Australia: Drilling survey offers positive assessment for 120 GWh pumped hydro project

Twin Hills engineering drill site, Queensland

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From pv magazine Australia

An investigative drilling program in Australia's northeastern state of Queensland has reinforced the suitability of a site to host a proposed $12 billion pumped hydro energy storage project.

State government-owned Queensland Hydro is developing the Pioneer-Burdekin project in the central Queensland coast's Pioneer Valley, about 70 kilometres west of Mackay. According to the company, the drilling program has revealed the presence of very strong, coarse competent granite rock, confirming the site is an ideal location for dam construction, tunnels, and potentially multiple underground multi-turbine powerhouses.

“Our geotechnical investigations have shown very promising, high-strength, highly competent granite throughout the proposed project site,” Queensland Hydro CEO Kieran Cusack said.

Cusack said investigations are continuing but the quality of the initial core samples could open up a broader range of options for the project’s design, including a potential capacity increase, and may also lead to an improved project schedule if it is approved.

The drilling was conducted by Mackay-based company Twin Hills Engineering, with assessments carried out by global engineering outfit WSP and Australian firm SMEC. To date, 33 boreholes and 20 test pits have been completed with investigations drilled to 850 metres.

The core samples reveal two main types of rock at the site which Queensland government geologist Tony Knight said looked to be very strong, competent and solid rock.

“This is exactly the type of rock needed for these projects for strong foundations and stability,” he said.

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The results compare favourably with the site of the troubled Snowy 2.0 pumped hydro project being delivered in New South Wales.

That site features more than 20 types of rock and the project has been beset by delays, the latest of which sees tunnel boring machine Florence wedged in “extremely hard and abrasive rock” and the developer said it cannot yet provide a timetable for when it will resume drilling.

This development comes after the 2000-tonne Florence, one of three tunnel boring machines deployed on the 2.2 GW expansion of the existing 4.1 GW Snowy Mountain pumped hydro scheme, was last year mired for months in soft and wet ground.

The Snowy 2.0 project is now not expected to be operating until 2029.

The first stage of the Pioneer-Burdekin pumped hydro project is estimated to be completed in 2032, with the final stage operational by 2035.

Author: Ken Braganza

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