The Tree Nurturing System (TNS™) captures and stores stormwater where it falls, then feeds it to the root zone – growing the canopy that cools the street, and protecting the waterways downstream.
Centralised pit-and-pipe drainage is built to remove water from a single point as fast as possible. Efficient at moving water – but it disrupts the natural cycle that keeps soil, waterways and trees alive.
Traditional systems collect and convey contaminants downstream, detrimentally impacting the health and function of the receiving environment.
Rainfall is piped away, leaving dead, barren soils. Groundwater falls deeper; soils lose oxygen, minerals and elements, and become hard and compacted.
The standardised approach commits cities to a significant end-of-line maintenance regime, alongside costly, time-consuming and insufficient manual irrigation.
Councils set canopy targets and plant to them. Each tree goes into a pit sized for the tree, kerbed off from the street, and the runoff that would water it passes into the pipe. Planting rates go up and canopy doesn’t follow.
Conventional drainage isn't climate-neutral plumbing. Every storm, it drives the very climate impacts cities are fighting – degraded waterways, urban heat, and lost water security.
Drainage flushes sediment and nutrients straight to receiving waters, where turbidity blocks light and smothers seagrass. TNS retains runoff at the source, reducing the volume leaving the catchment.
In Queensland, Moreton Bay's seagrass decline has been attributed largely to stormwater sediment and nutrient loads; higher sediment loads non-linearly shrink seagrass habitat.
Runoff sheets across sun-baked pavement, picks up heat, and carries it into creeks and downstream estuaries – stressing aquatic life and lowering oxygen. TNS holds runoff in cool subsurface storage instead of releasing it warm to the network.
Runoff from hot impervious surfaces can exceed 39 °C, and overseas studies document post-storm stream-temperature surges of 7–9 °C. The extension to downstream estuaries is a recognised risk pathway rather than a measured marine figure.
Draining water out of the landscape leaves no stored moisture for the evapotranspiration that cools cities, intensifying the urban heat island. TNS holds water in the soil to sustain vegetation and its cooling.
Evapotranspiration from well-watered vegetation is a core cooling mechanism in water-sensitive urban design; remove the water and you remove the cooling.
Rapid conveyance sends erosive peak flows through channels, strips groundwater recharge, and leaves streams to dry between storms – ‘urban stream syndrome’. TNS slows, stores and sinks flow to restore baseflow.
Hydrologic ‘flashiness’ from impervious catchments drives channel erosion, habitat loss and reduced dry-weather flow – a well-documented degradation syndrome.
Rain interacting with hot, low-albedo surfaces – and the pollutants mobilised off them – may amplify downstream thermal and water-quality impacts. Source control like TNS holds that runoff in subsurface storage instead of letting it sheet across hot pavement into the network.
This is an area of active BGI research and our working hypothesis (Richards, 2023), not settled science – presented to flag a question we're investigating, not an established result.
All of it – the floods, the heat, the dying waterways – shows up on your street as one thing you can actually see.
Many urban street trees are planted in shallow graves, surrounded by hard, compacted engineered soils – root zones starved of water, oxygen and minerals. Declining immunity lets pathogens like phytophthora attack the cell structure, slowly and surely. Without a healthy root mass to hold the trunk and canopy, trees fail and collapse – and in many urban areas, that costs community lives.
Street trees sit in 1.8 m pits with a root barrier down the kerb and pavement edges, and a 50 mm slotted pipe for hand watering the root ball. The contractor waters them through the 12 month establishment period. After handover each tree lives on the rain that lands inside its own pit. The kerb at the edge of that pit takes the rest of the street’s runoff into the new stormwater line.
Drawn to policy, on a project with a canopy target.
Imagine a system that works like a sponge in nature. The TNS™ soaks up rainwater, cleans it, and gently releases it where it's needed most – to urban trees and plants – while letting the excess seep down to replenish groundwater. A decentralised, source-control approach: slow it, store it, sink it.
The combined systems of soil, water and vegetation – known as blue-green (living) infrastructure – moderate the release of water in heavy rainfall and provide fresh water through heatwaves. This fosters vegetation growth, expands tree canopy, and lowers urban heat.
Unlike conventional drainage, the TNS™ is a decentralised approach. Water that infiltrates does not discharge. Retention at source is load reduction that needs no certification argument, because the load never leaves the site.
Source control reverses the logic of conveyance. By slowing, storing and sinking runoff, the system reconnects urban environments to natural hydrological processes.
Each unit manages its own micro-catchment. Units arrange wide or narrow, deep or shallow, independently or connected – added, removed or rearranged to suit local space, grade and site constraints.
Ideal for retrofitting existing streets without costly excavation or redesign – adapting from dense urban streets to open landscapes while holding consistent retention and storage performance.
The TNS™ distinguishes itself from other tree-pit devices through the permeability of the material at the kerb line and the volume it holds at the source.
Both units are precast products of PPC Australia, made from a patented permeable concrete formula. The ETI sits at the kerb line, where the everyday rain runs; the fully porous EnviroKerb® unit sits downstream, taking water across the whole kerb face.
See the EnviroKerb® & ETI page →
The number of units at each node is calculated from the micro-catchment runoff calculations. From the kerb line, this is where the water goes.
Sources: kerb unit dimensions, weights and load rating – PPC Australia, brochures PPCA-BRO-001 and PPCA-BRO-002 Rev B, September 2026 (envirokerb.com.au). TNS™ hydrologic and hydraulic performance designed and assessed against Australian Rainfall and Runoff (ARR) – the national standard, applying in every state – with the local drainage manual applied where an authority adds its own requirements.
Everyday rain enters the ETI at the kerb line. The tray is sealed and removable, so gross debris cannot enter the subsurface structure.
Immediately downgradient, the EnviroKerb unit takes water across the whole porous kerb face rather than at an aperture. Each unit sits over a precast water ramp that deflects water away from the pavement subgrade.
A manifold of 100 mm drainage cells directs water to modular storage tanks, sized to the design storm for the microcatchment that node serves.
From storage, water moves down through Star Water filter media within the structural soil cells, where it is available to the tree root zone. The configuration supports root mass growth and the transfer of oxygen and minerals through the profile – tree stability, tree health, canopy.
A small relief pipe at the base engages only once the connected systems have filled and the substrate is fully saturated. On an ordinary event it does not engage.
Every stage terminates in storage, substrate or root zone. There is no outlet – only a relief.
Each node serves the smallest practicable contributing area, so volume is never accumulated and conveyed – each node holding the water from the area it serves.
Not a proprietary device. The TNS™ is not a SQID assessed on a manufacturer's certification – it is a culmination of established technologies forming a constructed bioretention node, and every element is modelled in MUSIC as a standard in-built node. How it is assessed →
Quality and quantity, assessed separately. What infiltrates doesn't discharge, and the load reduction that follows from retained volume is shown as modelled in MUSIC on standard bioretention parameters. Quality obligations themselves are met by separate, appropriately certified measures. Runoff volume, frequency and peak rate are hydraulic, and they are assessed in ARR the same way any detention is assessed. Neither position rests on a manufacturer's certificate.
Serviceable by design. The ARI Water Filter beneath the ETI tray protects the void structure from fines and is replaced by removal. Manifold, tanks and soil cells are geotextile-wrapped. The full maintenance case →
Classification. The TNS™ is classified under SA HB 214:2023 Urban Green Infrastructure – Planning and decision framework and the IPWEA Green Infrastructure Management Manual. Neither is a certification instrument. Classification by variant →
Materials. The elements water touches – the ETI, the EnviroKerb® unit and the water ramp – are mineral aggregate and cement as standard. The materials case →
Storage volume at each node is set by the runoff calculation for the micro-catchment it serves, and the node takes water in on frequent rainfall, where most of the annual volume sits. Volume held at the source is volume that never arrives at the bottom of the catchment.
Where a site still carries conventional road drainage, that network is designed on the flows that actually reach it, modelled to Australian Rainfall and Runoff. On most layouts that means smaller pipes. It often means the existing downstream system can take the discharge without being upgraded, and it usually removes the detention basin built to hold flows back until they fit.
Conventional drainage doesn't disappear. There is less of it, because the holding is spread across the catchment in small units instead of one large structure at the outlet. What comes off a particular site depends on its rainfall, soils and layout, so the reduction is quoted from the model for that catchment.
Runoff retention, distributed detention and slowing the water reduce flood risk, replenish groundwater, and protect downstream water systems – while maintaining ecosystem health.
Matter SensAI sensors measure intake against a calibrated baseline, so a drop flags an inspection before it becomes a blockage – turning maintenance from a fixed schedule into a predictive, data-driven response.
See the full Matter integration →
EnviroKerb® · PPC Australia
The ETI and EnviroKerb unit, and the precast water ramp.
envirokerb.com.au →
ARI Water
The consumable filter element, replaced by removal at service.
ariwater.com →
Matter · watermatters.ai
Baseline intake monitoring and proactive maintenance.
watermatters.ai →
Star Water Group
Filter media in the structural soil cells; conditions the substrate for root mass, oxygen and mineral transfer.
starwater.com.au →
Industry partner of the ARC Training Centre for Climate-Resilient Water – a national research centre led by The University of Queensland. The Centre has not assessed the TNS™.
Star Water filter media is a supplier product; performance data published on their site relates to their product in their applications. The TNS™ is offered on retention and storage: load reductions that follow from retained volume are shown as modelled in MUSIC, and it is not offered as a certified quality device.
Integrating modular tank, structural cell and drainage void systems – configured to depth, capacity and site type.
A street tree over a structural soil cell and tank module – fed by the EnviroKerb® and ETI.
View details →
A grassed verge served by the EnviroKerb®, water ramp unit, tank module and drainage cell.
View details →
EnviroKerb® feeding a drainage cell and tank module for stormwater retention beneath the pavement.
View details →
Planted surface over Rigofill ST modular blocks and RigoFlor™ geotextile – amenity above, storage below.
View details →
Water is a living system – intrinsically connected with land, culture and community. Our approach reflects the enduring principle that water should return to Country and sustain life.
Aligned with Australia's National Water Initiative (2004), the Insights Paper – Pathway to Enduring Recognition of Aboriginal Peoples' Water Interests (2022), and the forthcoming National Water Agreement.
The TNS™ is granted in Australia, China, the European Union, New Zealand and the United States, with the Indian application in late-stage examination. Patent and trade mark are held and licensed by Blue Green Infrastructure Pty Ltd. The patent covers the arrangement, and it doesn't make the node a proprietary treatment device. Every element is modelled in MUSIC as a standard in-built node.
The node is an urban green infrastructure element within the meaning of SA HB 214:2023, integrating with the blue infrastructure network in the way the handbook describes at Clause 3.3.6 – a practical bridge between policy intent and real-world implementation.
Green infrastructure is an asset class under the SA HB 214:2023 handbook at Clause 3.3.5, and the IPWEA Green Infrastructure Management Manual sets out how such assets are registered, valued and carried in a long-term financial plan. The policy direction points the same way – the National Water Initiative, recognition of Aboriginal Peoples’ water interests, and the forthcoming National Water Agreement.
Each node is a repeatable unit rather than a one-off design, so the same arrangement scales from a single street retrofit to a whole precinct.
Each node holds the runoff from the area it serves, so the flows arriving downstream are smaller. The drainage that remains is designed on what reaches it, which is ordinary hydraulic design assessed under ARR and the local drainage manual.
Whether you're specifying WSUD for a council or development, or a capital partner backing climate-resilient infrastructure – start a technical conversation.
We work with capital and delivery partners as well as councils and developers. Choose that in the form and it comes straight to Owen.
Three decades in civil and water engineering, designing for flood, urban heat and street-tree health. Inventor of the TNS™.
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