Utility Locating Is the First Step in Preventing Utility Strikes
Preventing damage to buried utilities is an ongoing effort for utility providers, contractors who install utilities, and others who perform any type of construction or work that excavates or displaces the ground.
Damage to buried utilities disrupts essential services that are costly and time consuming to repair or replace. Utility hits also can cause severe injury and death – an equipment operator whose tool or machine cuts a power cable is at risk for serious shock or electrocution. Cutting or nicking a high-pressure natural gas line can result in a major disaster when migrating gas enters a building or buildings and is ignited by a pilot light or other flame.
While damage control initiatives have made great progress in recent years, much remains to be done. In fact, the latest Common Ground Alliance (CGA) Damage Information Reporting Tool (DIRT) report estimates that in 2016 there were approximately 379,000 utility hits with direct costs to stakeholders conservatively estimated at $1.5 billion.
CGA, the nonprofit, member-driven organization dedicated to establishing and promoting practices to prevent damage to underground utility infrastructure, is a driving force in developing guidelines that when correctly implemented help protect buried infrastructure, including Best Practices, and DIRT reports that provide data about root causes of accidents reported in confidence by industry stakeholders.
Most guidelines and best practices place accurately locating and marking existing utility as the first step in preventing accidental utility strikes.
DIRT reports have consistently documented that failure to request locates with the nation’s One-Call system is the root cause of a considerable number of utility incidents, said John Lamerton, director of Product Management at Subsite Electronics.
Utility owners and the contractors who serve them should have such awareness, but damage is frequently caused by other specialty contractors. To address lack of awareness, many utility companies are conducting public services announcements on local broadcast media to “Call Before You Dig.”
CGA has developed an 811-communications campaign available to stakeholders to support call-before-you-dig awareness about the national toll-free number that connects to the One-Call center nearest the caller. The program includes a suggested 811 calendar, 811 graphic standards, messages for use on social media, an 811 Day and National Digging Month.
“As a leading manufacturer of products that include utility locating equipment, Subsite Electronics actively supports these awareness programs,” said Lamerton. “We’ve designated our equipment as Underground Awareness Solutions.”
Awareness, Lamerton said, also means recognizing that all buried infrastructure is not located by One-Call. “One-Call makes locates for member organizations,” he said, “and not all utility providers are One-Call members. Typically, water and sewer lines are not located by One-Call.”
Neither does One-Call make locates on private property, so other arrangements must be made to find and mark buried utilities on property such as business complexes, universities, government properties such as military bases, and a host of other sites. “Many contractors carry their own locators and have personnel trained to use them. There are times when they may have to confirm or verify locates. When it comes to marking locates, a handheld electromagnetic locator is the most commonly used tool,” Lamerton said.
Electromagnetic locators consist of a lightweight handheld receiver and small transmitter. Underground pipe and cable is located by detecting electrical current that pass through them. To locate communications cable and metallic pipe, the transmitter is connected to the cable or pipe to send current through the line creating a signal which is detected by the receiver. For plastic and composite pipes with tracer wire, the wire is energized by the transmitter to provide a signal that the receiver picks up and processes.
The operator walks above where utilities are expected and reads information displayed on the screen at the top of the receiver. Different frequencies and modes help identify different types of utilities. There have been significant improvements in locating ability and screening out nearby signals that could compromise accuracy of readings.
For example, Subsite Electronics’ UtiliGuard multi-frequency locator has accuracy-enhancing features such as Ambient Interference Measurement (AIM) technology, which automatically recommends the best frequency.
Ground Penetrating Radar (GPR) locators use radio waves to penetrate the ground and bounce off buried objects which do not need to carry an electrical charge. The radio wave generating component is mounted on a wheeled platform that is pushed like a lawn mower across the work site while generating radio pulses downward. The radar waves bounce off buried objects and reflect back to a receiving antenna. A graphic representation of information is displayed on the unit’s screen.
The Subsite 2550GR Ground Penetrating Radar System can help locate any type of utility conduit or piping beneath soil, rock, pavement, and other surfaces. It has a user-friendly Window’s-based interface with productivity-enhancing benefits and easy integration of GPS data. However, GPR locating technology is not effective in all soil conditions, including dense soils.
Another option to locate utilities is potholing. How better to know the exact location of an underground pipe or cable than to expose it and see it? Today, the recommended method of potholing is by “soft” excavation with a vacuum excavator. Compact, trailer-mounted models are easily moved to and around job sites.
Vacuum excavators can dig a precisely-controlled hole 12 by 12 in. to depths of 5 ft in about 20 minutes. Excavation is accomplished either with high-pressure water or air, depending on brand and model. As the excavation is made, displaced soil can be sucked up by the machine’s vacuum system.
Most vacuum excavators used for potholing are compact models mounted on trailers, but truck-mounted models are preferred by some. Subsite’s sister company, Ditch Witch, offers a line of vacuum excavator models mounted on trailers and three truck mounted models. Passive Electronic Markers are passive RFID (radio frequency identification) marking “balls” that make plastic pipes locatable without the use of tracer wires. Installed at intervals along the path of the pipe they are located by a handheld locator. The maintenance-free markers have no electrical components and are corrosion resistant.
“New and better locating technologies, data identifying root causes of incidents, commitment of stakeholders, and a greater awareness of the importance of protecting underground infrastructure contribute to the shared goal of reducing accidental utility hits,” concluded Lamerton.
This article was submitted by Subsite Electronics, a Charles Machine Works Company. Subsite is committed to providing underground construction professionals the most comprehensive suite of electronic products in the industry, including utility locators, horizontal directional drilling (HDD) guidance equipment, equipment machine controls, and closed-circuit television remote inspection and monitoring cameras and accessories. By utilizing innovative technologies, extensive market feedback and outstanding customer support, Subsite has established itself as the premier source of electronic technology to support the installation, maintenance and inspection of underground pipe and cable. For more information, visit subsite.com.