Agnes Waters / 1770 Ocean Outfall

UEA was contracted by TRILITY to install a 600 metre section of 630mm PE pipe via horizontal directional drilling (HDD) for the raw sea water intake of the new desalination plant that was constructed for Agnes Waters/Seventeen Seventy.

Scope of Works

The installation of the last ocean outfall pipeline for the raw seawater intake needed to be completed before turtle season – within a short timeframe, UEA mobilised a HDD maxi rig spread to undertake the remaining scope. UEA and TRILITY agreed to use the abandoned bore that was re-surveyed as a part of the pilot hole installation. The bore was deemed usable as long as the exit could be plugged and professionally grouted for a safe exit angle through the rock formation. A 150-metre section at the exit point, 550 metres out, was grouted and once set UEA re-piloted the borehole and exited into the ocean floor at CH 610. Two reaming passes were completed out to 32 inches before a cleaning pass with the pipe installed over a 12-hour period.

Challenges

Many challenges had to be managed for this project to be successful, including: short timeframe, isolated location, tooling requirements from overseas, co-ordination of numerous highly skilled contractors, complicated diving works for underwater tooling connections, and environmental impacts.

Completion

UEA’s experience ensured that challenges were managed efficiently, and the project was successfully delivered one day before the first turtle wandered up onto the beach.