Changes

For more information on geotextiles, see the page on geotextiles.

For more information on geotextiles, see the page on geotextiles.

'''Impermeable liner'''<br>

'''Underdrains'''<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.

Construction Steps:

Construction Steps:

*Mark the locations of risers

*Mark the locations of risers

*Use video inspections to confirm that the interior of the underdrain remains free of debris after construction

*Use video inspections to confirm that the interior of the underdrain remains free of debris after construction

Key Inspection Points:

Key Inspection Points:

*Pipe grade matches design specifications

*Pipe grade matches design specifications

*Tie-in locations to municipal sewers meet City specifications

*Tie-in locations to municipal sewers meet City specifications

Mistakes to Avoid:

Mistakes to Avoid:

*Incorrect overflow risers – ensure single-elbowed ‘y’ connections or 45° elbows are used for overflow risers instead of ‘T’ connections

*Incorrect overflow risers – ensure single-elbowed ‘y’ connections or 45° elbows are used for overflow risers instead of ‘T’ connections

*Incorrect drain size – confirm underdrain has an internal diameter greater than or equal to 200 mm to reduce freezing and allow cleaning and camera inspections

*Incorrect drain size – confirm underdrain has an internal diameter greater than or equal to 200 mm to reduce freezing and allow cleaning and camera inspections

*Potential for clogging – Ensure gravel coverings have not been included with the underdrain

*Potential for clogging – Remove sock from underdrain prior to installation

 

For more information on the design of under-drains, see the page on under-drains.

For more information on the design of under-drains, see the page on under-drains.

                            

                            

'''Underdrain'''<br>

'''Impermeable Liners'''<br>

Impermeable liners can be applied when LID features are not intended to infiltrate runoff into the underlying soil. Where building foundations that are adjacent to the LID feature are not waterproofed, liners can be used to protect neighbouring infrastructure.

Impermeable liners can be applied when LID features are not intended to infiltrate runoff into the underlying soil. Where building foundations that are adjacent to the LID feature are not waterproofed, liners can be used to protect neighbouring infrastructure.

Construction Steps:

Construction Steps:

*Where pipes provide drainage from the practice, a flange should be sealed to the pipe and liner.

*Where pipes provide drainage from the practice, a flange should be sealed to the pipe and liner.

*Compact sand or apply cushion fabric on top of the liner to protect against punctures

*Compact sand or apply cushion fabric on top of the liner to protect against punctures

Key Inspection Points:

Key Inspection Points:

*Liner is confirmed to match design specifications

*Liner is confirmed to match design specifications

*Liner installation conforms to manufacturer’s specifications

*Liner installation conforms to manufacturer’s specifications

*Minimum overlap with  

*Minimum overlap between lengths of liner is achieved  

*Need for impermeable liner is confirmed through field verification of setbacks to adjacent infrastructure

*Need for impermeable liner is confirmed through field verification of setbacks to adjacent infrastructure

*Sand and/or geotextile are applied on both sides of the liner to protect against punctures

*Sand and/or geotextile are applied on both sides of the liner to protect against punctures

*Lengths of liner are bonded together to ensure protection against groundwater contamination

*Lengths of liner are bonded together to ensure protection against groundwater contamination

For more information on impermeable liners, see the page on liners.

For more information on impermeable liners, see the page on liners.

'''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.

Overflows are features of inline facilities and convey larger storm events out of the LID feature.

Construction Steps:

Construction Steps:

*Install overflow pit to grade at the location specified in the contract documents

*Install overflow pit to grade at the location specified in the contract documents

*Fit a metal, domed grate to the overflow

*Fit a metal, domed grate to the overflow

Key Inspection Points:

Key Inspection Points:

*Overflow grate matches design specifications

*Overflow grate matches design specifications

*Overflow grates that are located in high-traffic areas are screwed on or equipped with locks

*Overflow grates that are located in high-traffic areas are screwed on or equipped with locks

Mistakes to Avoid:

Mistakes to Avoid:

For more information on overflow drains, see the page on overflows.

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.

Monitoring wells are important for sampling procedures and ensuring that bioretention features are performing as intended.

Construction Steps:

Construction Steps:

*Anchor the perforated pipe to the bottom of the LID feature

*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

*Install a lockable cap to the top of the standpipe to protect against vandalism

Key Inspection Points:

Key Inspection Points:

*Well is installed according to contract documents

*Well is installed according to contract documents

*Geotextile sock is wrapped around the perforated portion of the well

*Geotextile sock is wrapped around the perforated portion of the well

Mistakes to Avoid:

Mistakes to Avoid:

*Incorrect sequencing – ensure that standpipe is installed prior to backfilling with granular material

*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.

For more information on monitoring wells, see the page on monitoring wells.