Wheatstone LNG Tanks Piling and Inclusion Trial

Case Studies

Onslow, Western Australia


Background

The Chevron Wheatstone Project is one of Australia’s largest resource projects. It will include an onshore facility located at Ashburton North Strategic Industrial Area, which is located 12km west of Onslow in Western Australia’s Pilbara region.

The project aims to extract Liquid Natural Gas (LNG) from the Wheatstone and surrounding gas fields that are approximately 200km north of the build site at Onslow.

The multi-billion dollar project was constructed with Bechtel as the lead design and build contractor.

Scope

During the initial geotechnical investigation, a potential liquefiable layer of soil (Unit 2b) was identified below the proposed LNG Tanks site.

The purpose of the piling trial was to assess if driving closed and open ended steel tube piles and inclusions through this Unit 2G layer would provide sufficient densification of Unit 2b to mitigate the potential for liquefaction during a seismic event.

The CMW Geosciences (CMW) scope of work included driveability assessments, a crane pad stability assessment and QA/QC monitoring of the pile driving trial.

The QA/QC monitoring involved a CMW representative being on site for the duration of the piling and testing programme to record and review driving characteristics. CMW was also responsible for directing and managing CPTu and pore pressure dissipation testing prior to, during and at the completion of the piling works.

PDA testing was carried out on two of the installed piles to gain an understanding of the pile capacity achieved.

Findings

The piling trial was completed well within the nominated timeframe and achieved the desired outcome whereby the CPTu and dissipation records indicated that the potential for liquefaction of Unit 2b had been effectively mitigated.

Category: Case Studies

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