Under section 19 of the WHS Act a PCBU has to eliminate the risks that arise from excavation work, and where elimination is not reasonably practicable, minimise them as far as reasonably practicable. The WHS Regulations add more specific obligations on hazardous chemicals, airborne contaminants, plant and other excavation hazards such as trenches. PCBUs must consult their workers on health and safety and may also need to work with other duty holders through consultation, cooperation and coordination. One person can hold several duties and several people can hold the same duty at once; early consultation and risk identification widens the options for eliminating or minimising risk and lowers cost.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.