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ACTIVITIES TO CONTAIN MERCURY POLLUTION FROM ENTERING THE RIVER IRTYSH IN PAVLODAR, KAZAKHSTAN
RANDALL, P. ACTIVITIES TO CONTAIN MERCURY POLLUTION FROM ENTERING THE RIVER IRTYSH IN PAVLODAR, KAZAKHSTAN. Presented at Mercury 2006, The Eighth International Conference on Mercury as a Global Pollutant, Madison, WI, August 06 - 11, 2006.
To describe a research and implementation program that will cost effectively contain mercury pollution from a former chlor-alkali plant at Pavlodar, Kazakhstan.
This paper describes a research and implementation program to cost effectively contain mercury pollution from a former chlor-alkali plant at Pavlodar, Kazakhstan. It has been estimated that about 1300 tons of mercury were lost into the environment. The primary source of pollution was the electrolysis plant. The fabric of the building typically contained about 2% mercury; the soil beneath the floor has extensive deposit of metallic mercury, and a dispersion plume of mercuric chloride. Secondary sources of pollution are the solid waste lagoons, leakage from the drainage system that conveyed both waste to the lagoons and the polluted 80 million m3 depression lake Balkyldak. Clean-up activities achieved dismantling of the factory, mixing it with a weak concrete and containing it in a clay lined landfill site. The contaminated floor and subsoil beneath the plant was isolated by a bentonite cut-off wall to a basal clay layer and capping it. Studies showed that there were 19263 m3 of top soil with mercury concentrations above 10 mg/kg around both the plant site and the waste lagoons. The risk management plan was to remove it to clay lined repositories on the most contaminated sites. A groundwater model accurately predicted the dispersion of the Hg plume which traveled north/west for 1k towards Pavlodarski village and the River Irtysh before turning north for 1 km towards the Balkaldak depression where capillary losses slowed its movement. The model showed that the plant cut-off wall and a cut-off wall around a wastewater pumping station should stop the plume spreading. The cut-off walls have now been installed. A cutoff wall and cap has also been constructed around the waste lagoons which contained sediments with typically 2 g/kg of Hg. Mercury concentration in lake Balkyldak ranged from 3.4 to 0.1 g/l in the water and 0.18 to 2.2 mg/kg in fish. Balkaldak still possesses an appreciable risk. Currently, the effectiveness of this management strategy is being monitored with support from local authorities, the U.S. and the European Union.