English: The construction of the Melbourne Sewer system, begun in 1892, was a huge civil engineering undertaking. Its design involved a network of gravitational sewers which would bring sewerage from throughout Melbourne to a central pumping station at Spotswood. From there, it would be pumped to a treatment plant at Werribee, on the western side of Port Phillip Bay.

In order to tunnel underneath the Yarra River, a special Gateshead tunnelling shield was imported from Britain. The shield incorporated a sharp steel lip on the leading edge of a 3.4m wide tunnelling cylinder, designed to cut into the rock as the shield moved forwards. Because the tunnel was below the water level of the river, pumps were employed to continually drain water from the work area. Eventually, an airlock consisting of two 1.5m thick brick walls set 4.5m apart in the tunnel, each with a thick steel door containing a small glass peephole, was constructed to reduce the water flow through the tunnel.

By Good Friday, 12 April 1895, construction of the tunnel had almost reached the centre of the river, where it was just 3.3m below the riverbed. Around 8:00pm that evening, water burst through the tunnel at the leading edge of the Gatehead Shield. Five men working the nightshift and an engineer were all drowned as water swamped the workings. All men were local residents. Their deaths are commemorated in a monument which was unveiled on 18 October 1996, and is now incorporated into the Westgate Memorial Park.