How Does Air Vacuum Excavation Reduce Construction Costs

Air Vacuum or Hydrovac, Which One Should You Use?

Air vacuum excavation
Air vacuum excavation. Photo Air-VAC

Air vacuum excavation is another method of digging safely without affecting existing conduits or buried pipes.The process consists of using high-pressure air combined with the vacuum action, to loosen the soil and suction it. It is a way to excavate fast and safely without damaging other pipes or conduits within the same trench.The process will allow the use of the spoils as backfill into the trench once the work has been completed.

What Soils are Suitable for Air Vacuum

The process of air vacuum is recommended for almost any soil type including clayey soils. When the process is applied to rock, it will not cut through it but if the rock is brittle it might tear it apart but it can take a while and will add some risks to your excavation process. Some contractors have been successful when performing over frozen soil but it is not recommended. Also, you might want to consider other digging processes when digging concrete and/or pavement.

How to Dig Using this Technique

The process will dig a couple of inches when it is used in hard soils and will be of greater help when the soil are loose or sandier soils. The air pressure and vacuum system need to be moved over the surface at about 2 feet per second and you should keep moving if the soil is loose enough so it can be extracted. A good tip is to spray some water over the soil before starting to reduce the amount of dust released into the air and sometimes the soil can be less hard when it has been moistened.

Benefits of Air-Vacuum Excavation

The process is designed to provide several benefits and some of them are:

  • Faster digging process than hand excavation
  • Workers will be less exhausted when compared to hand digging process
  • No sharp metal objects are used reducing the possibility of punctuating existing conduits
  • It can be used around buried pipes and conduits without damaging them
  • It can be used almost in any type of soil
  • Since the soil is not mixed with water, it can be reused as backfill.
  • It does not require any specialized equipment other than air-compressors.
  • It is non-conductive as opposed as other digging procedures that can prevent additional hazards
  • Spoils can be disposed easily
  • It won't damage any vegetation
  • Smaller units can be used and located in tight spaces

Drawbacks of Air-Vacuum Excavation

The method of excavation also has some areas that we need to be aware of or can be considered as limitations. These are some of those issues:

  • It won't be effective on frozen soils or hard soils
  • Sometimes, if the soil is too hard, it can take more time than other digging procedures.
  • It is not recommended on highly compacted soils

How to Decide Between Hydrovac or Air Vaccum

If you are analyzing both alternatives, make sure that you know the following key aspects:

  • Air is faster than water, so it might present an advantage.
  • Spoils can be reused in air vacuum and they need to be disposed of during the hydrovac process.
  • Water can create additional voids during the excavation.
  • Water can work in soils that air won't work.
  • Hydrovac will not create dust issues.
  • Air vacuum units are normally smaller and can be used around tighter spaces
  • Air vacuum excavation systems work best in sandy or gravel soil types.
  • Air excavation is considered cheaper than the hydrovac process