Two car parks, N & S. Both are 12m wide x 40m long with x16 parking bays each.
A narrow, 3m-wide strip of open ground along the north side lies in-between the hardstands of the Council carpark and adjacent industrial land of both carparks.
Trees to be planted in centre of strip, six (6) trees per carpark (i.e. 1×3 bays): sp. Angophora costata
Carpark North (control)
- Total surface permeable paved. Product: Midland Brick’s ‘aqua tri-pave’, being a copy of Adbri’s ecotrihex
- Over 50mm depth bedding 3–5mm dia. aggregate
- Geotextile
- Over 300mm depth 20–40mm dia aggregate
- Over in-situ native soil (sand), lightly compacted
- Kerb on conventional road base with 300mm ribbed root barrier against back of kerb (RER 300’)
Carpark South (custom soil)
- as described above except:
- Geoweb / cellular confinement system at 200mm depth to hold screenings
- Underlying soil: no compaction other than perhaps one run-over with plate compacter to smooth ground level
- Eight (out of the 16) parking bays in which the in-situ sandy soil is replaced with a custom mix of higher fertility
- Spray-on root barrier at back of kerb (instead of a rigid barrier)
- Vertical steel rods to identify and compare oxygen content between in-situ & custom mix in subsequent years
Measurements:
- Soil analysis (organic content/fertility, Ph) and infiltration rates (hydraulic conductivity) in 4 locations per site
- Annual canopy growth
- Settlement of pavement
Rationale:
The intent is for a design which factors the hardstand as a fully functional proper root-zone, in order to maximise the canopy potential and minimise the likelihood of pavement displacement.
The custom-soil is to be a cost/benefit analysis. Comparing canopy performance correlated with the monetary amenity values.
