Australian
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Teacher’s notes

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This clip shows the safe drilling practices of the Snowy Mountains Hydro-electric Scheme in about 1963. Workers known as scalers, with the help of a mechanical mucker, loosen rock spoil from a tunnel roof and sides after blasting. The clip shows the drilling jumbo, a three-tiered platform used in tunnelling work on the Scheme. It then gives a step-by-step demonstration of safe drilling techniques of the time, showing a drill in operation and the cleaning out of drilled holes that would later be packed with explosives. The clip emphasises the importance of workers’ safety throughout.

Educational value points

• The Snowy Mountains Scheme was Australia’s most important post-Second World War project. Built between 1949 and 1974, it was an integrated water and hydro-electric power project, and was a major construction and engineering feat. It consisted of 16 large dams, seven power stations and a pumping station. To divert water from the Snowy Mountains for use in power generation and irrigation, 145 km of tunnels and 80 km of aqueducts were constructed. The Scheme cost $820 million.

• The footage gives some idea of how tunnels were constructed. Excavating began simultaneously from both ends of the tunnel and proceeded incrementally. Workers drilled holes in the rock at regular intervals and the holes were then packed with explosives that would cause the rock to fracture. The 'mucker’, or excavator, was then brought in to clear the rock spoil. The different drills and drill bits used on the Scheme provided a model for the modern masonry drill bit set.

• The drilling jumbo illustrated here was a three-tiered platform that was moved along tracks using a hydraulic jacking system. It enabled drilling and scaling to be carried out at all levels on the rock face. The tunnels had an average width and height of 6 m. The jumbo was hinged in the middle so it could be swung back to allow the mucker through. Rock was also brought out of the tunnels on rail carts.

• Tunnelling was the most dangerous job on the Scheme and tunnellers were paid twice the average wage. They worked hundreds of metres below ground in cold damp fetid air and often stood in water for hours. These conditions were compounded by the noise of rock drills, fumes that made breathing difficult and heavy dust. Most tunnel injuries were caused by roof falls, premature explosions, or vehicles, such as muckers, navigating in the confined space.

• Industrial safety practices were poor by today’s standards. The workers in the clip have no ear or eye protection. During blasting in tunnels, workers blocked their ears with their fingers, and opened their mouths to prevent burst eardrums. Breathing apparatuses were not provided, even though the air in the tunnels was thick with dust. Many of those who worked in the tunnels experienced significant hearing loss; during construction of the tunnels, 35 men were killed.

• This is an excerpt from a film made for the Snowy Mountains Joint Safety and Rehabilitation Council. The Council was set up by the Snowy Mountains Hydro-electric Authority (SMA) to establish safety guidelines, but innovations were often introduced as a result of accidents. While 121 people died in work-related accidents on the Scheme, the number of fatalities was low compared to similar projects overseas. The SMA made safety hats mandatory, and seatbelts compulsory in all SMA vehicles. It also produced instructional films for its workers.