Grading and Excavation Contractor | Vacuum Excavation Sweeps the Industry

Comment On This

Create A Link
To This Article
On Your Website

A fast-growing hydro/air vacuum market is taking the hard work out of soft excavation.

By Carol Wasson

Vacuum excavation equipment manufacturers are all abuzz about a growing market. These players are talking about a technology that’s also referred to as hydro/air excavation. Pun intended—for those who’ve been in a vacuum—the equipment can basically be described as units that use pressurized water or air to complete carefully targeted and precisely controlled soft excavation. Spoil is sucked through a vacuum hose and is deposited into a debris tank for later disposal or is backfilled into the hole. Models range from large dedicated truck units, which have long been a staple in the Canadian oil and gas industry, to the small trailer- or skid-mounted units, which gained broad US appeal in the 1990s as support equipment for horizontal directional drilling (HDD) operations. Today, there is a vacuum-excavation option and opportunity for everyone—from the big-dig contractor to the small-town landscaper.

Manufacturers say that the reasons behind an expanding vacuum-excavation market are as numerous as the variety of applications for this versatile equipment. By far, the biggest benefit is safety and infrastructure damage prevention. Every day there’s another horror story about a backhoe hitting a pipeline, regardless of the fact that various safe-dig laws require soft excavation techniques (either hand digging or vacuum excavation) whenever digging within the tolerance zone of a designated utility. And surprisingly, there’s still a lot of time-consuming, labor-intensive hand digging still going on.

With more than 14 million miles of buried utilities and pipes in the US, vacuum excavation is a method that safely and cost-efficiently uncovers or “potholes” around pipelines and fiber optics, preventing injury and death from utility strikes and avoiding tremendous financial liabilities. Yet some barriers and misconceptions surrounding its use still remain in the minds of contractors who cling to conventional methods. Vacuum-excavation equipment manufacturers, consultants, and savvy users are quickly chipping away at the latter with a campaign of education, awareness, training, and effective performance.

The Cost of Doing Business?
Unfortunately, says Neal McLean, owner of Hydro Excavation Consulting Unlimited, utility hits are seen by some as “just the cost of doing business.” McLean trains companies on how to profitably manage and operate a hydroexcavation business. He explains that nobody really knows what is underground and that often plans are inaccurate. “So contractors follow state one-call procedures to locate a line, and then when they hit another line they say, ‘It’s not my problem.’ But it doesn’t matter if you’re right or wrong; if you hit something, it costs you money in repairs, labor, lost production, and much more,” says McLean. He adds that to many the cost of a utility strike is less worrisome than disrupting services, being on the evening news, and the resulting public perception.

“At first, companies often see hydroexcavation as costing them money, but when they realize that their hits go down while production goes up, they know that it’s making them money—with the added benefits of safety and liability control,” says McLean, who stresses that to be successful with hydroexcavation one must understand the processes involved. “A lot of contractors want it to be a production tool, but it’s designed to safely dig a hole, not to compete against a backhoe or trencher. However, once you’ve located the utilities with hydroexcavation equipment, that backhoe operator can certainly dig more productively and with peace of mind,” he says.

Choosing the Right Equipment
It’s key to match the right vacuum-excavation equipment to your application type, digging volume, and soil conditions. This will determine choices such as a truck versus a trailer unit, air versus water, and a fan versus a positive displacement (PD) blower. Deepesh Nayanar, Vactor Manufacturing product manager, feels that the latter is one of the most important issues. “As to a fan or a PD blower, manufacturers tend to push whatever technology they offer so this creates some amount of confusion. Each has its distinct advantages,” he says.

Nayanar explains that a fan system moves an incredible amount of air, excavating more rapidly than other systems. He says that they are easier to operate and maintain and are generally less expensive than the PD versions. He adds that a PD blower moves air over long distances, allowing for excavation at greater depths but at slower speeds than fan units. Since hydroexcavation jobs do not require digging to great depths or at long distances, he feels the fan type is more productive in the majority of applications.

“As to a truck versus a trailer unit, start with the amount of horsepower. That will define the amount of material that you will pick up and the volume of the spoils tank. Anything over the 25,000-pound range means you’ll need a truck package,” says Brent Bolay, Ditch Witch senior product manager over trenching and vacuum.

Digging depth is another factor that affects unit size and type requirements. “Depending upon the density of soil you’re picking up, a good rule of thumb is that you can go 1 foot of depth per inch of mercury you’ve got (the mercury is how you measure the vacuum capabilities). A lot of the trailer units offer about 15 to 16 inches of mercury, equating to 15 to 16 feet of digging depth,” says Ed Savage, Vermeer trenchless segment manager.

Savage says that towing capabilities are another common concern, as a certain gross vehicle weight requires a commercial driver’s license. “Most manufacturers will offer units that are under 10,000 pounds gross vehicle weight for that reason,” he says.

Air Versus Water
The topic of air versus water is hotly debated. Most manufacturers offer both options. “There are several benefits to using water as a nondestructive excavation tool,” says Nayanar. “It acts as its own lubricant, controls static electricity, avoids the sandblasting effect of air, works in almost all soil conditions, and can be heated to excavate frozen ground,” he says. Vactor recommends using water pressures between 1,500 and 2,000 pounds per square inch, as pressure higher than 2,500 is unsafe. Operating a hydroexcavator at the proper water pressure virtually eliminates the chance of damaging line covers or casings, says the company.

“In theory, air looks great until you realize the additional costs and limitations,” says Steve Schoenberger, president of Vector Technologies Ltd., a company that’s marking its 33rd year in the vacuum excavation business. “Air units require a large compressor, which becomes very expensive to run. Also, air vacuums will do about 70% of what water will do. It’s very limited in clay soils,” he says.

Alternatively, Roger Kirwan, vice president of marketing for Vacmasters, says that there are undeniable economical and safety advantages to using air over water. “Water is a noncompressible fluid, so it will try to cut whatever it encounters. Air is compressible, so if it hits something hard, it will compress and flow around it, avoiding any damage. Also, when potholing to locate utilities with an air system, the spoils stay dry and can be deposited right back into the hole. You don’t have to worry about disposal of wet material, which in some states is considered to be hazardous waste,” he says.

Application Versatility
Although the potholing of utilities and directional-drill project cleanup are the most common applications for vacuum excavation, the technology is used in many industries and in many different applications. A partial list includes projects such as caisson excavation, culvert and drain cleanout, sign and pole installation, sewer jetting, underground line exposing, digging under existing structures, frozen ground digs, pond excavation, slot trenching, tower base excavation, water-flood extraction, and sludge removal.

“There are about as many uses as you can imagine—anywhere you need to remove a dry or liquid material—as long as it’s nonhazardous. The smaller units are great for cleaning out the meter boxes in manholes. We’ve even sold them to zoos for cage cleanup,” says Vermeer’s Ed Savage.

A Vector HDD model with rail gear is used in Buffalo, NY, as a road or rail unit for potholing along the train lines prior to construction efforts. A Vector unit is also used to dig small blast holes into a mountain for Canadian mining explorations.

A truck-mounted Vacmaster air-excavation system was used to dig 6-inch-diameter, 5-foot-deep holes inside an elevator pit. Even though the digging location was located approximately 200 feet from the truck, the system was strong enough to dig and vacuum the holes efficiently using one 220-foot, 4-inch-diameter hose.

Ditch Witch units were used by a California contractor on an airport project that involved cleaning and smoothing the bottom of 32,000 feet of trench. The same contractor also routinely uses the unit to remove concrete cuttings when street cuts are made.

Directional drilling equipment, including a Ditch Witch FX30 vacuum excavator, was leased by the Naval Facilities Engineering Service to support the HDD installation of three shore landings of conduit to protect cable for an Air Force Hydro Acoustic Data Acquisition System monitoring station, which is part of a worldwide network to detect foreign nuclear explosions in violation of nuclear test ban treaties.

Equipment Highlights
The GapVax HV-57 industrial vacuum truck is a dedicated wet-and-dry hydroexcavator. GapVax Sales Manager John Snedden says that the unit’s success in wet-and-dry material is due to its unique filtration system. “There are seven cyclones on the side of the truck. Once debris goes into the system, it spins through all the cyclones concurrently at about 700 miles per hour. This forces debris to the sides of the cyclones, where it will fall out. Then the clean air goes through the center of the cyclone and down into the baghouse, with final filtration happening there. This patented filtration system cleans the air before it gets to the bag, preventing any choking,” says Snedden.

Vactor Manufacturing Inc. launched its new midsize HXX Prodigy truck-mounted unit in January 2007. “In addition to our larger units, we wanted to offer a more compact, single-axle midsize unit with air excavation as an option. Targeted toward municipalities, utility contractors, and construction companies, this model bridges the gap between the trailer unit and the large truck, while delivering maneuverability in terms of size and versatility with both air and water, and offering a more affordable yet productive machine,” says Nayanar.

The Vacmaster System 4000 is marketed as one of the largest and most powerful air-vacuum systems. The company says that this unit is 50% more powerful than its predecessor, the System 3000, allowing effective digging in all soil conditions. Additionally, the model offers selectable air or water digging. Crews can use air 95% of the time, with water available when needed. Its speed in potholing is an average of seven to eight minutes, says the company.

Through its alliances with McLaughlin Manufacturing and Vac-Tron, Vermeer offers a wide range of trailer- and skid-mounted units, from a 40-gallon unit that mounts on a mini-skid-steer to larger 1,500-gallon units. “On certain models we offer sewer-jetter options. Municipalities like the fact that they can use a compact unit for potholing or as a sewer jetter,” says Savage. “We also offer some new, improved features for ease of operation, such as hydraulic hose booms that actually hold the potholing tool or the hose; hydraulic rear doors so that the operator doesn’t have to stand right there when he opens the spoils tank; and a hot box that actually keeps the water hot for cold-weather operation,” he says.

The Ditch Witch FX60 vacuum excavation system is the quietest vacuum excavator in its class, permitting operation in noise-sensitive areas, says the company. Powered by a 56-horsepower diesel engine, the unit features a clutch that automatically disengages when water is not in use, allowing full power to the blower.

Vector Technologies says it offers a variety of contractor-driven features on its HDD vacuum excavators. “Our water pumps come with clutches so that they do not run continuously. Our machine shuts down automatically only when completely full, rather than when three-fourths full. Our tailgate is easier to open, and the internals will not rust out. Our trailers do not crack, and our machines do not have exposed belts or water pumps,” says Schoenberger. “We engineer our equipment as simply as we can to make it easy to maintain. We understand how tough contractors are on their equipment and that many do not have full maintenance staffs,” he says.

Hate Hand Digging?
Currently, contractors still have the option of hand digging when soft excavation is required; however, that may change in the future if OSHA regulations dictate that crews must operate with ergonomically correct methods.

“We still see a lot of hand digging, but it is diminishing. Even a hand spade can do damage. Some contractors still don’t want to invest in vacuum equipment, but compared to other excavation equipment, a vacuum unit is a minor purchase,” says Savage.

H2X Hydro Excavation of Bayfield, CO, compares the cost of hand digging versus doing the job with a hydroexcavation truck. A two-man crew dug a 12-inch-wide trench (the minimum for a hand-dug job). At 24 man-hours, at $10 per hour each, the cost of the trench is $240 plus travel, and there is still the risk of damage. The hydroexcavated trench is only 4 inches wide, no more than is required by the electric line. It took 20 minutes to dig at the standard rate of $230 per hour, so the actual dig was $76. Add to that the travel time to and from the job (half an hour at $150 per hour, or a total of $75), and the total cost of the trench is $151. And the method is 100% safe, says the company.

Says Deepesh Nayanar of Vactor Manufacturing, “Awareness comes into play here when you think of two people digging with spades and shovels—to know that you have a better choice. You can dig faster and more precisely with vacuum-excavation equipment. We work on awareness. It’s all about growing the market,” he says.

Carol Wasson owns JCL Marketing & Communications Inc.

GEC - July/August 2007

Back To Table
Of Contents