What is hydro-excavation?
Hydro-excavation uses water pressure and a powerful vacuum to cut through soil without damaging buried infrastructure. It provides contractors with a way to dig in areas with underground utilities. A hydro-excavator mounts to a beefed-up semi-truck. They’re becoming increasingly popular because they offer a safer, more efficient way to excavate.
Hydro-excavation is a way of removing soil with pressurized water instead of mechanical tools or typical excavators. The pressurized water creates a dirt slurry and gets vacuumed up by hydro-vac equipment to expose subsurface layers and existing infrastructure, like sensitive utility lines and fiber optic cables, while lowering the risk of damage.
How hydro-excavation works
Also called the “soft-dig” method, the process of hydro-excavation consists of the following steps:
The hydro-vac truck or trailer is positioned to access the designated excavation site.
Hydro-vac operators direct a high-pressure wand of water to cut through the soil and soften the ground.
Operators use a vacuum to suction the mud slurry into the tank of the truck or trailer.
After the underground utilities are exposed, and the work is complete, the slurry is released from the holding tank and spread out to dry or transported to a disposal location.
Some truck makers, like Vermeer, make trucks that can separate the slurry into liquids and solids to reduce disposal trips.
Applications for hydro-excavation
Excavation happens on almost every construction project, but there are numerous projects where buried electrical, plumbing, and gas lines pose a potential threat to safety. In these instances, a less-invasive method is crucial. Even safer than digging by hand, vacuum excavation is well-suited to digging in sensitive areas.
Soil trenching is digging a narrow trench for pipelines, cables, and underground utilities. Hydro-excavation trucks are ideal for this task because they can ensure that the only area being affected is the area marked for excavation. Hydro-vac trucks can also perform this work during cold weather conditions when the ground is frozen, which may prove difficult for a backhoe or a trencher. Warm water breaks down frozen soil and creates a slurry that gets vacuumed into the tank.
Daylighting, or exposing utilities, is digging beneath the surface to expose and locate underground infrastructure. Hydro-vac trucks break up the ground with water during daylighting and vacuum the waste onsite. If done right, hydro-excavation doesn’t disturb or damage any of the existing utilities. Contractors can determine underground lines' vertical and horizontal locations using this “soft dig” method.
Pilings are cross-section columns of reinforced concrete, timber, or steel-concrete composite. They anchor tall buildings to solid layers of strata or where the soil is unstable. The pilings are driven into deep holes in the ground to transfer the structure's load through the pilings to the strata below. These holes can be dug via hydro-excavation.
Because hydro-excavation can be very precise, it’s the perfect method for digging pilings to specific diameters and depths.
Hydro-excavation can happen in cold or freezing conditions, unlike traditional excavation or hand-digging methods. Hydrovac units can use heated water to break up even the coldest soil and get the job done.
One of the most valuable ways hydro-excavation is used is to remove debris and clean structures without affecting the surrounding areas. Traditional heavy equipment often needs a greater range of room to work correctly. But the boom of a hydro-vac truck provides the operator with more flexibility and maneuverability to strategically place the boom exactly where it needs to be in terms of height and depth. Whether the debris is wet or dry, sand or rock, a hydro-excavation can be used to remove it if it can break up to fit into the vacuum.
In addition to those mentioned, hydro-excavation is for:
- Installing lines, poles, and signs
- Sewer inspection, repairs, and rehabilitation
Benefits of hydro-excavation
Hydro-excavation offers unique qualities that can benefit a project in areas with buried infrastructure.
Because hydro-excavation minimizes the risk of breaking or tearing underground utilities, interruptions are minimal. This means the project can be completed on or ahead of schedule.
As mentioned around pile-driving, hydro-excavators can do precise work within a tighter range than a traditional excavator or backhoe.
Water pressure cuts through tough grass and soil without posing a significant risk to construction workers and residents. Compared to other heavy equipment, a hydro-vac truck poses a much smaller likelihood of injury to those close to the job.
Hydrovac trucks can use hot water to thaw and melt frozen soil or debris. So work can be done in cold months instead of waiting for warmer weather.
The safe way to dig
Traditional earthmoving is highly effective in most environments, but hydro-excavation is a much better approach for areas where there are underground utilities. It’s an accurate, safe, and efficient way to dig holes or trenches in the ground for a specific purpose without a traditional excavator or backhoe.
Looking to learn more about heavy equipment and the applications used in the Dirt World? Check out this article on the topic.
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Meet the Expert
Marilee Brewer's philosophy on heavy civil construction is that everything—even the Bingham Canyon Mine and the Willis Tower—starts with ideas put into words. An avid writer and researcher, Marilee brings inspiration, storytelling, and human candor to Dirt World information. Her writing focuses on providing content that enhances user experience, improves engagement, and ultimately increases revenue. A trained Linguist and social media storyteller, ask her for story and social media writing tips.