Rocla recently supplied specially designed Class 6.5 steel-reinforced concrete pipe for use as escape tunnels at a coalmine in the NSW Hunter Valley.
The Newpac No. 1 Colliery, 20km northwest of Singleton, is the largest remaining semi-soft coking coal reserve in the region. The colliery is currently mining semi-soft coal for export.
Coal from the underground mine is stored in two large stockpiles, one for the raw coal and another for the washed product.
Coal is removed from each 25-metre high stockpile from below, via reclaim valves with vibratory feeders located below ground at the centre of the pile, then transported via a conveyor belt through a 100-metre arched tunnel.
Because safety regulations require dual egress for the reclaim equipment operators, a separate escape tunnel had to be provided, running from the reclaim valves to the side of the stockpile, 100 metres in the opposite direction of the conveyer tunnel.
Consulting engineers Roche Mining JR established that the most suitable and economical method of constructing these smaller escape tunnels was to use large diameter precast concrete pipes.
Under a manufacture and supply contract, Rocla’s engineering team designed a custom 2550mm diameter Class 6.5 pipe for a load of 28 metres of fill, based on criteria supplied by Roche.
Rocla’s advice on the backfill specification allowed the reuse of much of the on-site material, while keeping within the strict limits of the pipe design.