Monitoring the underground roadway water quantity and quality for irrigation use around the Barapukuria Coal Mining Industry, Dinajpur, Bangladesh

Abstract

The influence of underground coal mining activities has become a leading issue in contaminating water resources as well as depleting the water layer around the mining area. The studied mining area is a plain land which is predominantly used for irrigation purposes where underground water is the main source of water for irrigation. In the case of Barapukuria Coal Mine (BCM), a huge volume of water is pumped regularly from the underground roadway to the surface. Thus, this study takes account of the estimated quantity and quality of water used for irrigation and other uses. Therefore, this study monitored and assessed the quantity and quality of inflow water in the roadway for 13 years. The observation shows that the inflow water volume was about 11,183.52m3/day in 2001, and it has increased up to 43,396.80m3/day in 2013. These results implied that the increment of inflow water intensities is very high with increasing the mining operation. As a result, it might be a considerable problem to deplete the natural water table, which could change the changing aquifer geometry and influence the safe extraction of coal in future. The qualitative assessment of water shows that the underground roadway water is suitable for irrigation purposes. The overall quality of water is largely controlled by rock weathering and evaporation natural processes in the area. In fact, the suitability of roadway water for irrigation was evaluated based on SSP, salinity hazard, sodium percent, sodium adsorption ratio, residual sodium carbonate, US salinity diagram, Wilcox's diagram, Kelly's ratio, permeability index, Magnesium Hardness, Total Hardness and so on. On the whole, the concentration of such parameters, major cations, anions, trace elements (e.g. As, Cd, Zn, Cr, Cl, Al, Mn), and other elements (e.g. TSS, DO, DOB, Oil and Grease, C. Count, T. Coliform, F. Coliform) did not exceed the permissible limit for irrigation purposes, and thus is suitable for irrigation uses. Conversely, the slight Mg hazard with moderately hard to hard tendencies of water bodies suggests the restricted utilization of this water for irrigation. Therefore, this study finally recommends that the ongoing monitoring program continues with necessary precautionary measures for maintaining the quality of roadway water in the underground tunnel of the mine.