Ocean Outfall - HDD
UEA’s ocean outfall skillsets have been developed on the back of the delivery of significant and complex projects over the last 25 years.
Having completed a number of significant projects in recent years, UEA has become a contractor of choice for delivering ocean outfall projects. Ocean outfalls, also known as shore approaches, can be successfully installed using HDD technology. With careful planning it is an innovative method of delivering an offshore pipeline or conduit to its required location on the land whilst avoiding significant damage to the ecosystems commonly found closer to the shore.
Ocean outfalls are completed in a very similar method to other HDD crossings. Usually involving an HDD maxi rig and a steering engineer, the pilot bore is drilled out to the agreed location and either punched out onto the seafloor or can be recovered on a jack-up barge for some specific applications.
In some cases, the drill string can be left in-situ if the internal diameter is suitable for the utility – such as communication installations – otherwise, the pilot hole is reamed to size and the required pipe pulled into place. The major difference between land and ocean installations is the interaction required with a diving team.
Ocean outfall installation via HDD can be used for any type of pipelines or utility but the following are most common:
- Communications such as overseas fibre connections
- Power cable crossings where the cable is to be dredged in place between the installed outfall or to a marine structure such as wind turbine or wave generator
- Desalination pipelines where intake and discharge lines are commonly required
- Seabed gas pipelines requiring to exit on to the land
After completing a number of successful ocean outfall projects, UEA was awarded a 1,300 metre design and construct HDD ocean outfall and beach manhole construction contract by Hawaiki Submarine Cable. The project at large involved a new submarine cable linking Australia and New Zealand to Hawaii and mainland United States, which will help eliminate the distance between all Pacific communities and boost socio-economic development through the provision of broadband access. With a design capacity of 42 Tbps, Hawaiki is now currently the highest cross-sectional capacity link between Australia, New Zealand and the United States.
HDD Installations on the Parmelia Gas Pipeline
The shifting sands of Perth can add complexity to trenchless projects. However, with good drilling practices and a swift, well planned schedule, running sand is no obstacle for HDD.