Power on in the Outback

In the harsh and hot Queensland outback, electricity infrastructure for the Dugald River mining project had to be built from the red dirt up.

The outback town of Cloncurry in Queensland has been alive with Zinfra field workers contracted by mining company MMG to design, construct and commission the high voltage electricity infrastructure to power their Dugald River mine.

The mine power supply will connect to a 220/11kV substation located on the mine premises and be supplied by the Energy Queensland (formerly Ergon Energy) 220kV network at their Chumvale substation, located 11 kilometres west of Cloncurry and approximately 65 kilometres south of the Dugald River mine site.

The project commenced in June 2016 and has demanded impeccable timing and project management by Zinfra. Up to 75 employees and sub-contractors, working on a FIFO roster, have been working on the project at any one time to deliver the many moving parts of this large-scale project.

Zinfra national manager power John Gardner visited the project in February and met with MMG’s senior management. Both parties were delighted with the progress, quality and safety record of the project, which was completed on March 10.

“We are proud of what we have achieved on this project. It is a prime example of tight project management, strong collaboration with all stakeholders and a solid focus on safety,” Mr Gardner said.

TRANSMISSION CONSTRUCTION

The stringing crews strung the conductor in three phases and the OPGW in sections of approximately 21 poles.

The work was awarded to Zinfra in two separate packages. The first package of works involved the design and construction, using helicopter-stringing methods, of a 220kV transmission line. The line covers a distance of 63.4 kilometres and extends from the existing Chumvale substation to the Dugald River mine site.

The transmission line construction used several separate teams working along the line concurrently. All workers faced daily challenges with variable rock conditions, difficult access in the remote location and hot working conditions. The average temperature during the day soars above 45 degrees Celsius in the height of summer.

The leading crew’s task was to drill the holes in which to stand the power poles. While some holes drilled easily, others were hard work through rock in the rugged outback terrain.

Closely behind the borers was the pole assembly crew, whose job was to construct and dress the poles. The poles were delivered in three separate parts that were aligned, clamped and then had insulators attached.

Following these crews was the pole erection team who, using large cranes, lifted and aligned the assembled 9.5 tonne poles into their vertical position, ready to receive their concrete foundation within a 24-hour timeframe to fix them in place.

The 182 steel poles required for the transmission line were sourced from China and were subject to special load testing in the factory to prove suitability.

Zinfra’s national business development manager and transmission line expert Barney Manga travelled to Nanjing and Beijing in China to inspect the quality of the factory and materials used to manufacture the steel 220kV transmission poles and observe load testing of the poles.

Mr Manga witnessed the massive poles being subjected to various weight loadings to eight different parts of the pole. The weight load testing ensured the poles could withstand load and also tested their integrity in wind – in this case, up to 180 kilometres an hour.

The arrival of the helicopter in November 2016 and commencement of conductor stringing signified a critical milestone for the project. The stringing crews strung the conductor in three phases and the OPGW in sections of approximately 21 poles.

The transmission line construction was completed on time and on budget.

SUBSTATION CONSTRUCTION

Zinfra’s substation team is now busy putting the finishing touches to the 220/11kV substation. Under Zinfra’s second contract with MMG, the substation construction scope includes the design, procurement, construction, testing and commissioning to power the mine’s 11kV distribution network.

Harnessing capabilities from around the country, the company utilised their design team in Melbourne for the civil, primary and secondary systems design. SCADA design and configuration was delivered from the Tasmania office, and the telecommunications design was undertaken in Sydney.

The electricity network supplying the mine is part of the North West Power System, which is an isolated electricity generation and transmission network centred at Mount Isa, and not connected to the national electricity grid. As such, the substation secondary systems and protection schemes in the substation had to be designed to meet the security and reliability requirements of the North West Power System Dispatch Protocol.

Procurement for the substation project was complex as Zinfra was responsible for sourcing all primary plant and materials. While power transformers, control building, steelwork, bus bars and protection and control panels were sourced within Australia, there were a number of long-lead items that had to be obtained from suppliers in Germany, Poland, China, Japan, Croatia, and Italy.

Zinfra self-performed the substation construction, including all services, steel and bus work, electrical installation, testing and commissioning. Specialised site assembly of 220kV circuit breakers and 220/11kV power transformers, as well as the civil foundations for the substation were sub-contracted but managed by Zinfra.

Substation testing was fully undertaken by Zinfra, again drawing from its national resource pool. The testing included protection, SCADA and communications interface testing with the regional network provider Energy Queensland.

MMG’s manager, site construction for the Dugald River project, Alan Shepherd said he was pleased with the outcome of the electrical infrastructure works.

“With such a large project, in such a remote location, there are always challenges,” Mr Shepherd said.

“The transmission line and substation components of the Dugald River project are a critical milestone for MMG to complete on time to enable the successfully commissioning of the process plant.

“Zinfra has successfully delivered these packages by taking a true partnership approach with MMG, and through open communication and a can-do attitude.”

The client, MMG Dugald River Pty Ltd, is based in Melbourne, Australia and listed on the Hong Kong Stock Exchange and Australian Securities Exchange. MMG operates and develops copper, zinc and other base metals projects across Australia, the Democratic Republic of the Congo, Laos and Peru.

Dugald River is one of the world’s highest-grade known zinc deposits. The mine is expected to produce zinc concentrate with first production and shipment of product during the first half of 2018.

This challenging project brought all of Zinfra’s capabilities to the fore – complex procurement and critical logistics management, working in a remote location, innovative construction methodology and working to stringent time-frames – to successfully deliver this significant, large scale, high profile project for their client.