South East Queensland Water Trunk Main Project

Trazlbat delivered the construction of a strategic trunk water main “Mini Link” between Queensland and New South Wales, extending from Coolangatta to Tweed Heads. The project was undertaken to enhance regional water supply reliability and strengthen network capacity for the Tweed Heads service area.

The works involved the supply and installation of a DN375 ductile iron cement lined (DICL) trunk water main, delivered predominantly within a live road corridor and under complex ground and service conditions. Construction required careful staging, traffic management, and coordination with multiple utility authorities to ensure safe delivery within a constrained urban environment.

Scope of Works

• Supply and installation of approximately 700 metres of DN375 DICL trunk water main.
• Installation of trench stops and bulkheads to manage steeper grade sections.
• Pipe installation predominantly within live road corridors (approximately 70% road alignment).
• Excavation, trenching, bedding, backfilling, and compaction of pipeline corridor.
• Concrete encasement and engineered trench fill using lean mix concrete and 5–7mm aggregate where required.
• Installation of the trunk main beneath private driveways and road crossings (including 3 road crossings).
• Connection into existing DN525 AC water main, completed within a tightly constrained 36-hour shutdown window.
• Installation of service crossings including:
  • Stormwater box culverts (x3 at approx. 2m depth)
  • Stormwater RCP pipelines (x3)
  • Water mains (x4)
  • Sewer mains (x5)
  • Telecommunications assets (Telstra x4)
• Full road restoration including 150mm asphalt pavement reinstatement.
• Daily temporary reinstatement of road surfaces at the end of each shift.
• Traffic management support including provision of a minimum of four traffic controllers per day.
• Testing, pressure testing, and commissioning of the completed trunk water main.

Project Challenges

• Excavation through hard rocky strata requiring specialised excavation methods.
• Steep grade sections requiring installation of trench stops and bulkheads for pipeline stability.
• Complex live connection works into an existing DN525 AC main within a strict 36-hour shutdown window.
• Dense underground service environment with multiple crossings including stormwater, sewer, water, and telecommunications assets.
• High-volume traffic corridor requiring continuous traffic management and staged construction.
• Working in groundwater-affected trench conditions with a high water table.
• Maintaining public safety and access along a busy arterial road throughout construction.
• Delivering full asphalt road restoration under tight programme constraints and daily reinstatement requirements.