Jeff Wage, vice president of McLaughlin Group Inc., notes a trend in which contractors are using utility locators to verify information.
“What we’re finding is, when the contractors get on job sites, they’re wanting to expose the utility and make sure they verify depth physically, put their eyes on it and verify for the owner, the engineering firm, or the inspector that’s out there,” he says.
As the vacuum excavation is being deployed on the job site, “one-call contractors do a great job of getting paint on the ground and giving you a good idea of where that utility is,” he adds.
“I can cite a number of times I’ve been on a job site where the contractor has had a utility locator they decided not to take out of a truck and go out and literally dig and hydro-excavate for 45 minutes and find that they’re off of it by a foot, foot-and-a-half, and they had dug under it,” he says.
“At that point, 45 minutes later, they get the locator, clip onto it in about five minutes, and realize they could have saved themselves a lot of time and money if they had just taken that step. Once people see that, we find they go more to that versus digging and wasting time.”
To locate utilities, one of the company’s most used pieces of equipment by contractors is the McLaughlin Verifier G2, a standard utility locator. Designed for rugged job-site conditions, PC boards and antennas are mounted in rubber isolators. Smart technology simplifies the operation of the transmitter and location of the utility with the receiver and is coupled with improved noise reduction. A multiple-frequency transmitter helps the operator locate all types of utilities, and a strong midrange frequency inductive locating ability is designed to aid in quick verification of utilities for excavation.
“The utility locator uses both direct connect and inductive, and also we do a uni-clamp for getting into high power, so there are three methods for locating,” says Wage.
The use of vacuum excavation technology eliminates the risk of damage using manual labor with a shovel, a pick, or a mechanical excavation technique, he points out.
“Vacuum excavation is more surgical, it is less intrusive and generates less risk of hitting or damaging a utility because you’re using water and air pressure versus a mechanical device to hit it,” he says. “The key is knowing exactly where the utility is and getting a good depth on it so as you are digging into it, you’ve verified that depth with the utility locator.”
As contractors get into the depth range using a vacuum excavator, they begin to take more precaution and safety measures, even if they’re using a hydro-excavator or air excavation technique, he adds.
The use of air versus water is the “great debate” on construction sites, Wage says.
“It’s the No. 1 question we hear,” he says. “Should we excavate with air? Should we go with water? The benefit of using air is if the soil is coming out of the ground, it can be reused and put back into the excavation dry.”
Air excavation is beneficial in that a contractor is not bringing in imported soils and hauling off the old, wet soil, he adds.
“The negative and the challenge is the productivity of air versus water: generally, hydro-excavation is a more productive method for excavating than air,” Wage says. “There’s a good amount of mess that takes place when you’re using air. You can have more airborne material, more dust, and some other things that you’re trying to control when you’re using air versus water.”
From his perspective as a manufacturer, Wage says he sees usage as being 95% hydro- or water excavation and 5% air.
“When we talk about that 5% use of air units, those are always combination air/water units, so if the contractor has an asset or a piece of equipment that they can’t dig with when they are on the job site due to job conditions, or if they’re not allowed to re-dump the soil back on the ground, they immediately go to water because they lost their benefit of reuse spoils. They’ll go to the more water and they always go with a combination air/water unit.”
Vermeer offers both air and hydraulic units by McLaughlin with spoil tank sizes ranging from 100 gallons to 3,000 gallons.
“You can do those in trailer units or skids, and once you get over 1,200 gallons you really need to go to skids and truck-mounted, because the trailers don’t want to carry anything larger than 1,200 gallons,” Wage points out.
Contractors wanting a combo unit need enough horsepower to run both the vacuum and air compressor simultaneously on the same power pack, Wage says.
“Once we get into the 99-horsepower category, that’s where we offer an air/water combo unit, so when we go to a 99-horsepower power pack, that’s where you can choose whether you want a 500-gallon all the way up to a 3,000-gallon,” he says. “You can get any of those in an air/water combo trailer or skid.”
The new Mega Vac line features 1,600-, 2,000-, 2,200-, 2,600-, and 3,000-gallon options with 1,025- and 1,200-cfm blower configurations with a new addition of a DEEP Blower option for HDD drill support, which creates 23 inches of mercury for handling heavy drill muds.
Another trend Wage notes is companies going to a boom when they’re doing a lot of potholing to minimize the labor involved in lifting and pulling the suction tool out of the ground.
“They do that with a hydraulic boom,” he says. “We’ve seen more and more booms, even on our smaller trailer units, 500-, 800-, and 1,200-gallon trailers, as well as our smaller truck-mounted units.
“If you’re potholing all day, running the water or air is not physically demanding, but when you’ve got all of that suction force and you’re lifting and pulling that suction tool up and down and in and out of the hole excavating the soils, that boom makes a big difference on that operator, just for the physical requirements and demands of the job.”
Miller Pipeline, based in Indianapolis, IN, installs natural gas pipeline systems in 27 states and uses McLaughlin systems.
“Most of our work is performed by an underground drill-directional boring-and, therefore, because we do directional boring, locating utilities or items that would be in the ground is very important to us,” says Jim Romer, fleet supervisor for the company’s Birmingham, AL-based south hub. “We want to avoid damage at all costs. Before we do a procedure, we need to first of all get a location on any known existing items in the ground, whether they be cable, water, or sewerage.”
Once those are located by the company’s crew or a contractor, the company will use water pressure to loosen up the dirt and the vacuum will pull material out of the ground so crew members can visibly see the located items.
Miller Pipeline uses primarily trailer-mounted McLaughlin units and a few of its older air-vacuum excavators from
Vacmasters. The company also builds its own air units.
In the South, the company prefers to use the McLaughlin units for their tank size and water pressure.
“If they have a long bore that they’ve got to get out ahead of-800 to 1,000 or 2,000 feet-they need to spot it out quite a bit in front of that boring machine, and they need something quick,” says Romer. “The McLaughlin machine is quick in that regard.”
The company will use the Vacmasters for jobs of a few hundred feet, he adds.
In the area around Birmingham, AL, hydro-excavation is the preference due to soil type, Romer says.
“The soil here is very different than in other areas of the country,” he says. “You’re going to run into rocky soils and also a bunch of clay. Because you don’t really know what you’re going to run into, you really need to be ready for whatever soil circumstance happens to be in that particular spot. The water allows you to be very versatile and use it no matter what, whereas air-once you got into clay or something like that-would not work there as well.”
Romer credits the McLaughlin units for being good at sucking up slurry from the drill and water process as to avoid damage to the area.
“When you’re pulling back a lengthy drill shot or a lengthy piece of pipe, you’re going to use a lot of water in that boring instance,” he notes. “Not only do we go out front and do the spot work, but we double back behind the drill and suck up the slurry as well.”
Miller Pipeline always does locating work, even if crewmembers are told there’s nothing under the ground.
“We’ll spot it anyway because that’s our procedure,” Romer says. “We’ve found sewers or water mains that we were told weren’t there. There’s definitely cable and fiber optics in the ground that supposedly isn’t there,” he says.
“Those surprises pop up on a daily basis. In using the wet-dry vac systems, that allows us to find it without damaging it, even though it was never supposedly in the ground in the first place.”
Romer notes that machine capabilities have evolved to become more powerful and allow his company’s crews to do jobs quicker than when they started using them 15 years ago.
“There are even larger vacs than what we use down here,” he says. “When you’re on a city street, you’re creating slurry, and that can cause very large problems.”
Romer says he believes that in the future, utilities and government entities-be it a transportation department or a municipality that owns its own utility-will request that a contractor have a vacuum truck in its fleet.
“Right now, it’s considered a luxury,” he says. “I think it will become a necessity versus a luxury.”
Underground Imaging Technologies (UIT) conducts the indirect measurement of utilities, specializing in 3D subsurface imaging and mapping.
“We match the tools to the conditions,” says Gary Young, vice president of operations and development. “Most people don’t find all of the utilities when they go out. The main reason for that is it takes more than one tool to find everything.”
Crews from Underground Imaging Technologies use many tools and will go over a site multiple times, Young says.
“You hear a lot about ground-penetrating radar, which is a wonderful tool, but there are many soil types that are not friendly to radar,” he says. “If we get out there and test it and see the radar is not working, we’ll do something else. Our goal is to find those utilities with the indirect and geophysical methods so that when someone goes out there with a vacuum excavator, they can find it the first time.”
Using 3D utility mapping, “instead of just getting a line drawing of the utility with your vacuum excavation effort, you find out what it is, what it’s made of, how big it is, and then you can actually make a full-scale model of that utility,” Young says.
One such technology is UIT’s MetaVision II mapping system. It can be used to cover a lot of ground or in smaller, tighter areas when used in a portable mode by one person, Young says.
“This tool operates like a standard pipe and cable locator in passive or inductive mode, but it carries its transmitter around with it and makes contour-able maps of the target signatures.”
At a recent job site for the installation of a new water transmission line near Osceola Parkway in Kissimmee, FL, UIT conducted a subsurface utility investigation using several geophysical tools to provide complete coverage of the investigation area with minimal public impact and traffic interruptions.
The results from the geophysical investigation and existing utility records allowed UIT and the client to develop a revised test hole program to confirm the locations and types of selected utilities.
The findings: Approximately 65% to 70% of utilities shown on client-provided records were mislocated by at least 2 feet at some point along their alignments. Numerous utilities, previously unknown, were mapped by UIT.
The utility depth information alleviated potential construction conflicts associated with select targets. The UIT results allowed utilities to be uncovered on the first test hole attempt, reducing the number of dry holes. Actual test hole costs were 50% less than planned.
UIT crews had worked on the second stage of the project.
“During the first stage, they knew about our capabilities but they decided to go it alone,” says Young. “They took the existing records and a vacuum excavation truck and tried to verify everywhere on the records where they thought their design would set with the existing utilities. And that makes sense until you understand the records are almost never right to some degree.
“During the course of the first phase of the project, they struck one of their own water transmission lines, and it cost them $750,000 to fix it,” he adds. “They asked us to come in on the second phase, which is another 1-mile section. Our total billings on the second phase were $170,000. That avoided that big strike, and they could have saved themselves a lot of money in the first place.”
When a contractor goes out to a job site with a vacuum truck with the intention of verifying other utilities just going by the existing records, it results in putting in a lot of holes, Young says.
“That’s expensive, it’s time-consuming, it’s aggravating to the people around you, it’s bad for the environment,” he says. “There are all kinds of reasons why you really should minimize the number of holes.”
UIT uses holes in a well-placed fashion, Young says.
On the second phase of the Kissimmee project, Young points out, the engineer working for the water authority had planned on doing 250 test holes on a 1-mile section of road.
“After we had done our work, they ended up doing everything to their satisfaction with only 68,” he says. “That savings paid for 50% of UIT’s billings.”
Also, being that the area is a huge tourist region in Florida, it minimized the disruption to traffic. Minimizing or avoiding disruption of any kind is the bottom line.
“We just finished a bunch of jobs in California for a gas company, and on one of those jobs we found 90 utilities in a 1-mile section of the project that were unknown before we got there,” Young says.
Young agrees with others in the industry that the line location and excavation technologies have become more sophisticated, enabling contractors to provide better solutions to the challenges of the unknown underground.
“In the utility industry, we started putting things underground in the 1870s,” says Young. “In those days, some people would try marking underground where that was and keep it for posterity, but most of them didn’t.”
If they did mark it, they would mark it from the corner of a building or the curb or a tree, which 50 years from that point wasn’t there anymore, he adds.
Many companies, such as gas companies, are becoming fastidious about records when they are constructing new lines, Young says.
“They’ll survey it and put really good data back into their records about where that line is,” he says. “Only one time in my career doing this work everything that’s on the records was right and that was with oil refineries up in Calgary in Canada. I’ve never seen that anywhere else.”
Essentially, the best way to make a job go well is to do the initial work correctly, Young points out.
“Our work is easy from the standpoint that you don’t have to dig in order to find the utilities, at least in that first level,” he says. “I believe you shouldn’t be doing any digging of any kind until you have a good target to go after because it’s safer and saves money.
“Vacuum excavation contractors don’t necessarily like to hear that. If they have to search for the utility, it’s more time and holes, but in this world where sustainability starts to matter and costs matter, that doesn’t add up for everyone. You do more efficient projects if you do this stuff in order and do it all right along the way. It’s critical to our work that if do it right, you don’t have to spend so much time and money.”
Among the offerings of SubSurface Instruments Inc. is the AML, which uses advanced, ultra-high radio frequencies to locate buried PVC pipe.
The technology utilized by the AML was originally developed by NASA engineers for a 2004 space mission to Mars to examine the density below the surface, says Joe Weiland, company president.
The AML is designed to function in clay, wet soil, snow, or standing water without the need for a separate transmitter and receiver, wires, clips, or clamps.
It is typically used in the utility, water, gas, and cable industries.
The AML works as such: While holding the handle parallel to the ground, the user scans the area of the suspected pipe or buried object until one or both of the AML’s target indicators activate.
While the left or right target indicator is activated, the AML is rotated until both LED target indicators light simultaneously, triggering its tone and laser marker, indicating that the pipe or object has been detected and that the AML is then parallel with the underground object
With the AML in parallel with the pipe or underground object, the end user can scan the entire length of the object’s edge. An alternative approach is to utilize the “˜W’ method of scanning by sweeping the area in a back-and-forth “˜W’ motion to mark the object’s location and run direction as it is tracked.
“While no single locator works for every need, the AML complements pipe and cable locators and is the only locator to have in looking for undetectable products,” Weiland says.
At We Energies in Milwaukee, WI, Mark Sobon, operations supervisor for the damage prevention group, has 15 AML units. They’re used as a secondary tool.
“When we try to locate our gas utilities or our electric lines, we would go to a method of trying to get a signal off of our utilities,” he says.
The company will use an AML as a secondary tool to locate a gas pipeline, especially those without tracer wires. Sobon has used it to locate an 8-inch pipe in the outskirts of a landfill.
“Soil condition really doesn’t play a factor in it as far as more gravelly to clay soil,” says Sobon. “The only part it plays is if you go from a hard surface to a soft surface because it goes for density change. If you’re jumping from one surface to the next, you’ll have a difficult time, because a grassy area is going to be a different density from the road. But the ground and water and snow doesn’t play a part.”
When using vacuum excavation, the in-house contractors will use water the majority of the time or do hand excavation, Sobon says.
Mala GeoScience manufactures ground-penetrating radar (GPR) systems. The company recently released the Mala EasyLocator HDR (high dynamic range).
“We don’t even call it GPR,” says Matt Wolf, president.
The system features the industry’s highest bandwidth and resolution, Wolf says.
“There’s a big push in the industry for the dual-frequency antennae, and that doubles the cost of the radar system,” he says. “For the locators and contractors who don’t want to do a lot of sophisticated processes, we thought a single-frequency solution would always be the best.”
Older, conventional GPRs possess bandwidths in a certain range acceptable for many applications, “but typically you’d want to have two antennas, and that’s why the dual-frequency looked to be attractive. We developed a new way with the HDR technology to incorporate or record data at a much higher bandwidth that’s useful. Because of the increased bandwidth, you’re almost getting two for one in the antennae.”
Soil can still present a challenge.
“All GPR is subject to the negative effects of conductive material, soils like clay, and wet concrete,” says Wolf. “There are some soils that will never be conducive to radar, even with our new HDR. However, it does get increased penetration in the average soil by up to 20%. We’ve seen it against our own conventional equipment.”
Nancy McMahon, a partner in Noalani’s Construction Consulting and Akamai Ground Penetrating Radar Services in Lihue, HI, uses Mala GeoSciences’ instruments in carrying out her underground locating work.
The company uses GPR in construction and engineering projects, as well as in archaeology, historic preservation, geology, and environmental studies.
For McMahon, her success in locating objects is a combination of using state-of-the-art technology and experience. An archaeologist by training, McMahon learned to read soil profiles with GPR when a USDA soil scientist brought that technology-as well as electromagnetic technology-to Hawaii in the 1990s.
“I worked for the state at the time, and we took it to all of the islands to try it on different soil types and different locations where we knew I had archeological sites and deposits and see how it worked,” she says.
Since then, many companies have adopted the technology.
Because of her experience, McMahon says she can fine-tune her observations to know what is a PVC pipe or a clay pipe, “and metal is really easy to detect.”
When the Mala unit came out, McMahon practiced with it at the local mall where there are sewer problems and leaks.
“I can pick up where a drainage was in the mall and where the excavations were for that and could clearly pick up in there that they have metal pipes-it was just ringing all over the place,” she says. “Clay pipes have a different signature and are harder to determine. I could see an excavation to the drainage, there was a storm line there, a sewer line, and then the water line was a little harder to detect.”
That case might call for more excavation, McMahon says.
“I could see where there’s something there, so if they were going to hit on anything, I could tell them what that would be,” she says.
McMahon says it takes experience to be able to catch a signature or see there’s a break.
“It reads soils in the breaks pretty well and the density as you’re hitting them. Do I know the depth of some of those things? I don’t know that I know it that well to tell that. There’s just something there. Water lines aren’t that deep, and I know sewers are really deep. It’s something that you have to keep proficient at and keep doing it. The more you keep doing it, the better your expertise is.”
Rycom Instruments makes cabling and pipe locating equipment designed to identify the approximate location of a buried facility.
The equipment induces a signal on the utility. Using an electronic receiver, its operator uses the signal to pick up a target.
“In the start of our manual and in every cabling and pipe location equipment manual is a simple statement that the only way to know the exact location or depth of the utility is to dig it up and expose it,” says Doug Reitz, vice president of operations and Midwest sales for Rycom Instruments. “That’s where the daylighting technology goes hand in hand with the locating technology.
“There is locating that’s done every day, and often people are working fairly close to that utility. It is in everyone’s best interest to use a cable locator in the beginning, identify where the line is, and then if you’re working near that line to use a vacuum excavator, expose it, and verify that it is actually the line you were thinking you were locating and that it is the set depth the locator told you it was at. Then you clearly know there was a utility there.”
Reitz contends there are “many myths and much folklore” about certain electronic locating units working better in certain environments.
“A drier soil environment makes it more difficult just to get a signal on the line, because you’re creating an electrical circuit,” says Reitz. “The drier soil conditions make it more difficult, but really there’s no reason other than superior manufacturing, engineering, and design makes one unit better in an environment or a soil condition than another unit.”
Rather, it’s a function of user’s power output and frequency, he adds.
“That gives them the best tools in the field to overcome variance in soil conditions and congested areas where there are a lot of other cables within the same area that could cause interference,” Reitz says.
“When it comes to the vacuum excavation equipment, there is a lot of thought process between clay soil and sandy soil and rock-what works best is to break it up and move it,” he adds. “On our side, soil either interferes, or if there’s iron in the soil, it’s going to interfere with the system more.”
If there’s sand or rock, it makes the task more difficult to get the circuit going, but once the signal is applied to the line, it does not matter what soil is above it, Reitz says.
The two units Rycom manufacturers for this type of work are the 8879 and 8869. Reitz notes that the 8869 is a “jack of all trades” and costs $1,000 less than the 8879.
The 8869v3 Pathfinder Locating System includes FrequencyFlex, which allows users to adapt the system to their specific needs. Multiple active frequencies allow users to accurately locate with a minimum of “ghosting” to adjacent lines, while maintaining the ability to continue locating past faults and poor utility conductors.
Passive frequencies-50 Hz, 60 Hz, radio frequency, cathodic protection rectifier, and CATV-identify “live” lines by their naturally occurring electromagnetic fields, allowing line locating without the use of a transmitter.
Transmitter functions include improved transmitter induction and automatic impedance matching when using direct connection.
All functions are accessed via weatherproof membrane buttons. User input and transmitter status are verified with audible responses. Signal application methods include direct connection, induction mode, and coupler induction.
The receiver provides instant push-button depth up to 25 feet and current measurement to identify the target utility in crowded easements.
Audible proximity cues to the tracing signal are given to the user through either peak or null tones while the backlit digital display provides both relative and actual signal strength.
The 8869v3 can quickly and simply locate line faults when used with the optional A-frame ground return probe. As the operator moves towards the fault, the receiver responds with a rapidly peaking signal. When the A-frame is placed directly over the fault, the receiver will provide a null response.
Conduit pinches can be located using the optional Sonde accessory operating on active frequencies of 512 Hz, 640 Hz, 815 Hz, 8 kHz, and 33 kHz.
Rycom Instruments Sondes are pushed into nonpressurized conduits and pipes until they reach the point of pinch or blockage. Traceable 25 feet in the air and 10 feet in cast iron, the 8869-RF receiver is designed to identify the precise location of the line blockage.
The Rycom 8879v3 cable and pipe locator also offers utility locators FrequencyFlex, enabling them to adapt the system to their specific needs. Multiple active frequencies are designed to allow the user to accurately locate with a minimum of interference while maintaining the ability to continue locating past faults and around conduit bends.
Updated transmitter functions include improved transmitter induction, multifrequency coupled induction ranging from 8 kHz to 118 kHz, and automatic impedance matching for direct connections.
The 5-watt or 10-watt transmitter has the ability to simultaneously apply two frequencies to a utility. From one transmitter setting, the user can locate the main line as well as other services by “lighting up” the entire site.
The set-and-forget feature is designed to save time and money by reducing the need to repeatedly relocate the transmitter.
The 8879v3 receiver provides instant push-button depth up to 25 feet and current measurement to help identify target utilities in crowded easements. Proximity cues to the tracing signal are given to the user through either peak or null tone modes while the backlit digital display provides both relative and actual signal strength.
The 8879v3 is designed to quickly and simply locate lines with faults when used with the optional A-frame ground return probe. Conduit pinches can be located using the optional Sondes.
“If you’re going to bore under a pipe, and your cable locator says that pipe is 4 feet deep, and you think you can go 6 feet deep and bore right under it, until you daylight it, there is no real way to identify the exact depth,” says Reitz. “You can be a foot-and-a-half off, and then you end up boring right through the pipe.
“The technology isn’t perfect on the cable-locating side for depth to give you an exact depth reading,” he adds. “For that, it’s strongly recommended in the front of everyone’s manual that you expose the line before you dig near it.”
End users will specify the type of excavation medium required for their particular applications, says Ben Schmitt, product manager for Vactor Manufacturing Inc.
“It’s also helpful to know the size of a typical application so that the correct size debris body is selected to complete the work as efficiently as possible,” he says. “Knowing the soil conditions is paramount for selecting the right equipment. For example, air excavation is not particularly well-suited for harder or frozen soils. In those conditions, hydroexcavation is the perfect choice.”
Air vacuum excavation is desired in applications where the soil is loose, water is not readily available, in small-scale excavation projects or where immediate backfill of the hole is required, he adds.
“When working around buried electrical lines or brittle utilities, air vacuum excavation is often preferred due to the lower operating pressures,” Schmitt says. “Hydroexcavation is the preferred method in larger excavation projects or in harder, more compact soil conditions.”
Other factors include travel distance to a disposal site, state and local weight restrictions, excavation distance from the unit, and availability of water.
With more than 19 million miles of buried utilities in the United States, vacuum excavation helps contractors to locate underground utilities quickly and efficiently while protecting the vulnerable and expensive infrastructure, Schmitt says.
“Using vacuum excavation prior to a large excavation mitigates the risk of striking underground utilities,” he points out. “Typical electronic locating methods aren’t always reliable and can sometimes mismark a utility by several feet. The only accurate way to verify the utility location is to visually locate with vacuum excavation. The risk of striking a fiber optic, electrical, or gas line is too great not to visually locate the utilities in the area before excavating mechanically. The result can be thousands and sometimes millions of dollars in fines, lawsuits, and even death.”
There has been tremendous growth in the industry, resulting in an increased number of new vacuum excavator operators to meet the demand, says Schmitt.
“Vacuum excavators must be easy to operate and safe for both new equipment operators and experienced operators,” he points out, adding that a struggle for many contractors is finding skilled workers to operate the vacuum excavation equipment.
Vactor designed its excavators with simplified controls make it easy to operate so the “on-boarding” of a new hire is significantly condensed, Schmitt says.
“Vactor Manufacturing provides safe, operator-friendly equipment for our customers,” he says. “We have simplified our operation to allow the operator to quickly and easily set the unit up for operation. Vactor equipment also has built-in system protection to prevent improper use of the equipment and remove the guesswork from the unit’s operation. The end result is a quick, efficient, long-lasting, and operator-friendly vacuum excavator.”
The advantage of air vacuum excavation is that “air is limitless,” says Schmitt.
“Onboard compressors generate the required pressure on demand, so there are is no need to refill water,” he says. “Air is nonconductive. When vacuuming around live electrical wires, pneumatic excavation can be a preferred choice over hydroexcavation.”
Air vacuum excavation provides dry spoils that can be returned to the excavation site immediately, Schmitt points out.
“Many applications in the utility segment require exposing the utility, making the repair, and then backfilling the material,” he says. “This can’t be done with hydroexcavation.”
Air vacuum excavation uses lower excavation pressures compared with hydroexcavation, Schmitt says. Protective coatings and brittle underground utilities can easily be damaged when using hydroexcavation if the operator is not careful, he adds.
“Air vacuum excavation allows utilities to locate a utility to verify its location, while also allowing dry backfilling of the hole with the same soil it excavated,” he adds. “It does not require disposing of wet/muddy slurry of material.”
Hydroexcavation is generally the preferred method of vacuum excavation due to its speed and productivity, Schmitt says, adding that air vacuum excavation also has its own advantages.
The benefit of hydroexcavation is that it is much faster than air vacuum excavation, says Schmitt, adding that water is able to move more material faster and more efficiently.
“In frozen ground or harder materials, water can be heated with onboard water heaters to aid in cutting through these materials,” he adds.
Hydroexcavation equipment can often be used for adjacent applications, such as tank cleaning.
“With the onboard high-pressure water pump, hydroexcavators can perform many alternate applications that cannot be completed with pneumatic excavators,” Schmitt says.
Another benefit is that hydroexcavation does not produce the sandblasting effect the way air does, reducing the potential for damage to underground utilities, he adds.
“Water is also a lubricant, which helps to prolong the life of the excavation equipment by reducing wear on the vacuum hose and other components in the airstream,” Schmitt says.
The speed of hydroexcavation is too significant to overlook for general potholing, which is why utilities are looking for a machine with both capabilities, he says.
Vactor Manufacturing’s HXX Prodigy serves the utility market with hydroexcavation as its primary medium and air excavation as an optional medium for excavation, offering a dual-purpose machine that delivers the speed of hydroexcavation and the dry spoil feature of air vacuum excavation.
One company that uses HXX extensively is the SiteWise Corp., a 240-employee company based in Denver, CO. The company works primarily on natural gas pipeline construction in Colorado and in surrounding states, building, repairing, renewing, or doing some kind of measurement on natural gas pipelines.
Additionally, the company’s engineering operations include hydroexcavation and utility locating.
The company runs six Vactor HXX Prodigy units and a seventh unit, a Vacmaster. Five of them are for outside customers, and two are used for supporting the company’s own crews in doing hydroexcavation.
The equipment selection for daylighting is tied into the soil conditions in Colorado, points out Joe Kramer, vice president of engineering operations for SiteWise.
“A lot of our soil out here is hard clay and a lot of rock,” he says. “For the most part, we like to use hydroexcavation versus air excavation because it’s pretty impractical to dig in a lot of places where we’re at with the air excavation.”
The crews use various digging tips and water tips on its water wands for protecting the facilities upon which they are digging.
“If we’re digging on an electric facility, we might run lower water pressure and spinning tips versus a straight tip and higher water pressures for other utilities,” Kramer points out. “The only applications we utilize the air for would be digging around tree roots, and we might do that once a year.”
That approach is used in doing work in right-of-ways when a city arborist might want the company’s crews to ensure they’re not damaging a certain tree.
“We might use a lot of air around those tree roots to help protect the roots,” Kramer says. “Other than that, we pretty much use water or hydroexcavation.”
Kramer says his company doesn’t encounter any issues with water damaging the area during procedures.
“We’ve been doing this for 12 years, and over the years, you find there are best practices you use for digging around facilities,” he says. “As long as you’re following those pressures and digging tips for the proper facility, you really don’t have issues.”
