By Chris Thompson, Ditch Witch Vacuum Excavation Product Manager
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 fibre, gas, electric, water or sewer lines – can result in dangerous and often costly consequences.
Enter the vacuum excavator, specifically, the hydro excavator – the underground professional’s secret weapon. When operated using best practices, vacuum excavators can help contractors effectively, efficiently and safely uncover utilities and navigate complex underground environments in a variety of ground conditions. 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 jobsite safety.
Navigating utilities
In an industry that continues to evolve with new technology and new risks, it takes a village to keep crews and infrastructure safe. From utility locating technicians to underground construction professionals, everyone plays an important role in damage mitigation.
Not to mention, today’s jobsites 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, hydro excavators have the power to support work in complex underground environments.
Unlike a traditional excavator or trencher that can cause immense disruption, hydro excavators are much gentler at removing soil and debris when working underground. When exposing utilities, contractors should always keep their nozzle about 20 cm 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 best practices, hydro excavators can be used to expose utilities while mitigating potential damage. On today’s underground construction jobsite, a strike or cross-bore can be extremely costly and potentially dangerous, so a hydro excavator is a key jobsite addition.
Ground conditions
Today, most equipment manufacturers design vacuum excavators with both air- and hydro-excavation 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 jobsite conditions and stay productive in a variety of ground conditions.
When choosing between hydro or air excavation, contractors should consider the jobsite 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 jobsites that are at risk of washout near roadbeds.
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Hydro excavation 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. As hydro excavation requires operators to dispose of liquid spoils and replenish water sources while on the jobsite, following best practices for water conservation is important. However, the ability to conquer various soil conditions quickly and efficiently makes hydro excavation 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 onsite as backfill. This method works best on softer soils such as topsoil, sand and some clay formations. Unlike hydro excavation, which requires access to water, air excavation keeps machines running and operators on the jobsite without having to make trips to acquire water or dispose of liquid spoils. Additionally, many operators are turning to air excavation on jobsites 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.
Lead with safety
Proper exposure and excavation on a jobsite are the most common and efficient ways for contractors to avoid damage to underground infrastructure and utilities. By following hydro excavation best practices, operators can streamline efficiency and ensure jobsite safety.
From understanding the differences in ground conditions on the jobsite to using the correct psi, operators can ensure they are set up for success
