Due to the booming demand for iron ore, coal, LNG, and other bulk commodities, new seaports and mooring facilities are being built all over Australia – not to forget extensions of existing ones. But nowhere on the continent, and indeed in the whole southern hemisphere, can a port development project even be compared with the sheer size of the Wheatstone project on the remote northwestern coast.
The onshore Chevron-operated Wheatstone facilities involve the construction of two liquefied natural gas (LNG) plants, with a combined capacity of 8,9 million tonnes per annum (Mtpa), as well as a domestic gas plant. The site is located near the small coastal town of Onslow on the Pilbara coast, at 1.400 km north of Perth. First gas is expected in 2016, and will be transported via subsea pipelines from an offshore processing platform at 225 km of the coast. The full scope ofdredging activities was awarded to Dredging International (Australia) Pty.Ltd.
Challenges are many. Located in the midst of the so-called ‘Cyclone Valley’, very heavy storm surges may threat operations at sea. Conditions in summer are tough just as well, with temperatures sometimes exceeding 45 degrees – which requires workers to drink up to 10 litres per day in order to avoid dehydration. Due to the remote location and the very limited existing facilities in Onslow, accommodation, flights, emergency procedures, logistics, etc became challenges that needed to be tackled in early stage.. The expectations from Chevron/Bechtel were to commit to excellence in execution to achieve world-class safety and environmental performance.
The marine contract at Wheatstone LNG Plant calls for dredging a 17-km approach channel, a swing basin, berth pockets, a tug harbour, and related infrastructure. Total dredging volume exceeds 26 million m³. The work is executed by several large-sized trailing suction hopper dredgese (TSHD), a seagoing self-propelled cutter suction dredge (CSD), and a large backhoe dredge (BHD) which are all able to operate safely and efficiently in the prevailing sea/climatic conditions at this remote location.
A camp facility to accommodate the workforce was built in Onslow including full catering, medical and recreational facilities. A purchase & logistical centre was set up near Perth to support the operations due to the remoteness of the site.
Project specific safety programmes were developed which include amongst others 100% adherence to specific marine absolutes, detailed procedures for safe crew transfer during rough weather conditions, full engagement and support of the Proponent’s Zero Accident Vision including the People Based Safety initiative.
The project has undergone a rigorous and thorough environmental assessment and had to be executed in full compliance with the stringent environmental conditions as set out in the Permit Conditions for this greenfield LNG export port.
Dredging International implemented a vigorous environmental monitoring campaign using an adaptive environmental management plan. Dredging works are adjusted in real time if necessary to avoid potential damage to the marine environment. To support the operations and protect the marine habitat, dedicated marine fauna spotters were employed on every dredging unit.
These strenuous environmental efforts led to a stellar environmental and safety record. This achievement was also recognised by the client by naming Dredging International “the Wheatstone Project Safety Excellence Subcontractor’, adding to their record as five-time “Subcontractor of the Month” awardees and achieving over 2.6 million hours without Lost Time Injury to date.
The works were completed without any Lost Time Injury, without any environmental breach, well ahead of schedule and within budget.
The marine and dredging ‘Downstream’ project at Wheatstone LNG Plant is distinct from the ‘Upstream’ Wheatstone project, whereby DEME offshore subsidiary TIDEWAY in joint-venture is executing trench dredging, backfilling, and stabilization works. In addition, Dredging International (Australia) was also engaged to execute the pipepull operations to pull the subsea gas pipeline ashore.