Following heavy rainfall in the Latrobe Valley, water was discovered seeping into one of the four conveyor tunnels that pass below the Morwell River Diversion (MRD) in the Yallourn coal mine.
The situation worsened and resulted in the failure of the MRD aqueduct and the closure of nearby mining pits and associated infrastructure, including major coal conveyor systems that represented a significant proportion of Victoria’s energy generation.
Response
With reduced ability to transport coal to keep the power station operational, a rapid response was required to divert the river, de-water the coal mine and reinstate coal supply to the power station.
The first stage of the emergency solution was to build dams both upstream and downstream of the breach.
A total of 40 km of 500 mm and 630 mm diameter PE100 pipe connected to pump floats was quickly installed.
At the same time plans were being implemented to re-establish the river diversion and return the mine to a fully operational state while the levee was being re-built.
The design of the river-diversion called for a flow of 800 ML per day, with a maximum flow of 2,800 ML.
PE100 was seen as the material that was best positioned to meet all of the requirements of the application.
The intrinsic properties of the PE100 pipe compound and the extruded PE100 pipe such as toughness, impact strength and slow crack growth resistance are known to ensure excellent application abuse resistance, providing high pipe system integrity even after being subjected to rough installation.
A PE pipeline of 1,600 mm diameter was selected, with a total of 4 km of pipe needed to be priority manufactured.
Extrusion of the pipe was undertaken by Iplex at their manufacturing sites in Albury and Perth on extrusion lines with 2,000 mm diameter pipe capacity.
Qenos PE100 grade AlkadyneTM HDF145B was chosen to manufacture the pipe due to its proven capability of delivering high extrusion output while enabling the production of pipe to tight dimensional specifications.
GEM Industrial Services was tasked with the around-the-clock pipeline installation.
This involved welding ten lengths of pipe into 120 m strings which were then dragged to the installation site for final joining.
This was enabled by large diameter pipe welding equipment which was air freighted from the United States.
It was critical to use a high quality PE100 pipe grade to ensure the finished pipe maintained its fitness for purpose after rough treatment during installation.
For example, the 120 m length of welded pipe strings had to be towed along the road to the installation site for the final pipe assembly.
It was important for the extruded pipe to have a highly uniform wall thickness and tight control of ovality to enable quality welding.
The welds needed to withstand the extremely high tensile forces of the 120 m pipe strings being dragged into place.
The tie-ins were completed and the pipeline was commissioned within seven weeks of installers arriving on site.
The entire Morwell River was then flowing through the pipeline allowing repair of the mine infrastructure to begin.
Two years later, the pipeline is still in service securing the long-term supply of power to Victoria.
To read more about the Morwell open-cut mine operation, read Iplex’s account on page 104.
For more information on Qenos’ products and services visit www.qenos.com.au.