Blasting in the North Shore driven tunnels

Seventeen metres below one of Australia's premier residential areas, Thiess Thyssen North Shore Tunnels Joint Venture is driving two land tunnels. The tunnels are being driven using a combination of drill and blast and mechanical methods. The primary method of excavation is by drill and blast and because of the sensitivity of the area and the licence conditions enforced by the State Pollution Control Commission all aspects of this method must be strictly controlled and monitored. The areas of discussion are the design work leading up to the commencement of blasting, the various changes made in the blast design to comply with the licence conditions, blast monitoring and the use of various explosives products (A).