By GREGOR MACTAGGART
STATE Resources Minister Jaclyn Symes has revealed a previously undetectable weakness in the ground as a key factor behind the current woes at the Yallourn coal mine.
Work continues on the Morwell River diversion wall following the state government’s energy emergency declaration last week.
The declaration allows owners EnergyAustralia to divert the Morwell River away from the mine so it can repair issues without the need for approvals.
Speaking in the Legislative Assembly, Ms Symes said the immediate focus was on understanding the nature of the cracking and to undertake immediate repairs.
“The recent cracks do appear to be linked to a previously undetectable weakness in the ground between the diversion channel and the active mine field,” Ms Symes said.
“Once we ensure the stability of the site and mitigate the risks, it will be important for us to look at how the event happened and what we can learn from it.
“Detailed geotechnical and hydrotechnical investigations are underway to inform of the course the important remedial work as well as future preventative measures, all in order to keep the community safe and the power on.”
EnergyAustralia estimates that the average daily flow rate of water through the Morwell River diversion is more than half a gigalitre, which equates to more than 200 Olympic-sized
The company said on June 11, the day after the severe storm which lashed the Latrobe Valley and wider region, the average daily flow rate swelled to 17 gigalitres or about 6800 Olympic-sized swimming pools.
EnergyAustralia energy executive Liz Westcott said the company was working with the state government to finalise a proposal that will help manage water flows and relieve pressure around the impacted area to enable longer-term repairs.
“We are working through the final details together,” she said.
“Our focus remains on the immediate work in front of us.
“That is, the continued safety of our people, undertaking temporary measures to seal the cracking, assessing options to diver the water away from the mine and increasing mining activity where it’s safe to do so.”
Ms Westcott said the impacted area of the diversion wall has stabilised.
“It does remain vulnerable. Depending on the weather, later this week we are aiming to seal visible cracking,” she said.
“So far we have been able to secure modest amounts of coal by selectively mining parts of our fields where it was safe to do so and within areas away from the area of concern.
“This has meant we’ve been able to maintain minimum generation on one unit and meet the evening energy peak.
“This will continue, and the community can be reassured that we are in constant contact with (the state) government, regulators and unions from a safety and environmental perspective, and work is always conducted according to strict requirements.”
Ms Westcott said EnergyAustralia continues to update the Australian Energy Market Operator (AEMO).
Yallourn Power Station’s usual generation capacity is up to 1480MW and typically supplies about 20 per cent of the state’s electricity demand.