PAS128 Underground Utility Surveys

PAS128 Underground Utility Surveys

Utility Mapping & GPR surveys are an essential during the initial design & planning stage when considering the construction of new structures or infrastructure. The need for detailed and accurate plans which show where utility services are located allow a safer working environment and a cost-effective way to help plan any construction or building works. Castle Surveys Ltd offer a full underground utility survey that can be overlaid onto our topographical land surveys. Although based near Leicester, we can cover the whole of the UK.


Prior to the commencement of an Underground Utility Survey, we offer the option to undertake a desktop-based assessment of the site. We acquire plans from all the statutory bodies relating to your site which aids in the quality of the survey. It may also flag up services that cannot be located (for whatever reason.)

Some clients may not require a full underground utility survey, but need to know what might be underground. Here at Castle Surveys we can source recorded information relating to the presence of existing underground pipes, cables and services, which can then be overlaid onto a topographical land survey, or simply made into one single document.


The next stage of the process is for us to undertake a full underground utility survey. This will map out the locations, depths & identify the type of services on site. All surveys are surveyed utilising Electromagnetic Detection Methods (EDM) & Ground Penetrating Radar (GPR) equipment and post-processed in CAD. The final drawings are sent in PDF & DWG format.


GPR allows us to locate metallic & non-metallic pipes, along with the indication to buried services, voids and ducts within the site location plan.


Castle Surveys can undertake a range of manhole & inspection chamber assessments. This information includes the inspection chamber cover levels, chamber size and pipe details including the invert levels, material and pipe diameter. This can be added onto our topographical land surveys as an additional service if required.


Drain CCTV surveys and inspections can now be implemented to determine the pipe condition and any defects or faults you may have. This type of drain survey can provide a fast and cost-effective way to diagnose any drainage problems. We can then record the findings and produce a detailed report, plan and DVD.

PAS 128

With a range of different survey types, detection methods, quality levels and geospatial locations, the PAS 128 utility survey provides a more detailed selection criteria to facilitate the confidence in the data provided. It covers the project planning and scoping process, classification system for quality levels, desktop utility records search and detection, verification and location.

Below are the classifications levels Castle Surveys can offer as part of our PAS128 service:

PAS 128 Survey Category Type D

Underground utility plotted from utility record data only (not detected by geophysical methods). This survey can also be offered as part of our Desktop service.

PAS 128 Survey Category Type C

Underground utility plotted from utility record data only, but with site reconnaissance to match utility records with physical utility street furniture as a best fit.

PAS 128 Survey Category Type B

Utility detected by geophysical methods (single or multiple) to obtain a horizontal position and/or vertical position. (Depth) For the positional accuracy of each QL-B sub category, please refer to the accuracy diagram.

PAS 128 Survey Category Type A

Utility verified and positioned by physical identification. This may be by strategically positioned vacuum excavation, hand dug trail pitting, or by visual inspection within a utility chamber.