Utility survey

Another powerful technology we employ when performing utility detection survey is EML (Electromagnetic Locator). It is one of the primary tools used if conducing utilities survey. It operates by detecting and tracing the electromagnetic signals emitted by underground utilities. Our surveyors use advanced EML equipment to precisely locate buried utility lines, enabling us to provide you with accurate information about their depth, alignment, and type.

Please note that not all utility surveys must meet level A of PAS 128 industry standards (the most precise survey involving trial pits) if you choose to keep the cost of utility survey down. 

A utility survey is a crucial step in any construction or excavation project, as it allows for the identification and mapping of underground utilities. These utilities can include electrical cables, drainage, water pipes, gas lines, telecommunications infrastructure, and more. By accurately detecting and mapping these utilities, potential conflicts and hazards can be avoided, ensuring the smooth progress of your project.

Having utility survey completed in an early stage of the development might allow your company to extend the boundary of the project. That is especially important nowadays with the ongoing shortages of developable land.

Another important aspect of utility survey is increased site safety. Utility strikes during construction or excavation projects are serious risk. Damaging existing underground infrastructure can have substantial financial repercussions on your business, not to mention injuries to the workers and public or in the worst-case scenario on site fatalities.

According to UK DIRT Report, in 2023 there were 4 million holes and excavation dug across United Kingdom every single day with 60,000 utility strikes which costed UK economy £2.4 billion. The report observed that utility strike numbers over the recent years show increasing tendency.

Utility survey performed by trusted surveying company will greatly mitigate that risk and should be considered in your utility damage prevention plan.  

Ground Penetrating Radar (GPR) is one of the primary tools used if conducing utilities survey. By sending high-frequency electromagnetic waves into the ground and analysing their reflections, GPR allows us to create detailed subsurface images. This helps us identify not only the location of utilities but also detect additional features such as voids, rebar, and geological anomalies. By combining EML and GPR data, we deliver comprehensive utility survey that leaves no room for uncertainty.

Utilities located with geophysical methods, such as Ground Penetrating Radar (GPR) meet category B at PAS 128 accuracy levels. That means you will know horizontal and vertical position (depth) of any detected object.

As already mentioned, Ground Penetrating Radar (GPR) and Electromagnetic Location (EML) are totally different technologies:

GPR works by sending a signal into the ground and listening for reflections from that signal and contains its own transmitter and receiver within the unit.

EML works by detecting the electromagnetic signal that may be emitted by power cables, or the energy from low frequency communications signals which has ‘coupled’ onto metal services. Alternatively, in the case of a metal service which is not a power cable, it can be induced to emit a signal by accessing the service and clamping a separate transmitter onto it.

Let us explore the main differences between those two techniques as when conducting a survey, they need to be approached in a logical way and require training and experience to produce the best results.

Based on our experience and controlled experiments, Ground Penetrating Radar will recover the locations of more underground features compared to Electromagnetic Location methods (within the penetration and resolution limitations of a GPR) in a like for like test with no manhole access.

PAS 128 refers to the Publicly Available Specification 128, which is a widely recognized standard developed by the British Standards Institution (BSI) for all utilities survey providers. PAS 128 provides guidelines and recommendations for conducting utility surveys and determining the accuracy level of utility information. It aims to improve the quality and consistency of utility data collection and mapping processes.

PAS128 defines four survey levels (D, C, B, and A), each representing different levels of accuracy and data quality. These levels guide utility survey practitioners in selecting the appropriate survey method based on project requirements.

Level D: Desk-based utility records and historical information are used for preliminary identification of utilities.

Level C: Site reconnaissance and visual inspection are conducted to verify the existence of utilities.

Level B: Detection technologies, such as Ground Penetrating Radar (GPR), are used to locate and map utilities.

Level A: Precise, high-accuracy methods, such as trial pits or vacuum excavation, are employed to expose and verify the location and attributes of utilities.

Our utility survey processes are strict and follow the steps below:

Desk-based research

The first step in a utility survey is to conduct a desk-based study to gather information about an area. This can include obtaining utility records and plans, site history, photographs, and any previous survey data.

If you cannot provide records information (STATS) we can obtain them ourselves. STATS records offer us valuable insight into which utilities and services are supposed to be present in the ground and roughly where they may be. The STATS information is also very helpful for ruling out what is not expected within a given area. Finally, having access to STATS records can help to identify services which would otherwise be classified as unknown.

Site reconnaissance

We begin by understanding your project requirements and objectives. Our team assesses the site and reviews available plans and records to gather essential information about existing utilities.

Utility survey cost is estimated on the project-to-project basis.

When requesting a quotation, it would be helpful if you could include a clear survey boundary (something like a google maps image or a topographic survey, with a clear line showing the extents of the area), in addition it would be helpful if you can specify what kind of survey you would like (if you know).

If you are unsure exactly what you need, contact us and we can discuss your requirements in more detail.

For more information about utility surveys, or to request a quote. Please contact us at info@kbgprsurveys.co.uk or fill in the contact form below.