Universiti Malaysia Sabah,(UMS) lecturer and geologist Prof Dr Felix Tongkul said the controlled filling of the 80m Mamut Copper Mine in Ranau district would take about 10 years and cost at least RM100mil.
He said the work would essentially involve filling up the pit with rocks and earth while the acidic mine drainage (AMD) is pumped out and treated before being discharged into the nearby Sungai Mamut.
“The treatment would involve adding limestone into the acidic water,” Prof Felix said.
He pointed out that Sabah had limestone deposits in places like Sukau in the east coast and Pulau Balambangan in the north.
Once filled, the disused mining area could then be used for other purposes including tourism and recreation activities.
Prof Felix said filling up the open pit of the copper mine that had been in operations between 1975 and 1994 had been proposed before and he had brought it up again with state government officials recently.
He said though the cost seems high, it would be spread out over the duration of the work.
“If it’s RM100mil, this would work out to just over the RM10mil a year to reclaim a valuable area,” Prof Felix added.
State Tourism, Culture and Environment Minister Datuk Masidi Manjun had said the state was looking at filling up the open pit containing 20.6mil cubic metres of stagnant water.
He said ministry officials were consulting local and foreign experts as well as personnel from the Mineral and Geoscience, Public Works, Drainage and Irrigation and Environmental Protection departments on the matter.
He said the open pit was not affected by the June 5 earthquake on Mount Kinabalu.
Masidi said according to the Mineral and Geoscience Department, the open pit could withstand seismic movements up to a magnitude of eight.
He said the walls of the open pit were made of granite rocks and the amount of water collected in the pit had been steadily decreasing from 100m to the current 80m.
Mining at Mamut had earned Sabah some RM3.4bil in export revenue from the 100,000mil tonnes of pure copper extracted but it has had a detrimental impact on the environment.