Tree Box Filter
Tree box filters are mini bioretention areas
installed beneath trees that can be very effective at controlling
runoff, especially when distributed throughout the site.1
Runoff is directed to the tree box, where it is cleaned by vegetation
and soil before entering a catch basin. The runoff collected in the
tree-boxes helps irrigate the trees.
Tree box filters are based on an effective and
widely used “bioretention or rain garden” technology with improvements
to enhance pollutant removal, increase performance reliability, increase
ease of construction, reduce maintenance costs and improve aesthetics.
Typical landscape plants (shrubs, ornamental grasses, trees and flowers)
are used as an integral part of the bioretention / filtration system.
They can fit into any landscape scheme increasing the quality of
life in urban areas by adding beauty, habitat value, and reducing urban
heat island effects.
The system consists of a container filled with a soil
mixture, a mulch layer, under-drain system and a shrub or tree. Stormwater
runoff drains directly from impervious surfaces through a filter
media. Treated water flows out of the system through an under drain
connected to a storm drainpipe / inlet or into the surrounding
soil. Tree box filters can also be used to control runoff volumes /
flows by adding storage volume beneath the filter box with an outlet