Determination of ground water quality associated with lignite mining in arid climate

Ground water and suface water create a range of problems in lignite mining utilizing surface miing methods.in order to create a safe and economic mining environment,it is essential to carry out mining after dewatering the rock mass surrounding the lignite mines by advance dewatering techniques.this paper briefly describes the ground water regimes including pressure gradients associated with various lignite deposits together with the practical examples of some important lignite deposits in the world.an rffective method of controlling ground water in multi-aquifer environment in lognite deposits is to carry out mass dewatering using borehole pumps.this approach will help reducing the inflow rates of grounnd water to the mining excavation and also increase the effective strata,thus,increasing the slope stability of the mining excavations.the main theme of this paper is to present a as history analysis of thar lignite deposit in sindh,pakistan which has lignite reserves of some 193 bilion tonnes.the paper presents a proposed method of dewatering the thar prospect together with an assessment of the quality of aquifer water which can be used to improve the quality of life of people inhabiting in the thar desert area of sindh pakistan.water samples from three aquifers were can be classified as (sodium+ potassium) - chloride type water with a TDS range of 1000 to 20000 ml/L.consequently, this grround water is classified as brackish (saline water) requiring treatment before it can utilised for domestic or including arsenic,mercury and lead or cyanide.however, results indicate taht groundwater from a few locations contained traces of silver(<4oppb)owithozinc 0<0.1.ppm.

کلیدواژه ها:

open cut mining ، hydrogeology ، Aquifers ، lignite ، Advanced dewatering ، piper diagram