Summary
Introduction
Purpose of project
Streetscape enhancement
Installation type
Structural soil
Tree planting date
1999
Tree species
Caesalpinea ferrea (Leopard tree)
Botanical name (Common name)
Number of Trees Planted
50+
Tree Stock Size at Planting
100+ or ex-ground
Number of Trees Surviving
100%
Survival Assessment Date
2018
Features
Other WSUD type
Owner of Site
Brisbane City Council
Contact Details
Contact Name
Dr. Lyndal Plant
Contact Phone
0408-779-488
Contact Email
Location Details
Location Address
Adelaide Street Brisbane, between George St and Edward St.
As above
Council/LGA
Brisbane City Council
Technical Detail
If you require details not available here, see contact details.
Case Study Description
Continuous tree trenches within new footpath extension from back of kerb within portions of 2 city blocks on both sides of street (Portions considered 6 existing trees along footpath outside City Hall)
Geotextile lined trench
Structural soil mix = 200mm bluestone spalls, clay-loam media (filler soil) of calculated void volume (40%) washed in during installation stages, 2 horizons of soil mix used within tree planting sites
Design &/or as constructed detail
Refer to earlier Case Study Description.
Depth of Engineered Space
1.0
Volume of Engineered Space
Total volume for project approx. 450 cubic metres. Volume per tree – approx. 9 cubic metres
Drainage Type
Under drainage in bottom layer of trench to stormwater inlet (see design detail within attached paper)
Drainage Type Resource/Image/Document
Surface Treatment
Tree Grates Within Reinforced Concrete
Growing Media Detail
Clay-loam media (filler soil) of calculated void volume (40%) washed in during installation stages, 2 horizons of soil mix used within tree planting sites (see design detail diagram within paper)
Surrounding Site Soil Detail
Geotech core sampling survey done for the project – report not available
Findings were predominantly mixed fill, stiff clay with some portions of sandy loam where existing trees were growing well
Surrounding site soil detail Resource/Image/Document
Watering Regime
Manual
Maintenance Detail
watering regime is manual for the establishment period of 24 months only
initial aluminium tree grates replaced with new alloy style in 2013
clearance pruning of trees two yearly to maintain bus, car, truck clearance
Images:
Primary Case Study image = 2018 view of portion of boulevard, looking south from cnr Adelaide St and Albert St, City Hall side
Other images of related projects within the paper (Treenet Symposium paper link)
Non-Technical Detail
Challenges Overcome
Justifying the need for tree trench space Satisfying pavement engineering standards
Stakeholder Feedback
Positive
Stakeholder Support for future projects of this kind
Yes
Funding Source
Brisbane City Council and Australian Government Grant Funding
Project Cost
Estimated 5% of total project cost of $35m in 1999
Total project included street narrowing, new kerb and channel, services relocations, new footpath paving, street furniture and street resurfacing