In regulatory terms the Tree Nurturing System (TNS™) is not a proprietary device seeking a device approval. It is a culmination of established technologies assembled into a constructed bioretention node – modelled in MUSIC as standard in-built nodes, with a subsoil relief drain rather than a stormwater outfall.
A stormwater quality improvement device is assessed on a manufacturer's certification and proprietary test data. The TNS™ is not that. Every element of it is a conventional civil component, and every element is modelled in MUSIC as a standard, in-built node.
Kerb inlet, water ramp, drainage cell, tank module, structural soil cell, filter media and subsoil relief. Each is an established civil component with known behaviour – nothing in the arrangement is a black box.
Every element is represented using the standard in-built nodes of MUSIC – the Model for Urban Stormwater Improvement Conceptualisation. No custom node, no manufacturer coefficient, no proprietary performance curve.
Because the arrangement models as a constructed bioretention node, it is assessed the way bioretention is assessed – a deemed-to-comply path, rather than a device approval resting on proprietary test data.
The node arrangement is built from the nodes already in MUSIC and linked in the ordinary way – source nodes for the contributing catchments, standard in-built nodes for the system itself. The model is provided with the specification package, with the parameters used for each node set out.
| In the model | Standard node | What it accounts for |
|---|---|---|
| Lot Catchment [Mixed] | Urban source node | Roofs, driveways and private hardstand draining to that node. |
| Road Catchment [Mixed] | Urban source node | The road pavement and kerb-line area draining to that node. |
| EnviroKerb + TNS™ | Media filtration node | The inlets and the storage held at source – both catchments drain into it. |
| Structural Soil Cells & Tank | Bioretention filter node | The media profile, extended detention and the vegetated surface above it. |
| Sub-soil relief | Outflow link | The saturated case only – flow leaving at seepage rates once storage is satisfied. |
Two source nodes, two system nodes, ordinary drainage links. Both system nodes are standard MUSIC node types – a media filtration node and a bioretention filter node – with parameters set per project against the relevant local guideline.
The subsoil component of the TNS™ is often mis-read as a conveyance pipe. It isn't. Classified correctly, it sits in AS/NZS 3500.3 territory as a subsoil relief drain – not a minor/major conveyance outfall in the drainage-manual sense.
The line only relieves excess soil water once the TNS™ storage is exhausted. It is a relief mechanism for the saturated case – not a primary conveyance path that carries the storm.
Any relief flow leaves at seepage rates, once the storage and substrate are saturated. It is excess soil water being relieved, not stormwater being conveyed.
This is the same class of relief drain that road authorities themselves daylight onto batters and footpath flow paths. The classification is well-trodden, not novel.
Why it matters for approval: framed as a relief drain rather than an outfall, the TNS™ does not require a lawful point of discharge demonstration in the conveyance sense. We provide the classification basis and supporting detail as part of the specification package.
| Reference | Applies to |
|---|---|
| MUSIC | Modelling of each node, using standard in-built nodes. |
| Australian Rainfall and Runoff (ARR) | Hydrologic and hydraulic design and assessment of the system – the national standard, applying in every state. |
| Local drainage manual | Where a state or council adds its own requirements on top – QUDM in Queensland, the equivalent manual elsewhere. |
| AS/NZS 3500.3 | Classification of the sub-soil relief drain. |
| ASTM 1701 | Inflow capacity of the permeable concrete inlets – up to 500 mm/min (PPC Australia). |
| Class D load rating | The kerb-line tray in the traffickable zone – fully trafficable. |
| AustRoads | Limits on standing water in traffickable zones during an event. |
The assessment approach is national. ARR applies in every state, and the node arrangement is modelled the same way wherever the site is – so a position agreed with one authority does not have to be re-argued from scratch with the next. Where a council or state manual sets additional modelling or classification requirements, those are picked up in the pre-lodgement discussion.
Everything an assessing engineer needs to check the system, sized to the actual site rather than to a product catalogue.
The model for the node arrangement, with the standard node parameters used for each element.
The relief-drain position set out with supporting detail, so the subsoil line is assessed as what it is.
Runoff calculated per node, setting the storage volume and the number of ETI and High Flow Inlet units.
Node details for the variant selected, and the kerb-line arrangement for the run.
The tiered response framework, the equipment required, and what the council already owns to service it.
Provided with every installation, against the cost of the centralised basin it displaces.
Where quality obligations sit. Where a development also carries stormwater quality obligations, those are met by separate, appropriately certified measures. The TNS™ is assessed on retention and storage – it is not offered as a substitute for a certified quality device where one is required.
Send us the catchment and the guideline you're assessing against. We'll provide the model, the node parameters and the classification basis – and talk them through with your assessing engineer.
