Preserving of the geoenvironment by filling of underground spaces with hydraulically transported waste slurries

The geological hazard in many regions in Bulgaria with a developed mining industry is higher because of the risks of collapse of terrain over abandoned mine galleries, with all the harmful consequences for the neighbouring structures and equipment. An example is shown for the preserving of the natural geoenvironment and the strengthening of a massif near a railroad by means of hydraulically transported inorganic waste hardening slurries formed from power plant ash, and used in the backfilling of an abandoned uranium mine. 11 refs., 5 figs., 1 tab