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Client: QCLNG Pipelines Contract: EPC Location: Queensland   |
Fast Facts
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The Narrows Crossing contract was awarded to the McConnell Dowell and Consolidated Contracting Company (CCC) Joint Venture (MCJV).
The contract involved the connection of the QCLNG and APLNG 42” export pipelines from their termination points across the Narrows Channel to the LNG plant on Curtis Island. It was one of the most diverse and challenging pipeline projects ever completed in Australia. The scope also included the QCLNG Delivery Station.
The twin pipelines scope of work consisted of five distinct sections, each requiring a specific construction technique to suit the challenging conditions.
The five sections were:
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Phillipies Landing Road section - a 2.5 km onshore section crossing the Queensland Energy Resources land bridge. Traditional trench and bury techniques were used in this section.
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Creek section - a 1.34 km section through culturally significant and environmentally sensitive mangroves. Horizontal Directional Drilling was used in this section for the least impact.
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Marshland section - a 1.56 km section through marshy tidal mud flats. The pipes were pulled through a temporary sheet-piled cofferdam in this section.
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Narrows Marine section - a 2.45 km crossing of the tidal water course between Kangaroo Island and Curtis Island. This section lies in close proximity to the Great Barrier Reef and has cultural significance to the local indigenous community. A subsea trench was dredged and the twin pipelines were pulled (bottom-towed) into place.
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Curtis Island section - this 5.4 km long hilly section extended from the shore crossing at Laird Point to the QGC Delivery Station on Curtis Island, with a further 1 km of pipeline from the delivery station to the plant. Traditional pipeline techniques were used for this section.
Delivery Station Scope
The QCLNG Delivery Station was a complex, multi-discipline construction project in its own right and involved:
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Earthworks - 40,000 m3 of cut and 30,000 m3 of fill
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Pavement and surfacing - 9,000 m2 of hardstand surfacing
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1500m3 of concrete bored piles and foundations
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180 tonnes of structural steel platforms and pipe supports
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Procurement and installation of three 60" dia by 6 m tall dry gas coalescers
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Procurement and installation of a 12" dia by 40 m tall cold vent tower
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6,800 dia-inch of pipework welding - the largest diameter being 42" at 40 mm wall thickness, which consisted of both manual and semi-automatic welding processes.
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Site activities related to pipeworks also consisted of post-weld heat treatment, strength hydrostatic pressure testing, nitrogen/helium leak testing @ 95% of design pressure, and on-site coating.
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All electrical and instrumentation installation.
The Narrows project had the added complexity of moving plant, equipment and materials from the mainland, across the waterway to Curtis Island. A number of marine vehicles were purchased, re-purposed and used to transport both workers and equipment across. For logistical and safety purposes, several roads in the area were upgraded at no cost to the community. This has had wide-reaching local transport benefits.
