What is Hydro Excavating?

Hydro excavation, which is sometimes referred to as vacuum excavation, is a process that makes use of pressurized water and a vacuum system to rapidly remove large amounts of soil from an area that requires excavating. Traditional excavation methods involve the use of heavy equipment such as backhoes, or for sensitive digs, the use of a dig crew to manually break up and remove soil using shovels. However, these traditional processes have limitations that make them less desirable in many applications.

For one, manual digging is slow and laborious. Furthermore, shovels, picks, and other metal hand tools are sharp instruments, which can inadvertently strike and damage infrastructure that is underground in the dig area, such as gas lines, water lines, and electric utility service lines. Digging with heavy machinery can be faster than manual digging, but also has the potential to induce even more damage to buried utility service connections.

Hydro excavation equipment typically comes in the form of specially designed trucks or trailers that contain the components needed to perform hydro excavating.

Key functional components of equipment used includes:

1. One or more onboard water tanks which hold a supply of clean water that will be used to generate a pressurized stream of water to cut through the soil
2. A powered pump system that boosts the pressure of the water jet to several thousand psi, similar pressure levels to those found in a pressure washer, and high enough pressure levels to easily cut through dirt and compacted soil
3. An articulating boom that is fitted with suction hoses whose function is to direct the slurry mixture of soil and water from the excavation area back onto the truck or trailer’s storage tank.
4. A vacuum blower or vacuum pump system that creates the suction on the vacuum hoses to recover the slurry
5. A debris tank of sufficient volume to capture the deposited slurry drawn by the vacuum system
6. On some models, a boiler that can heat the water prior to pressurization so that the hydro excavator can be used in conditions where the ground is frozen

To perform hydro excavation, an operator directs the pressurized water jet to the area of the ground where excavation is to take place. The jet immediately cuts through any grass or topsoil and begins to loosen the soil as the water penetrates and mixes with it. A second operator uses the articulating boom that contains the vacuum system and hoses, using that to draw away the mixture of water and soil as it is loosened, which enables the water jet to loosen additional soil at lower depths.

The process continues in this manner until the desired depth and size of the dig has been accomplished. Once the work on site has been completed, the hydrovac truck or trailer needs to be driven to a designated dumping location where the slurry mixture that was collected can be offloaded, and the debris tank can be cleaned and readied for subsequent use.