Along with spewing pollutants into the air, the fly ash being produced by the Narla Tatarao Thermal Power Station (NTTPS) and stored in the ever-growing ash tanks is causing surface and ground water pollution that will have devastating consequences for those living in villages located on their edges.
The public hearing, mandatory before granting of Environmental Clearance to any new thermal project, seems to have stirred the hornet’s nest with green activists, who came to make environmental impact appraisals prior to it, crying foul.
Toxic constituents in fly ash depend upon the specific coal used for power generation.
Traces or percentages of toxic substances like arsenic, cadmium, mercury, lead, beryllium, boron, chromium, manganese, selenium, strontium, thallium and vanadium, along with dioxins and polycyclic aromatic hydrocarbon compounds are found in fly ash. But it is the heavy metals – arsenic, mercury, cadmium and lead – that are causing concern to green activists here. Nearly 45 per cent of the coal used gets converted into ash. This works out to thousands of tonnes of fly ash.
The fly ash is mixed with water and pumped into huge ash tanks. The heavy metals that get into the water get leeched into the ground water because the fly ash tanks of the NTTPS are not lined, or, they end up contaminating the surface water and get into the food chain. The water is used for drinking by the people and the cattle. Contaminated grass is again consumed by the cattle and humans consume the milk.
The heavy metals, particularly mercury, which are ingested faster then they are excreted, get accumulated in living tissue in small amounts acting like slow poison.
The detection of high levels of mercury in some medicinal herbs collected from the Krishna river-bed downstream the Prakasam Barrage gives credence to the fears of the environmentalist.
The bio-accumulation of mercury causes the ‘Minamata’ disease, named after the place in Japan where it first occurred due to the consumption of fish in which the concentrations of mercury were very high.
Production capacity
Environmental engineer Sagar Dhara, who came to make an appraisal of the environmental impact, said the production capacity of the thermal power station had been increased more then once. It was very important to make a thorough study into the impact of the increase in production on the surrounding environment and community, he stressed.
