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Air and water (hydro) vacuum excavation give operators a way to dig in locations where more invasive digging methods are not a good option. While, hydro vacuum excavators dominate the soft digging market, air units do offer some advantages in many certain applications and work environments.
To determine which vacuum excavator — air or water — you should choose consider the following factors.
1) Soil and environmental conditions
Your environment — namely the soil conditions and temperature in which you’re working — goes a long way to determining which type of vacuum excavation method is best for your operation.
Air excavation is best suited for work in soft, loosely compacted dirt or sandy soils at shallow depths, particularly in warm temperatures. It is also recommended for use in applications where water is not readily available, including drought or extremely dry ground conditions.
Water excavation is more versatile because it works in all types of soil conditions. It’s a better choice than air when working in more aggressive ground conditions, such as wet or rocky soil, or harder materials, such as heavily compacted dirt or clay. It can also be used to break up frozen soils and permafrost.
2) Project requirements
The jobsite where you are working will also give you insight into which method is right to use. Water moves more material around underground pipes and utilities faster, so if time is of the essence, water is likely the right choice for the job.
That said, there are certain conditions, such as digging near electrical wires, where air excavating is a better option to consider because air is not a conductor — unlike water. Air should should be considered if it’s possible that the downhole material combined with water could cause a chemical reaction.
Also, if you need to make sure your crews do not disturb tree roots, utility lines or other sensitive infrastructure, you should consider choosing air.
Another important note, water is recommended in conditions where blasting sand could cause damage to the surrounding area.
3) Material management
Backfilling holes is another a factor for selecting the right vacuum excavation method. A benefit to using air is that it enables the operator to use the material from the excavation as backfill immediately — eliminating the time and cost involved in hauling off wet material and trucking in dry soil.
Also, air excavation tends to be quicker and easier to clean up after work is done. This is a big advantage on urban jobsites where handling, as well as disposing of, wet debris is a challenge. So, if you’re filling in holes more frequently and want to minimize travel time — and related costs — associated with introducing new material to the jobsite, air excavation is the way to go.
Although it is known for being faster and more efficient than the air method, water excavation does come with a messier, more time-consuming and costly clean-up process. Not only will you need to make trips to dump the backfill slurry, but you will also need to haul in other backfill, as spoils material can’t be reused for that purpose. When choosing water, it is important that you factor in the travel distance to and from the nearest dump site, as well as the time and expense of importing dry backfill, to your project estimates.
4) Transportation and logistics
Hydro vacuum excavators require greater payload capacity that air vacuum excavators. Depending on the distance between the water source and jobsite, operators must account for travel time, any state and local weight restrictions on transport, and cost to sustain the necessary water supply.
To learn more about specific vacuum excavator models and determine which type of system will work best for you, discuss your operational needs with the team at your local Vermeer dealer or visit vermeer.com.
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