Vacuum excavation is known by several different names such as, keyhole excavation, hydro excavation, non-destructive digging (NDD), safe dig and pot holing.
Essentially, it is the safest digging method for exposing below ground utilities and minimising risk avoidance to utilities
An industrial strength vacuum hose is placed at ground level to suck up the soil to a large holding tank; this collected soil can be taken away or disposed of on site. If the soil is hard and compacted, high-pressure water is used to turn the soil into slurry, which is also sucked up into the holding tank. This whole process is similar to using a wet and dry vac, except on a more powerful scale.
There are two approved methods for safely exposing below ground utilities, one is digging by hand and the other is pot holding by hydro/vacuum excavation.
Remember these four simple safety tips, it's everyone's responsibility:
P - Plan - Decide what you want to do and where it is, check for indications of existing utility locations on the site, then contact "Dial Before You Dig" www.1100.com.au for asset service locations (free service)
P - Pot Hole - Gently hand dig or vacuum excavate to find services
P - Protect - Mark clearly to protect the utilities or fence them off and inform others of existing located services
P - Proceed - Carefully.