SESL Australia has recently completed work on the Melbourne Metro Rail Tunnel project as part of a consortium under the umbrella of Loci Environment & Place. Loci is a registered charity that aims to extend information into the public domain via its Urban Well.
SESL Australia’s participation was led by Declan McDonald, SESL’s Senior Soil Scientist. Declan developed a range of soil specifications that formed part of the contract documentation. This ensured that tenderer proposals included optimised soils for various installations. The specifications included provisions for the development of tree pits to maximise the performance of new tree plantings in congested urban soils. The use of tree pits reduces the overall footprint of tree planting, but through shared root zones and access to native soils where possible, a substantially higher number of trees can be accommodated in a given area.
Another significant innovation in the project was the inclusion of passive irrigation for street trees. This required the careful specification of soils capable of receiving large quantities of stormwater during rainfall events, while also draining rapidly. These soils filter pollutants from the stormwater and retain sufficient water for optimal tree growth.