ASSESSMENT OF THE CURRENT ECOLOGICAL AND HYDROGEOLOGICAL STATE AND FORECAST OF ITS CHANGES IN THE CHITA TPP-1 ASH DUMP TERRITORY (EASTERN TRANSBAIKALIA)

Abstract

The article provides an assessment of the current state of groundwater and shows the dynamics of its transformation based on the analysis of geoenvironment monitoring results for 2008–2022. The geological environment monitoring program included hydrodynamic and hydrogeochemical observations on the Chita thermal power plant № 1 ash dump territory placed in the west of the city. Regime observations were carried out over the aquifer of the Lower Cretaceous sediments of the Doronin formation using hydrogeology boreholes. The hydrodynamic data correlation analysis indicates the relationship of groundwater levels in boreholes located at a considerable distance from the ash dump with the water level in the nearest borehole. The expansion of technogenic object influence zone in the southwest direction is confirmed by this circumstance, together with the appearance of an ascending spring and the previous studies results of the filtration properties of soils which lie at the ash dump bowl base. As revealed earlier, the ash dump appeared to be the source of significant contamination of groundwater in this area. Nowadays, the polluted area is estimated approximately at 12 km2. The concentrations of sulfates, boron, total dissolved solids, as well as total hardness exceed the norms for drinking water within the area of about 12 km2 in the boreholes on the filtration flow route in the southeast direction from the ash dump. The chemical composition of water taken from boreholes in the southwest direction is currently close to the background values of the water quality indices for the Chita-Ingoda intermountain artesian basin. Meanwhile, the composition of the spring located 1 km southwest from the third ash dump bowl indicates worsening of groundwater quality. As proceeds from the study performed, the operation of the third ash dump bowl will create conditions for the spread of the groundwater contamination front in a new direction with flooding of previously unaffected areas.