View source for Sub-surface components

[[File:construction process.jpg|400px|thumb|right|The five-step construction process for sub-surface and ground-level LIDs.]]

The [[construction]] guidance in this section applies to all sub-surface and ground-level LID practices: [[bioretention|bioretention gardens]], [[bioswales]], [[rain gardens]], [[exfiltration trenches]], [[enhanced swales]], [[permeable pavements]], [[infiltration trenches]], [[infiltration chambers]], and [[soakaways]]. In general, this section describes construction and inspection processes for below ground installed materials and infrastructure that are part of the LID practices noted above. 

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==Overview==

This section gives guidance for project managers, engineers, and contractors on the installation of sub-surface components of LID practices.

==Geotextiles==

{{:Geotextiles: Installation}}

==Underdrains==

{{:Underdrains: Installation}}

==Impermeable liners==

{{:Impermeable liners: Installation}}

==Overflows==

{{:Overflow: Installation}}

==Monitoring wells==

{{:Monitoring wells: Installation}}

==Storage reservoir==

{{:Construction: storage reservoir}}

==Permeable pavement sub-base and base course==
{{:Permeable pavement sub-base and base course}}

==Trench, Chamber, and Perforated Pipe Installation==
The guidance provided in this section is applicable for the construction of soakaway pits, infiltration chambers, infiltration trenches, and exfiltration pipes of varying size and shape, since the installation of each of these features is similar.

[[File:Chamber-excavator.jpg|400px|thumb|right|An excavator covering units of unfinished infiltration chamber rows with perimeter stone. Stone can be applied progressively as the rows are completed to ensure that space is provided for the excavator to work within the LID footprint. Photo provided by [https://www.mswmag.com/g/product-focus/2015/08/stormwater_management_advanced_drainage_systems_stormtech_mc_4500 Municipal Sewer & Water].]]
#Apply clear stone to the floor of the excavation to act as the base for chambers, pipes, and trenches.
#For infiltration chamber construction, install chamber feeder-pipes to the top of the base, connecting to the inlet control manhole, where applicable.
#Roll out scour fabric length-wise beside any feeder-pipes that have been installed, if specified in the design.
#If specified, lay out scour fabric where the base of the infiltration chamber, soakaway, or pipe is anticipated to be installed. No seams should be present where the fabric underlies chambers.
#Install chambers, trenches, or perforated pipes at the location and elevation specified in the contract documents. Where infiltration chambers need to be assembled from units, install each piece of the chamber row, as per the manufacturer’s instructions, until the entire length of the chamber is in place. The ends of the chamber may be installed just prior to perimeter stone being applied to the ends of the rows, if desired, to ensure ease of inspection.
#Connect any perforated pipe connections, underdrains, roof leaders, or observation wells at the appropriate elevations, per the design.
#With a stone conveyor or excavator, begin placing clear stone as specified in the design. For domed chambers, place stone along the centreline of the chamber rows. Doing so will distribute stone to either side of the chamber, anchoring each side in roughly equal proportion.
#Backfill the excavated area with clear stone to the depth specified in the contract documents. Ensure that the depth of stone does not differ by more than 300 mm between the sides of any given chamber row at any point during the backfilling process.
#Once backfilling is complete, level the perimeter stone with a small dozer. Only push material in the direction parallel to the rows.
#If specified by the design, roll geotextile parallel to rows over the top of stone. Provide sufficient overlap, as specified by the manufacturer.

'''Note:''' where many rows of infiltration chambers are being installed, it may be advisable to construct the chamber rows piece-wise as the application of perimeter stone progresses to provide space for excavators to apply the stone from on top of the stone base. See the adjacent photo for an example.

'''Key Inspection Points:'''
*Feeder-pipes protrude into the storm chambers at the appropriate length, per manufacturer’s specifications.
*Scour fabric does not overlap beneath the walls of open-bottom chambers.
*Minimum distance between adjacent chambers is provided.
*Minimum depth of stone below and stone above chamber is provided, per manufacturer specifications.
*Depth of chamber inverts are installed correctly, relative to the elevation of the inlet, such that the storage potential of chambers are maximized.
*Infiltration chambers are assembled as specified by the manufacturer.
*Perimeter stone extends to the excavation walls.
*LID practice is protected with applicable ESC to avoid contamination of infiltration area or materials.

'''Mistakes to Avoid:'''
*Equipment on the perimeter stone – Perimeter stone should be applied with a stone conveyor or excavator from the outside of the LID footprint or on the stone foundation.
*Uneven perimeter stone – Perimeter stone must be applied such that the depth of stone on one side of the chamber is not unacceptably higher than the other. Refer to design details. 
*Incorrect inlet elevation – For applications where infiltration chambers overflow into a sewer, it is important that the top of chamber is positioned at an elevation below the lowest invert of the other sewer connections. Otherwise, only part of the chamber volume can be utilized.
*Damaged or missing ESC – Ensure that ESC protection is adequately inspected
*Putting system online prematurely -  Do not allow the feature to receive stormwater when contributing drainage area is not stabilized and sediment and debris is present.

<gallery mode="packed" widths=300px heights=300px>
Alton-chamber.JPG | Chamber resting on top of scour fabric at Alton Main Street.
20170605_164302.jpg | Components of an infiltration chamber being overlapped.
East_Gwillimbury.png | Example of "crate style" Infiltration chambers being installed in East Gwillimbury. Photo credit: [https://www.makeway.ca/products/stormwater-management-systems/ Make-Way Environmental Technologies Inc.]

Parking-lot-infiltration-chamber.JPG | Example of an infiltration chamber system under a parking lot.]
North Dakota State U infiltration trench.jpg | Infiltration trench equipped with a perforated pipe.]

ADS-manifold.jpg | Manifold connecting to infiltration chamber rows. Photo provided by [https://www.adspipe.com/water-management-solutions/detention-infiltration Advanced Drainage Systems].
Scour-fabric.jpg | Scour fabric rolled out below an infiltration chamber during assembly. Photo provided by [https://assets.ads-pipe.com/m/770e887b972da86f/original/SC-160LP-SC-310-SC-740-DC-780-StormTech-Design-Manual.pdf Advanced Drainage Systems].
Alton-Envirohood.jpg | A storm chamber inlet protected from debride by an envirohood. It is essential that the top of the chamber is lower in elevation than any other outlets from the catchbasin. This is because the chamber’s capacity should be fully utilized before runoff is allowed to travel farther downstream.

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[[Category:Gallery]]

<references/>

==Stone choker layer==

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In LID facilities, a choker layer of ≥ 100 mm depth is recommended to prevent migration of finer filter media into the underlying storage reservoir aggregate. Similar to the storage reservoir material, this aggregate layer should be a washed 5 – 10 mm stone free from fines and debris.  Installation of aggregate choker layer should not be done when frozen. 

Follow the construction guidance shown above in the section “Storage reservoir” 

For more information on the choker layer, see the page: [[Choker layer]] and [[OPSS aggregates]].

==Curbing==

"'INSERT VIDEO FROM HAGGERT AVE: \\Hqcvcfs01\cvc2\Watershed Management\Integrated Water Management Implementation\Fletchers Creek SNAP\Haggert Ave Road Retrofit\3 - Photos\Construction Photos\Site Visit_20201120\Riverstone Construction   Haggert Ave Inlet_F.mp4''

It is very important to make sure that the contractor responsible for curb construction understands curb cut designs and elevations. This is often a new technique for contractors, and they may not understand the overall concept of water in the gutter line being directed behind the gutter.<br> 

'''Construction Steps:'''
#Place the right forms (rolled curve vs standard) in the inlet location.
#Pour concrete.
#Shape the inlet 
#Add the river stone on top of the fresh concrete (if applicable) 
#Provide sufficient curing time, according to CSA standard A23.1-09.

[[File:20150618 114542.jpg|thumb|500px|right|Caption]]
[[File:P1160129.JPG|thumb|400px|right|Caption]]
'''Key Inspection Points:'''    
*Use of proper curb form by sub-contractor.
*Curb type aligns with design.
*Curb cut location, type and dimension aligns with design.
*Designated concrete wash out is in place and away from LID facility.

'''Mistakes to Avoid:<br>'''
*Elevated curb cuts and reverse slopes (sloping from back of curb towards instead of depressing from gutter line towards the back).
*Wrong curb cut width size. 
*Use of wrong curb form. 
*Concrete wash out within or upstream of LID facility.
*Ensure curb granular base (granular A) does not spill over into LID infiltration area. If material spills over, remove as best as possible while still maintaining the 2:1 slope for curbing
*Lack of communication to concrete contractor or ready-mix driver explaining the function and importance of protecting the LID feature.

For more information on curb cuts, see these pages: [[Curb cuts]], [[Curb cuts: Gallery]] and [[Bioretention: Streetscapes]]<br>

==Pretreatment and inlet==

Pre-treatment structures are most cost effective when they slow down incoming flows, collect sediment for easy clean out, and slowly release water to the bioretention facility mitigating erosion. [[Pretreatment]] structures/strategies can include [[curb cuts]],  [[Aggregates]], proprietary devices like filters or hydrodynamic separators,  vegetation, concrete sumps, membrane filters, overland flow sumps, etc. 

'''Construction Steps:'''
*Installation of pre-treatment features will vary based upon type. Similarly, installation timeline will range with type and could occur at excavation and mass grading, curb work or at finishing grade. Given pre-treatment features are typically integrated with the LID inlet coordination amongst multiple sub-contractors is sometime needed. The following details steps for various pre-treatment types:
*Vegetation: Follow the guidance shown below in the section “Plant Material Verification and Installation”
*Curbing: Follow the guidance shown above in the section “Curbing”.
*Aggregate: Follow the guidance shown above in the section “Stone reservoir”.
<gallery mode="packed" widths=300px heights=300px>
IMG_0891.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden.
IMG_0744.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden.
IMG_0788-1.JPG|Aggregate material (rock) installed as the inlet and pre-treatment device in the rain garden at Glendale P.S. in Brampton, ON. The runoff comes from a vegetated swale into the inlet, conveying it into the rain garden.
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[[Category:Gallery]]

*Proprietary pre-treatment device: 
#Excavate and prepare base for proprietary pre-treatment device according to design. 
#Install proprietary pre-treatment device according manufacturer directions.
#Manufacturer representative may need to confirm proper installation and functioning through approved testing and inspection. <br>

<gallery mode="packed" widths=275px heights=275px>
P1160102.JPG|Installation of Jellyfish filter and sorbtive media vault at the IMAX bioswale project in Mississauga, ON.
P1160117.JPG|Installation of Jellyfish filter and sorbtive media vault at the IMAX bioswale project in Mississauga, ON.
P1160121.JPG|Installation of Jellyfish filter and sorbtive media vault at the IMAX bioswale project in Mississauga, ON.

</gallery>

[[Category:Gallery]]

'''Key Inspection Points:'''
*Verify that the correct pre-treatment device (jellyfish filter, vegetation, curbing, etc.) is being installed.
*Verify that all components of the pre-treatment device are installed
*Verify correct size and location of pre-treatment device.
*Verify correct elevation, slope, and footing according to design
*Is it tied into the curb, downspout, or other inlet? Or could happen before the curbing?
*Wet weather performance check: 
**Does it work? 
**Is water entering the LID facility properly?
**Is sediment and debris accumulating?
**Is it dissipating erosive forces?

'''Mistakes to Avoid:'''
*Pre-treatment component parts are missing
*Grading/elevation errors that deviates from design
**Incorrect pipe inverts causing short circuiting
**Insufficient grade drop or slope into pre-treatment to ensure positive flow of water 
**Improper grading from pre-treatment to LID feature inhibiting positive flow
**Insufficient sump depth to account for sediment and debris accumulation
*Using wrong concrete forms if concrete curbs are part of pre-treatment.

For more information about pre-treatment strategies and their design, visit these page: [[Pretreatment]] and [[Pretreatment features]].

==References==
<references/>