Scope of Works
Once HDD was determined as the preferred method, a feasible design was the next step. Given the proximity to Sydney Airport and the busy road and rail corridors, a fit-for-purpose, achievable design was a must in minimising risk to this vital infrastructure. “Prioritising HDD design geometry played a major role in this approach. “The vertical geometry in particular was vital to ensure we gained sufficient depth of cover to mitigate hydrofracture risk to the critical road and rail infrastructure, while minimising our drilling in the more challenging geotechnical layers and the deeper harder layers,” said Stephen Sullivan, Senior Project Engineer – Utilities Stage 1 for the Sydney Gateway Project.
With design and approval stages complete, and UEA’s Maxi rig spread mobilised, drilling commenced. Almost immediately after punching in, an uncommon obstacle arose in the form of significant quantities of large shells and timber fragments returning in the drilling fluid. “While some shell and timber fragments were picked up in geotechnical reports, the quantity and size of these materials coming back in fluid returns was remarkable,” Jonathan de Vos, UEA Operations Manager, said.
Despite the difficult ground conditions the pipe was installed without a hitch much to the satisfaction of the client. “When incorporating several parties into crucial HDD operations, the importance of clear knowledge and consensus on the end goal and how to get there cannot be overstated,” said Stephen Sullivan “This project going off so successfully is a testament to that and a credit to all involved.”
