Accurate utility locating is important for various reasons, such as preventing costly mistakes, ensuring worker safety and keeping infrastructure intact. For workers of all experience levels, understanding and implementing best practices can make a major difference in the quality and accuracy of work.
In this article, we explore 10 practical, field-tested tips to help you learn how to locate underground utilities.
1. Always Call Before You Dig
Before you break ground on any job, be sure to call 811, the national Call Before You Dig number. You can also visit the 811 state directory to learn about the location you wish to dig. This isn't just an industry best practice — there are critical legal and safety factors involved.
Local utility companies will be notified and mark the locations of underground lines, reducing the risk to people and infrastructure. Failing to make this call can lead to severe legal, financial and safety consequences, including service disruptions and injuries.
2. Conduct a Thorough Site Visual Inspection
Make sure you have a full understanding of your work area. Perform a detailed walk-through of the site to look for signs that may indicate the presence of underground utilities. These include manholes, valve boxes, electrical cabinets and utility poles. You can cross-reference what you see with existing utility maps and job records. Any discrepancies you notice should be investigated further.
3. Use Appropriate Locating Technologies
Today, there's no shortage of tools and technologies that can be used to locate utilities. However, there isn't one single tool that will work perfectly in any situation. To improve accuracy, match your technology to the task and site conditions:
- Electromagnetic (EM) locators: These devices are ideal for detecting conductive utilities like metal pipes and electrical cables.
- Ground penetrating radar (GPR): This technology is highly effective for locating non-metallic utilities, such as plastic or concrete pipes, and for assessing complex subsurface layouts. Ground penetrating radar for utilities uses radio waves for underground utility detection.
- Probes: Soil probes for utility locating can help trace both metallic and non-metallic lines when used in conjunction with EM locators. Different types of soil probes are available for utility locating, each offering unique capabilities, from penetrating dry soil to frosted ground.
- Magnetometers: These devices measure magnetic forces and can effectively detect the magnetic fields produced by ferrous metals. They can be used in underground storage tanks, well heads or valves.
- Acoustic leak detectors: For utility technicians locating leaks in pressurized water pipes, acoustic leak detectors offer one of the most accurate ways to find affected lines. These tools use a sensitive ground listening device to deliver leak vibrations.
Using the right tools in the right situations makes detection more precise and minimizes the chance of missing underground infrastructure.
4. Understand Factors Affecting Accuracy
Several environmental and site-specific variables can interfere with locating accuracy. Be mindful of:
- Soil conditions: Moisture content or certain soil types (like clay or sand) can impact signal strength.
- Utility depth and material: Deeper utilities or non-metallic lines are harder to detect and may require specialized tools.
- Interference: Things like nearby lines, electronic devices or rebar can cause signal distortion.
Understanding these variables will help you plan, be prepared to adjust your approach in the field and interpret data more reliably.
5. Employ Multiple Frequencies and Methods
One of the best ways to improve your accuracy is to use multiple frequencies when operating EM locators. Low frequencies can help track deeper utilities with less interference, while high frequencies are better for shallow or congested environments. Likewise, pairing technologies like EM, GPR or soil probing offers cross-verification, significantly reducing the risk of misidentification or oversight.
6. Maintain and Calibrate Equipment Regularly
Even the most advanced locator won't perform properly if it's poorly maintained. Regularly inspect and clean your equipment. Follow manufacturer guidelines for calibration, and make sure firmware and software are up to date. Periodic checks help ensure the readings you rely on are accurate and consistent.
7. Mark Clearly and Accurately
Once you've identified a utility, mark it using the standardized American Public Works Association color code system. Each color represents a different utility type:
- Red = Electrical
- Blue = Potable Water
- Yellow = Gas
- Orange = Telecommunication
- Purple = Reclaimed Water
- Green = Sanitary/Sewer
- Pink = Temporary Survey
- White = Proposed Excavation
Make sure your markings are precise, visible and durable. Avoid vague or sloppy line work, as this can confuse excavation crews and increase risk on-site.
8. Log Findings and Maintain Accurate Records
Accurate documentation is key for use now and in the future. Compile accurate records by recording the exact location and depth of utilities, taking photographs of markings and making detailed notes on any anomalies or uncertainties you encounter. These records can serve as a valuable reference for future projects and site visits and help resolve any disputes or discrepancies.
9. Recognize and Avoid Common Mistakes
Locators of all experience levels can make mistakes or overlook details that result in errors. For accurate utility locating, avoid these common pitfalls:
- Relying solely on old maps: Historical records may be outdated or incomplete. Always verify on-site.
- Assuming utility depths: Never presume the depth of a line. Even small misjudgments can lead to damage.
- Neglecting to re-verify marks: Environmental factors like weather or foot traffic can fade or distort markings. Always double-check before excavating.
Staying vigilant helps maintain the highest standards of safety and accuracy.
10. Stay Updated With Training and Industry Standards
Technology, regulations and techniques in the utility locating field are constantly evolving. One of the best practices for utility locating is staying updated.
Stay sharp by participating in ongoing training and certification programs. Organizations such as the Common Ground Alliance, National Utility Locating Contractors Association, Center Line Resource and Meridian Technology Center offer valuable educational resources, standards and credentials.
You can then rely on your continuous learning to remain compliant, competitive and competent.
Improve Your Utility Locating Process With T&T Tools Inc.
Accurate utility locating requires technical knowledge, attention to detail and practical field skills. Incorporating these 10 utility locating tips into your process will reduce risk, improve safety and produce more reliable results for your clients and colleagues. Whether you're using advanced technologies like GPR or time-tested tools like soil probes, accuracy depends on smart, methodical preparation and precise execution.
If soil probes are among the tools in your inventory, take a look at the high-quality products from T&T Tools. Our subsurface probe tools, headlined by the exceptional Mighty Probe, are durable and crafted for multiple applications. For more information, browse our website, email sales@mightyprobe.com or call (800) 521-6893.
