drainage

Effective drainage is essential for the longevity and safety of any civil works – and it’s something we do exceptionally well.

TWC combines technical expertise with practical experience to deliver compliant, high-performance drainage solutions, from stormwater and wastewater networks to complex multi-staged installs.

Our crews understand the importance of getting levels, falls, and flow right the first time – saving time, reducing risk, and keeping programmes on track.

“I am really happy to say that the final product that we anticipated was perfectly achieved.”

— Stormwater Delivery Manager, NZ Transport Agency

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Gross pollutant traps (GPTs)

TWC has developed specialist capability in the design, modification, and installation of gross pollutant traps (GPTs) across Auckland’s transport and stormwater networks.

At TWC, our specialist teams excel in the ECI, installation, and retrofitting of Gross Pollutant Traps (GPTs) across Auckland’s transport and stormwater networks.

Whether working in live traffic environments, 7m+ deep excavations, tight urban spaces, or around critical services, we deliver high quality end product results – partnering with quality suppliers like Hynds Pipe Systems Limited, Humes - a Division of Fletcher Building and Stormwater360 – to remove sediment, debris, and pollutant loads effectively before they reach our sensitive waterways.

Our hands‑on experience, proactive construction management, and collaborative design approach have earned us trust and recognition from councils, consultants, and delivery partners. Proud to play a pivotal part in shaping healthier waterways across Auckland.

Construction worker in safety gear working on a Gross Pollutant Trap installation, including large concrete panels, deep excavated walls, reinforcing steel bars and wooden formwork around.
Construction worker in safety gear working on a Gross Pollutant Trap installation, including large concrete panels and reinforcing steel bars.
Construction worker standing inside a deep excavation, with trench shield walls around.
Construction worker standing inside a deep excavation next to a large concrete drainage structure, with trench shield walls around.
Construction site featuring a yellow CAT excavator and a large concrete sumps in the foreground, with workers in orange safety vests and helmets, around a deep excavation. Residential houses, trees, and a car are visible in the background under a clo
Construction workers operating an orange excavator on a hillside, clearing dirt on a rural road, with a traffic cone in the foreground and green hills in the background.
Construction workers operating excavation equipment near a body of water, with orange cones and safety barriers, as they work on laying or repairing underground utilities.
Construction workers installing a large concrete culvert pipe in a hillside on a construction site.
Construction site with deep excavation, an orange excavator, temporary concrete barriers, and safety fencing near a busy road.
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