Are Hydrovacs the Future of Excavation?

Hydrovacs, or vacuum excavation trucks, have gained acceptance with contractors and utilities because they allow for safe excavation around underground utilities. Utility strikes remain a huge issue for the industry. According to the latest DIRT (Damage Information Reporting Tool), in 2022 there were more than 160,000 utility damage events, with damages per million dollars of construction spending up 12.5% from 2021. With excavation practices being the root cause for nearly a third of damages, increased use of hydrovacs to pothole and excavate safely around utilities can have a positive impact on those numbers.

“You can pay for a hydrovac if you avoid one utility strike,” says Chris Thompson, Product Manager for Ditch Witch, a manufacturer of hydrovac machines. Hit a utility line and you will not only be responsible for repairing the utility line, but also for penalties and fines, costs for clean-up, damaged equipment, and project delays. “We have more and more contractors insisting on buying them for those reasons,” he says.

It's not just backhoes that can cause damage. “A shovel is a huge offender for utility damage,” says T.J. Steele, Product Manager for Vermeer’s MV Solutions Division. Hydrovacs can use water or air to break up the material. The material is then removed with a vacuum. Both air and water are considered safe forms of excavation.

How it works and what to consider when buying

A hydrovac uses high-pressure water to cut through the soil and soften the ground. Next, the wet soil and slurry are sucked into the tank that is either mounted on a truck or trailer. The three main components are the vacuum pump, the water pump, and the tank.

The vacuum pump is typically powered by a fan system or a positive displacement blower. Positive displacement blowers can pull heavy, wet material over long distances, while a fan system generates higher airflow, and is more suited to working with light and loose materials over short to moderate distances.

According to Thompson, Ditch Witch customers have been seeking out higher suction power which allows them to dig faster and remove more debris. “Our PTO-drive hydrovacs use the power from a truck's engine to operate without requiring additional horsepower,” he says.

The water pump sends a high-pressure stream of water through a hose and a wand to break up and loosen soil, sand, and other debris. The pump pressure should be able to extract various types of materials, including clays, gravels, silts, and rock. The majority of nozzles range from 2,000 to 3,000 psi. Thompson recommends limiting the PSI to 2800 “You don’t want to exceed that range or you get around the idea of safe digging,” he says. Instead, he recommends heating the water with a boiler to facilitate breaking up the soil. 

Your location will determine where you are allowed to dump materials. In some areas, the spoiled material can be used as backfill, while in other places you may need to pay to dispose of material at designated sites. Whether or not you will be needed to haul material to a dump site is key to selecting the right capacity tank and size of the unit you purchase.

One way to avoid the challenge and expense of dumping is to purchase a unit that will separate the water and dirt so that the material can be used as backfill. According to Steele, the Vermeer XR2 Vacuum Excavator combines hydrovac technology with the separation technology of a reclaimer. “Once you dig the hole, you can use that same dirt to backfill the hole. You just have to get rid of the dirty water at that time, versus actually having to get rid of mud.”

Thompson sees a trend in acceptance of truck-mounted units. Ditch Witch trailer hydrovacs can carry up to 600 gallons of water, while a 12-yard truck can carry 1,200 gallons. Larger freshwater tanks allow contractors the ability to work in more rural areas due to expanding time between refills.

According to Steele, the weight of the unit when fully loaded is an important consideration to avoid fines for overloading. “We design our trucks around the federal bridge law,” he says. “Our VXT600 Gen 2, a 12-yard truck, was designed to be as lightweight as possible to allow customers to legally haul more spoil.

Newer models might also be less noisy than their predecessors. “Our latest model operates around 85 decibels, which is very quiet,’ says Vermeer’s Steele. “Minimizing the sound of the hydrovac means you can operate earlier and later without disturbing the neighborhood.”

Of course, dealer support is important for any type of equipment, so you’ll want to evaluate the local support for your repair and maintenance needs.

What you can do with a hydrovac

In the utility world, hydrovacs have become essential tools for potholing, also known as daylighting. During this excavation process, the hydrovac is used to make a series of small test holes to accurately locate the height and depth of underground gas lines, water mains, electrical conduits and telecommunication cables. Pressurized water breaks up the soil cover, which is then sucked into the tank, revealing buried utility lines.

Hydrovacs can also be used for placing telephone or utility poles. They allow digging to the exact depth and diameter required, with little damage to other areas. Lastly, hydrovacs can dig slot trenches, and narrow trenches (typically less than 1 foot wide) to install utility lines. The mobility of a hydrovac makes it especially useful for digging a trench in hard-to-reach areas.

Increasingly, contractors are choosing to avoid a utility strike that could wipe out their profits on a job in seconds. With a hydrovac, they know they can excavate without major disruption and damage to their hard-earned reputation for safety.

See the chart below for a list of all the leading players in the field you can find at The Utility Expo.

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