BHP Tug Harbour Project

Mobile Dewatering

Project Owner: BHP Billiton

Contractor: Lend Lease Engineering

Project Value: $96 million

A new tug boat harbour and material offload facility at Hunt point on Port Hedland’s Finucane Island was being built to house an extra eight tugs and to lay foundations for the proposed outer harbour expansion in the near future.

Contracted to deliver the dewatering works for the development Mobile Dewatering’s scope of works included the design and construction, supply, installation and maintenance of the site’s dewatering system. 

The draw-down requirements on this project saw never-before encountered challenges, major ecological considerations and unique requirements. 

Mobile Dewatering delivered a plan that enabled a 250-metre by 250-metre excavation to be constructed, 22 metres below ground level and 16 metres below sea level, inside a highly permeable rock wall. 

The primary focus was to keep the excavation area dry while infrastructure works were completed. Strategically placed bore holes were drilled and installed. The welding and positioning of two interdependent ring mains circled the entire construction zone with 355 millimetre pipes, measuring in excess of 2.5 kilometres. 

Each day on site saw in excess of 24,000 cubic metres of water extracted and treated, in line with the site environmental management plan. Water was discharged through a series of sedimentation ponds and a purpose-built point to the ocean. 

The possible environmental impact on the surrounding ecology by this project was a prime focus for the Mobile Dewatering team. Mobile Dewatering and environmental divisions worked closely together to successfully deliver the project, exceeding client expectations.