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.
The project comprises of the design, construction, operation and maintenance of a new RO seawater desalination plant, with associated infrastructure. The desalination plant will have a capacity of 1.5 ML/day with the potential of being upgraded to 7.5 Ml/day. Also involved in the project is the Operation and Maintenance of existing facilities, which includes two water treatment plants that are bore water supplied and a lagoon sewage treatment system and irrigation system.
The project had one main component to be completed before the Turtle season of 2011, which was to install the last ocean outfall pipeline for the raw sea water intake successfully, for unknown reasons the previous contractor was removed from site. UEA and Direct Hit Trenchless joined forces to install the 600 metre section of ocean outfall pipeline using a 1.1 million pound directional drill. TRILITY had a very short time frame to finalise the installation due to the high importance of the turtle season which meant no work activity on or near the beach after October 2011.
UEA Trenchless 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 were engaged to plug and grout a 150 metre section at the exit point 550 metres out, once this was set UEA Trenchless re-piloted the borehole and exited into the ocean floor at CH 610. Two reaming passes were completed out to 32 inch before a cleaning pass and then the pipe was pulled back during a 12 hour pull back. The completion of the bore was critical for TRILITY who had numerous contractors working around the clock to finish the project.
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.
For more information about this project or UEA Trenchless, please send enquiries to Steven Hopkins.