There’s a video circulating on the Internet that shows a man, presumably in a Third World country, walking atop a train car at a busy station. At one point he reaches up to touch an overhead cable, with shocking results. It’s a tragic incident, to be sure, but it serves to illustrate well the dangers of what can happen when utility lines are carelessly mishandled.
In many cases, contractors are in a similar position when faced with the prospect of working with underground utilities when digging foundations and other structures.
Experts estimate that there are more than 13 million miles of buried utilities in the United States alone-that’s more than 500 times the circumference of the earth, and that number is only increasing with time. A growing number of excavations for inspection, maintenance, and construction combined with a lack of records for buried features and poor regulation, greatly increases the risk of not only encountering these facilities, but doing so at great risk of damage or worse.
According to the Congressional Transportation Equity Act for the 21st Century “…unintentional damage to underground facilities during excavation is a significant cause of disruptions in telecommunications, water supply, electric power, and other vital public services, such as hospital and air traffic control operations, and is a leading cause of natural-gas and hazardous-liquid pipeline accidents.”
Contrary to what most people believe, underground utility maps can often be unreliable. Sometimes, they don’t even exist. Sometimes, utility pipes or cables are relocated during repairs and renovations, but maps are not updated. Sometimes, maps represent proposed plans that don’t show as built locations. Sometimes, old maps are lost or have disintegrated. People who fulfill their legal obligations to contact a central utility marking clearinghouse before digging or drilling may feel a false sense of security since lost or mismapped utilities generally will not be marked as a result of such a call. The result of digging or drilling in the presence of unknown, unmarked, or incorrectly located utilities can be wasted excavation time (translation: money), expensive damage (translation: more money), utility downtime (translation: still more money), and worse of all-personal injury or death.
Fortunately, with the growth of the field of underground utility detection, contractors can take their future into their own hands with state-of-the-art equipment and techniques to detect, trace, and map buried utility lines. This technology includes ground-penetrating radar (GPR), seismic waves, field variations, nuclear detection, and gas detection. Multiple techniques are required in order to provide confident detection of metal, plastic, concrete, masonry, ceramic, and fiber optic pipes and cables.
Seismic waves are ground vibrations that travel through soil and rock. These can be introduced into the ground via explosives, hammers, vibrating elements, and acoustic signals in buried pipes. Seismic waves travel at different velocities in different materials and will also be reflected by discontinuities belowground.
GPR uses radio frequency signals to penetrate the ground and reflected from subsurface materials at varying rates, allowing users to determine the makeup of those surfaces.
Electrical, gravitational, and temperature field variations are used to identify subsurface objects and exhibit appropriate density reactions.
Nuclear methods typically introduce a form of radiation into the ground and measure the response of the ground with applicable detectors.
Gas detection is used to locate objects such as plastics that outgas during their lifetime. The gas defuses through the earth, and can be detected with equipment that identifies these materials in quantitative amounts.
Thanks to the development of systemwide integration of sister technologies, these techniques are often augmented with the inclusion of global positioning systems (GPSs) and optical total stations for marking and geographic information systems (GISs) for making maps or separate overlays for existing utility maps.
As mentioned earlier, proper underground utility detection methods can eliminate what in the past have often proved to be destructive methodologies. These include the following:
Soil borings-This traditional method of determining the zonation and properties of subsurface materials. Since underground utilities can be damaged if struck, borings must be used carefully in the vicinity of existing utilities. For obvious reasons, this method is not frequently used.
Test pits-This method utilizes excavation by machines (frequently backhoes) or by hand to determine the presence and extent of utilities. Test pits are employed to create a sufficiently large sample hole for the direct physical examination of the in-place utilities during the excavation process, and the cost of a test pit rises rapidly as the hole becomes deeper, the soil becomes weaker or the excavation extends below the water table. Although this method is still used, its weaknesses are obvious.
Hand excavation-This method is most commonly used when utilities are known to exist in an area of concern. Unfortunately, even when underground utilities are known to be present and such manual methods such as picks and shovels are employed, considerable damage can still occur. Although this method is sometimes still employed, it must be used with great caution.
Vacuum excavation-Also called “pot-holing,” this method is used to create holes of approximately 12 inches by 12 inches in diameter to physically confirm the position and depth of an underground utility. With this method, a hole is cut in the road pavement using a rotary core drill or jackhammer, and then the excavation is advanced utilizing compressed air jets and/or high-pressure water jets. The excavation process does not normally damage an existing utility, and the hole in the street pavement is kept to a minimum and is easily repaired. This procedure can be used to confirm, within hundredths of an inch, the exact horizontal and vertical positions of known utilities, providing elementary data regarding the size, shape, and composition of the pipe/cable and general soil conditions. This is a primary excavation method used to determine the X, Y, and Z coordinates of all utilities.
“Fortunately, the drawbacks of many of these methods are obvious,” says Jonathon Tan, president and chief executive officer of Geotrack Inc. in Lake Forest, IL. “They’re better than nothing. But often, after contractors contact the one-call system, they often have a false sense of security. They think they’re covered, and often that’s true, but it also doesn’t hurt to have the extra insurance of using modern underground utility detection methods to verify the all-clear that often comes with one-call systems.”
Nondestructive geophysical methods of determining the location of underground utilities consist of methods that utilize a wave or other signal that is introduced into the ground. An instrument is then used to measure the ground response, and, based on this response, information is inferred about the position and type of object that is belowground as well as soil properties. Many of the methods can be used in several different arrangements that vary in terms of what can be detected, depths of penetration, sizes and types of objects that can be resolved, and implementation cost.
One of the most popular methods is GPR, which uses radio frequency signals to penetrate the ground. These signals are introduced to the ground with antennas that determine the frequency of the wave introduced.
“There is no one method that should be considered the single best tool for underground utility detection,” Tan warns. “Fortunately, the technology available today is excellent. But as is the case with most technology, there are drawbacks to each one.”
What You Want Is What You Get
The proper resources for utility detection often boil down to a simple matter of “rent or buy.”
Matt Wolf, president of Mala GeoScience USA Inc. in Charleston, SC, advocates purchase of GPR systems, thanks in large part to the combined attributes of accuracy and ease of use of today’s technology. According to Wolf, regardless of the subsurface testing needed, Mala has the technology that can accomplish the mission.
Purchasing easy-to-use GPR equipment that is readily available to users is also a prime reason given by Don Plosser, president of Pipehorn Locating Technology (Birmingham, AL). Plosser, a longtime developer of GPR systems explains, “When contractors are intimately familiar with the equipment and what it can do for them, it takes all the mystery of what it can do out of it.”
Edward Reitz, president of Rycom Instruments Inc. in Kansas City, MO, takes the locating task one step further by providing what he calls “total packages” not only for utility detection but also underground cameras and phase-identification systems.
Not to be outdone, Goldak Inc. president Bob Mulcahey attributes the success of his Glendale, CA-based company to providing quality locating systems as well as leak detectors and other equipment for approaching specific work with specially made tools. “I think that too often contractors approach their work with the wrong equipment,” he explained. “Contractors know exactly what they are approaching, but when they are sold equipment, they frequently will be sold what the vendor has that most closely approximates what they need. In our case, we pride ourselves on having the specific equipment they need for their work. Nothing else.”
The same approach is used by the Vivax Corp. of Emerson, NJ, which produces locating and inspection systems for utility operations. According to company representative Norma Holland, “Ease of use by field technicians is important to us in producing equipment that is practical to use,” she says. “With our vLocPro tool, field technicians can locate, trace, and position buried utility pipes and cables.”
Simplicity and ease of use are important attributes for users, whether they be experienced or novices. Accuracy is important, of course, but the vLocPro was designed with a highly intuitive interface that minimizes the training time for first-time users as well as those transferring from other systems.
Vivax expands the capabilities of its vLocPro capabilities with two camera tools which record images made from the locator. Further, images can be made to attach to reports, and DVDs with recorded information can be made for clients and other parties.
Specialty is also the watchword of Schonstedt Instrument Co. of Kearneysville, WV, which makes locating equipment for every use from cable television lines to well casings.
Paying an Expert
Not up to the task? Not a problem. Several firms bill themselves as experts in the GPR business.
Greg Summers, a sales representative for Sensors & Software Inc. in Mississauga, ON, calls his company a “keen eye in subsurface imaging.” According to Summers, “We provide a large number of services when it comes to GPR technology. Sometimes, a client just needs an expert. Other times, clients need to whole gamut of products and services. We can easily accommodate those too.”
Indeed, Sensors & Software has been called upon to detect utilities of practically all types. The company has located pipes and cables of metal, plastic, and concrete, among others. It has also used its personnel and equipment to locate ducts and vaults and other subsurface items.
Sensors & Software is also known for its quality training of outside equipment owners, which, according to Summers, leads to maximizing the return on purchased equipment quicker than simply trial-and-error methods.
SubSurface Instruments Inc., of De Pere, WI, also augments its wide range of equipment sales with repair services, a feature not offered by many equipment manufacturers.
According to Ron Davenport, president of the firm, “We specialize in providing equipment that can not only detect pipes and other underground equipment, but we also have gradiometers that can detect ferrous metals underwater. These are often used in forensic investigations where someone is looking for weapons or perhaps a treasure hunter is looking for things like cannons, anchors, ships, and other items.”
Seeing What Can’t Be Seen
Knowing what is happening belowground is important but often requires that the methodology used be noninvasive. That’s when a combination of technologies is most likely used.
Not only sensing but seeing what is happening below the surface is the specialty of Underground Imaging Technologies of Latham, NY, a firm that offers integrated hardware and software solutions that provide not only data but 3D imaging and mapping of the hidden world of utilities to owners and other interested parties concerned with design, construction, and management of the underground infrastructure.
Laurie Karian, a company representative, says risk management has become a growing concern among contractors who depend on the data collected about utilities for assessing risk.
Another key element in the equation is GIS, which allows for the production of and maintenance of infrastructure data. Regarding the data layers used, including subsurface utility engineering (SUE) data and existing records, they can be made available for use of all data clients.
Getting to the Goods
You’ve successfully found the utility lines you are looking for. What sense does it make to find them without damaging the sensitive equipment, only to cause expensive damage when trying to reach them? This scenario is best prevented with good digging equipment, says John Bieberdorf of Perry, OK-based Ditch Witch, a firm specializing in a variety of trenching tools often used to prepare for laying utility pipes and other lines as well as to help find those resources.
“Most contractors who use this type of equipment have learned that they will use it frequently to verify the location of lines and pipes,” Bieberdorf explained. “Often, they are so successful and happy with the results that they end up saving considerable amounts of money by buying the equipment.”
Vendors also supply a multitude of ancillary tools and equipment. Stanley Works in West Lafayette, IN, produces industrial hand tools and toolboxes, professional and industrial mechanic’s tools, electronic diagnostic tools, pneumatic fastening tools and fasteners, hydraulic tools, shearers, breakers, and crushers.
Renting the Needed Equipment
Let’s face it. Sometimes, purchasing equipment is just beyond the budget of some contractors. In other cases, utility-detection equipment will be used, at most only a limited number of times.
For those, rental of equipment can be a viable option, although most agree that this should be considered only when operators are qualified to interpret data collected.
United Rentals in Greenwich, CT, RSC Equipment Rental in La Porte, TX, and Sunbelt Rentals in Charlotte, NC, all provide numerous locations for renting utility-locating equipment on short-term or contract basis.
Where’s it Going?
Obtaining reliable subsurface utility data is important to the successful completion of a project, but when a project requires extensive recording of data, specialists in not only gathering data but mapping relevant information are critical. That’s the reason many contractors nationwide use the services of such firms as Utility Mapping Services Inc. in Clancy, MT. Steve Wolowina, manager of general operations and marketing for the company attributes the success of the firm to being focused on SUE.
Wolowina explains, “We’re a small firm, but we take pride in the teaming approach we use to build relationships between those who know the specific needs of a project with the technological solutions available.”
UMS approaches SUE as a highly specialized and strategic professional service. Each project inherently has unique problems and characteristics that can be best handled through a suitable application of professional experience, technology, and local knowledge. UMS works at forming relationships with the most apt local firms to best leverage institutional knowledge and perform the project with optimal speed and efficiency. Likewise, UMS utilizes industry-leading expertise and state-of-the-art technology in high-resolution geophysics, vacuum excavation, GPS land survey, GIS data management, and utility engineering and construction from across the United States. Although UMS is a small business, no SUE project is too complex, large, or fast-paced under UMS project management.
Using Subsurface Data
The drawbacks presented by such issues as redundant data capture, poor record keeping, non-integrated data systems, and inaccurate utility maps still plague the industry. Fortunately, by using utility detection equipment that is quickly evolving to keep up with demands, these shortcomings are quickly being solved and will present new opportunities for growth of the industry in the future.
Regardless of the methods used for utility detection and maintenance, cost-benefit analysis is the bottom line for any information technology project.
Despite what are often considered to be difficulties in quantifying the benefits of these methodologies, the history of the use of these methods is beyond a doubt.
The irrefutable history of these technologies is clear. Underground utility detection equipment and methods don’t cost: They pay. In relative terms, the equipment available today can be either purchased or rented at nominal costs. Further, a minimal number of technically trained staff is required to access, maintain, and analyze data.And when compared to the benefits from the use of utility data, practically all users, from accounting to engineering and construction to repairs and maintenance, will come out ahead in the long run.