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Vacuum excavation is a method of material removal that relies on suction rather than heavy machinery. Air or water is sprayed into an area to break up the soil, and a large vacuum system pulls out the loosened material. This process is generally used when either the workers need protection from something in the ground or something in the ground requires protection from heavy machinery. Vacuum excavation systems are well-suited for making small, deep holes, a process called potholing.
The vacuum excavation process is actually quite simple. A very powerful vacuum pump is connected to a water or compressed air sprayer. The sprayer forces air or water down into the ground, loosening the material. The vacuum then pulls the material up out of the hole and into a pile or a storage container.
This process makes extremely precise holes. Since the soil doesn’t loosen up enough to vacuum without being sprayed down first, the workers can control exactly what is brought up and what is left behind. As a result, these systems can make holes of very specific dimensions or shapes that are impossible for a typical excavation method.
The holes made by vacuum excavation, often called potholes, may be planed out in advance to create the smallest necessary area for the project. One major advantage to potholing is making holes that are larger on the bottom than the top. Since typical powered machinery weighs so much and often works at sharper angles, they typically make holes that are funnel-shaped. Vacuum excavation methods allow workers to cut under overhangs, making holes that are cone-shaped. This means the surface is disrupted less and is, therefore, easier to repair.
While hole shape is very important, the largest reason to use this excavation method is for protection. When the underlying structure of the dig site is unknown, it is often safer to vacuum material from a hole rather than use large equipment. For instance, if a gas line ran through an area, it would be extremely hazardous to hit it with a metal digging tool. The resulting sparks could cause an explosion, and even if it didn’t, the gas is hazardous to breathe. When vacuuming the material out, the line would remain secure as the material is moved away from around it.
On the flipside, if there are important items buried in a dig site that need to be removed quickly, vacuum excavation will protect them from heavy machines. The air or water will loosen the soil and allow the important materials to separate out of the surrounding dirt. They can be removed my hand or filtered out of the waste pile as they come up.