Research on water quality characteristics in the process of dewatering test for Ordovician limestone aquifer

Nantun coalmine lies in the south of Yanzhou Coalfield which locates in Jining city, Shandong province, China. In order to correctly understand hydrogeological characteristics of Ordovician limestone aquifer, utilize boreholes in roadway to put on large discharge and large drawdown blow down dewatering test. In the dewatering test, regularly collection water sample of Ordovician limestone aquifer and testing hydrochemistry parameters. Research results show that, the hydrochemistry type of Ordovician karst water are single, displaying typical karst water quality feature, and also show that the condition of Ordovician karst's water cycle alternative is poor. On the whole the water quality changes of Ordovician limestone are small, mainly because of in the middle-shallow and deep of Ordovician karst water are interblended in the outlet. During the entire dewatering process the water quality of Ordovician limestone and the upper NO.14 limestone are greater difference. These show the poor relation of the two limestones, the rocks between the NO.14 limestone and Ordovician limestone has better water resistance and safety mining of lower group coal. (C) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of School of Environment, Beijing Normal University.