An introduction to underground utility surveys and PAS 128: why these services are necessary

Assessing the site allows workers to understand the ground conditions they are working with before excavation begins, preventing serious damage to the underground infrastructure.

Using the latest technology, including Ground Probing Radar and Electro-Magnetic detection, utility surveys can identify metallic and non-metallic utilities such as electricity cables, gas pipelines, water mains and drainage systems, locating accurately their position and depth in the ground.

SOCOTEC UK & Ireland provide a range of complementing surveying services consisting of PAS128 Underground Utility Surveys, Topographical Surveys, Measured Building Surveys, Laser Scanning & 3D BIM models, Aerial Drone Surveys, CCTV drainage and CSO surveys, Structural Monitoring, Setting-out services, Utility Clearance Surveys, Desktop Searches and Asset Management Surveys.

Why underground utility surveys are necessary:

The primary reason for carrying out utility surveys is to save lives and prevent serious injury to workers. Damaging utilities like electricity cables and gas pipelines can cause severe harm. On average there are 12 deaths and approximately 600 serious injuries attributed to contact with the electricity network each year – this can be prevented by using surveys to identify the location of utilities to avoid unexpectedly contacting them during construction work.

The financial impact on businesses and individuals as result of bypassing utility surveys can be significant. With an estimated 60,000 underground cable strikes every year (which could be avoided by conducting utility surveys), it can cost businesses millions of pounds in associated damages, delays, and investigations, as well as compensation costs from the serious injuries and potential deaths from these cable strikes.

The accurate identification of underground utilities and their precise location saves time, as the information can be used to plan and design future construction schemes in the most cost-effective way, reducing the chances of finding unknown utilities. Encountering utilities without prior knowledge from surveys can drastically delay work and construction because it can require significant re-planning and damage control.

The British Standards Institution (BSI) introduced PAS 128 in 2014, later revised in 2022, to establish best practices for detecting utilities and standardise underground utility survey procedures and deliverables. The specification is primarily aimed at practitioners, detailing how each survey should be undertaken to ensure the necessary methodology and application.

PAS 128 establishes four survey category types for utility surveys, from D to A.

Survey Type D, Desktop Utility Records Search – to identify underground utilities through the collation of existing utility records, providing a preliminary remote overview of the site.

Survey Type C, Site Reconnaissance – to validate and support the existing records by a visual inspection of the site, producing an annotated plan.

Survey Type B, On-Site Detection – to locate and detect underground utilities using geophysical techniques.

Survey Type A, Verification – to physically observe and inspect underground utilities through a manhole or inspection chamber, or they are excavated and exposed.

Utility surveys consist of thorough investigations into the potential issues that can arise with excavation and construction work. By identifying the underground utilities, it can save lives, save money, and save time. For more information regarding SOCOTEC’s underground utility survey services, please contact us.