Vacuum excavation and mechanical digging can both move soil, but they are not always suited to the same job.
If you are working around underground services, dealing with tight access or only need to expose a small section of ground, a vac truck can give the crew more control. If you are moving a large amount of open ground with plenty of room to work, an excavator may be the more practical option.
When we look at a job, we do not automatically assume vacuum excavation is the answer. We look at what needs to be exposed, how much material needs to come out, what is already in the ground and how the site can be accessed.
What Is the Main Difference?
Mechanical excavation uses equipment such as an excavator or backhoe to physically dig and move the ground.
Vacuum excavation takes a different approach. The ground is loosened and material is removed through a vacuum system rather than being dug out with a bucket.
Hydro excavation is one form of this process, using water to loosen the ground before the material is vacuumed into the truck. We explain that method in more detail in our guide to how hydro vacuum excavation actually works on site.
The important question is not which method is better overall. It is which method makes more sense for the work in front of you.
Vacuum Excavation Makes Sense When Underground Services Are Close By
This is one of the clearest situations where a vac truck can be useful.
If pipes, cables or other buried services are already known or suspected to be near the excavation area, crews often need more control than they would have with a large bucket moving through the ground.
Vacuum excavation can be used to expose a service so the team can see exactly where it sits before other excavation continues.
That does not mean the crew can ignore service plans, markings or site information. Those details still matter.
If your main concern is working around buried infrastructure, our article on using non-destructive digging to expose underground services goes further into that type of work.
Mechanical Digging Can Be More Practical in Open Ground
There are plenty of jobs where an excavator still makes sense.
If the work is in an open area, there are no nearby services to expose and a large amount of material needs to be moved, mechanical digging may be the simpler way to get through the bulk excavation.
That is why we would not tell someone to use a vac truck for every excavation job.
Sometimes the best approach is also a combination of methods. A vac truck may be used first to expose services or confirm what is in the ground, then mechanical excavation can continue once the work area is better understood.
What About Potholing?
Potholing is a good example of a job where vacuum excavation can make sense because the crew is usually trying to expose a relatively small area rather than open up the whole site.
The aim may be to confirm the position or depth of a pipe, cable or other underground asset before the next stage of work begins.
Using a large excavator for that first investigation can be unnecessary, especially when the exact service position is not yet visible.
Once the service has been exposed and the site team knows what they are working around, the rest of the excavation can be planned with much more information.
Tight Access Can Change the Decision
Sometimes the biggest issue is not what needs to be dug. It is whether the equipment can physically reach the work area.
A mechanical excavator needs enough space to enter, position and operate safely.
A vac truck can sometimes stay further away from the excavation area and work through hose, which may be useful when the job is behind a building, inside a fenced area or somewhere the truck itself cannot sit directly beside the work.
That does not make access irrelevant. We still need to know where the truck can park and how far the hose needs to reach.
If access is likely to be the difficult part of the job, our practical guide to checking truck access, positioning and the work area before a vac truck arrives covers the details worth looking at beforehand.
How Much Material Needs to Come Out?
Volume matters.
Vacuum excavation can be very useful for controlled excavation, but the truck still has a limited amount of space for collected material.
If the project involves a large volume of open excavation, an excavator may be more practical for moving the bulk of the material.
If the work involves smaller excavation areas, potholes, trenches around services or difficult sections of the site, vacuum excavation may be a better fit for those parts of the job.
The type of material matters too. Soil, mud, slurry and wet spoil can all change how the work needs to be approached. We have a separate guide covering the materials a vacuum truck can remove and what affects handling.
What If the Ground Is Hard or Compacted?
Ground conditions can affect both methods.
Loose soil is very different from compacted ground, heavy clay or mixed fill.
If you already know what the site is like, tell us. Even a simple description can help us understand how the excavation may behave.
On some jobs, the question is not only whether a vac truck can remove the material, but how easily that material can be loosened in the first place.
What About Trenches?
Trenching can go either way depending on the job.
If the trench is long, open and clear of services, mechanical excavation may make sense for much of the work.
If the trench crosses existing utilities or needs to pass through a congested area, vacuum excavation may be used where more control is needed.
Again, the methods do not always have to compete with each other. On many sites, the sensible approach is to use each one where it is most useful.
What If There Is Mud, Slurry or Wet Spoil?
This is another situation where the decision can change.
An excavator can move wet material, but a vac truck may be useful when the material needs to be collected through suction or is sitting in an awkward location such as a pit, trench or restricted work area.
Before we plan that kind of job, we want to know what the material is, roughly how much there is and where it came from.
If the material may be unusual or contaminated, that also needs to be raised before work starts.
Does Vacuum Excavation Mean Less Site Disturbance?
It can, particularly when the work only needs to expose a specific point in the ground.
A smaller excavation area can mean less surrounding ground needs to be opened just to find or confirm a service.
That can be useful in landscaped areas, around existing infrastructure or anywhere the crew wants to keep the excavation as targeted as possible.
But we would still look at the whole job before deciding that vacuum excavation is the better option. If a large area already needs to be opened, the advantage may be smaller.
Which Method Is Faster?
There is no single answer.
An excavator can move a lot of material quickly in the right conditions.
A vac truck may save time when the alternative is carefully digging around known services, working in a restricted area or stopping repeatedly because the crew is unsure what is below the ground.
The faster method depends on what the job is actually trying to achieve.
Which Method Costs More?
Comparing hourly rates on their own does not tell you much.
The final cost can depend on the amount of material, time on site, truck access, disposal, travel and how much other work needs to happen around the excavation.
For example, a lower hourly rate does not necessarily mean a lower total project cost if the method takes longer or creates additional work afterwards.
If you are budgeting a vac truck job, our breakdown of the site and job details that can change a vac truck quote gives a better idea of what actually affects pricing.
What If the Work Is Beside a Road?
The excavation method is only one part of the planning if the work is beside live traffic.
We also need to think about where the truck or excavator will sit, whether access is being blocked and how workers will move around the site.
Where traffic management is required, Get Group can coordinate traffic control alongside excavation work rather than treating the two parts of the job separately.
Do You Need to Choose the Method Yourself?
No.
You do not need to call us already knowing that you need hydro excavation, a particular truck or a specific setup.
Tell us what you are trying to achieve.
We want to know what needs to be exposed or removed, what is already known about the ground, how much material is involved and what access looks like.
From there, we can talk through whether vacuum excavation makes sense for the job.
If the next question is what sort of vac truck setup would suit the project, our guide to how site conditions and the scope affect the vac truck setup explains that decision in more detail.
When Would We Lean Towards Vacuum Excavation?
We would usually look more closely at vacuum excavation when the job involves underground services, potholing, restricted access, a small controlled excavation area or material that is better suited to vacuum removal.
We would be less likely to recommend it simply because a vac truck is available.
The method needs to make sense for the site.
When Would Mechanical Digging Make More Sense?
If the ground is open, the excavation area is large, services are not creating a major constraint and there is room for machinery to work, mechanical digging may be the more practical option.
There is no benefit in making a simple excavation more complicated than it needs to be.
That is why we prefer to understand the project before recommending a method.
What Should You Tell Us Before We Look at the Job?
You do not need a long technical brief.
Start with the useful details:
- what needs to be exposed, excavated or removed
- where the site is
- whether underground services are known to be nearby
- roughly how large or deep the excavation is
- what the ground or material is like if you know
- what access is available for the truck or machinery
- whether the work is near live traffic
Plans and photos can also help, particularly when the work area is difficult to describe.
If the project date is already starting to take shape, it is also worth reading our guide to working vac truck excavation into the project schedule.
Vacuum Excavation vs Mechanical Digging FAQs
Is Vacuum Excavation Always Safer Around Underground Services?
Vacuum excavation can give crews a more controlled way to expose services, but the work still needs proper planning, service information and site procedures.
Can Vacuum Excavation Replace an Excavator Completely?
Not always. On some projects, vacuum excavation is used for specific parts of the work and mechanical excavation is used for the larger open areas.
Is Vacuum Excavation Suitable for Large Excavations?
It depends on the scope. For very large volumes of open excavation, mechanical equipment may be more practical. Vacuum excavation is often most useful where control, access or underground services are important.
Can a Vac Truck Work Where an Excavator Cannot Reach?
Sometimes. The truck may be able to remain further from the work area and use hose to reach the excavation, but the available truck position and hose route still need to be checked.
Do I Need to Know Which Excavation Method to Book?
No. Give us the site details and explain what needs to happen. We can discuss whether vacuum excavation suits the job.
Not Sure Which Excavation Method Makes Sense?
You do not need to make the decision from a checklist.
Tell us what you are trying to excavate, what is already in the ground and what the site looks like. From there, we can talk through whether a vac truck is a practical option for the work.
For more information about the service itself, visit our vacuum excavation service page or call 1800 828 723.
