Two units of the 275 MW Kopili Hydel Project in Assam, owned by the North Eastern Electric Corp (NEEPCO), has been temporarily shutdown due to "acidification" of the reservoir water, a senior official said Wednesday.
The reservoir at Umrangso, a border area between Assam and Meghalaya, was found to contain acidic water discharged from the Kharkhar river, a tributary of the Kopili river originating in the Jaintia Hills.
"The closure of the two units was due to acidification of the reservoir water of both Kopili and Umrangso reservoirs, which led to severe corrosion in the under-water parts of the units and hydraulic structures of the hydro-electric plant," said NEEPCO's technical director Utpal Moral.
He said the shutdown had to be taken up for safety of the power station as there was heavy leakage of water while running them.
"Expeditious remedial actions are taken by plant engineers for earliest resumption of units," Moral said.
Power plant experts said that "unscientific" coal mining in Meghalaya has affected the Kopili Hydel Project, and its life-span is very uncertain as most of the machinery is corroded due to sulpuric acid content in the reservoir, due to toxic wastes discharged from the mines.
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"Rat-hole coal mining carried out unscientifically has led to severe degradation of the environment," said one of the experts.
A recent study by the Geological Survey of India (GSI) said the potential hydrogen value of water in the Kopili river is between 2.3 to 2.7 at present while the normal scale should be seven.
The fall is due to a rise in the level of sulfuric acid, the survey said.
Twelve percent of the power generated in the plant, commissioned in 1984, is distributed equally between Assam and Meghalaya, while 17 percent is given to other northeastern states.