Shillong June 08: The Central Ground Water Board (CGWB) has carried out an in-depth study in the Jaintia Hills region on the availability of water in the coal belt area which the board found that water in that region is highly polluted said the repot.
The district is a major coal producing area of the state with an estimated coal reserve of about 40 million tones. The areas where coal mining is prominent are Sutnga, Lakadong, Musiang- Lamare, Lumshnong, loksi, Ladrymbai, Bapung, Jarain Shkentalang, Sakynphor, Khliehriat and Rymbai. The thickness of coal seams vary from 30to 212 cm and is found to occur imbedded in sedimentary rocks (sandstone and shale) of the Eocene age.
The main characteristics of the coal found in the district are its low ash content, high volatile mater, high colorific value and comparatively high sulphur content. The coal is mostly sub-bituminous in character. The physical properties characterize the coal as hard, lumpy bright and jointed except for the coal in Jarain which is both soft and hard in nature.
Coal extraction is done by adopting obsolete and primitive surface mining method which is commonly known as ‘rat-hole’ mining. In this method the land is first cleared by cutting and removing the ground vegetation and then pits ranging from 5to 100m2 are dug into the ground till the coal seam is reached. Thereafter, tunnels are made into the seam sideways to extract coal which is dumped on the ground surface nearby till carried away by trucks. Coal mining in the district undoubtedly has brought wealth and employment opportunities but leads to large scale denudation of forest cover, scarcity of water, pollution of air, water and soil and degradation of agricultural land.
The chemical quality of surface is worst affected as a result of coal mining in the district. Most of the rivers and streams in the mining areas are polluted. The main source of this pollution in the mining areas is “Acid Mines Drainage” originating from mines and spoils, leaching of metal from soil and rocks, organic enrichment, silting etc. The water of the mining areas have been found containing sulphate concentration between 16to 161 mg/L.
The high concentration of sulphates is mainly due to presence of iron sulphide in coal and rocks and its reaction with water and oxygen. On the other hand, water of the non-mining areas very low concentration of sulphates. Water pollution is exhibited by the colour of the water in the mining areas which varies from brownish to reddish colour. Others parameters which characterized the degradation of water quality are low pH, high conductivity, high concentration of iron and toxic metals low dissolved oxygen and high BOD.
As a people in the rural areas are totally dependent on springs, there is an urgent need for scientific approach for proper development and management of it. It may be recommended that the development of springs will help in catering the water requirements of the people to a large extent. Unutilized springs should be scientifically for providing safe drinking water.
The CGWB has also suggested to the state government that they should hove the Groun water cell with the Public Health Engineering Department. Since this is a state subject their duty is just to advises the state government on conservation of water.(SP News)
