As you might have guessed from the name alone, vacuum excavation is a form of excavation performed with a vacuum-type suction. It’s a specialised form of excavation that can be used not only in traditional construction projects but in industrial cleaning processes – ever wonder how they clean large storage tanks? These babies. Obviously, vacuum excavation is a bit different from regular excavation methods, so let’s take a deeper look into it.
What is Unique About Vacuum Excavation
Unlike other forms of excavation, vacuum excavation is non-destructive – meaning it doesn’t involve breaking or destroying the materials being removed. Instead, it simply sucks it up and deposits it elsewhere. This does, however, mean it is quite specialised in what it can do. Vacuum excavation can be used against any type of loose soil, muck or fluid – and it is exceptional at these – but against large rocks on heavily compacted earth, more destructive methods are required. But some of the best parts of vacuum excavation are that it’s extremely fast and extremely safe.
The high localised precision minimises any possible damage – such as accidentally hitting sewer or electrical pipes – and due to the fact that the vacuum deposits the excavated material into tanks, this also minimises the total amount of required manpower required on site. All of this amounts to a low-cost, highly efficient excavation method that is cleaner and safer for both site workers and the general public.
How does it work?
Suction excavators have been used since 1993, with newer and more powerful models having been developed over the subsequent thirty years. Like all vacuums, vacuum excavation makes use of suction-based technology, however broadly speaking there are three distinct types of vacuum excavators. There are three types of vacuum excavation, these are Jet Rodding, vac trucks and sucker trailers. Jet Rodding utilises a high-pressure hose that shoots out water cleanly and powerfully in order to clean and remove mud, soil and other debris. They can also be used for digging if the pressure is high enough.
A vac truck (or vacuum tanker) is a truck that has a pump and a tank and is primarily intended to suck underground materials into the tank. Sucker Trailers are the final class of excavator units. Typically, this takes the form of a large internal fan with a negative pressure of between 15-47kPa. The trucks associated with them are typically designed to carry between 7 and 32 tonnes, and the maximum depth the hose can reach is between 10 and 50 metres. Unlike vac trucks, sucker trailers can often operate independently of the truck, however, they still require a tank or other vessel for storage.
What is it used for?
Vacuum excavation is typically used for loose, muck or wet excavation. This includes the cleaning of storage tanks, pits and culverts, draining waterlogged areas and clearing loose soil from working sites. However, this is only speaking in broad terms as vacuum excavators are also used for:
- Replacement of pipes and fittings
- Renovation and new installation of gas, water or heating pipes, cables, and sewage lines
- Exploratory excavations
- Railway trackside maintenance and repair
- Use of ground displacement rockets
- Clearing away environmental damage
- Replacement of contaminated soil around the roots of trees
- Removal of material in demolition projects
- Removal of gravel from flat roofs
- Cleaning blocked street gutters and gullies
- Operations involving the use of horizontal boring units
- Leaf removal
- Application for special operations
Of particular note, vacuum excavators were once used to help clean and restore the old centre of Venice by cleaning 40 years of deep silt out of the Rio Terà San Polo. This silt was over 1.6 metres deep and was quickly and quietly extracted out of a roofed sewer. More traditional methods would have required the use of significant manpower and physical labour and also would have resulted in much of the smelly silt being exposed to pedestrians and local traffic. Via the use of the vacuum excavator and its tank, the entire process was contained causing minimal disruption.
How much does it cost?
Around Australia, hiring a vac truck usually costs around:
- 3000L – $150 to $175/hour for 1 operator, or $200/hour for 2.
- 6000L – $200/hour for 1 operator, or $270/hour for 2.
- 9000L and above – around $220 to $250/hour for 1 operator.
Of course, some costs may be higher depending on whether the location is rural or urban, or be affected by many other factors including the quality of the truck, the density of the work and the expertise of the workers. Other costs may include water usage fees, which are highly dependent on the regulations set by the local council, and the cost of waste disposal which is typically set at $6 per cubic metre of waste.
