Modelling geologist Chris Osborne (pictured) said workers had successfully drilled 23 metres on the first full day of coal exploration at the Parwan site.

The borehole requires a depth of 109 metres. Coal discovered will be inspected this week before being sent off for further analysis.

Mr Osborne says it won't take long for surrounding landscape and vegetation to return to its original condition.

"I have visited two previous sites and everything has regrown. Top soil will be removed then put back on. It'll go back to looking like any other paddock in no time."

Drilling will stop for Christmas-New Year and resume in early January.

Mantle's exploration manager, Callum Lamont, says the company is allocating seven days for each of its 11 remaining holes.

Maps of drilling locations can be found at moorabool.vic.gov.au