Narrows Crossing Armour Rock Back-Filling Works

Scope of work

The QCLNG and APLNG export pipelines cross from the mainland to the liquefaction plants on Curtis Island. They cross at The Narrows which is approximately 10km North of Gladstone. This is within Gladstone Harbour. 2.3km of pipeline crosses from Friend Point on Kangaroo Island to Laird Point on Curtis Island.

MCJV required the 2 x 42 inch pipelines which were installed in the dredged trench to be buried under rock backfill for protection.

PMG were awarded the project to urgently set-up the barges, mobilise to site and complete the works.
PMG utilised the following 2 x 120 foot barges fitted with deck protection and bunding for transfer of material, 150 foot positioning barge with 6 anchor system and GPS tracking, 3 excavators for unloading, chute system, 12 tonne drag bar, 2 tugs, 2 transfer vessels plus miscellaneous equipment to complete the works.

Statistics
  • PMG set-up all barges and equipment and mobilised to site within 5 weeks of contract award.

  • Approximately 130,000 tons of rock was placed.

  • PMG covered 2.35 km of pipe twice. First layer with 0.45 metre (min.) layer of Filter Rock followed by 0.75 metre (min.) layer of Armour Rock.

  • A total of 356 Barge loads dropped.

  • First barge unloaded on 20th April 2013.

  • Last barge unloaded on 14th July 2013.

  • Rock placement completed in 86 days – with Day and Night Shift

  • Rock Placement over approximately 160 x 13 hour shifts

  • The width of channel dredged, in the shallows, was 50m. The length of PMG150 is 45metres.

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Client
MCJV - McConnell Dowell and Consolidated Contracting Company Joint Venture

Time
March - July 2013

Contract Value
9M

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