documents
*Geotextile sock is wrapped around the perforated portion of the well
Mistakes to Avoid:
*Incorrect sequencing – ensure that standpipe is installed prior to backfilling with granular material
For more information on monitoring wells, see the page on monitoring wells.
===Backfill Granular and Pipes (SPC)===
===Backfill Granular and Pipes (SPC)===