Changes

'''Stormwater tree trench installations include:'''

'''Stormwater tree trench installations include:'''

* Overlying impermeable or [[permeable pavements]]

* Overlying impermeable or [[permeable pavements]]

* Trees (tolerant to northern. urban conditions)

* Trees (tolerant to northern urban conditions)

* Planting soil

* Planting soil

* Modular soil support or "soil cell" structures (optional)

* Modular soil support or "soil cell" structures (optional)

===Drainage Area===

===Drainage Area===

Typical contributing drainage areas are between 150-300 m2 per tree, with a maximum of 450 m2 per tree.

Typical contributing drainage areas are between 150 to 300 m² per tree, with a recommended maximum of 450 m² per tree.  For optimal performance recommended ratios of impervious drainage area to pervious facility footprint area (I:P area ratio) range from 5:1 on low permeability soils (HSG C and D) to 15:1 on high permeability soils (HSG A and B).

===Setback from Buildings===

===Setback from Buildings===

You can also review Urban's presentation he gave at the University of Washington in 2014 about some of the lessons learned in his book here: [https://botanicgardens.uw.edu/wp-content/uploads/sites/7/2014/10/Urban_Soils_Jim_Urban.pdf Urban Soil and Site Assessment Presentation] <ref>Urban, J. 2014. Urban Soil and Site Assessment [Presentation]. University of Washington Botanic Gardens. Seattle, WA https://botanicgardens.uw.edu/wp-content/uploads/sites/7/2014/10/Urban_Soils_Jim_Urban.pdf.</ref>

You can also review Urban's presentation he gave at the University of Washington in 2014 about some of the lessons learned in his book here: [https://botanicgardens.uw.edu/wp-content/uploads/sites/7/2014/10/Urban_Soils_Jim_Urban.pdf Urban Soil and Site Assessment Presentation] <ref>Urban, J. 2014. Urban Soil and Site Assessment [Presentation]. University of Washington Botanic Gardens. Seattle, WA https://botanicgardens.uw.edu/wp-content/uploads/sites/7/2014/10/Urban_Soils_Jim_Urban.pdf.</ref>

==Inspection and maintenance==

==Inspection and Maintenance==

Tree trenches have fewer maintenance requirements than bioretention cells or bioswales, but maintenance is still critical to their success. The most critical maintenance task is the removal of trash, sediment and debris accumulated in inlet structure sumps, gravel diaphragms and tree openings at curb cuts. This should be done at least once per year, however the frequency will depend on pavement uses, traffic volumes and tree canopy size. Inspect new trenches closely during the first two years of operation to measure the rate of accumulation and set an optimal maintenance frequency.  

Tree trenches have fewer maintenance requirements than bioretention cells or bioswales, but maintenance is still critical to their success. The most critical maintenance task is the removal of trash, sediment and debris accumulated in inlet structure sumps, gravel diaphragms and tree openings at curb cuts. This should be done at least once per year, however the frequency will depend on pavement uses, traffic volumes and tree canopy size. Inspect new trenches closely during the first two years of operation to measure the rate of accumulation and set an optimal maintenance frequency.  

See further details here: [[Stormwater Tree Trenches: Maintenance]]

See further details here: [[Stormwater Tree Trenches: Maintenance]]

==Performance==

==Performance==