Jet cutting, also known as hydro excavation, involves using pressurized water to move or remove a specified area of soil. High-pressure water is jetted from a specialized nozzle and impacts the surface at a high velocity, effectively breaking up soil or debris to create a slurry.
A high-pressure vacuum system is typically used concurrently with the high-powered jetting equipment to transport the slurry from the excavation site to a containment unit called a holding tank. The simultaneous jetting and vacuuming operations ensure excavated material is not washed away from the site to contaminate other areas.
One of the main advantages jet cutting has over other trenchless technology methods is its lack of physical cutting tools. Water, although ejected at high pressures, is considered to be a relatively minimal impact medium. This is especially useful when subsurface pipelines and utilities need to be exposed (daylighting).
Equipment such as excavators and backhoes lack adequate precision and can potentially cause damage to pipelines and adjacent utilities during daylighting. The low impact nature of pressurized water significantly reduces the probability of utility damage during daylighting excavation and ultimately minimizes the risk of catastrophic events such as explosions and electrocutions.
Another benefit of jet cutting is its superior precision. Water jet cutting is controllable, and the width of the jets can be adjusted to ensure that boreholes are created in accordance with specifications and within tolerances. For this reason, jet cutting is frequently used in slot trenching, where pipes, cables, and other underground utilities need to be installed in narrow, precisely cut trenches.
Other trenchless drilling methods, such as horizontal directional drilling (HDD), often require a certain amount over over-excavation to minimize pipe friction during pullback operations. HDD can also be potentially expensive and result in more wastage for larger diameter pipes and conduits.
The precision offered by jet cutting allows utility corridors to be cut to specifications while minimizing backfilling, concrete encasement, and asphalt patching requirements.