Digging Deep With Vacuum Excavators

There are three ways to dig a hole, points out Brian ­Metcalf, CEO of Ring-O-Matic.

“You can dig it by hand, you can dig it with a mechanical method, or you can utilize vacuum excavation,” he says. “Vacuum excavation obviously is significantly safer and is a completely different approach to digging a hole as opposed to using an excavator to do so.”

Vacuum excavation uses either water or air. When water is used, it’s called hydro excavation.

Vacuum excavators, especially hydro excavators, may be the most versatile piece of equipment in a contractor’s fleet, notes Ben Schmitt, Vactor Mfg.’s product manager.

Hydro or air vacuum excavation offers a number of advantages to contractors, not the least of which is a safety value proposition when locating and digging around underground utilities, says Schmitt.

This safety aspect gives contractors a competitive edge, lowers insurance costs, and reduces job-site downtime.

The precision of hydro and vacuum excavation also lowers the cost to return the site to its original condition because the overall size of the excavation can be minimized, points out Schmitt.

Contractors appreciate the versatility of the equipment, he adds.

“Over the past five years, we’ve seen a significant gain in acceptance of vacuum excavation throughout the United States,” says Schmitt. “Contractors are targeting larger, more productive truck-mounted vacuum excavation units for increased productivity and flexibility. Hydro excavation also appears to be the lion’s share of the market for its versatility and productivity.”

Some utility companies, transportation departments, or power plants specify air vacuum excavation for a given job for a number of reasons, says Schmitt. “Air vacuum excavation is desired in applications where the soil tends to be loose, water is not readily available—in small-scale excavation projects—or where immediate backfill of the hole is required. When working around buried electrical lines or brittle utilities, air vacuum excavation is often preferred due to the lower operating pressures.”

While the utility segment appears to be somewhere around 20% of the total vacuum excavation market, there has been a substantial shift to the oil and gas production sector, where demand continues to increase, notes Schmitt.

In the oil field market sector, contractors have used the Vactor HXX, a hydro excavator, not only to daylight utilities, but also to clean the inside of mud or storage tanks, clean up oil spills at job sites, and perform various cleanup applications after the drilling process is completed, says Schmitt.

Other applications for utilities, ­construction, and municipalities include installing light poles, repairing water main breaks, long trenches for burying cable, fiber optic repair, cathodic protection for gas and water lines, pressure testing, hauling fresh water to a job site, towing a trailer, and even window well installation, he adds.

“Hydro excavators, like the Vactor HXX, are designed for safer, non-destructive location of buried utilities,” he notes. “This application is often called daylighting or potholing.”

The equipment can do much more, adds Schmitt.

“A hydro excavator consists of a ­powerful vacuum system and an onboard water blaster and water tank, so anything that can be sprayed, washed down, or vacuumed can be completed with this equipment,” he points out.

When exploring vacuum excavation system choices, the decision between an air or hydro unit is an important one, points out Schmitt, adding that both mediums have “very distinct advantages.

“Air vacuum excavators use compressed air to loosen the soil and positive displacement blowers to vacuum the spoils into a tank. Hydro excavation uses high-pressure water to loosen soils, and the residual slurry spoils are easily extracted into the debris tank via positive displacement blower or centrifugal compressors,” says Schmitt. “Air excavation is slower, but allows for dry material to be immediately backfilled into the hole and eliminates the need to find disposal locations, while hydro excavation is much faster and versatile, but requires clean fill to be brought in.”

The key to efficient hydro excavation is to only use enough water to cut the soil effectively, says Schmitt.

“All too often, operators use more water than is required and spend more time offloading material,” he adds. “Using the proper amount of water for the job will maximize the operator’s efficiency and maximize productivity.”

Jeff Wage, vice president of McLaughlin, says the biggest use of hydro excavation that he sees among grading and excavation contractors is “getting out in front of their open cut operations to spot utilities or dig around high risk or anything that may divert their productivity of the project.”

The technology replaces the need for an individual to get down in a hole with a shovel looking to expose a 12-inch water main as he or she gets direction to take one more scoop with the bucket, says Wage.

Instead, the hydro excavator enables contractors to locate the water main and expose it as the excavation project either crosses or intersects it or parallels the line, he adds.

“They’ve safely dug around it and exposed it, so when they get into an excavation operation, they can do what they’re good at, which is stay productive, move dirt, and lay pipe,” says Wage.

Hydro excavation is indicated for digging around not only water mains, but sensitive utilities such as fiber optics, electrical boxes, and gas lines “where you’re not quite sure where the utility is and you don’t want to use mechanical excavation,” notes Wage, echoing that safety is a primary benefit.

“As you’re excavating, the ability to dig around a line and not damage it is safety for the people on the job site as well as property owners and third-party utilities,” he notes. “You wouldn’t want to mechanically damage that, have an explosion, harm the operator, and damage equipment on the job site.”

Another safety consideration comes into play when avoiding damaging a utility and creating a leak, says Wage.

“There are long-term risks in safety implications of back feeding a sewer system with some natural gas and creating a large explosion,” he says. “There are a lot of risks in damaging or creating a small leak on gas and having that seep into another utility, mainly a sewer system.”

Whether to use water or air excavation “is the great debate and the question everyone asks,” notes Wage. “Hydro excavation really helps you when you’re digging in any of the colder climates because you can dig and cut in frost and do that excavation in cold weather. Hydro excavation typically is 75% more productive than air in most soils because it will cut and erode the soil more rapidly.

“People who want to use air want the ability to pick up and reuse material on the same job site without having to haul it off and bring in other material.”

Air-based excavation is useful in working around granular soils and sand, such as is found in coastal areas, says Wage.

Bruce Kane uses three Ring-O-Matic excavators on a daily basis for the work his company Kane Konnections in Goodlettesville, TN, does in fiber optic construction. Another company he owns, National Trenchless Inc., serves as a subcontracting company that does all of the excavation for the fiber optic business as well as for gas, water, and sewer lines.

Kane’s company uses the vacuum excavators to expose existing utilities and to do trenching in high-risk areas of other utilities such as gas and other fiber optic lines.

“In this town, we have a lot of rock, so there is no feel with an ­excavator,” says Kane. “We use vacuum excavation to expose those lines or sometimes dig trenches across those lines with very low risk to the existing utilities we’re digging around.”

Kane prefers using hydro excavation.

“Air works in loose soils and the water works where air will not work most of the time,” he says. “I don’t use a whole lot of air. The air does work good if you want to put spoils back in the hole that you make, but a lot of times we’ll just haul spoils offsite.

“Air isn’t very useful for us in the soil conditions in this town because we have a lot of hard-packed clays and where we don’t have hard-packed clays, we either have chunky rock or solid rock, and in those conditions the air isn’t very useful.”

Kane’s company has three vacuum excavators: one is an 800-gallon heavy-duty excavator from McLaughlin and two are 500-gallon excavators from McLaughlin and Ditch Witch.

The 800-gallon McLaughlin hydro excavator has a higher horsepower engine and has a 4-inch suction hose that works well for potholing to expose existing utilities, says Kane, adding it also works well for open trenching. “It’s got higher water pressure and more suction power,” he adds.

“The two 500-gallon units work for potholing, but we use them a lot for sucking up our drill mud to keep it from getting into the streets,” says Kane. His company uses the Ditch Witch to suction out sand contents on rock drilling jobs.

Meanwhile, in Levelland, TX, Dave Campbell, owner/president of Air Vac Systems, prefers to use air-based vacuum excavation for the work his company performs.

Campbell was the first contractor in the United States to purchase a System 6000 from Vacmasters, which manufactures a line of air vacuum excavators, including the System 6000, the largest available on the market.

Campbell’s acquisition of the vacuum excavator added to his company’s fleet of four Vacmasters.

“Here in west Texas, we pothole and trench in all kinds of soil, including caliche and rocky dirt. It takes one mean machine to dig in that stuff,” notes Campbell. “Vacmaster’s System 6000 is the most powerful air-vacuum excavation system in the world and it gets the job done fast.”

Many of Air Vac Systems’ jobs entail potholing with air for the oil and gas companies. Campbell says he likes that the System 6000 enables him to dig trenches with air.

“We use the air power of the System 6000 to open up trenches for the power plants’ electrical lines and to visually locate the ones that are already buried,” says Campbell. “If you’re using high-pressure water and hit those utilities, it can rupture fiberglass conduits or blow the coating off the lines.”

Air Vac Systems uses the System 6000 to vacuum up soil as it digs, and crews then backfill with the same dry spoils right away.

“The remote-operated boom arm makes things easy for a two-man crew, and our guys really like the hydraulic, full-opening rear door for easy dumping and cleaning,” says Campbell.

The vacuum systems are typically used on jobs being executed by oil and gas, pipeline, underground utility locating, and telecommunication companies, as well as municipalities, says Bell.

Ring-O-Matic’s line of vacuum excavation equipment is primarily used for utility construction projects, says Metcalf.

The company offers both air and hydro vacuum excavators. Its hydro excavators use the cutting power of high-pressure water along with a powerful vacuum for such uses as potholing for utility location, sewer jetting, pit cleaning sumps and catch basins, and environmental cleanup, such as oil spills and the aftermath of a hurricane.

The equipment can go on trailers, vacuum trucks, and skid mount systems.

The company’s air vacuum excavation machines are heavy-duty industrial vacuum systems used in applications such as drilling fluid cleanup, pit cleaning, environmental cleanup, and construction site cleanup.

There are several factors to keep in mind when choosing between the use of air or water, says Jim Zylstra, Ring-O-Matic’s sales and marketing manager. In addition to job conditions that may favor the use of one over the other, budget is another deciding factor, he points out.

“The smaller contracting company might not have the budget for a full-fledged vacuum excavator but still needs to do some of the cleanup and mud management, so the vacuum only machine might be a better option,” he says, adding that if a company has the budget for it, the vacuum excavator is the best option.

Metcalf adds that the hydro vacuum excavator “fully replaces a loader backhoe on a job site with regards to utility locates for new utility construction or rehab. It’s far easier to use a vacuum excavator to locate and dig down and pothole as opposed to using a loader backhoe or excavator operationally.”

The machines are user-friendly and have built-in fail-safes and safety features, says Zylstra.

Another option is the Viper pothole tool, a “gun”-like device designed specifically for potholing. “It takes a two-person job to a one-man job,” says Zylstra. “It’s the safest, fastest, and cleanest way to get down to the utility locating.”

McLaughlin manufactures vacuum excavators for Vermeer. One segment is trailer vacuums from 100–1,200 gallons that include gas- and diesel-powered vacs. They come in two performance categ­ories driven by hose diameter.

Most of the trailer-mounted vacuum excavators are three- or four-inch systems for small- and medium-sized jobs of potholing and utility spotting.

Three-inch systems run a 575-cubic feet per minute (cfm) vacuum blower with horsepower levels of 31 or less and are typically used for fluid management, such as sucking up mud, dirt, and debris.

The 1,025-cfm vacuum excavators—generally used for potholing—utilize a 4-inch hose so it will ingest larger material and be more productive when potholing, says Wage. They typically run on 49–100 hp.

Some contractors opt for truck-mounted vacuums that cost thousands of dollars and are typically 6-inch systems of 3,200–7,000 cfm and sometimes even larger at up to 8 inches. These systems also have greater suction capabilities.

“Contractors select equipment based on the application, how much work they’re going to do in a day and the desire to stay on the job. They also look at capital investment versus utilization,” says Wage.

The trailer-mounted vacuum market suits a lot of directional drilling contractors, small utility contractors, or somebody who’s just spotting utilities in front of an open-cut operation, says Wage.

“When you get into the big trucks, that would be called bulk excavation for somebody who’s digging large holes—maybe working on a power plant where there is a lot of big excavation to be done. There’s a lot more capital invested in those big machines, but also much more productivity.”

To help contractors learn how to use the machines, McLaughlin will do “train the trainer” sessions. The focus is on safety and maintenance.

“Within one to two hours, you can get somebody up to speed on basic vacuum excavation, cover a good safety course on things to do and not to do and also the maintenance of the machine,” says Wage.

“There are not a lot of buttons or high-tech features. You’re basically running water or air and using a big suction hose. It comes down more to about how you dump it, making sure that you know your load, you’ve got the right tow vehicle, and you’ve inspected all major pins, joints, and connections because you’re dealing with high-pressure water or air and suction.”

There is also an emphasis on that which can be taken for granted, such as not putting one’s hand in front of a 3,000-psi water hose to see what the pressure is, says Wage.

Air- and water-based excavators are common in the rental industry, which helps contractors get their first exposure to the machines and learn of the many useful purposes they serve, says Wage.

Hydro- and air-based excavation technology is constantly changing, says Wage, noting that there are a few trends now taking place.

One is core sawing and vacuum combinations, offering the ability to carry dry spoil on the vacuum machine.

Some jobs call for the contractor to cut a hole in the middle of the intersection and the specifications allow them to core saw a hole, vacuum it, then put the core back into the ground the same day and keep traffic disruption to a minimum, says Wage.

Although a trend, core sawing is a “spotty market” that has become standard in some areas such as Colorado and practically unheard of in other regions of the country, says Wage.

Another feature contractors are favoring is the company’s standard three-stage cyclonic filtration system, allowing a vacuum to be used for both wet and dry vacuum excavating where cyclones reduce airborne particulates from reaching the final filter and vacuum blower, helping to prolong filter life and reduce maintenance costs.

Drying spoils is another trend Wage sees developing. Contractors want the ability to dry wet material after it’s excavated.

“With hydro excavation, 30 to 50% of the material in that debris tank is water and the rest is earth,” points out Wage. “So now you’re going to dump it. The question is how you can separate out the solids and the water?”

He cites technology that is akin to a large shaker deck that’s shaking and vibrating, letting the water drop through fine settings and enabling the material to dry as it’s shaking, vibrating, and bouncing in the air.

It comes off the end of the shaker deck and can be used as a dry material or earth to be able to go back into the ground, says Wage.

For safer operation around utilities, Vactor recently released its DigRight Technology, enabling the operator to select the maximum desired working water pressure for the application based on vacuum excavation best practices.

“This selection will limit the water pump from exceeding site, industry, or customer maximum pressures to ensure a safe and non-destructive method of excavation,” says Schmitt. “DigRight ­Technology also reduces wear and tear on the water system, which extends the life of the product.”

Vac-Con’s hydro excavation equipment is capable of liquefying the ground using vacuum technology to convey it into a tank, which is particularly useful in sensitive areas where there are natural gas pipelines and high electrical lines in remote locations, notes Mike Selby, national service manager.

“You can vacuum excavate a long way away from where you’re actually excavating,” Selby says of the equipment. “You don’t have to transport a piece of equipment over land in order to get to that location.”

Vac-Con offers a “double excavator” that features two vacuum generators or positive displacement blowers on the truck, enabling an operator to vacuum upwards of 1,000 feet away from the truck and convey material into the tank.

The equipment is beneficial on job sites such as hydro power generation plants requiring that work be performed a safe distance away from high-voltage lines, says Selby.

“They can literally park the truck outside of the facility and run hosing and the tools they use to excavate within the facility to keep all of the danger away from the equipment contacting any of the electrical line.”

Vac-Con also offers air-vacuum excavation through an on-demand air compressor to break the ground up using pneumatic means.

The company is making strides in technology that will enable contractors to use the equipment in cold weather, says Selby.

“We’ve developed an arctic package for ultra-cold weather where you start getting 20 to 40 degrees below zero,” he adds.

Ditch Witch offers a range of vacuum excavator models, including both truck- and trailer-mounted excavators, such as the Ditch Witch FX20 trailer mount with a 25-hp engine to the FXT60 truck mount with a 74-hp engine.

The excavators are designed for ­efficient potholing while offering a ­versatile solution for a range of cleanup and excavation tasks, notes Jason Proctor, product manager for Ditch Witch vacuum excavators.

The FX20 is intended for small projects including valve box and storm drain clean-out, commercial and residential debris cleanup and landscaping, underground utility location, posthole digging, and construction site stormwater control, says Proctor.

“The FX20 excavator combines the suction power of a 540-cfm package with a 150-gallon spoils tank while still offering a smaller footprint,” he says, adding the belt-driven blower is designed for reliability and easy maintenance. It can fit in the back of a standard pickup truck or flatbed trailer.

The Ditch Witch FX30 vacuum excavator is suited for projects that require a cost-efficient and maneuverable excavator option, says Proctor. It offers the “necessary water pressure and suction power along with a curbside operator’s station allowing single-operator control,” he adds. Contractors can choose between a 500- or 800-gallon vacuum tank and 80-, 200-, or 300-gallon water tanks.

“Contractors have successfully used the machine in jobs such as exposing buried utility lines, cleaning out storm drains, cleaning up at directional drilling sites, repairing water leaks, and cleaning out valve boxes,” says Proctor.

For heavy spoil municipal, construction, and oil and gas projects, the Ditch Witch FX50 is used for potholing and posthole digging, sewer cleanup, supporting horizontal directional drills, and removing road construction debris, he adds.

The Ditch Witch FX60 is designed for directional drilling and municipal project sites that need power for large cleanup tasks, says Proctor.

“In addition to potholing and other soft excavation tasks, the machine is tailored for cleanup jobs such as the removal of non-hazardous wastewater, industrial machine cleaning, and a multitude of post-emergency ­restoration jobs,” he says, adding the equipment can also vacuum unwanted fluids and spills in and around manholes, catch basins, meter boxes, and directional drilling sites.

The FX50 and FX60 can be configured with choices of tank sizes, trailer configurations, and options such as hydraulic booms, water heaters, and hydraulic valve exercisers to meet job-site needs, says Proctor.