Difference between revisions of "Stormwater Tree Trenches"
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| + | <imagemap> | ||
| + | Image:Extended tree pit.png|thumb|700 px|This is an image map of an extended tree pit, clicking on components will load the appropriate article. | ||
| + | rect 241 1143 296 1338 [[Soil cells]] | ||
| + | rect 616 1143 669 1338 [[Soil cells]] | ||
| + | rect 359 1148 517 1248 [[Bioretention: Filter media]] | ||
| + | rect 361 1250 517 1277 [[Choking layer]] | ||
| + | rect 299 1280 428 1337 [[Reservoir gravel]] | ||
| + | rect 540 1280 613 1337 [[Reservoir gravel]] | ||
| + | rect 468 1280 514 1337 [[Reservoir gravel]] | ||
| + | rect 360 1124 411 1146 [[Forebays]] | ||
| + | rect 510 1124 562 1146 [[Forebays]] | ||
| + | rect 368 440 415 492 [[Forebays]] | ||
| + | rect 513 440 560 492 [[Forebays]] | ||
| + | rect 560 1099 594 1123 [[Inlets|Slotted drain]] | ||
| + | rect 321 454 366 498 [[Inlets|Depressed drain]] | ||
| + | circle 421 256 152 [[Trees]] | ||
| + | poly 433 1078 447 1083 443 998 502 977 562 989 598 971 610 784 570 657 433 581 393 594 297 680 264 756 239 866 272 937 331 1000 432 1002 433 1076 [[Trees]] | ||
| + | poly 362 1115 366 1091 406 1068 446 1087 466 1095 499 1078 552 1093 555 1111 530 1104 504 1120 504 1140 419 1141 419 1121 [[Perennials: List]] | ||
| + | circle 464 442 48 [[Perennials: List]] | ||
| + | circle 464 86 46 [[Perennials: List]] | ||
| + | poly 518 1148 518 1348 2 1351 1 1369 524 1369 537 1356 539 1147 [[Overflow]] | ||
| + | circle 530 107 18 [[Overflow]] | ||
| + | circle 447 1315 21 [[Underdrain]] | ||
| + | </imagemap> | ||
| + | |||
{{TOClimit|2}} | {{TOClimit|2}} | ||
==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. |
| + | |||
==Planning considerations== | ==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=== | ||
| + | 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== | ||
| + | There are many design configuration options for including trees into stormwater management plans. | ||
| − | == | + | ==Soil cells== |
| − | + | These are (usually plastic) supporting structures placed around the trees and beneath adjacent paved areas. They prevent compaction to the roots of the tree and prevent root damage to the paving. They are sometimes configured to receive stormwater and to enclose ponded water which can then infiltrate the soil surrounding the tree. | |
| + | Things to consider in design: | ||
| + | *If the system is unlined it is hydraulically equivalent to a [[bioretention]] and provides similar water quality benefits. | ||
| + | *If the systems is lined, it is hydraulically similar to a large [[stormwater planter]]. Depending on the design detail it may retain significant stormwater within the planting volume soil and will provide water quality benefits. | ||
| + | |||
| + | ===Species selection=== | ||
| + | [[Trees: List]] | ||
| + | ===Planting pit Sizing=== | ||
| + | [[Bioretention: Sizing]] | ||
| + | ===Inlets=== | ||
| + | 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=== | ||
| + | [[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)]] | ||
*http://www.wastormwatercenter.org/tree-resources/ | *http://www.wastormwatercenter.org/tree-resources/ | ||
*http://www.itreetools.org/eco/international.php | *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== | ||
| + | {{:Trees: Gallery}} | ||
| + | ===Open tree pits=== | ||
| + | {{:Extended tree pits: Gallery}} | ||
| + | ===Soil cells=== | ||
| + | {{:Soil cells: Gallery}} | ||
==External links== | ==External links== | ||
| + | {{float right|{{#widget:YouTube|id=Un2yBgIAxYs}}}} | ||
| + | *http://gievidencebase.botanicgardens.sa.gov.au/contents/7-water-management#Canopy-Interception | ||
| + | *[http://www.jamesurban.net/specifications standard details and specifications from James Urban] | ||
| + | |||
{{:Disclaimer}} | {{:Disclaimer}} | ||
*[http://cupolex.ca/ Cupolex] | *[http://cupolex.ca/ Cupolex] | ||
*[http://www.deeproot.com/index.php Deeproot] | *[http://www.deeproot.com/index.php Deeproot] | ||
| + | *[http://www.conteches.com/Products/Stormwater-Management/Biofiltration-Bioretention/Filterra Filterra] | ||
*[http://www.greenblue.com/na/ GreenBlue] | *[http://www.greenblue.com/na/ GreenBlue] | ||
*[http://citygreen.com/products/stratacell/ Stratacell] | *[http://citygreen.com/products/stratacell/ Stratacell] | ||
| − | + | ---- | |
[[Category:Green infrastructure]] | [[Category:Green infrastructure]] | ||
Revision as of 15:59, 16 May 2019
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]
There are many design configuration options for including trees into stormwater management plans.
Soil cells[edit]
These are (usually plastic) supporting structures placed around the trees and beneath adjacent paved areas. They prevent compaction to the roots of the tree and prevent root damage to the paving. They are sometimes configured to receive stormwater and to enclose ponded water which can then infiltrate the soil surrounding the tree. Things to consider in design:
- If the system is unlined it is hydraulically equivalent to a bioretention and provides similar water quality benefits.
- If the systems is lined, it is hydraulically similar to a large stormwater planter. Depending on the design detail it may retain significant stormwater within the planting volume soil and will provide water quality benefits.
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
.jpg)
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]
- http://gievidencebase.botanicgardens.sa.gov.au/contents/7-water-management#Canopy-Interception
- standard details and specifications from James Urban
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/