When you excavate only what is necessary, you have to backfill only that amount.
There have probably been advances and inventions that have failed because we didn’t really know what to do with them. When Dow Chemical (back in the 1940s) produced the first Styrofoam, it wasn’t immediately obvious what its best uses might be. It resisted water, so where should we use it? In one of its first applications, the Coast Guard used it for a life raft. (Styrofoam is blue and used extensively for building materials today, but it is not used for coffee cups, packaging, or coolers.) We could probably find and wonder at several good inventions in the construction sector that never succeeded as expected. They may have been materials, machines, or instruments. Sometimes it has not been the quality of the invention or product but the wariness of potential users and their perception that no benefits will be gained. Vacuum excavation could fit into this category.
This method of excavation, especially when you don’t need a large hole or may not have room for even a small excavator or loader to access the site, has been a natural follower of trenchless technologies. It seems to be the benefit of making only small excavations that has given the continuing momentum. Todd Gray, who has worked with crews for many successful water and sewer repairs in the Midwestern states of Kansas, Minnesota, Nebraska, Iowa, and Illinois, reminded me of a big advantage with vacuum excavation for many contractors. “The more soil we dug out, the more expensive it was to fill it back again,” comments Gray. “Hydro excavation let us remove only as much soil as needed. The backfilling was less, and the resurfacing, if you’re working in city streets. One problem we had several times before we started using vacuum excavating was waiting for another contractor to finish off the surface, because he had bigger paving equipment than we had. When you’re waiting around like that, virtually doing nothing, it still costs you money.”
Vacuum excavation (whether you are using air or water) is not just a matter of throwing a new machine at the job and letting it prove its worth. This method of excavation does not simply involve different equipment, because its adoption incorporates a new technique and some thorough preparation. “At our company, I preach the Six Ps all the time,” advises Dave Crilly, president of California Hydro Excavation Inc. “The six words tell us that Prior Proper Preparation Prevents Poor Performance. In our business, that starts well before we ever reach a job site. During the setup for the job, we have to ensure that we have things such as traffic control, water sources, and dump sites worked out in advance. Failure to recognize such aspects can cause big problems. We also have to ensure as far as possible that there is no contaminated soil and, if there is, we have a backup plan on how to handle the spoils.” Safety is a prime concern for this contractor. “We sell safety,” says Crilly. “It’s why we are hired—because our clients know we will not damage any personnel, equipment, or facilities.”
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Photo: McLaughlin Manufacturing Co. |
| An expanding market for vacuum excavators is their use to excavate post holes for highway guard rails and to install fencing in residential or commercial areas. |
New Applications
Portable vacuum excavators have been regulars on job sites for years. These unique units were originally used to clean septic tanks and car-wash pits and to remove the resulting slurry from horizontal directional drilling projects. Now contractors are discovering that these machines have a wide range of uses on the job site, from potholing for utilities to cleaning valve boxes to digging post holes. “The vacuum excavator has come of age,” says Dave Gasmovic, president and chief executive officer of McLaughlin Manufacturing Co. “Contractors are discovering that vacuum excavators have multiple uses to help reduce labor costs and speed up projects. Damaging existing utilities can be costly in terms of project downtime and potential contractor fines. The low-pressure water and air will not damage existing utilities like a backhoe, compact excavator, or shovel. In fact, the air and water move around the existing utilities, giving the operator a clear view.” Operators can select the amount of air or water pressure depending on the utility; a lower pressure may be used for fiber and higher pressure for water or gas lines.
Every day, contractors are finding new uses for vacuum excavators that save time and labor. These units are being used to clean out valve boxes for routine exercising and storm sewer catch basins. Some contractors are even using these units to remove grain and coal trapped in the corners of barges, to clean gutters, and to remove the chips from stump-removal projects. “An expanding market for vacuum excavators is their use to excavate post holes for highway guard rails and to install fencing in residential or commercial areas,” observes Gasmovic. “Using a vacuum helps eliminate the chance of damaging an existing fiber line with an auger along a highway or existing utilities in a residential or commercial development. Today’s vacuum excavators are well suited for these applications because they are more portable compared to units in the past. The displaced spoil can be moved up to 200 feet from the source and only one person is required to operate the unit.”
Vacuum excavators come in all sizes and options, so it’s important to select a unit that will best fit your intended use. Water-based units typically dig faster through a wide variety of spoil types and reduce the volume of the material, meaning you can get more displaced wet spoil into a holding tank, compared with an air system. However, the displaced spoil is wet and cannot be returned to the site immediately without drying. On the other hand, spoil from air systems can be directly returned to the site, but these systems do not cut as well in hard ground conditions, such as clay. “I encourage contractors to look for a unit with a good quality vacuum pump, the heart of the vacuum,” says Gasmovic. “They should also select a tank that has the capacity to hold one half-day’s worth of spoil. This will reduce the number of trips you need to make to dump the holding tank.”
McLaughlin also encourages contractors to pay special attention to the filtration system and select a system that will filter the spoil and avoid clogging. Finally, be sure to select a strong trailer frame that will support the weight of the unit and a full tank of spoil. There are number of options available: controls that allow the contractor to reverse the flow of the vacuum to blow the spoil back into the hole; booms that support the weight of the hose, placing less effort on the operator; combo units that include a jetter to clean sewers and remove the resulting trash; automatic tank clean-out systems; and auxiliary hydraulic systems that allow the contractor to run a concrete saw or breaker off of the unit. “When you have a vacuum excavator, the number of uses will just multiply with a little creativity,” adds Gasmovic. A situation that shows the importance of vacuum excavation with underground construction is that Vermeer Manufacturing has formed alliances with McLaughlin Boring Systems and Vactron Manufacturing.
Choosing the Equipment
Vacuum excavators are self-contained units that use pressurized air or water to displace spoil and a pump to remove the displaced spoil. The displaced dry or wet spoil is stored in a holding tank on the vacuum. Vacuum excavators can be mounted to a trailer or the back of a truck and range in size from 100 to 1,200 gallons of capacity. Good equipment is critical to success. As important as the choice of equipment—and there are several good manufacturers and models in the market—is the routine for looking after what you have chosen. Performance of the vacuum excavation equipment will be best when that equipment is well maintained; it will also be safer for everybody at the site. “Our trucks are inspected with each and every use,” comments Crilly. “They are lubed weekly and scheduled for depot inspections monthly. These prevention steps save us countless hours of time.” California Hydro Excavation uses trucks that are unique in that they are set up so that any parts required in the event of a breakdown can be acquired quickly. The company uses components from well-known vendors like Roots blowers, Hotsy boilers, and Parker fittings and hoses. In that way, no matter where the crews are working, they can get parts fairly locally. “We never had a truck down for more than two days,” says Crilly.
There are supporters for vacuum excavation techniques that use water and for those that use air. There is plenty of material available about the differences and the potential owner should make his or her own decision. I will not take sides. I can tell you, however, that I have heard positive comments from those who use either method, and it reminds me of asking contractors which is the best brand of excavator or loader. You’ll get many answers, differing opinions, but most of the users are satisfied with what they chose. That’s good news, not reason for arguments.
“The Vacmasters System 4000 air-vacuum excavation system offers utilities and contractors the ability to pothole using supersonic air in any kind of soil, no matter how hard, wet, sunbaked, or compact, even ground frost,” states Roger Kirwan, vice president for the manufacturer. “This system’s ability to use air rather than water when potholing means the job gets done faster (just seven to eight minutes in most soils), more efficiently (with spoils staying dry for backfilling) and more economically (because mud-hauling and disposal costs are eliminated. It also does the work more safely, because air will not damage utilities and is nonconductive. We have discovered that air-vacuum excavation is DOT friendly because it does not damage the road base.”
The System 4000 mentioned in the previous paragraph is installed on a 25,950 (non-CDL) diesel chassis. You can select air or water digging from this unit. All the systems, including compressor, vacuum, and high-pressure water, are powered by a single, enclosed John Deere 115-horsepower diesel engine for quiet, dependable operation. The system also offers a self-purging filtration system, remote control up to 200 feet away, a fast-acting interceptor canister, fully supervised control panel, enclosed power head, and a low-maintenance design.
“The features and capabilities of the FX60, a higher-horsepower version of our popular FX30, reflect a growing trend of vacuum excavation systems being used to perform more excavation tasks than just cleanup,” comments Brent Bolay of Ditch Witch. “It is designed for a wide range of cleanup and soft excavation applications for many different industries, including drilling, utility, construction, water and sewer, landscaping, telecommunications, disaster recovery, and railroad. Earlier, gas-powered systems were used primarily to clean out trenches and remove debris from construction sites, but this new breed of diesel-powered vacuum excavators is called upon increasingly to excavate in congested areas, to clean utility boxes, perform street repairs, and dozens of tasks that are aboveground rather than below.” The Ditch Witch FX60 is described as a high-end, belt-driven vacuum system with a 5.2-gallons-per-minute water pump and 900 cubic feet per minute of suction power. It can be configured with a 1,200-, 800-, or 300-gallon debris tank and is powered by a 60-horsepower Cummins 3.3-liter engine. The system is available in either a trailer-mounted or a loose-configuration style.
Crilly (who does this work all the time) believes it is important to have the hydroexcavation module mounted on a quality chassis that matches up well with the local environment, and is efficient under your operating conditions. He also praises the usefulness of a good remote-control boom, from both the efficiency and safety aspects. “Our setup time from arrival to the start of digging is less than four minutes with a good remote-control boom,” notes Crilly. “It eliminates handling of heavy dig hose. And size isn’t everything in this business. Our 6-yard trucks can carry 6 yards legally, while many larger trucks are not able to carry legally their debris body load, as they may end up overweight, which can be a huge liability for the contractor and client. Smaller trucks are more maneuverable, too, and that’s an advantage at certain sites.”
As every gardener knows, digging can become difficult if the soil is hard or heavy. One of the questions asked about vacuum excavation concerns its efficiency when the ground is frozen. The HXX Prodigy vacuum excavator, introduced this year by Vactor Manufacturing (a subsidiary of Federal Signal Corp.), offers water heaters so that the operator can cut through frozen ground or heavy clay. The HXX Prodigy is smaller than its big brother, the full-sized HXX, and its compact size and price are expected to appeal to contractors just getting started in vacuum excavation. It blasts away soil with jets of 10 to 20 gallons of water per minute, at rates from 1,500 to 2,000 psi, depending on the pump selection, pressure adjustment, and nozzle tip configuration. “Excavation using pressurized water or air can be very precise, providing minimal ground disturbance and virtually eliminating the risk of damage to existing underground utility lines,” comments Deepesh Nayanar, product manager at Vactor Manufacturing. “The Prodigy can be used for slot trenching, potholing, water valve box repair, plus the locating of existing fiber optic lines, cables, and other utilities.”
“Think of the X-10 vacuum excavator as a surgical instrument,” suggests Kelly Clark, chief operating officer for H2X, who has been a successful contractor and is now also a dealer for Hi-Vac Corp.’s X-vac line. Hi-Vac has a global presence in vacuum excavation, with locations that include the UK, China, and the US. “It increases productivity, eliminates the high cost of utility repairs and causes less damage to the surrounding site, so that there are minimal restoration costs.” The X500 and X800 models in the X-vac line come complete with all the attachments you may need. These include a 3-inch-by-6-inch combination nozzle with rotating water jet (to allow for a one-person operation); a 30-inch water lance for wash-down and cleanup; a 6-foot water lance with rotating jet; a 3-inch-by-6-inch aluminum vacuum lance for two-person, directional operation; 50 feet of 3-inch abrasion-resistant vacuum hose with storage area on the trailer; and 50 feet of water hose on a hand-cranked hose reel. The multi-function remote control serves boom and water pump. There are four water tanks (side mounted) and room for 10 cubic yards of solids collection.
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Photo: Vactor |
| Contractors are discovering that portable excavators have a wide range of uses on the job site, from potholing for utilities to digging post holes. |
Before You Excavate
Most people don’t take a refresher course in driving when they get a new car, and many equipment operators are soon comfortable with new models of loaders, dozers, and excavators. Without wishing to nag, we should emphasize the importance of training before the onsite use of vacuum excavation equipment. It is a completely new way of excavating, and some of our good habits from old techniques must be put aside. Where would you get the right training? “Most of our training on vacuum excavation equipment is handled by our dealer distribution,” comments Brent Bolay, product manager at Ditch Witch, a manufacturer with one of the most extensive dealer networks.” They are the ones who have the closest contact with the customer. It is typically handled by the sales representative but may also be done by a service technician. Because the ultimate goal of Ditch Witch is to have a happy customer, we know it is important to give clear operation and safety instructions when the vacuum excavation unit is delivered.”
“A customer should also take advantage of any available resources that can make his job easier,” continues Bolay. “Our first recommendation would be to utilize either the new Nationwide One-Call (811) or your state one-call system. This gives the local utility companies the notice to have all underground pipes and cables located and marked before you operate equipment. Secondly, reading and using the operator’s manual provided by the manufacturer can be an extremely valuable tool that provides the proper operating information as well as service and lubrication information.”
It’s obvious that you should know what you are digging, but it can be equally important to know why you are digging. People with whom we have spoken tell us it helps to know what the end goal is, in order to complete the excavation job as safely and efficiently as possible. Are you simply locating underground objects? Are you making a hole for a power pole? Will concrete be poured in the hole? Your crew will not just turn up at the site and start digging, will they? Before the digging begins, the crew should have seen and understood the markings on the ground. Your crew, or least the person in charge of it, should know the meanings of the different colors. “Walk the job,” advises the experienced Crilly. “This important step takes one or two minutes and allows us to spot many potentially helpful and/or problematic issues, such as overhead power lines, unmarked lines, and truck placement options. That’s all before we start to dig.”
“We have an enormous amount of experience to pass on to buyers of our units,” notes Clark. “We spend a lot of time with our clients and provide whatever support we can to help them ensure their success in the business. We start by determining the exact truck each contractor (or municipality) will need. When the vacuum excavation truck is delivered, we help the customers with their safety and maintenance programs. We also take time to rain their personnel in the operation of the truck and teach them how to dig efficiently and quickly.”
One of the good points made by Vactron is that a contractor can forget that a system with a good reputation in one type of application may be equally good in another. The Vactron Flowmaster (one of several models from that manufacturer) has won acclaim for its use as a valve exerciser, but it is also efficient at locating underground utilities, cleaning up spoils and drilling mud from underground boring, and cleaning storm drains—all jobs that can bring good income to the alert contractor. The current and future value of a vacuum extraction system is in its potential for accomplishing tasks that we have always considered to be slow, often manual, chores. All the manufacturers and dealers of these systems have accumulated data about successful applications. It would certainly be worth consulting with them to see if there is a good avenue for expansion in the ownership of a vacuum excavation system in addition to your present, traditional, excavation equipment.