The excavation of the access drift and the silo cavern was completed in 1998, with the construction of the silo and instrumentation being finalised in 2001.

Some images of the excavation, construction and instrumentation can be found below.

View of the cavern wall (west side) and drilling of borehole GMT 98.004. The red line at the right side of the picture defines the shear zone section further extending to the north.

GMT Silo cavern drill and blast pattern

Final configuration of profile boreholes. Approximately 24 hours before blasting every second profile borehole was filled with Bristar (chemical expansion agent with water) in order to pre-stress the rock mass. The explosive loading in the remaining boreholes could thus be reduced.

During this final excavation the rock fractured along the profile boreholes giving a surface roughness of less than 10 cm.

GMT Silo cavern with mylonitic shear zone. drill and blast pattern. The contact zone Matrix - Shear-zone section is indicated by the red line View to the west.