Summary

Introduction
Feature-Image-City-of-Moreland
Purpose of project

Streetscape enhancement

Installation type
Tree planting date

June 2015

Tree species

Acer campestre (Field Maple)
Botanical name (Common name)

Number of Trees Planted

25

Tree Stock Size at Planting

20 - 45L container

Number of Trees Surviving

22

Survival Assessment Date

12 months

Features
Owner of Site

City of Moreland

Contact Details

Contact Name

Vaughn Grey

Contact Phone

(03) 9240 2481

Contact Email

Location Details

Location Address

Barrow Street

Section of Barrow Street south of Mitchel Street, Brunswick

Council/LGA

City of Moreland

Technical Detail

If you require details not available here, see contact details.

Case Study Description

Water management and streetscape enhancement

Design &/or as constructed detail

Five replicates each of five different tree-pit treatment types – Control, Soil, Sand, Drained and Adjacent. The treatments are described in Figure 1 and Table 1 attached and as per “Establishing street trees in stormwater control measures can double tree growth when extended waterlogging is avoided”

Figure 1

Table 1

The ‘Control’ treatment was a standard method for planting new street trees into native soil using a 1.2 m x 0.6 m opening cut into the asphalt footpath. While the Control treatment only received rainfall input from directly above, i.e. it received no runoff from the road, the other four treatments (Soil, Sand, Adjacent and Drained) captured runoff from a larger catchment (median catchment area 390 m2; range 180 m2 to 1900 m2) via a 1.2 m wide cut in the kerb. As per the Control, the ‘Soil’ treatment contained only native soil, however, the kerb was cut and an extended detention depth of 100 mm was excavated to capture runoff. The ‘Sand’ treatment was the same as the Soil treatment except, that the soil in the tree pit was removed to depth of 400mm and replaced with (from bottom to top): 75 mm of gravel (drainage layer), 25 mm of coarse sand (transition layer) and 300 mm of sandy loam (filter media, as per Payne et al. (2015)). The ‘Drained’ treatment was identical to the Sand treatment, except the gravel base layer contained a perforated PVC underdrain with a raised outlet connected to the stormwater drainage system. The ‘Adjacent’ treatment differed from the other three treatments receiving runoff, in that it combined aspects of the Sand and Control treatments. That is, runoff was directed into pit identical to the Sand treatment except that the tree was planted into native soil adjacent to the pit, rather than planted into the sandy profile.

Depth of Engineered Space

0.5 m

Volume of Engineered Space

See Figure 1 attached. Volume of biofiltration media in Sand, Drained and Adjacent treatments = 0.288 m3 (1.2 m x 0.6 m x 0.4 m)

Drainage Type

Three drainage scenarios were investigated: 1. Under-drain return to the stormwater system – tree in the pit 2. No under-drain – tree in the pit 3. No under-drain – tree planted adjacent to the pit.

Drainage Type Resource/Image/Document
Surface Treatment

Other

Growing Media Detail

Two media substrates:

  • insitu soil (heavy clay)
  • Biofilter sand
Surrounding Site Soil Detail

Heavy clay, median exfiltration rate 6 mm hr-1

Surrounding site soil detail Resource/Image/Document
Watering Regime

None

Maintenance Detail

Bi-monthly inspection and removal of debris that may clog tree pit inlet or 10 cm deep extended detention zone

Non-Technical Detail

Challenges Overcome

Installation quality control

Stakeholder Feedback

Positive

Stakeholder Support for future projects of this kind

Yes

Funding Source

50% funded by Moreland City Council, 50% funded by Melbourne Water’s Living Rivers program

1

Project Cost

$165,000

Partners/Sponsors Information

Waterway Ecosystem Research Groups (WERG) and Green Infrastructure Research Group (GIRG) in the Faculty of Science, The University of Melbourne, Burnley campus. Stephen Livesley, Tim Fletcher, Chris Szota and Jasmine Thom