Difference between revisions of "Stormwater Tree Trenches"
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==Overview== | ==Overview== | ||
Trees can be incorporated into [[bioretention]] cells with other plant types, or otherwise into their own planting pits. | Trees can be incorporated into [[bioretention]] cells with other plant types, or otherwise into their own planting pits. | ||
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| − | A | + | ==Planning considerations== |
| + | A commonly held view is that a tree's root system will be similar to it's visible crown. For many trees, this is not the case, as roots will more often spread much more widely, but to a shallower depth <ref>Crow, P. (2005). The Influence of Soils and Species on Tree Root Depth. Edinburgh. Retrieved from https://www.forestry.gov.uk/pdf/FCIN078.pdf/$FILE/FCIN078.pdf</ref>. For more detailed information on planning (site) considerations see [[Bioretention]] | ||
| − | == | + | ===Planting in slopes=== |
| − | A | + | Smooth slopes should be amended into localised terraces by the landscape Architect when planting large trees into slopes > 5 %. <ref>Wilkus A., 'Slope Style', Landscape Architecture Magazine, April 2018, accessed 21 December 2018, https://landscapearchitecturemagazine.org/2018/04/24/slope-style/</ref> |
==Design== | ==Design== | ||
| − | + | ===Species selection=== | |
| − | === | + | [[Trees: List]] |
| − | + | ===Planting pit Sizing=== | |
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| − | ===Sizing=== | ||
[[Bioretention: Sizing]] | [[Bioretention: Sizing]] | ||
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===Inlets=== | ===Inlets=== | ||
Multiple methods for distribution and conveyance of runoff into the system are recommended for redundancy and conservative designs. | Multiple methods for distribution and conveyance of runoff into the system are recommended for redundancy and conservative designs. | ||
| Line 59: | Line 47: | ||
*direct infiltration from permeable paving. | *direct infiltration from permeable paving. | ||
See also [[Inlets]] and [[pretreatment]] | See also [[Inlets]] and [[pretreatment]] | ||
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===Underdrain=== | ===Underdrain=== | ||
[[Underdrain]] | [[Underdrain]] | ||
| − | == | + | ==Performance== |
| − | + | ===Interception=== | |
| + | Tree canopies intercept and store rainfall, thereby modifying stormwater runoff and reducing demands on urban stormwater infrastructure (Xiao et al., 1998; Xiao et al., 2000; Xiao and McPherson, 2002; Xiao et al., 2006). Canopy interception reduces both the actual runoff volumes, and delays the onset of peak flows (Davey Resource Group, 2008). | ||
| − | + | The extent of interception is influenced by a number of factors including tree architecture and it has been estimated that a typical medium-sized canopy tree can intercept as much as 9000 litres of rainfall year. (Crockford and Richardson, 2000). | |
| − | + | ||
| − | + | A study of rainfall interception by street and park trees in Santa Monica, California found that interception rates varied by tree species and size, with broadleaf evergreen trees provided the most rainfall interception (Xiao and McPherson, 2002). Rainfall interception was found to range from 15.3% for a small jacaranda (Jacaranda mimosifolia) to 66.5% for a mature brush box (Tristania conferta now known as Lophostemon confertus). Over the city as a whole the trees intercepted 1.6% of annual precipitation and the researchers calculated that the annual value of avoided stormwater treatment and flood control costs associated with this reduced runoff was US$110,890 (US$3.60 per tree). | |
| − | + | ||
| + | *http://www.mdpi.com/2072-4292/9/11/1202/pdf | ||
| + | *http://lfs-mlws.sites.olt.ubc.ca/files/2014/10/an_analytical_model_of_rainfall_interception_by_urban_trees.pdf | ||
| + | *https://www.nrcan.gc.ca/earth-sciences/land-surface-vegetation/biophysical-parameters/9162 | ||
| + | *https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999WR900003 | ||
| − | == | + | ===Transpiration=== |
[[File:TreeTranspiration.png|thumb|Trees suck! (Abstracted from Phyto, by K. Kennen)]] | [[File:TreeTranspiration.png|thumb|Trees suck! (Abstracted from Phyto, by K. Kennen)]] | ||
Revision as of 21:02, 21 December 2018
Overview[edit]
Trees can be incorporated into bioretention cells with other plant types, or otherwise into their own planting pits.
Planning considerations[edit]
A commonly held view is that a tree's root system will be similar to it's visible crown. For many trees, this is not the case, as roots will more often spread much more widely, but to a shallower depth [1]. For more detailed information on planning (site) considerations see Bioretention
Planting in slopes[edit]
Smooth slopes should be amended into localised terraces by the landscape Architect when planting large trees into slopes > 5 %. [2]
Design[edit]
Species selection[edit]
Planting pit Sizing[edit]
Inlets[edit]
Multiple methods for distribution and conveyance of runoff into the system are recommended for redundancy and conservative designs. Combinations may be made of:
- tree well flow,
- catch basins and distribution pipes, and
- direct infiltration from permeable paving.
See also Inlets and pretreatment
Underdrain[edit]
Performance[edit]
Interception[edit]
Tree canopies intercept and store rainfall, thereby modifying stormwater runoff and reducing demands on urban stormwater infrastructure (Xiao et al., 1998; Xiao et al., 2000; Xiao and McPherson, 2002; Xiao et al., 2006). Canopy interception reduces both the actual runoff volumes, and delays the onset of peak flows (Davey Resource Group, 2008).
The extent of interception is influenced by a number of factors including tree architecture and it has been estimated that a typical medium-sized canopy tree can intercept as much as 9000 litres of rainfall year. (Crockford and Richardson, 2000).
A study of rainfall interception by street and park trees in Santa Monica, California found that interception rates varied by tree species and size, with broadleaf evergreen trees provided the most rainfall interception (Xiao and McPherson, 2002). Rainfall interception was found to range from 15.3% for a small jacaranda (Jacaranda mimosifolia) to 66.5% for a mature brush box (Tristania conferta now known as Lophostemon confertus). Over the city as a whole the trees intercepted 1.6% of annual precipitation and the researchers calculated that the annual value of avoided stormwater treatment and flood control costs associated with this reduced runoff was US$110,890 (US$3.60 per tree).
- http://www.mdpi.com/2072-4292/9/11/1202/pdf
- http://lfs-mlws.sites.olt.ubc.ca/files/2014/10/an_analytical_model_of_rainfall_interception_by_urban_trees.pdf
- https://www.nrcan.gc.ca/earth-sciences/land-surface-vegetation/biophysical-parameters/9162
- https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999WR900003
Transpiration[edit]
- http://www.wastormwatercenter.org/tree-resources/
- http://www.itreetools.org/eco/international.php
- http://treesandstormwater.org/
- http://cvc.ca/wp-content/uploads/2016/06/CaseStudy_CPW_Final.pdf
- https://cvc.ca/wp-content/uploads/2016/06/TechReport_CPW_Final.pdf
Galleries[edit]
Birch trees in parking lot bioretention 'IMAX site' Mississauga, ON
Trees in parking lot bioretention 'IMAX site' Mississauga, ON
Open tree pits[edit]
Rainwater harvesting cistern, which discharges to tree pits during dry conditions. Image credit Mississippi WMO
Extended tree pit planting in USA
Photo credit: USEPA
A right of way bioswale installed by the New York City Department of Environmental Protection on Dean Street, Brooklyn
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Soil cells[edit]
Soil cells under construction.
Soil cell installation on Central Parkway in Mississauga.
Built in 2014, this stormwater planter on Central Parkway in Mississauga uses supported soil cells and is functioning well.
Soil Cell installation along the Moynes and Berl Avenues on north side of The Queensway in Toronto. The picture depicts stormwater distribution pipes through the system, used to help provide water to the trees that will be later planted in the BMP feature.
Photo credit: City of Toronto
Silva Cell “top” deck prior to organic layer and screenings for pavers. Photo credit: City of Toronto
Soil Cells being installed along Edgewater Drive for Waterfront Toronto.
Photo credit: DeepRoot
Stormwater Tree Trenches at East Bayfront Promenade, Toronto.
Photo credit: DeepRoot
Seawall Soil Cells (Tree Trenches) located in Vancouver.
Photo credit:City of Vancouver
Stormwater tree trenches designed with a structural concrete pad over top of the installation.
Photo credit:DeepRoot
External links[edit]
In our effort to make this guide as functional as possible, we have decided to include proprietary systems and links to manufacturers websites.
Inclusion of such links does not constitute endorsement by the Sustainable Technologies Evaluation Program.
Lists are ordered alphabetically; link updates are welcomed using the form below.
- ↑ Crow, P. (2005). The Influence of Soils and Species on Tree Root Depth. Edinburgh. Retrieved from https://www.forestry.gov.uk/pdf/FCIN078.pdf/$FILE/FCIN078.pdf
- ↑ Wilkus A., 'Slope Style', Landscape Architecture Magazine, April 2018, accessed 21 December 2018, https://landscapearchitecturemagazine.org/2018/04/24/slope-style/