Vacuum excavation prevents damage to buried utilities.
Some explosions caused by excavator, dozer, or backhoe blades striking buried utilities are dramatic. Some are fatal. Sometimes it’s simply a plume of earth and little stones that fly up and the workers watching gasp a bit, cuss a bit, and wonder where they’d be now if it had been worse. Frequently there are costs and damages that travel far from the site, like cracks in glass. If it’s telephone lines that are cut, businesses stop, emergency services may be unavailable, and repairs can take more than a few minutes. If it’s a sewer line broken, the health hazards may be significant, the air awfully aromatic. If it’s a main water line, people suddenly realize how important their good water is. If it’s an electric or gas line, somebody almost always gets hurt, even killed. The ramifications of broken utility lines are expansive and expensive. Damage doesn’t have to happen, but when it does, people are always looking for somebody to blame, and pay. |
Photo: Vermeer Ring-OMatic |
| One person can work a vacuum excavator, and the hole is smaller than any backhoe can dig. |
For most people, the very word excavation seems to imply a big hole in the ground, because work for new highways and buildings can move thousands, even millions, of yards of soil. Big excavators do the job magnificently. If the sites are restricted, as in urban projects between buildings or much of our residential work, compact excavators go in and do the job. Vacuum excavation is most useful in applications where, in the middle of a big site, there are hidden underground utilities. Excavators don’t take up much space, just a line of pipe and wire, perhaps less than a yard wide. You wouldn’t try to excavate the whole area with vacuum excavation, but you would clear the way around pipe and conduit so that the bigger excavating machines could do their work without fear of striking dangerous obstacles.
Find the Rules and Follow Them
There are local regulations about excavation where utilities may be present. They vary a little from state to state, but the central theme is common to all: Do the job right, without endangering people or property. The regulations/statutes/acts have names like Underground Utility Damage Prevention Act (Virginia), Underground Utility Facilities Damage Prevention Act (Illinois), and Underground Facility Damage Prevention and Safety Act (Florida). They are not all lengthy pieces of complicated prose. They are easy to read and all of us involved in excavation should read them.
What are underground utility facilities? Illinois says they include wires, ducts, fiber-optic cable, conduits, pipes, sewers, and cables, and their connected appurtenances, installed beneath the surface of the ground by a public utility or by a municipally owned or mutually owned utility providing a similar utility service; or by a pipeline entity transporting gases, crude oil, petroleum products, or other hydrocarbon materials within the state; or by a telecommunications carrier. There are a few other definitions in the act, related to relevant legal definitions of companies and organizations providing service, but you see the principal idea. The definitions are all very legal-sounding and that in itself should warn us. We shouldn’t spend too much time trying to find out the party affiliation, family history, or religious persuasion of the owners of the underground obstacles. Just don’t cut or break them, regardless of who owns them or put them there in the first place. It’s like those signs in stores where they sell fine china: You break it, you pay for it.
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Photo: Amerivac |
| Vacuum excavation is a compact operation. The equipment requires little space to use. |
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Photo: Vacmasters |
| Two workers use air to dif a hole and remove the spoils. |
You can tell the topics considered relevant by the State of Virginia, because it gives careful definitions of these words used in its act: abandoned, contract locator, damage, demolition, designer, emergency, excavation, extraordinary circumstances, notification center, notify, notice and notification, operator, person (more on that one in a minute), soft digging, special project notice, utility line, willful, and working day. In the State of Virginia’s act, person includes any individual; operator; firm; joint venture; partnership; corporation; association; or municipality or other political subdivision, governmental unit, department, or agency. It is also synonymous with trustee, receiver, assignee, or personal representative thereof. It seems unlikely, then, that anybody in any state is going to get away with careless digging. Our biggest help may be vacuum excavation.
There are still many cities that do not have their own vacuum excavation equipment. Smaller communities cannot afford the necessary equipment and rely on their local utilities to do the digging around the buried lines, or they do the work manually. “One call is so helpful,” says Wilbur Wallace, the public works engineer for our own city, Glendive, MT. We have less than 5,000 people and the city is always low on funds and uses a lot of outdated equipment. “We let the cable, telephone, gas, or electric company find the buried utilities and let them do the exposing. It means we don’t have to spend the money on equipment or labor. And sometimes we dig around them with shovels.” Some immediate reactions were that such a policy may delay a project contrary to the city’s wishes or remove control of the safe excavation out of the hands of the communities’ representatives. Larger cities are little different. “The City of Alexandria, Louisiana, does not do vacuum excavation and makes sure the correct details are in the contractors’ contracts for work around buried utilities,” notes James Branch, a professional engineer there. It’s not just the municipalities that get others to do the delicate work.
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Photo: McLaughlin Boring Systems |
| With its small footprint, vacuum extraction is ideal for use in residential settings. |
“We get the utilities to do that kind of work before we go in with our excavator,” advises Mrs. Dean Fairchild, part owner of DD Excavation in Midvale, ID. “We’re a small contracting company and could probably not justify the investment for the small amount of that work required in this area.” In Gladstone, MO, Bill Ballard of W.R. Ballard Excavating says there is one company in his area that has the vacuum excavation equipment and will contract to do the work. His own company has not invested in the necessary machinery and he sees only rare applications, because he does few jobs that involve utility work or easements. Based in Sand Springs, OK, Carter Excavating Inc. (owned by Jerry Carter) is a much larger excavation contractor. The company has between 110 and 180 employees, depending on the projects under way, and much of it is highway work, ground preparation for new building complexes, and applications of that size. They handle their own excavation around buried utilities; it’s part of the day’s work, one of many jobs in a big company’s portfolio. Using a shovel is still popular with many contractors and municipalities. “We call first to see if there are buried utilities at the job site and locate their exact position,” explains Shirley Baughman of Baughman Trucking & Excavating in Sheldon, WI. “If we have to dig carefully around the hidden obstacles, we use shovels and do it manually. It has not been a problem.”
We have the impression that vacuum excavation could be another market into which grading and excavation contractors could go profitably in some territories, if they have not done so already. We are cautioned, however, by several contractors that you can do a lot of excavation and grading without coming anywhere near a buried utility. You should investigate the potential for vacuum excavation work and purchase or lease accordingly. It depends on where you live and work. In Wakefield, MA, Peter Cameron is owner of Rental Equipment Co. “We have no demand for vacuum excavation equipment,” says Cameron. “In these parts you rarely see that technique. We have many rocks in the soil and I’m not sure if vacuum excavation could handle that.”
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Photo: PacificTek |
| Remote control of the operation has found supporters for some applications. |
Techniques and Applications
Vacuum excavation to uncover buried and hidden utilities—some contractors use water and air, some use only air—is similar to vacuum cleaning the living room. The person doing the actual excavating holds a hose that sucks up the debris. It is a non-destructive technique. It doesn’t cut, stab, or hammer. “This method is even safer than hand digging,” asserts Tab Siegrist of Vactor Manufacturing. “With manual digging there is still a chance the worker may strike a line and the costs of a strike are not only direct, like property damage, loss time at the site, fines, medical bills, and equipment damage. The indirect costs may be increased insurance, administration costs, legal fees, judgments, delays in the project, and damage to the image of your company.” Hydroexcavation can cope with tough soil conditions like rock and clay, as well as frozen ground (with heated water). Several contractors commented that some incidents of line damage were caused by the fact that as-built drawings were non-existent or inaccurate. “Under those circumstances you don’t tell your backhoe operator to plunge down and see if there’s anything there,” warns Todd Richards, a contractor in Bend, OR. One of the first steps after ascertaining that there are hidden utilities below is to call somebody to let them know that you have work to do around their utilities. The One Call service is invaluable. It has different names in different states and communities. One excellent fact we learned was that everybody we spoke with always calls that number first.
In Greenville, SC, hydroexcavation was needed to benefit the landscape and solve runoff problems at a residence. When the original house was built, there was only minimal landscaping. When the second owners took occupancy, they decided to improve everything and added a raised berm, attractive beds, flowers, and plants in front of the circular driveway. They cut the grass with a reel mower. It looked wonderful … until water started collecting at the edge of the lawn and in front of the house. Garden Vistas, a local landscape and yard maintenance company, looked at the problem. “The existing French drain was useless because the conduit used to filter off the water was too small,” observes Bob Moffett of Garden Vistas.
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Photo: Ditch Witch |
| It is surprising how little space is needed for vacuum excavation. |
“We suggested removing the existing drain system and installing surface drains and a 4-inch connecting line that would handle the runoff.” To achieve this Moffett needed a tunnel (6 inches in diameter and 13 feet long) to go under the double entry pad of the house. He got his plan approved, made the right call to the appropriate utilities, and used a vaXcavator from McLaughlin Boring Systems to cut the starting trench. That was 12 inches wide, 12 inches deep, and 7 feet long. The job took two hours, with no damage to the landscape. The first 6 feet took only 10 minutes, with the rest of the time spent collecting concrete, wooden two-by-fours, insulation, and unused brick from the original construction of the residence. After the tunnel was made, a vaXcavator pavement sweeper cleaned up the site to the owner’s delight.
The cold, damp winters in Woodridge, IL, west of Chicago, can damage water valve boxes. Crews used to do the maintenance with backhoes, or manually, but that was expensive and there was frequently a need for restoration of damaged property for the residents. Now they use vacuum excavation. The process takes about 15 minutes for each unit and officials say they have reduced their costs for labor and repairs significantly.
“We have been successful with applications as diverse as mud removal, cleaning treatment plants for local authorities, and manhole cleanouts,” notes Don Buckner, president of Vac-Tron. “Our equipment has also vacuumed down retention ponds, cleaned storm drains, cleaned around valve boxes and meter boxes, cleaned up emergency road spills, and even vacuumed dry sand and rocks.”
Water or Air?
Vacuum excavation systems use mostly water or totally air; the manufacturers of each style generally like one or the other. We must insert here that neither “side” says the other doesn’t work. Everybody who has used vacuum excavation or who makes the equipment to do it will argue with conviction about its advantages for contractors. Your choice of system—just like your choice for loaders, excavators, graders, or personal vehicles—is up to you. It has become a question of preference, not ability.
“The Vacmasters System 4000 offers utilities and utility contractors the ability to pothole using supersonic air in any kind of soil, no matter how hard, wet, sunbaked, or compact—even when there’s ground frost,” advises Roger Kirwan, vice president of marketing at Vacmasters (a division of Barone Inc.). “This system’s ability to let the contractor choose air rather than water when potholing means the job gets completed more quickly, in just seven to eight minutes in most soils. It’s more efficient because the spoils stay dry for backfilling, and it can be more economical because your mud hauling and disposal costs are eliminated. We also believe that this air-based technique is safer because air will not damage utilities and it is non-conductive.” Kirwan adds that air-vacuum excavation is Department of Transportation–friendly and will not damage the road base. On the technical side, a John Deere 150-horsepower diesel engine powers all the systems (including compressor, vacuum, and high-pressure water). It has a self-purging filtration system, selectable water or air digging, remote operation up to 200 feet away, a fast-acting interceptor canister, and an enclosed powerhead.
In the Vactor HXX (engineered with advice from excavation contractors, says the manufacturer), pressurized water breaks apart the soil and a high-flow vacuum removes it. “There is no damage or disruption of the lines,” notes Siegrist for Vactor. Successful uses of the HXX have included excavation at residential sites, slot trenching, installation of poles and signs, potholing, directional drilling, water line repair, and location of underground pipe and other utilities. The machine will give the user up to seven hours of continuous operation with the onboard water. “Lower water flow results in less operator fatigue and a cleaner, more accurate digging process,” Siegrist adds. “Add to that the benefit that the fan’s 8,000-cubic-foot-per-minute airflow is more than double that of some competitors.” The debris tank holds 12 cubic yards and the stainless steel water tank (single cell) has a capacity of 1,300 gallons.
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Photo: Pacific Tek |
| While standard excavation can leave gaping holes in streets and sidewalks, a vacuum operation has minimal impact on the job site. |
Partnering With Other Equipment
As vacuum excavation manages underground obstacles and their safe exposure, it is not surprising that two companies well known in the field of underground construction should produce excavation equipment to match their drilling machines and tools. Ditch Witch and Vermeer are probably the best-known makers of directional drills and associated products in the United States. Ditch Witch offers a group of vacuum excavation products, known as the FX30 series. There is also the FX60, the big brother in the family. The first FX30 is a 500-gallon system and claims to be the quietest on the market today. It has been used successfully for residential work and Ditch Witch reports that municipalities and rental centers like its compact operation, too. That low noise level (73 decibel-amps) is also welcomed by the operator. The next size up in the series is the 800-gallon model with its powerful two-lobe blower that develops 500 cfm and 15 inches of mercury for efficient suction. The FX60 is the largest of the group. Its dry weight is 11,230 pounds and, with full tanks, it weighs 24,880 pounds. The tank has a 1,200-gallon capacity. The vacuum system has a belt drive, the hydraulic system works at 2,500 psi, and the maximum pressure for the water system is 3,500 psi. It can be trailer mounted or be used in a loose configuration.
A few months ago, Vermeer and Ring-O-Matic, two national leaders in underground construction and vacuum excavation, announced that they were merging production and distribution. For 2004, Ring-O-Matic introduced a handheld wireless remote-control hydraulic boom for their hydroexcavation equipment. With that, the operator can retract or extend the length of the boom, and raise or lower the height of the boom. It’s an advance that has been particularly helpful for crews working at multiple utility locations, such as the holes for installation of streetlights or vacuuming catch basins.
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Photo: Vactor |
| Vacuum excavation on residential property has become especially popular. |
The E550 and E900 Evacuator vacuum excavation systems from Vermeer—the model numbers indicate the capacity in gallons of the spoil tanks—can deliver 1,000 cfm. They were designed to assist contractors in horizontal directional drilling, for companies specializing in locating utilities, and for public works and municipal applications. In the excavation mode, the units will expose buried utility lines (or other underground obstacles), and in the vacuum-only mode, they will perform a good cleanup job of non-hazardous materials at your job site. Both models offer a patented multinozzle wand system and automatic shutdown switches for the high-pressure pump when the level of the water tank is low. To make removing spoil and cleaning the tank easy for the operator, there is a full-swing door, while mounting of the system can be on a skid or trailer, depending on the preference of the customer.
Companies or equipment names we should mention in this field are Keith Huber, Amerivac, Vactor, Miller Pipeline, Vacuum Source (now merged with McLaughlin Boring Systems), Ditch Witch, PacificTek, Vac-Tron, Vermeer and Ring-O-Matic, MBW, VacStar, Vacmasters, Super Products, Vac-Tron, Utilivac, GapVax, Versa-Vac, Vector, Vac-Con, Aquatech, and Hi-Vac. Not surprisingly, there’s plenty of “vac” in that collection. It pays to look at all the specifications of equipment. From them you can deduce what is considered important structurally and what you should be looking for in the equipment you purchase or lease. The most commonly emphasized points seem to be the size of the tanks (for water and spoils) and the actual power of the vacuum. What is best for your applications is not necessarily the biggest machine; it is the one that handles your work most efficiently and cost-effectively.
The subsurface infrastructure of North America is growing rapidly. As cities spread out and suburbs increase, the utilities must go with them. Most of the newer lines are underground. Unfortunately, the as-built drawings for some earlier expansions are unavailable or inaccurate and contractors are becoming more aware of the challenges offered by buried obstacles to their excavation. Vacuum excavation is not a passing fancy, a solution that will go away quickly. (It’s been around for about 50 years already.) It seems to be gaining popularity with both private contractors and public works professionals as a method to continue a tradition of safe excavation in any community, whatever is hidden below the surface.