Several agencies — both international and indigenous ones — have shown interest in the underground mining of coal in a part of the proposed coal mine in Birbhum’s Deocha-Pachami.

Underground coal mining assumes significance for the state government as it can evade acquiring land unlike in the case of open-cast mining, given that the state failed to acquire land in the 376 acres where open-cast mining was planned.

“An EoI (expression of interest) was floated globally in December. Agencies of repute from Canada and Poland have shown interest besides indigenous companies like Reliance Power. It is expected that they will take part in the bidding process that can be final by April,” said a senior state bureaucrat.

Of the 1,200 lakh tonnes of coal reserve, about 400 lakh tonnes can be extracted through underground mining.

With heavy basalt overhead in the project area across 3,500 acres, open-cast mining was possible on 376 acres where the thickness of the basalt was between 100 and 300 metres.

As most coal reserves lie under basalt overhead of thickness of over 300 metres, open-cast mining is not economically feasible in the remaining 3,000-odd acres.

This was why the state was exploring underground coal gasification on 1,000 acres where coal lay under over 500-metre-thick basalt.

“But in 2,000 acres where the thickness of basalt is between 300 and 500 metres, underground mining is the only option," said an official. “Although 90 per cent of landowners have agreed to sell land to the state, we won't have to wait for physical possession of the entire land parcel in the case of underground mining."

An underground incline in a coal mine is a sloping tunnel that provides access to coal seams below the surface.

Multiple officials said it was important to get a positive response from agencies in Poland and Canada as underground coal mining in Deocha-Pachami was not easy due to heavy basalt overhead.

“Agencies in Poland and Canada are experienced in underground mining. Poland is known for underground mining across the globe. Canada has the only subsea coal mine – the Donkin mine — in the world,” said a source.

Starting underground coal mining is important for the ruling establishment as it wants to kick off the project before the 2026 Assembly polls, said a source.