Hydroexcavting benefits for underground utilities

The action of removing soils from an area using water and vacuum is known as hydro-excavating. We use the Aquatech B-10 jet/vac trucks here at Cloud 9 Services, Inc. for our hydro-excavation work. The Aquatech trucks we have are similar to other jet/vac trucks such as Vactor, Guzzler, Camel and others. The trucks use a positive displacement blower to produce great vacuum on the debris tank on the truck. The tank is connected to a large 8” vacuum hose which is connected to aluminum vacuum tubes. If the material being excavated is wet such as a sewage spill or drilling mud or just wet soil, then no additional water is needed in order to vacuum the material into the debris tank. However, if the material is dry, water must be added before it can be vacuumed. This is because the dry material may be so light that it will be blown through the debris tank and into the vacuum blower. This will cause wear and premature failure of the vacuum blower. If the material is dry, then we use the jet hose and the onboard water tank to wet the materials as they are vacuumed.

There are many uses for the jet/vac truck performing the hydo-excavations. If you have to repair or replace an underground utility pipe in an area where the surrounding utilities are very close and you are afraid you may damage them, then you can vacuum the soil from around the area without damaging the utilities. In other words if you are afraid to use a backhoe, then the hydro-excavating is the answer.

Another use for hydro-excavating is for caisson installations. In a situation where you want to install a very deep manhole or wet well in a confined space, you can install the structure with hydro-excavating. This is how we perform the work in Florida where we mainly have sandy soils. Most of the time we have to dewater the area by means of wellpointing before we can start the hydro-excavating. Then we dig a shallow hole for the first section of precast wetwell structure to be placed. Then we use the water from the truck and the vacuum tubes to remove the soil from the inside of the structure. As the soil is removed, the precast structure drops evenly into the excavation. Then we set the successive sections of precast on top and continue to vacuum until the precast is at the correct elevation.

There is much more to this operation which I will address in future articles. For any questions on hydro-excavating, please feel free to contact us at Cloud 9 Services, Inc.