Vacuum excavation (non-destructive drilling)
Vacuum excavation (also referred to as non-destructive drilling or hydro excavation) involves removing soil and debris using highly pressured water and an industrial vacuum to excavate underground services (e.g. electrical and communication cables). This technique breaks up the ground, turns it into a slurry with water, then the slurry is vacuumed up into a debris tank. The resultant slurry is known as drilling mud waste.
Drilling mud waste arising from vacuum excavation may comprise of a mixture of naturally occurring rock, soil, organic matter (i.e. tree roots, grass and other plant material) and drilling fluid, which primarily consists of water and may also contain non-synthetic additives such as bentonite.
Managing drilling mud waste
It is the responsibility of operators (drillers/transporters/receivers) to manage drilling mud waste in accordance with the General environmental duty (under s.319 of the Environmental Protection Act 1994 (EP Act) and take all reasonable and practicable measures to prevent or minimise any environmental harm.
If there is reason to believe that your drilling mud waste is contaminated with a regulated waste or has come from a site listed on the Environmental Management Register or Contaminated Land Register (EMR/CLR), it may need testing and categorisation prior to disposal. The information sheet Overview of regulated waste categorisation (ESR/2019/4749) (PDF, 664KB) will assist further with this process.
There are a range of potential management options dependent upon the categorisation of the drilling mud waste and will often include the separation into a solid and a liquid waste stream. Without further testing results of the drilling mud waste, the specifics of the disposal method cannot be determined. The composition of the drilling mud waste must be cross-checked against the list of regulated wastes in the Environmental Protection Regulation 2019.
Drilling mud waste generated from vacuum excavations is most commonly classified as a general waste and may be clean earth. However, when the vacuum excavation occurs on a site listed on the EMR/CLR or where the soil is contaminated with regulated waste (e.g. asbestos residues) it is classified as a regulated waste. Clean earth used as fill can be used without a permit if you meet your general environmental duty under the EP Act.
Waste disposal facilities for drilling mud waste
Waste disposal facilities must hold relevant environmental authorities to take different types and amounts of waste. Some facilities may have conditions to accept only certain types of waste (or to not accept specific wastes). If you propose to dispose of this waste, contact your local council or waste management service provider in your area.