Tree Boxes & Trenches
About the Practice
The value of trees in communities is immeasurable. Trees provide shade on a hot summer’s day. They clean the air and provide habitat and food for wildlife
And they play an important role in managing urban stormwater. Trees are mini-reservoirs for rain and reduce urban stormwater runoff at the source by:
- Intercepting rain on leaf canopies and evapotranspiring moisture back into the air
- Increasing infiltration and uptake of rainwater through the tree’s root system
- Uptake of nutrients such as nitrogen and phosphorus
- Reducing soil erosion by slowing rainfall before it strikes the soil
Tree boxes are containment systems like small bioretention cells that include trees as vegetation. They include an engineered soil mix, underdrain, over flow and are usually tied to the storm sewer system or connected in a stormwater treatment to other stormwater BMPs. There are specific tree species that thrive in these systems.
Tree Trenches are typically elongated surface systems in sidewalk areas that consist of engineered soils placed within a plastic network of support that can be placed beneath permeable pavers. The tree roots have a large subsurface area to expand rather than be confined in a very small containment system.
Tree filter boxes can be either designed by licensed engineers and constructed by contractors or proprietary designs and products can be used. Tree trench information can be found at the following links.