PT CPM Prepares 4-Kilometer Underground Mine as River Reef Open Pit Nears End in 2026
Sun 19 Jul 2026, 11:28 AM
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PT Citra Palu Minerals (CPM) has confirmed that open-pit mining operations in the River Reef area will end in 2026. As a continuation, the company has prepared an underground mining system with a tunnel network extending approximately four kilometers.
PT CPM Director Yan Ardiansyah said the transition in mining methods is part of the company’s long-term plan, which has been developed based on technical studies and occupational safety considerations.
“Open-pit mining operations will end in 2026 and will subsequently continue with underground mining. The boundary between the open pit and underground areas will use a crown pillar approximately 40 meters thick, in accordance with recommendations from geotechnical experts,” Yan said while presenting the River Reef mining plan in Palu on Sunday (19/7/2026).
He explained that the gold ore reserves are located approximately 200 meters below the surface, with a thickness ranging from 15 to 25 meters and a length of around 300 meters. The underground mining operational area is also located approximately three kilometers from the nearest residential area.
To access the mineralized zone, PT CPM will construct access tunnels measuring 5 x 5 meters with a total length of approximately four kilometers surrounding the ore body.
The gold ore extracted from mining activities will then be transported to the processing plant to be processed into dore bullion. Meanwhile, the remaining processing waste, or tailings, will be mixed with cement and returned into the mine void through the backfilling method to maintain the stability of the former mining area.
According to Yan, this method is part of the underground mining system designed to maintain operational safety while supporting production sustainability after the open-pit mine officially closes in 2026.
Through this transition, PT CPM is targeting that gold production activities in the River Reef area will continue without interruption even after the open-pit mining phase has ended.
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