The TREENET Inlet system is an emerging WSUD tool which harvests road runoff from residential streets and arterial roads to irrigate street trees. By intercepting the ‘first flush’ of stormwater, TREENET Inlets remove pollutants near their source and promote biosequestration of nutrients such as phosphorus and nitrogen that might otherwise cause algal blooms in receiving waters downstream . TREENET Inlets are installed in the kerb; they connect to an infiltration trench or ‘leaky well’ which detains the water until it soaks into the soil in the nature strip. By placing this water in the soil profile at a distance from the tree (ideally midway between two street trees) a moisture gradient is set up whereby root development is toward the source and away from other hard infrastructure. Trees are then able to redistribute this water to other drier locations in the root zone by a process known as hydraulic lift. This reconstructed root array also creates biopores through seasonal growth of finer absorption roots thus increasing the natural permeability of the verge profile.
R750 Treenet Inlet Model Specification
• Kerb anchor block
• R 750 stainless steel faceplate
• M8 × 30 mm stainless steel cap bolts
• 100×50×90 mm PVC coupling
Goodwood Road is a major thoroughfare through the suburb. A makeover in 2017 has improved the ambience and attraction for locals and visitors to the shopping and entertainment precinct.
The design by Jensen
In November 2017 the City of Manningham in Victoria Australia installed 36 TREENET inlets in a problematic area subject to flooding to improve the recovery time after rain events .
Each inlet was connected to a 300 mm perforated pipe surrounded by aggregate in a 450 diam hole excavatedby hydrovac around existing infrastructure to the maximum depth permitted by bed rock.
The installation of the inlet component by Enviro Eng Civil is the best first effort by any contractor, particularly as no onsite instruction was available . This demonstrates that provided the simple process is followed , particularly the sequence of steps from formwork set up to removal and final finish before fitting the face plate, the result will be to specification.