Stormwater Tree Trenches

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Overview[edit]

Trees can be incorporated into bioretention cells with other plant types, or otherwise into their own planting pits.

Performance[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).

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].

Design[edit]

Canopy interception[edit]

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


Components[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]

Underdrain

Species selection[edit]

Tree species[edit]

Sortable table, click on header you wish to select tree by
Scientific Name Common Name Soil Moisture
1=Dry
2=Med
3=Wet
Partial shade tolerance Drought Tolerance
1=Low
2=Med
3=High
Salt Tolerance
1=Low
2=Med
3=High
Pollution tolerance Compaction tolerance STEP Star Illustration
Acer rubrum Red Maple
2-3
Y
2
1
Y
Y
Canadian maple.jpg
Acer saccharinum Silver Maple
2-3
2
1-2
Y
Acer saccharinum leaves.jpg
Acer saccharum ssp. saccharum Sugar Maple
2-3
Y
2
1
Fall-orange-maple-tree - West Virginia - ForestWander.jpg
Acer x freemanii Hybrid Maple / Freeman Maple
2-3
Y
2
1-2
Y
Autumn Blaze Maple in Toronto.jpg
Alnus incana Speckled Alder / White Alder
2-3
N
2
1-2
Y
Y
Alnus incana 010703.jpg
Betula papyrifera Paper Birch
1-2
2
2-3
Three Betula papyrifera by McDonald Lake.jpg
Carpinus caroliniana American hornbeam / Blue Beech
2-3
Y
2
1
Carpinus caroliniana 3.JPG
Carya cordiformis Bitter-nut Hickory
1-2
Y
2
1
Bitternut-fruit.jpg
Carya ovata Shag-bark Hickory
1-2
Y
3
1
Carya ovata bark.jpg
Celtis occidentalis Common Hackberry
2
2
2
Y
Celtis occidentalis 20090606.jpg
Fraxinus americana White Ash
2
Y
1-2
2-3
Fraxinus americana-bark.jpg
Fraxinus nigra Black Ash
2-3
Y
1-2
2-3
Y
Fraxinus nigra leaves.jpg
Fraxinus pennsylvanica Green Ash
2-3
2
1-2
Y
Fraxinus pensylvanica a1.jpg
Ginkgo biloba Ginkgo
2
Y
2
2-3
Y
Y
Ginkgo Tree Ginkgo biloba Autumn Leaves 3008px.jpg
Gleditsia tricanthos var. inermis Thornless Honey Locust
1-2
Y
3
3
Y
Y
Gleditsia triacanthos var. inermis Sunburst 1zz.jpg
Gymnocladus dioicus Kentucky Coffeetree
1-2
Y
3
3
Y
Y
Gymnocladus dioica Kłęk kanadyjski 2020-07-31 05.jpg
Juglans nigra Black Walnut
1-2
Y
3
1-2
Tournai AR1aJPG.jpg
Juniperus virginiana Eastern Red Cedar
1-2
Y
3
2
Y
Juniperus virginiana Maine.jpg
Larix laricina Tamarack / American Larch
1-3
Y
3
3
10 31 2008 Stand of Tamarack.jpg
Liriodendron tulipifera Tulip Tree
2
Y
1
1
Liriodendron tulipifera1mscaprikell.jpg
Picea glauca White Spruce
2
2
1
Y
Picea glauca cone 0695.jpg
Picea pungens Colorado Spruce
2
2
3
Picea pungens `Glauca globosa`a1.jpg
Pinus mugo Mugo Pine
1-2
Y
2
3
Pinus mugo cone 02.jpg
Pinus strobus Eastern White Pine
1-2
2
1
Pinus strobus foliage Adirondacks.jpg
Platanus occidentalis Sycamore
2-3
2
1
Y
American-Sycamore-Bark.jpg
Populus balsamifera ssp. balsamifera Balsam Poplar
2
2
3
Populus balsamifera (5002913574).jpg
Populus deltoides Eastern Cottonwood
2
3
2-3
Y
Y
Populus deltoides monilifera foliageseeds.jpg
Populus grandidentata Large-tooth Aspen
2
3
2-3
Populus grandidentata.JPG
Populus tremuloides Trembling Aspen
2
2
2-3
FallPando02.jpg
Prunus serotina Wild Black Cherry
2
2
2-3
Amerikaanse vogelkers bessen Prunus serotina.jpg
Quercus alba White Oak
1-2
Y
3
3
Duke Forest fall Oak high.jpg
Quercus bicolor Swamp White Oak
2-3
3
2-3
Y
Quercus bicolor 002.jpg
Quercus macrocarpa Bur Oak
1-3
3
2-3
Y
Quercus macrocarpa USDA.jpg
Quercus muehlenbergii Chinquapin oak / Yellow oak
3
3
2
Quercus muehlenbergii-leaves-immature-acorns.jpg
Quercus palustris Pin Oak
2-3
3
1
Quercus-palustris.JPG
Quercus rubra Red Oak
1-2
2
3
Y
Quercus-rubra-fruits-11-10-2007-080.jpg
Salix amygdaloides Peachleaf Willow
3
1-2
3
Y
Salix amygdaloides(01).jpg
Salix lucida Shining Willow
3
1-2
3
Y
Salix lucida lasiandra(02).jpg
Salix nigra Black Willow
3
1
2-3
Y
Salix nigra catkins 8001.JPG
Thuja occidentalis Eastern White Cedar
2-3
3
1-2
Thuja occidentalis C.jpg
Tilia americana American Basswood
2
Y
2
1-2
Tilia americana in Toronto.jpg
Ulmus americana American Elm
2-3
Y
2
2
Y
Y
Img ulmus americana 2209.jpg

Performance and research[edit]

Trees suck! (Abstracted from Phyto, by K. Kennen)

Galleries[edit]

Open tree pits[edit]

Soil cells[edit]

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.


  1. 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