What is Underground Service Locating


Do you know exactly what’s beneath your site before undertaking any excavation or digging activities? 

You might be surprised to learn that there is a vast network of underground services that are essential for modern living.

Located underground utilities in Sydney by Geoscope

But how do we locate them? Join me as we dive into the interesting world of underground service locating and learn what it is, and the techniques used to ensure the safety and efficiency of your construction and excavation projects.

What is Underground Service Locating?

Underground service locating is the important process of identifying the location and depth of underground utilities and infrastructure, such as gas lines, water pipes, electrical cables, telecommunication lines, sewer, or stormwater drainage pipes.

It’s a mix of art meeting science.

Underground service locating is important to ensure that these underground utilities are not accidentally damaged or disturbed during construction or excavation work.

The process typically involves using various techniques and equipment such as ground-penetrating radar, electromagnetic service locating, and vacuum excavation to identify the exact location and depth of the utilities.

Using GPR and Electromagnetic Induction method in locaitng underground utilities in Sydney by Geoscope

Tools for Underground Service Location

Underground service locating teams can locate services and mark them straight onto the ground with marking paint, chalk, crayon, or flags

Concrete Slab Scanning service by Geoscope

We can capture the data with site photos, detailed utility reports, draft plans in the office, or survey the findings down to millimetres using precision surveying instruments.

Professional and certified service locating companies like Geoscope offer these services to help prevent damage to underground utilities and ensure the safety of workers and the public.

The Underground Service Locating Methods

Electromagnetic Service Locating

Electromagnetic service locating utilises various techniques to detect and locate underground utilities using electromagnetic signals. Here are the specific methods employed:

Direct Connection


This method involves physically connecting a transmitter directly to the utility or pipe using an exposed access point, such as a valve box or meter box and directly connecting a signal through it. 

By inducing a signal onto the line, a receiver can detect and determine the location of the electromagnetic field the utility is radiating.

Induction Clamp

Induction clamping is a technique used for locating buried utilities, such as pipes and cables, without the need for a direct physical connection. 

An induction clamp, placed around the suspected utility, induces a signal onto the line. The receiver detects the signal and identifies the location of the utility.

Geescope ring clamp induction method of utility locating in Sydney, NSW, Australia


The induction method uses a transmitter placed directly above the suspected location of the utility via placing it directly on the ground or via a 2 person sweep to induce a signal onto a utility or pipe, and a receiver detects the signal to determine the location. It does not require physical connection or clamping.


Passive Locating Method of underground utilities in Sydney, service provided by Geoscope

Passive locating method involves detecting naturally occurring electromagnetic signals emitted by buried utilities. 

This method does not require a signal transmitter but relies on the presence of electrical currents and frequencies flowing through the utilities.

The different modes used in electromagnetic service locating are as follows:

Power Mode

Power mode locates buried metallic lines and conductors by detecting power frequency signals (e.g., 50-60Hz) present on most buried cables and pipes. It is useful for detecting conductors carrying power frequency signals, although it may not provide identification or precise depth measurements.

Radio Mode

Radio mode utilises Very Low Frequency (VLF) radio energy present in the atmosphere. Buried metallic lines act as aerials and re-radiate these signals, allowing the detection of conductors such as telecommunication cables and metal pipes. It complements power mode by detecting lines that may be missed using power-frequency-only detectors.

Ground Penetrating Radar Service Locating – GPR

Ground Penetrating Radar (GPR) is a non-intrusive method that uses radar pulses to create images of subsurface structures. 

In underground service locating, GPR can be used to detect and map the location of utilities and other buried objects. Particularly in identifying non-metallic utilities like plastic pipes, as well as providing detailed information about the depth and composition of subsurface structures.

Ground Penetrating Radar being used in a perpendicular angle in Sydney service provided by Geoscope

If you are interested to learn more about how GPR works in finding underground utilities, this article is for you!

How Ground Penetrating Radar Works To Find Underground Utilities

Ground Penetrating Radar (GPR) is a powerful geophysical tool that enables non-destructive detection of subsurface objects and structures, such as pipes and cables.

Utility Surveying

Utility surveying is a systematic approach to gather accurate information about underground utilities and their spatial characteristics. It involves using various techniques and instruments to identify, locate, and map the utilities. 

Utility Surveying Services in Woolloomooloo NSW by Geoscope

Overview of utility surveying and its significance

Data Collection

Utility surveying employs a combination of methods such as field surveying, geophysical surveys, and data analysis to collect comprehensive data about underground utilities. This includes their location, depth, size, material, and other relevant attributes.

Surveying Techniques
GPR & Total Station Utility Survey Equipment service provided by Geoscope

Utility surveying utilises techniques such as electromagnetic detection, ground-penetrating radar (GPR), electromagnetic locators, and GPS/GNSS (Global Navigation Satellite System) to accurately identify and map utilities. 

These techniques provide non-intrusive means of collecting data without causing damage to the utilities.

Mapping and Documentation

The data collected through utility surveying is used to create detailed maps, drawings, and utility records. This documentation aids in visualising and understanding the underground infrastructure, facilitating effective planning, design, and decision-making during construction and maintenance projects.

Risk Mitigation

Utility surveying plays a crucial role in mitigating risks associated with underground utilities. By accurately mapping the location of utilities, potential conflicts or clashes with proposed construction or excavation activities can be identified in advance. This helps prevent accidents, service disruptions, and costly repairs resulting from accidental utility strikes.

Efficiency and Cost Savings

Utility surveying enhances project efficiency by providing accurate and up-to-date information about utilities. This information allows for better project planning, design optimisation, and coordination with utility providers. 

By reducing the likelihood of unforeseen conflicts or delays, utility surveying helps save time and costs associated with construction or excavation projects.

Utility Surveying Services by Geoscope Enhances the Project Efficiency

Utility surveying enhances project efficiency by providing accurate and up-to-date information about utilities. This information allows for better project planning, design optimisation, and coordination with utility providers. By reducing the likelihood of unforeseen conflicts or delays, utility surveying helps save time and costs associated with construction or excavation projects.

Legal Compliance

Utility surveying ensures compliance with regulations and guidelines regarding the identification and protection of underground utilities. It helps meet the requirements set by authorities, utility providers, and industry standards, ensuring safe and responsible construction practices.

Quality Level B Subsurface Utility Investigation (SUI)


Quality Level B SUI investigation is a classification system used in utility surveying to determine the accuracy and reliability of the gathered data. 

QL-B investigations involve using GPR, desktop studies, and other techniques to provide a general indication of utility locations. 

Here’s an explanation of Quality Level B SUI investigation:

Data Collection

Quality Level B investigation involves using various non-destructive methods to collect data about underground utilities. 

This includes conducting surveys, reviewing existing utility records, and using geophysical techniques to determine the approximate location and attributes of utilities.

Utility Surveying Services in Woolloomooloo NSW by Geoscope

Quality Level B investigation provides a higher level of accuracy compared to lower quality levels. The data collected helps establish the horizontal position of utilities with reasonable certainty, allowing for more accurate project planning and design.


The data gathered during Quality Level B investigation is typically depicted on utility maps, drawings, or other visual representations. 

This visualisation aids in understanding the spatial relationships between utilities and assists in decision-making during construction or excavation projects.


It’s important to note that Quality Level B investigation has its limitations. While it provides a more detailed understanding of the utilities, it may not provide precise vertical information, such as the depth of utilities, or detailed information about utility materials or conditions. These limitations are addressed in higher quality levels.

Quality Level A Subsurface Utility Investigation (SUI)

Quality Level A SUI investigation represents the highest level of accuracy and precision in utility surveying. 

It involves more comprehensive data collection and verification such as physically exposing utilities through techniques such as potholing, non-destructive digging (NDD), and slit trenching compared to lower quality levels. 

QL-A investigations provide more accurate data about the precise location and depth of utilities. 


Here’s an overview of Quality Level A SUI investigation:

Data Collection

Quality Level A investigation employs the use of advanced techniques to gather highly accurate data about underground utilities. This includes methods such as potholing, NDD, or other geophysical methods that allow for direct exposure and measurement of the utilities. It involves physically excavating the ground to visually confirm the presence, location, depth, and attributes of the utilities.

Precision and Accuracy

Quality Level A investigation provides the highest level of precision and accuracy in utility surveying. 

By directly exposing the utilities through techniques like potholing or non-destructive digging (NDD), precise measurements and observations can be made to determine their exact characteristics. This level of detail ensures the most accurate mapping and documentation of the utilities.

Verification and Validation

Quality Level A investigation focuses on verifying and validating the data collected during lower quality levels. It aims to confirm the accuracy of utility records and resolve any discrepancies or uncertainties. By physically exposing the utilities, it provides a reliable source of information for decision-making during construction, maintenance, or infrastructure projects.

Risk Mitigation and Safety

Quality Level A investigation significantly reduces the risk of accidental utility strikes during excavation or construction activities. 

By directly exposing the utilities, potential conflicts or clashes with proposed work can be identified and addressed. 

This enhances safety for workers, minimises disruptions to utility services, and prevents costly damages.

Comprehensive Documentation

Quality Level A investigation results in comprehensive documentation of the utilities. This includes accurate measurements, detailed descriptions, photographs, and mapping of the exposed utilities. The information obtained during Quality Level A investigation is crucial for future reference, utility management, and ongoing maintenance or upgrades.

Legal and Regulatory Compliance

Quality Level A investigation ensures compliance with legal requirements and regulations pertaining to utility identification and protection. 

It helps meet the standards set by regulatory authorities, utility companies, and industry guidelines. 

By following the highest level of investigation, project stakeholders demonstrate a commitment to responsible construction practices.

If you are interested in learning more about Quality Level A of Subsurface Utility Information, we’ve written an article just about that, click the link below for your reference

Quality Level A (QL-A) | Subsurface Utility Information (SUI) Survey

Have you ever wondered what a Quality Level A (QL-A) Subsurface Utility Information or SUI Survey is?

The integration of these underground service locating methods ensures that construction and excavation projects can proceed safely and efficiently. By accurately identifying and mapping the utilities beforehand, the risk of damaging critical infrastructure is significantly reduced, ensuring the safety of workers, the public, and the integrity of essential services.

Do-It-Yourself Underground Service Locating Methods

Although underground service locating can include state-of-the-art locating and surveying instruments, it’s important to understand that locating pipes and cables also includes less precise activities. These tasks can be completed by professionals, certified locating organisations, or excavation crews that are adequately trained in the role. Some of these do-it-yourself methods include:

Ordering BYDA Plans

BYDA (Before You Dig Australia) plans provide information about underground utilities in a specific area. 

By obtaining these plans, you can gain insight into the location and type of utilities present.

Before You Dig Australia new logo and service name

Desktop Utility Investigations

This involves researching and gathering information from utility providers, local authorities, and historical records to understand the underground infrastructure in a particular area. It can provide preliminary knowledge about the utilities present, although it may not be as accurate as other methods.

Speaking with Site Owners

Talking to site owners to gin insights on underground utilities on-site

Engaging in conversations with owners or occupants of the site can offer valuable insights. 

They may have information about any previous utility work or any known utilities on the property.

Walking the Proposed Route

A physical walkthrough of the proposed construction or excavation area allows for visual inspection and identification of any visible signs of utilities, such as above-ground markers, utility covers, or exposed utility lines.

Walkthrough inspection of visible utilities on-site service provided by Geoscope

Discussing the Project with Asset Owners

Contacting utility companies or asset owners directly can provide specific information about the location and depth of underground utilities. They can guide you on any precautions or additional steps required for safe excavation.

Hand Digging and Manual Excavation

Do it yourself potholing method of locating underground utilities

In some cases, manually digging small test holes or trenches can help verify the presence and location of underground utilities. 

This method allows for visual confirmation and can be combined with other locating techniques for increased accuracy.

In some cases, manually digging small test holes or trenches can help verify the presence and location of underground utilities. This method allows for visual confirmation and can be combined with other locating techniques for increased accuracy.

It’s essential to note that while these do-it-yourself methods can be helpful, they may not provide the same level of accuracy and reliability as professional service locators. Professionals are trained to use advanced equipment and techniques to ensure precise and comprehensive underground service locating.

If you are interested in hiring an Underground Service Locator instead of just doing DIY locating by yourself, this article is for you!

Hiring an Underground Service Locator in Sydney – Everything You Need to Know

Are you planning a construction project, or any kind of excavation work in Sydney, it is essential to hire an Underground Service Locator to ensure the safety and integrity of underground pipes and cables, here's why...

Underground service locating is a crucial process for identifying the location and depth of underground utilities before construction or excavation projects. It involves a range of methods that we have mentioned. By understanding and utilising these methods, projects can be carried out with enhanced safety and efficiency, ultimately saving time, and money, and preventing accidents.

Remember, always prioritise safety when working near underground services, and if you’re unsure about the location of any underground utilities, don’t hesitate to contact a professional service locator like Geoscope Locating. By doing so, you can help prevent accidents, make informed-decision, save time and money, and ensure that your project is completed efficiently and effectively.

If you are interested in getting in touch with Geoscope Locating, you can e-mail us at info@geoscopelocating.com.au or call us at 1300 750 350, or simply fill out the contact form below.

Thank you for reading this article on underground service locating. We hope that you now have a better understanding of the different methods and technologies used to locate buried utilities and other underground services.

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Patricia Cupiado

Co-Author of this Article

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