Utility Surveys
The Health and Safety Executive recommend that a utility survey should always be carried out prior to any excavation works.
Sandberg offers utility surveys ranging from a small local ‘virtual trial hole’ to full site surveys. In order to provide the best possible results, a range of techniques tailored to detect different services is utilised. For utility surveys, we recommend the following methods:
- Ground Penetrating Radar (GPR)
- Electromagnetic Radio Detection (CAT)
- Signal Transmitter (sonde)
- Lifting of Manholes
- Statutory undertakers search
Sandberg will use the most appropriate methods for the utility survey, record site information using a Total Station to ensure accurate positioning, analyse and collate all the data and present the information on a CAD drawing and easy to understand report.
Ground Penetrating Radar (GPR)
Ground penetrating radar detects changes in the ground. It is able to detect metallic and non-metallic services including plastic and clay pipes; as well as other features such as culverts, tanks and obstructions. GPR also provides depth estimates; under good site conditions accuracy is generally within +/-10%
The GPR site survey involves collecting scans on a regular orthogonal grid. The collected data is then analysed off-site and detected services plotted on a CAD drawing. The GPR data can be interpreted on site in real time. This can be useful in some instances, however the detail is inferior and services can be easily be missed.
Electromagnetic Radio Detection (CAT)
A CAT is a radio frequency detector that responds to low-frequency radio signals which can be radiated by electric cables and long conductors. A signal can also be induced into a conductive service using a signal generator, to enable the service to be traced. Detected services are marked up on site and can be plotted on a CAD drawing if required.
Signal Transmitter (sonde)
Where suitable access is available, we use a flexible cobra rod and sonde to trace drainage runs. The sonde is a signal generator enabling accurate plotting of deeper drainage runs which may be out of range of GPR.
Lifting of Manholes
Where possible, all manholes within the survey area are lifted and details of chambers, gullies, services and drainage recorded. By recording all physical data, the accuracy of the survey is improved. Depth information can also be used to carry out insitu depth calibration of the GPR.
Statutory undertakers search
Sandberg can undertake a desk study of existing utility drawings. We can contact utility companies on your behalf and obtain copies of available records. The report outlines features below the surface such as gas and oil pipelines, electricity cables, telecommunication cables, mains water, sewers and fibre-optic cables.
For further information contact: Rom Gostomski, Associate
Direct Tel: 020 7565 7054
Email:
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
|
Ground Radar (GPR) 
