Evaluation on karst leakage of coal ash site in Wanhe

Coal ash site in Wanhe is located in the typical peak-cluster depression in central Guizhou. Serious polluted water leakage exists in the site. To evaluate the leakage characteristics exactly, the hydro-geological exploratory works and connectivity tests have been carried out around the site. The results show that the groundwater table under the site is 6.5 meters lower than the adjacent water level of the Boyu River. Thus, the waste water of the site can not leak to the Boyu River. In fact, waste water runs across the peak cluster region at the northwest of coal ash site and leaks along the F1 fault towards west into S2 and S3 springs in the neighboring valley which is beyond 3 km from the sit. The leakage points are the beady sink-holes which are scattered over the depression in the coal ash site, and the leakage is in the type of pipe fissure. Flow velocity of groundwater is 57.2 m/h, and hydrodynamic condition of the leakage is complicated. Water pollution leakage evaluation on the site is not only to solve seepage-proofing of beady sink-holes in the site, but also to ensure karst seepage-proofing of unsaturated zone at the north of the site. Therefore, it is suggested project of horizontal seepage-proofing be adopted.