Agnes Waters / 1770

Project Overview

UEA Trenchless 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 being constructed for Agnes Waters/Seventeen Seventy. TRILITY was originally contracted to provide new infrastructure for the towns of Agnes Water and Seventeen Seventy, including a new waste water treatment facility and desalination plant. The new infrastructure will service both townships, reducing reliance on local bores for drinking water.


Agnes Waters / 1770 QLD






610 metres


630mm PN 16 PE100 polyethylene


HDD ocean outfall

Scope of Works

The project included the design, construction, operation and maintenance of a new RO seawater desalination plant, with associated infrastructure. The desalination plant was built to have a capacity of 1.5 ML/day with the potential of being upgraded to 7.5 Ml/day. Also involved in the project was the operation and maintenance of existing facilities, including two water treatment plants that are bore water supplied and a lagoon sewage treatment system and irrigation system.

The installation of the last ocean outfall pipeline for the raw sea water intake needed to be completed before turtle season. Within a short timeframe UEA mobilised a 1.1 million pound directional drill, cleaning systems and pumps to undertake the remaining scope.

UEA and TRILITY agreed to use the abandoned bore which had to be re-surveyed during 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. Trican Pty was engaged to plug and grout a 150 metre section at the exit point 550 metres out, 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, and then the pipe was pulled back during a 12 hour pull back.


There were many challenges to the project, not just the time frame but the final conditioning and reaming of the bore hole; tooling was shipped from the US to cater for the rock ground conditions while divers from Civil Tech were used to complete underwater connections of the rock tooling, which was not an easy task. All in all everyone involved in the project worked extremely hard to deliver a successful outcome and the project was completed in time.

UEA’s experience ensured that these challenges were managed efficiently and the project was successfully delivered.

For more information about this project or UEA Trenchless, please send enquiries to Steven Hopkins.

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