Gas: Colongra Lateral Pipeline

Client: Delta Electricity
Location: Colongra, New South Wales

Zinfra Group delivered one of the most unique and innovative projects in Australia by designing and constructing the largest diameter, (42 inch lateral) onshore gas pipeline ever constructed in the country. The Colongra Lateral Pipeline not only delivers gas to Delta’s 600MW gas-fired peaking power station, but stores sufficient gas to allow the station to run at full capacity for five hours because the existing Sydney to Newcastle gas supply could not meet the peak demand of the station.

Zinfra Group’s design, accounted for the lateral pipeline to be pressurised over a 24-hour, off-peak period and held at pressure until the power station was brought online during peak periods.

Route restrictions complicated the project, requiring Zinfra to find a way to store 9 km of fully-pressurised gas pipeline in a 1 km stretch of land. The innovative solution utilised cantered on double loop to create the required storage capacity with an operating pressure of 3.4 to 13MPa. This complex looping design was a first in Australia and the continual cycling of gas pressure meant Zinfra had to engineer and construct the pipeline to AS2885 to withstand both the fatigue stresses from its pressure cycling and the potential earth movement due to local mine subsidence.

This innovative project drew on expertise from across the Zinfra Group – including engineering, project planning project management, major projects and operations. A major factor in the Colongra Lateral Project’s success was our proven capability of delivering similar projects, such as the Sydney Primary Loop and the Mila Compressor Station.

To maintain the schedule, Zinfra planned a number of key activities in parallel that would normally have been completed sequentially. These activities included route selection, procurement, detailed design and contractor selection.

Other highlights included:

  • cold field bend the API 5L X70, 42 inch pipe with wall thicknesses of 24 mm and 30 mm
  • providing a welding methodology and procedure to ensure the stringent design considerations could be met and exceeded. This occurred with a very low repair/rejection rate.
  • 3.5km of 10 inch feeder pipeline, a compressor station and a let-down station
  • successfully managed the safety, health and environmental issues associated with this project with very large equipment and did so on time and within budget