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{{:Geotextiles: Installation}}
{{:Underdrains: Installation}}
{{:Impermeable liners: Installation}}
{{:Overflow: Installation}}
{{:Monitoring wells: Installation}}
{{:Construction: storage reservoir}}
no edit summary
==Geotextiles==
==Geotextiles==
[[Geotextiles]] are filter fabrics that can be installed to separate dissimilar soils and prevent the migration of materials. Geotextiles are recommended for installation at the bottom and side limits of the LID feature and should be implemented at the discretion of the engineer.
'''Construction Steps:'''
#Roll out fabric on the flattened sub-grade surface.
#Provide a minimum overlap of 300 mm between adjacent lengths of geotextile. If the manufacturer specifies a greater overlap, follow the manufacturer’s specification.
#Secure fabric in place with stakes along the edge of the sub-grade surface and where lengths of fabric overlap.
#Provide 500 mm of excess at the ends of each length of fabric. Fold excess materiel on top of the infiltration medium/choker course once installed.
#Provide cuts for trees and shrubs where appropriate.
#Assess on-site conditions to ensure that the tensile, tear, and puncture strength ratings of the geotextile are suitable for expected structural loads (e.g. traffic). If not properly considered, geotextiles can be adversely impacted by loading from adjacent infrastructure uses.
'''Key Inspection Points:'''
*Geotextile is clean and free of damage.
*Geotextile delivered to the site matches the design specifications and is approved by the engineer prior to installation.
*Sufficient overlap is provided between lengths of fabric.
*Geotextiles have been applied as per the manufacturer’s guidelines.
*Structural considerations for geotextiles have been made when applied adjacent to infrastructure and the geotextile can handle expected structural loads.
*Class II geotextiles conform to OPSS 1860.
'''Mistakes to Avoid:'''
*Wrinkles in the fabric – follow the manufacturer’s procedure for installation to ensure geotextiles lie smooth on sub-grade.
*Unnecessary application of geotextile – mixing of media is negligible where structural loads are not expected, so geotextile does not need to be applied. Also, geotextiles should not be used where root growth is encouraged to penetrate different layers of media.
<gallery mode="packed" widths=300px heights=300px>
geotextile-facility-side.jpg | The shape of the LID feature required the geotextile to be rolled out prior to being laid on the subgrade surface.
geotextile-with-excess-and-granular.jpg | Excess fabric is draped over the edges of the LID practice, and backfilling with granular is taking place.
geotextile-backfill-underdrain.jpg | Footprint with geotextile, granular, and underdrain.
</gallery>
[[Category:Gallery]]
==Underdrains==
==Underdrains==
[[File:underdrain-subgrade.jpg|300px|thumb|right|Underdrain installed to subgrade.]]
[[File:underdrain-with-risers.jpg|300px|thumb|right|Underdrain installed with maintenance risers. Note the 'T' joints, which are no longer recommended.]]
[[Underdrains]] are perforated pipes that collect subsurface water and convey water out of an LID facility once it reaches capacity. Their design is determined by the drainage requirements of the feature.
'''Construction Steps:'''
#Install the underdrain to grade with a consistent slope of 0.5% to 1.0%.
#Connect overflow risers with single-elbowed ‘y’ connections or 45° elbows.
#Situate maintenance risers where siltation is expected in drain lines (such as at junctions or where grade and direction changes occur), in accordance with the design drawings.
#Mark the locations of risers.
#Use video inspections to confirm that the interior of the underdrain remains free of debris after construction.
'''Key Inspection Points:'''
*Size, type, and material of the underdrain conforms to the design specifications.
*Underdrain is perforated prior to arrival on-site.
*Drain material is resistant to UV radiation and any chemicals in the soil and groundwater.
*Clean-outs are positioned correctly and spaced appropriately for the size of the underdrain.
*Any manual perforations are approved by the design or field engineer.
*Pipe grade matches design specifications.
*Tie-in locations to municipal sewers meet municipal specifications.
'''Mistakes to Avoid:'''
*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.
*Potential for clogging – Remove sock from underdrain prior to installation or geofabric wrap. A choker course is recommended, instead, as field change.
For more information on the design of underdrains, such as materials and connections, see the page on underdrains linked above.
==Impermeable liners==
==Impermeable liners==
[[Liner | Impermeable liners]] can be applied when LID features are not intended to infiltrate runoff into the underlying soil. They protect building foundations or other subsurface infrastructure. They also prevent infiltration through contaminated soils. Where building foundations next to the LID feature are not waterproofed, liners can be used to protect adjacent infrastructure.
'''Construction Steps:'''
#Compact 30 – 50 mm of sand over the soil onto which the membrane will be installed to protect against punctures. Alternatively, a geotextile can be used in the place of sand.
#Place lengths of liner on the bed of the facility as per the manufacturer’s specifications.
#Provide 150 mm of overlap between adjacent lengths of liner.
#Secure liner in-place and bond together the overlapping portions of liner as specified by the manufacturer.
#Seal a flange to the pipe and liner when pipes provide drainage from the practice.
#Compact sand or apply cushion fabric on top of the liner to protect against punctures.
'''Key Inspection Points:'''
*Liner matches design specifications.
*Liner installation procedures conform to manufacturer’s specifications.
*Minimum overlap between lengths of liner is achieved.
*Need for protection of building footprints and adjacent infrastructure confirmed through field verification of setbacks.
*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 penetration and contamination.
<gallery mode="packed" widths=300px heights=300px>
liner-roadside.jpg | An impermeable liner was placed along one side of the LID facility to prevent infiltrated water from contacting the nearby watermain in the road right-of-way, which runs parallel to the feature.
bentonite-clay-liner.jpg | Impermeable Bentofix® liner being rolled out in LID practice area.
</gallery>
==Overflows==
==Overflows==
[[Overflow|Overflows]] are features of inline facilities and convey larger storm events out of the LID feature.
'''Construction Steps:'''
#Connect the overflow drain to the underdrain.
#Fit a metal, domed grate to the overflow.
#Install overflow pit to grade at the location specified in the contract documents.
'''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 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.
<gallery mode="packed" widths=300px heights=300px>
overflow-pipe-install.jpg | Overflow pipe installed to an underdrain T-connection.
overflow-plastic-cap.jpg | Overflow installed with a plastic cap. Note that the use of plastic grates is discouraged.
</gallery>
==Monitoring wells==
==Monitoring wells==
[[File:monitoring-well-subgrade.jpg|400px|thumb|right|Monitoring well stack installed next to underdrain within the LID practice.]]
[[Monitoring wells]] allow for measurement of water levels in the sub-surface components of LID practices. They are important for sampling procedures and ensuring that the LID feature are performing as intended.
'''Construction Steps:'''
#Install a cap stand at the required elevation to anchor the monitoring well.
#Wrap the perforated pipe with a geotextile sock (to prevent migration of soil into the well).
#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 monitoring equipment (e.g., a level logger) if required.
'''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.
==Storage reservoir==
==Storage reservoir==
''INSERT YOUTUBE LINK: https://www.youtube.com/watch?v=Ng_s2ErvPqk&t=58s <br>''
The storage reservoir layer holds and directs the stormwater into the underlying/native soils. The LID facilities, if applicable, should be filled with uniformly graded, washed stone (20 mm – 50 mm) that provides 30 to 40% void space.
'''Construction steps:'''
#Backfill material from outside of the LID facility to avoid compaction and sediment entering the facilities. Use a slinger truck if possible.
#Place the material to the elevation and thickness as per the design specifications.
'''Key Inspection Points:'''
*Material arrival to the site:
**Check chain of custody
**Verify it meets specifications as per design
**Verify no debris or fines within the aggregate (it’s a washed stone)
*Granular material should be 19 - 50 mm clear stone or as per design. See [[Aggregates]] for further details.
*Installed aggregate is at the correct elevation as per design.
'''Mistakes to Avoid:'''
*Accepting material that does not meet design requirements and specifications.
*Installing material with heavy equipment from the inside of the LID facility
*Installing frozen aggregate. Do not install frozen aggregate
*Leaving heavy equipment (excavator) for long periods of time within the LID facility.
For more information on the storage reservoir, see the page: [[Reservoir aggregate]] and [[OPSS aggregates]].
==Permeable pavement sub-base and base course==
==Permeable pavement sub-base and base course==