Hydroexcavation Best Practices for Complex Underground Environments

By Chris Thompson

From understanding the differences in ground conditions to using the right water pressure, hydroexcavator operators can streamline efficiency and ensure job site safety with these best practices.

With today’s increasingly complex and congested underground environments, there is no room for error when excavating or exposing utilities.

Underground professionals know that damaging existing utilities — whether it be fiber, gas, electric, water or sewer lines — can result in dangerous and often costly consequences. To help ensure operator safety and minimize downtime, contractors have turned to vacuum excavators — and often more specifically, hydroexcavators — as their secret weapon on a variety of underground projects.

From ground and soil considerations to ensuring the proper water pressure, following key best practices can help underground construction professionals improve efficiency, increase productivity and maximize job site safety while hydroexcavating.

Best practices for complex underground
Damage mitigation is the name of the game in the underground construction industry. In an industry that continues to evolve, it takes a village to keep crews safe. From utility locating technicians to underground construction professionals, everyone plays an important role in damage mitigation.

Not to mention, today’s job sites are rarely simple, especially when considering the complicated web of utilities and infrastructure that weave underground. In addition to managing a variety of ground and soil conditions, hydroexcavators have the power to support work in complex underground environments. Unlike a traditional excavator or trencher that can cause immense disruption, hydroexcavators are much gentler at removing soil and debris when working underground. When exposing utilities, contractors should always keep their nozzle 8 inches away from the utility to prevent damage to both the equipment and utility. Water pressure should be kept below 2,800 psi with the nozzle consistently moving when actively excavating.

When operated according to these best practices, hydroexcavators can be used to expose utilities while mitigating potential damage. On today’s underground construction job site, a utility strike or cross bore can be extremely costly and potentially dangerous, so a hydroexcavator is a key job site addition.

Best practices for various ground conditions
Today, most equipment manufacturers design vacuum excavators with both air and hydro capabilities, so operators don’t have to choose between the two. For example, contractors can start excavating the ground surface with air and switch to hydro once they reach harder soil formations. With the ability to switch from hydro to air, operators can better adapt to changing job site conditions and stay productive in a variety of ground environments.

When choosing between hydro or air excavation, contractors should consider the job site and soil conditions to ensure the method used is the most efficient. For example, pressurized water typically exposes utilities faster than air, however, air is often the better choice for more delicate job sites that are at risk of washout near roadbeds.

Hydroexcavation uses pressurized water to do the hard work. It is the most widely practiced form of soft excavation because it can be used in a range of soil conditions, including tightly compacted and hard soil, cobble and clay. Because hydroexcavation requires operators to dispose of liquid spoils and replenish water sources while on the job site, following best practices for water conservation is important. However, the ability to conquer various soil conditions quickly and efficiently makes hydroexcavation the preferred method for many contractors.

Air excavation allows operators to break up soil with compressed air and vacuum dry spoils, which can be reused on site as backfill. This method works best on softer soils such as topsoil, sand and some clay formations. Unlike hydroexcavation, which requires access to water, air excavation keeps machines running and operators on the job site without having to make trips to acquire water or dispose of liquid spoils. Additionally, many operators are turning to air excavation on job sites as liquid spoils disposal restrictions tighten and certified disposal sites become more difficult to find.

For both hydro and air excavation situations, the recommended pressure for soft excavation is no greater than 2,800 psi. Although many vacuum excavators and nozzles offer higher psi capabilities, too much pressure can damage utilities and other underground infrastructure. The pressure should be reduced even further if using heated water.

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