The Tree Nurturing System (TNS™) captures and stores stormwater where it falls – cooling the city, protecting waterways, and keeping street trees alive.
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.
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.
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. That decentralisation significantly reduces the displacement of flows and volumes – mitigating rapid runoff and pollutant mobilisation by a magnitude of scale.
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 its inflow rate and the volume it holds at the source.
Frequent, low-intensity flows enter the EnviroKerb Frequent Flow Inlet (EFFI). The inlet is sealed with a removable tray, so gross debris cannot enter the subsurface structure.
Immediately downgradient, a fully porous EnviroKerb High Flow Inlet takes the larger events. Each unit sits over a precast water ramp that deflects flow away from the pavement subgrade.
A manifold of 100 mm drainage cells directs flow 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 — many small volumes managed at source rather than one large volume at the low point.
Serviceable by design. The ARI Water Filter beneath the EFFI tray protects the void structure from fines and is replaced by removal. Manifold, tanks and soil cells are geotextile-wrapped. watermatters.ai units at the manifold entries measure flow against a baseline, so a drop flags an inspection before it becomes a blockage.
Materials. Up to 20% recycled plastics replace mined aggregate in the EnviroKerb body and water ramp, and up to 20% repurposed soil material in the tray aggregate.
The key differentiator is the decentralised approach, which reduces the negative impacts of conventional drainage by a magnitude of scale. Through a range of proprietary stormwater-management solutions, the TNS™ is configured for both minor and major rainfall events.
Runoff retention, distributed detention and slowing the water significantly reduce flood risk, replenish groundwater, and protect downstream water systems – while maintaining ecosystem health.
Both inlets are precast products of PPC Australia, made from a patented permeable concrete formula. The EFFI takes the frequent, low-intensity flows at the kerb line; the fully porous EnviroKerb™ High Flow Inlet sits downstream to admit the larger events.
See the EnviroKerb™ & EFFI page →
How they work together: the EFFI sits upstream to take the frequent, low-intensity flows, with fully porous EnviroKerb High Flow Inlets downstream, adjacent to it, taking the larger events. The number of units is calculated from the micro-catchment runoff calculations.
Sources: EnviroKerb™ inflow capacity – up to 500 mm per minute, tested to ASTM 1701 (PPC Australia, envirokerb.com.au). TNS™ hydrologic and hydraulic performance designed and assessed against QUDM.
Matter SensAI sensors measure flow 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 EFFI and High Flow Inlet, and the precast water ramp.
envirokerb.com.au →
ARI Water
Filter beneath the EFFI tray; protects the void structure from fines.
ariwater.com →
Matter · watermatters.ai
Baseline flow 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 →
Research partner: UQ ARC Training Centre for Climate-Resilient Water.
Star Water filter media is a supplier product; performance data published on their site relates to their product in their applications. BGI makes no stormwater quality claim for the TNS™.
Integrating proprietary 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 EFFI.
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 Tree Nurturing System (TNS™) is owned and licensed by Blue Green Infrastructure Pty Ltd. The patent is made, and the TNS™ trade mark used, under licence from BGI.
Four modular variants integrate proprietary tank, structural cell and drainage void systems – a practical bridge between policy intent and real-world implementation.
Growing national and international recognition that water is a living system – the National Water Initiative, recognition of Aboriginal Peoples' water interests, and the forthcoming National Water Agreement.
The decentralised, source-control approach reduces the negative impacts of conventional drainage by a magnitude of scale – runoff retention, distributed detention, and slowing the water.
Whether you're specifying WSUD for a council or development, or a capital partner backing climate-resilient infrastructure – start a technical conversation.
