Utility Clearance Surveys For Lighting Column Replacement
Our client required a utility clearance survey on a construction project involving the replacement of lighting columns on an industrial site in Birmingham. The existing car park lighting infrastructure was to be improved to provide increased energy efficiency and public safety. Due to the dense underground utility network in the area, a comprehensive utility clearance survey was required to avoid accidental utility strikes when excavating.
The project involved surveying 50 individual locations with a specified clearance diameter of 10m around each point. Prior to the clearance surveys commencing on site we carried out a desktop utility search of the area to collate data from 30+ main utility providers to review their record information of what services are believed to be in situ. These statutory records provide an excellent starting point for understanding the existing infrastructure.
Once our survey teams were on site and the statutory records reviewed the clearance surveys were completed by using two non-invasive geophysical techniques;
- Electromagnetic Locating (EML): Using a multi frequency transmitter and receiver, conductive utilities were traced either passively, through the naturally occurring signals present, or actively through the transmitting of various frequency signals along the utility itself. Empty utility ducts and sewer pipes were detected by inserting a radio sonde and locating it from the surface.
- Ground penetrating radar (GPR): The GPR unit was used across the various survey areas and the signals analysed on site to confirm utility locations identified via EML and to locate any buried infrastructure not already identified, especially non-metallic services as these cannot be located by EML.
The underground utility survey results were clearly marked on the ground to inform the excavation team of the below ground utility positions and depths. These markings were then surveyed to GPS coordinates, allowing us to provide a digital CAD drawing to the client as part of our final deliverable.
Our experienced underground utility survey team delivered the project on time and to budget whilst operating in a challenging environment. Our client was very happy with the results and avoided all the complications and costs involved with accidentally striking a buried utility.
If you have a project where you need to break-ground, please contact us to discuss our utility clearance survey services.