An expert advisory group warned of the possibility of 8 sites on brown coal mines across the Latrobe Valley collapsing. The warning is the result of an independent investigation in the collapse of the Morwell River diversion that inundated the Yallourn mine with 60 billion litres of water, damaged infrastructure and cut electricity for months from the nearby power plant.

The seven mines include the Yallourn mine which is undergoing repair expected to be finished in September, but due to heavy weekend rains, 5 billion litres of water had flooded again the Yallourn mine.

The owner of Yallourn and the power plant, EnergyAustralia, are spending $150 million to repair the diversion, while the Victoria state government has committed $4.2 million to speed up mine stability work.

The review by the technical review board on mine stability found a series of technical problems in terms of design and construction, particularly the design and location of filters, cracks on a flood plain and reliance of a sole seal over joints in coal conveyor tunnels.

EnergyAustralia said it is working with the state government and the findings of the report are being incorporated into new designs as well as having the designs reviewed by a third party expert. The designs for a permanent repair include a complex liner system and extra drainage for added protection to the new Morwell River diversion.

However, EnergyAustralia Group Executive Manager Michael Hutchinson said the mine and ongoing repairs to the diversion remain vulnerable to rain until the project is completed.

Meanwhile, the unexpected wet weather in Pilbara has led the Fortescue Metals Group (ASX: FMG) to cut its production guidance for the current financial year. The initial guidance between 82 million and 84 million tonnes of iron ore output for the 2013 financial year was cut to between 80 million and 82 million tonnes.

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