In this paper the physical and mechanical properties of powdered coal slag from an electropower plant and its use as a filling material for construction of a high (10. 5m) slag dam are decribed. The operation of this plant shous highquality of the slag, which was used in construction of the highest slag dam in China. indicating its stable storage and safe operation. The obtained results on the engineering geological indexes and the developed techniques can be used as a reference for relevant engineering projects.