Vacuum excavation is a highly effective, minimally invasive method for digging which has a wide range of applications. It is an extremely efficient tool for construction projects, drilling, excavating and locating utilities. Yet contractors and workers continue to debate whether air or hydro vacuum excavation is better.
Both techniques involve using jets of air or water to break up soil and ground fill that is then sucked up to clear the area. The main benefit of vacuum excavation is that pressurized air or water does the digging rather than metal tools; this makes it much safer for workers, buried utility lines and the integrity of the site. The risk of injury on the job or damage to underground utilities and the site is greatly reduced. Vacuum excavation is the only non-destructive way to safely dig around buried electric, fiber optic and gas lines.
The choice between utilizing hydro excavation or air excavation for a specific job, however, depends on a few important things. To decide which method will excavate quicker or complete the job with greater cost-effectiveness, there are some key factors to consider.
Which is Better: Air and Hydro Vacuum Excavation?
Everyone in the industry seems to have a strong opinion on this question. They all have different reasons for a preference for either air or hydro vacuum excavation methods. But there is no clear-cut answer about which is better. It depends on multiple factors about the type of job, work conditions and goals, as well as some specifics about the site.
Safety is always the number one priority on job sites. When a specific job requires digging near electrical wires, air excavating is recommended. This is because, unlike water, air is not a conductor. Regular vacuum excavation allows workers to move soil away from underground electrical wires, or other more delicate utilities, without coming into direct contact with it.
Air excavation should also be utilized in areas where it’s possible for water to cause a chemical reaction with the material.
Many contractors and workers prefer hydro excavating because it can move more material faster. While this is usually true for the excavating phase of the job, it’s not always true for refilling the site. If the project requires exposing a utility line, fixing it, then backfilling the material in a short amount of time, hydro isn’t the best option. Air excavation may be slower for removing the material, but it can save time overall. It’s important to consider the time and resources needed to transport and dump heavy, muddy soil and then to bring in new soil for backfill.
Each site is different and soil condition is a big factor. Experience tells us that vacuum excavation is better suited for loosely compacted soil or sand.
Hydro is more versatile in this respect. It’s effective at breaking up wet or rocky soil, hard and compact dirt and clay. In colder climates or during the winter in northern states, hydro is helpful because hot water can be employed to break up tough, frozen ground and permafrost.
Preserving the surroundings is more important on some job sites. When workers need to be careful not to disturb tree roots, utility lines or nearby buildings and infrastructures, air excavation might be the better choice.
On the other hand, hydro is advised in certain conditions when blasting sand could damage something in the immediate area.
Air excavation doesn’t require hauling off wet material and trucking in dry soil. This makes it the better choice for many urban job sites.
When using hydro, it’s best to factor in travel distance to the nearest dump site, plus any state and local weight restrictions on transport. Estimate also the time and expense of importing dry backfill.
It’s important to factor in the consumption of energy and resources when trying to pick the best type of equipment for the job. With vacuum excavation, there is no need to refill. Hydro relies on a constant supply of water. So, it’s important to calculate the availability and cost of water.
Smaller excavating crews generally prefer vacuum excavation. This is because it requires less vehicles, equipment and manpower.
Equipment Wear & Maintenance
Because water is a natural lubricant, it can help reduce wear on components and extend the life of hydro excavating equipment. Though the presence of water does make winterizing trucks an important aspect of maintenance.
Pneumatic digging tends to be quicker and easier to clean up after. The ability to reuse excavated soil to fill in the hole when the work is completed is a huge advantage. This decreases – or eliminates – the need to make trips to dump slurry or haul in other backfill.
Water makes sites messier. But it also adds significant weight and volume to the material removed; this causes trucks to fill up faster with slurry which then must be dumped somewhere. This can add up to a lot of time and workers needed to get the job done.
Find out more about Potholing Methods Using Vacuum Excavation.
Private Excavating and Utility Location Services
As always, you should know what lies below when you are excavating. Get informed about if the utility is capable of withstanding a direct impact from high-pressure air or water. You must call 811 and notify public authorities of any plans to dig below ground. Plus, a private utility locator can mark any lines which run beyond a service meter before you break ground.