At Technics, we have been at the forefront of delivering precise and reliable underground utility surveys across the UK for over 25 years. Our commitment and expertise in underground utility mapping ensure clients across various sectors receive accurate, detailed, and reliable results tailored to their project needs.
Underground utility mapping is an essential process in modern construction and infrastructure development, involving the accurate detection and mapping of the subsurface environment, such as:
Utilising technologies like Ground Penetrating Radar (GPR) and Electromagnetic Location (EML) systems can provide a clear and comprehensive view of the assets beneath the surface. This information is crucial for planning, design, and excavation activities, ensuring safety and efficiency throughout the entire project lifecycle.
Our Vacuum Excavation service further enhances our capabilities by safely exposing utilities to fulfil the PAS 128:2022 specification quality level Quality Level A (QL-A).
The PAS 128:2022 specification, developed by the British Standards Institution (BSI), provides comprehensive guidelines for underground utility detection, verification, and location of underground utilities. It includes updates on training and qualifications for practitioners, post-processing in detecting surveys, and controls for the accuracy of detection methods. This standard sets a benchmark for all practitioners, ensuring high-quality and reliable survey data for clients.
PAS 128:2022 outlines four survey types:
Each type corresponds to a different quality level, with Type A (QL-A) providing the highest level of accuracy.
| PAS 128 Type | Quality Level | Method | Typical Accuracy | Typical Use |
|---|---|---|---|---|
| Type D | QL-D | Desktop records search | Low | Feasibility & early planning |
| Type C | QL-C | Site reconnaissance | Low–Medium | Visual confirmation |
| Type B | QL-B | GPR & EML detection | Medium–High | Design & excavation planning |
| Type A | QL-A | Vacuum excavation | Highest | High-risk or critical excavations |
This tiered approach ensures survey techniques are proportionate to risk, project stage, and budget.
Underground utility mapping involves the detection, verification, and accurate recording of buried services using a combination of desktop research, advanced geophysical survey techniques, and on-site verification methods. The aim of this process is to provide a full and comprehensive picture of the subsurface environment before any ground is broken.
A full utility mapping survey typically includes the following:
This approach helps project teams avoid costly surprises, manage risk, and plan with greater certainty.
A desktop utility records search is often the first stage of an underground utility survey and forms the basis of a PAS 128 Type D survey. This process involves collecting and reviewing existing records from statutory utility providers including gas, water, electricity, telecommunications, and drainage authorities.
Desktop searches help to:
However, desktop records should never be relied upon in isolation. Records may be incomplete, inaccurate, or out of date, which is why Type D surveys are typically followed by geophysical detection (Type B) and verification where required.
At Technics, we use a wide range of industry-approved technologies and methodologies to deliver accurate, reliable utility mapping surveys in line with PAS 128:2022.
The main techniques include:
GPR is a non-invasive method that uses radar pulses to image the subsurface. It’s effective at detecting both metallic and non-metallic utilities and provides a cross-sectional view of buried features and utilities.
Ideal for: Plastic pipes, ducts, voids, and concrete-encased utilities.
Benefits: Works in areas where EML fails, such as concrete slabs or plastic utility pipes.
Acoustic techniques involve transmitting sound waves into the ground and listening for reflections or changes. These are sometimes used to pinpoint pressurised water leaks or trace difficult-to-locate utilities and buried services.
Ideal for: Water pipe tracing, leak detection.
Limitations: Less commonly used and more situational.
Electromagnetic location is one of the most widely used techniques for detecting utilities such as electric cables and metal pipes. A signal is applied using a transmitter, and a receiver is used to trace the path and depth.
Ideal for: Metal pipes, electrical cables, telecom lines.
Limitations: Cannot detect non-metallic or poorly conductive utilities (e.g. plastic water pipes).
Vacuum excavation (also known as suction excavation) is used to verify the exact position and depth of utilities. This method safely exposes underground services by removing soil through a suction hose without damaging the utility.
Ideal for: Achieving PAS 128 QL-A accuracy level.
Benefits: Minimises the risk of a utility strike during verification.
Utility data is typically combined with a topographical survey to accurately show the position of utilities relative to ground-level features, site boundaries, and structures. This integration is essential for planning and BIM (Building Information Modelling).
Conducting an underground utility survey offers numerous advantages, especially before breaking ground. Here are some key benefits:
Not obtaining accurate utility mapping data when commissioning, planning, managing, and carrying out works on or near underground services poses a significant risk.
To mitigate these risks, it is crucial to conduct thorough utility surveys using methods such as ground penetrating radar, and electromagnetic location devices, and procuring utility reports before commencing any excavation work.
UK health and safety guidance strongly recommends identifying underground services prior to any ground disturbance. Utility surveys support compliance with the following:
Failure to undertake appropriate surveys can result in legal liability, enforcement action, and significant safety risks.
At Technics, we recognise the critical importance of understanding the purpose of your survey from the outset. This understanding enables our team of experts to tailor methodologies in line with industry specifications, including PAS 128:2022, ensuring cost-effective solutions within your budget. With over two decades of experience, our team is adept at overcoming limitations to deliver thorough and precise results.
By choosing Technics, you can proceed with confidence, knowing that your project is supported by accurate and reliable subsurface data which will help you to minimise risks.
For more information on our services and to discuss your project needs, please contact the Technics team today at enquiries@technicsgroup.com.