Shillong, June 16: The National Green Tribunal (NGT) which observed that “unscientific” coal mining in Meghalaya can never be allowed keeping the ecology in mind, has found an echo.

Now, the Comptroller and Auditor-General (CAG) report has come up with an observation that Acid Mine Drainage (AMD) from “unscientific mining” has damaged the environment.

The tribunal had banned rat-hole coal mining and transportation of coal across Meghalaya on April 17. However, on Monday, it allowed transportation of already extracted coal with several riders.

“We are of the considered view that such illegal and unscientific method can never be allowed in the interest of maintaining ecological balance of the country and safety of the employees,” the tribunal had observed on April 17.

Giving more teeth to the claims that coal mining has an adverse impact on the environment, the CAG report, for the year ended March 31, 2013, (tabled today in the Assembly), specifically pointed out that not only have rivers been polluted, a Neepco power plant, too, was damaged because of the AMD from the coal mines.

The report said the Meghalaya State Pollution Control Board had conducted an investigation in November 2011 to ascertain the water quality of the Lukha and its tribtaries in the Jaintia hills vis-a-vis a similar investigation carried out in February 2007.

Eight water and sediment samples were collected from the same sampling locations investigated during 2007. These include the Lunar river, Lukha river, the confluence of Lunar and Lukha rivers and others. “The water quality characteristics in terms of pH, sulphate and iron concentrations with respect to four locations indicated that there is significant deterioration of water quality in comparison to that of 2007, the major cause of which was the AMD from coal mining in these areas,” the CAG report pointed out.

The investigation made by the board further revealed that the river water on the entire stretch of the sampling locations was unsuitable for drinking purposes.

The board had also recommended certain measures to be adopted to minimise the impact of mining activities on water quality.

These include filling of abandoned mines to prevent generation of AMD, proper management/treatment of AMD in mining areas for mitigation of water pollution, afforestation and vegetation of the mined areas, prohibition from direct discharge of both solid and liquid wastes generated from the mines into the rivers/streams.

Both the findings and recommendations of the board were forwarded to the Meghalaya mining and geology department and the deputy commissioners of all districts in February 2012.

“No efforts have been made by the state government either to implement the recommendations made by the board or take alternative effective steps to control AMD,” the report added.

Neepco plant: The report mentioned that Neepco had developed the Kopili hydroelectric project in stages since 1984. The plant, located in Assam, has a total installed capacity of 275MW, and caters to the states of the region.

Both Meghalaya and Assam, however, gets six per cent free power from the project being the two “host” states of the project as the project’s reservoir falls in these states.

The report pointed out that during a routine test done by Neepco of the reservoir water in 2006-2007 it was found that the water was “acidic”.

The Geological Survey of India (GSI), which carried a study, stated that the acidity of the reservoir water was “mainly due to unscientific coal mining in the catchment area”.

Subsequently, severe corrosion was observed in guide vanes, top cover, runner and others due to the acidic nature of water. Frequent power outages were also observed due to failure of cooler tubes and cooling water pipes of the power stations.

A multi-disciplinary team of experts from the Central Water Commission, Central Electricity Authority and Central Soil and Material Research Station further confirmed that the effect of acidic water on power plant equipment had become severe from 2008-2009 onwards, which made Neepco replace the equipment.

Neepco had taken up the matter with the Meghalaya directorate of mineral resources and the Meghalaya chief secretary between January-August 2009 to initiate necessary measures like educating coal-mining agencies and adopting rules and methods for extraction of coal to eliminate the problem of acidic water.

“The directorate of mineral resources had replied in November 2009 that the state government had no control over coal mining by private mine operators,” the report said.

Between 2008-2009 and 2012-2013, the Kopili project had suffered 336 numbers of outages due to damage to machinery by acidic water, the CAG report said. The loss of generation during the same period was 972.28 million units worth Rs 103.79 crore.

As the state was entitled to six per cent free power from the project, the loss to the state exchequer during the five-year period (2008-2013) was Rs 6.23 crore, the report added.