It will be at least three years until demolition work begins at Hazelwood power station, plant owner ENGIE revealed at a community meeting held last week.
The meeting marked the first time plant owner ENGIE has publicly revealed its plans for what will happen at the plant after closure on 31 March.
Following the closure of the business the plant will enter its 'shutdown' phase which will involve draining fluids and removing oil and industrial gasses.
This stage will continue until at least 31 May before actual decommissioning begins.
About 135 ENGIE workers and about 100 contract staff will remain employed at the site throughout the work.
Station director Wayne Buckley said operations at the plant would be gradually wound down during its last week in operation, with its eight generating units to be progressively taken offline over several days.
"We're currently anticipating the decommissioning period will take approximately 12 months," Mr Buckley said.
"So as at the end of this whole decommission we will hand over a whole volume of documents to a demolition contractor to say that the plant has been shut down and safely decommissioned."
Services such as security and fire fighting will remain active once generating ceases.
But it will be some time yet before the final form of mine rehabilitation is known, mine director Garry Wilkinson said.
The two major options being considered are a partial and full lake.
"Confirmation of the final mine landform will require further communication with the community and that's a given," Mr Wilkinson said.
"A significant body of work has been carried out already in a short space of time but we've still got a fair way go to.
"It will take a year or two before we land on what we're actually going to do with the mine."
That work will be undertaken in consultation with parties such as the mine rehabilitation commissioner when one is appointed and the Latrobe Valley Mine Rehabilitation Advisory Committee.
More work will need to be done to finalise where water to fill the lake would be sourced from.
Potential water sources include water from the mine's underlying aquifers, natural fill, seepage, the station's licenced allocation from its Gippsland Water bulk entitlement and managed water from the Morwell Main Drain, information documents distributed by ENGIE on the night revealed.
Diverting the Morwell River to fill the mine was one "possibility", according to the documents, but this would require State Government approval.
About four years of rehabilitation and stability work would be needed to prepare the mine to be flooded.
A partial lake relying on pumping from the aquifer would take about six years to fill, while a full lake drawing on a variety of sources would take 10 years.
About 150 people attended the forum, the company confirmed.