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Stormwater Tree Trenches: Specifications (view source)
Revision as of 16:05, 24 February 2022
, 2 years agoCreated page with "{|class="wikitable" |+Specifications for Stormwater Tree Trenches |- !Material !Specification !Quantity |- |'''Growing Medium''' | * Should be Canadian Soil Classification Sys..."
{|class="wikitable"
|+Specifications for Stormwater Tree Trenches
|-
!Material
!Specification
!Quantity
|-
|'''Growing Medium'''
|
* Should be Canadian Soil Classification System sandy loam with combined silt- and clay-sized content between 18-35%; and sand- to fine gravel-sized content (0.074 to 5 mm dia.) between 65-82%.
* pH value (6.0 - 8.0).
* Salt level <u><</u> 2 mmhos/cm.
* Percent organic matter shall be 3-5%, by dry weight.
|
* Growing medium compacted to 80-90% below the tree root ball to prevent settling.
* Bioretention filter media (see [https://wiki.sustainabletechnologies.ca/wiki/LID_BMP_Fact_Sheets#Bioretention| Bioretention Fact Sheet]) may be suitable for use as growing medium, depending on climate and tree species.
|-
|'''Modular Soil Support System'''
|
* Structural soils consist of 3 components, mixed in the following proportions by weight: crushed stone (79.07%), clay loam soil (20%), and hydrogel tackifier (0.03%).
* Total moisture at mixing should be 10% as per AASHTO T-99 optimum moisture.
* The clay loam soil should conform to the Canadian soil classification system (gravel <5%, sand 25-30%, silt 20-40%, clay 25-40%). Organic matter should range between 2 to 5% by dry weight.
* Hydrogel (potassium propenoate-propenamide copolymer), is added as a tackifier to prevent separation of the stone and soil during mixing and installation.
|
* Crushed stone (granite or limestone) narrowly graded from 20 to 40 mm diameter, highly angular with no fines.
* The entire pile is turned and mixed until a uniform blend is produced. The structural soil is then installed and compacted in 150 mm lifts.
|-
|'''Structural Concrete Panel'''
|
* Decompact native subgrade soil under tree openings and between granular bases of modular soil support structure rows during installation for better infiltration drainage performance.
|
* Structural concrete panel is 250 mm thick, contains rebar reinforcements and sits on equal-sized concrete footing supports on rows of modular soil support structures
* Modular soil supports are supported by a minimum 150 mm base of compacted granular material.
|-
|'''Aggregate Base'''
|
* Aggregates are used in modular soil support systems below the structures as the trench base layer, and sometimes, on top of the structures, as the pavement base layer.
|
* Specifications for aggregate base materials determined by the designing Engineer based on varying levels of structural loading and hydraulic requirements.
|-
|'''Geotextile & Geogrid'''
|
* Geotextile material specifications should conform to Ontario Provincial Standard Specification (OPSS) 1860 for Class II geotextile fabrics.
* Geotextile installed on tree trench sides and around perforated distribution and underdrain pipes should be woven monofilament or non-woven needle punched fabrics. '''Note''': Woven slit film and non-woven heat bonded fabrics should not be used as they are prone to clogging.
|
* Where a root barrier is needed to prevent the migration of roots out of the tree trench, use impermeable ribbed barrier material with a thickness of 1-2 mm.
|-
|'''Underdrain'''
|
* A standpipe from the underdrain pipe to the growing medium or pavement surface can be used for inspection and maintenance. The top of the standpipe should be covered with a sealable cap and secured with a vandal-proof fastener.
|
* Should be minimum 150 mm dia. perforated HDPE or equivalent material, smooth interior wall and continuously perforated with geotextile sock
|-
|'''Stormwater Distribution Pipe'''
|
* Perforated pipe should be minimum 150 mm dia. rigid, smooth interior wall HDPE or PVC with perforations on sides, wrapped with geotextile sock, with capacity and perforation specifications confirmed by the designing Engineer based on hydraulic requirements.
|
* Solid pipe from inlet structures should transition to perforated pipe once 300 mm inside the trench.
|}
|+Specifications for Stormwater Tree Trenches
|-
!Material
!Specification
!Quantity
|-
|'''Growing Medium'''
|
* Should be Canadian Soil Classification System sandy loam with combined silt- and clay-sized content between 18-35%; and sand- to fine gravel-sized content (0.074 to 5 mm dia.) between 65-82%.
* pH value (6.0 - 8.0).
* Salt level <u><</u> 2 mmhos/cm.
* Percent organic matter shall be 3-5%, by dry weight.
|
* Growing medium compacted to 80-90% below the tree root ball to prevent settling.
* Bioretention filter media (see [https://wiki.sustainabletechnologies.ca/wiki/LID_BMP_Fact_Sheets#Bioretention| Bioretention Fact Sheet]) may be suitable for use as growing medium, depending on climate and tree species.
|-
|'''Modular Soil Support System'''
|
* Structural soils consist of 3 components, mixed in the following proportions by weight: crushed stone (79.07%), clay loam soil (20%), and hydrogel tackifier (0.03%).
* Total moisture at mixing should be 10% as per AASHTO T-99 optimum moisture.
* The clay loam soil should conform to the Canadian soil classification system (gravel <5%, sand 25-30%, silt 20-40%, clay 25-40%). Organic matter should range between 2 to 5% by dry weight.
* Hydrogel (potassium propenoate-propenamide copolymer), is added as a tackifier to prevent separation of the stone and soil during mixing and installation.
|
* Crushed stone (granite or limestone) narrowly graded from 20 to 40 mm diameter, highly angular with no fines.
* The entire pile is turned and mixed until a uniform blend is produced. The structural soil is then installed and compacted in 150 mm lifts.
|-
|'''Structural Concrete Panel'''
|
* Decompact native subgrade soil under tree openings and between granular bases of modular soil support structure rows during installation for better infiltration drainage performance.
|
* Structural concrete panel is 250 mm thick, contains rebar reinforcements and sits on equal-sized concrete footing supports on rows of modular soil support structures
* Modular soil supports are supported by a minimum 150 mm base of compacted granular material.
|-
|'''Aggregate Base'''
|
* Aggregates are used in modular soil support systems below the structures as the trench base layer, and sometimes, on top of the structures, as the pavement base layer.
|
* Specifications for aggregate base materials determined by the designing Engineer based on varying levels of structural loading and hydraulic requirements.
|-
|'''Geotextile & Geogrid'''
|
* Geotextile material specifications should conform to Ontario Provincial Standard Specification (OPSS) 1860 for Class II geotextile fabrics.
* Geotextile installed on tree trench sides and around perforated distribution and underdrain pipes should be woven monofilament or non-woven needle punched fabrics. '''Note''': Woven slit film and non-woven heat bonded fabrics should not be used as they are prone to clogging.
|
* Where a root barrier is needed to prevent the migration of roots out of the tree trench, use impermeable ribbed barrier material with a thickness of 1-2 mm.
|-
|'''Underdrain'''
|
* A standpipe from the underdrain pipe to the growing medium or pavement surface can be used for inspection and maintenance. The top of the standpipe should be covered with a sealable cap and secured with a vandal-proof fastener.
|
* Should be minimum 150 mm dia. perforated HDPE or equivalent material, smooth interior wall and continuously perforated with geotextile sock
|-
|'''Stormwater Distribution Pipe'''
|
* Perforated pipe should be minimum 150 mm dia. rigid, smooth interior wall HDPE or PVC with perforations on sides, wrapped with geotextile sock, with capacity and perforation specifications confirmed by the designing Engineer based on hydraulic requirements.
|
* Solid pipe from inlet structures should transition to perforated pipe once 300 mm inside the trench.
|}