Hydraulic transport system of Tailings Dam ‘Benkovski 2’ – new technological solutions regarding prolongation of the operational lifetime and raise of the final filling contour of the hydraulic structure Authors: eng. Stoil Dimitrov – ‘Ellatzite Med’ eng. Nikolai Evstatiev – ‘Geoproject’ LTD eng. Georgi Boiadjiev – ‘Ellatzite Med’ ‘Ellatzite Med’ is the biggest mining company in Bulgaria, processing about 12 000 000 tons of ore per year. Waste materials, left after the extraction of copper concentrate are deposited in tailings dam ‘Benkovski2’. The hydraulic structure is built according to the Downstream method, through hydrocyclonization where the downstream batter and the body of the wall are formed by the separated coarse sand particles of the separated tailings. In connection with the prolonged concession of ‘Ellatzite Med’ and the enlarged capacity of ‘Benkovski 2’, the tailings dam expands on new neighboring terrains. To guarantee a normal hydrocyclonization and build up of a tailings wall during the waist deposit from the ore mill, a change in the technological scheme of the hydraulic transport system of ‘Benkovski 2’, has been made. With the use of HDPE and steel pipes with inner rubber coating to build up the pressure tailings pipelines can be achieved the following: - Lowering the pressure losses by inserting hydraulically smoother pipes; - Raising the capacity of the hydraulic transport system and the final work altitude of the hydraulic pipes of the tailings dam; - Prolonging the operational lifetime of the tailings pipelines, while at the same time reducing maintenance and repair work operational expenses.