COTTER TUNNEL

PROJECT DESCRIPTION:

Stabilisation of an existing, rough-hewn, unlined tunnel to protect an existing water main which passes through it. Scope included removal of loose material from the tunnel surfaces, removal of existing support members, placement of primary shotcrete surfacing to stabilise the tunnel surfaces, placement of reinforcement up-stands and placement of a final, permanent 150mm thick layer of structural shotcrete with weep holes.

Complex Challenges:

To protect workers in the tunnel while it was in an unstable state, a protective steel cage was designed, fabricated and mounted on a movable trolley.

Business unit:

Tunnelling

Client:

ActewAGL Distribution

Current status:

Complete

Start date:

August 2008

Completion period:

August 2009

Contract type:

Lump sum

Value:

$1.5 million