Vacuum excavation, otherwise known as NDD (non-destructive digging) makes use of a pump mounted on a vacuum truck to generate a powerful suction and remove earth and debris from an excavation. The wide-mouthed intake nozzle is held by one or more operators, and is used to vacuum away material that has been loosened by a powerful water jet or compressed air.
It has a major advantage in that it is essentially non-destructive, and greatly reduces the chance of damaging underground utilities. This in turn reduces the risk of costly delays and additional expense for construction companies.
Pressure Works provide vacuum excavation to Melbourne construction companies, contractors, and government departments. Excavating with a suction excavator may called “vacuum excavation”, or “hydro excavation” if a water jet is used.
Vacuum excavation (also known as suction excavation) is considered a best practice for safely locating and witnessing underground utilities, reducing the chance of utility strikes by more than half.
More details regarding detailed technical specifications for typical vacuum truck operation are available here at Wikipedia.