Employer: Ellatzite-Med AD
Designer and contractor: Geotechmin OOD
Project implementation period: 2006 – 2008
Main data: length – 2,100 m; cross section – 14 sq.m.; excavation volume – 3,000 cub.m.

Description of the project:
The driving of the drainage gallery is performed by the drill-and-blast method. Three drainage chambers are constructed at the end of the tunnel. With a view to strengthen the rock massif, 10,000 friction anchors are inserted during the driving process. In the areas with low weight-bearing capacity, three-joint steel frames of BSP-28 type (bell-shaped profile) are used. The drilling works are done by a direct controlled hydraulic tunneling and mining rig with one BUT. The loading and transportation of rock mass are carried out by front loaders and dumpers. Water cleaning facilities are constructed at the entrance of the gallery. The purified waters are transported to Negarshtitsa River. The building of the drainage gallery has solved the problem with the dewatering of Ellatzite mine for a period of 12 years.