Solid Energy exports up to 3 million tonnes of coal annually, but has been unable to export from Lyttelton Port of Christchurch for the past 12 days, since the June 13 earthquake disrupted operations.
The port company has estimated repairs to the coal wharf infrastructure may take a further two weeks to complete.
Solid Energy's Southland mine manager, Antony Stodart, said yesterday 50,000 tonnes had been identified at the Ohai site's northern end and a small-scale mining operation employing eight staff could see domestic South Island sales begin by early to mid-August.
"It's early days yet, but this is going to be a very small mining operation, with some ongoing exploration yet to be completed," he said.
Solid Energy closed the Ohai mine in June 2009. Under conditions of its coal mining licence, it is part way through a three-year site rehabilitation programme.
