Southwest
Environmental LimitedSouthwest
Environmental Limited| London |
| 02076 920 670 |
| Exeter |
| 01392 927 961 |
| Manchester |
| 01612 970 026 |
| Bristol |
| 01173 270 092 |
Striking a buried utility during site investigation or construction is a risk you cannot afford to take. Beyond the severe health and safety hazards of hitting live gas, electric, or water lines, utility strikes cause massive project delays, redesign costs, and heavy fines. Southwest Environmental Limited (SWEL) provides PAS 128 utility surveys to minimise these risks. Whether you are an architect in the design phase or a developer breaking ground, our comprehensive underground mapping ensures you know exactly what lies beneath your site before any excavation begins.
PAS 128 is the current British Standards Institution (BSI) specification for underground utility detection, verification, and location. Before PAS 128 was introduced, utility surveys were highly variable, leaving clients unsure of the accuracy or thoroughness of the data they received. Today, a PAS 128 survey provides a standardized, robust methodology for mapping active, abandoned, and unknown buried services. It ensures that every utility survey is conducted to a recognized national standard, giving engineers, designers, and site workers absolute confidence in the site data.
PAS 128 utility surveys offer several advantages over other underground mapping methods:
PAS 128 is not a one-size-fits-all survey. It is categorized into four distinct Quality Levels, representing a progression from basic desktop research to precise physical verification.
This level involves collecting data using a variety of methods, such as field surveys, interviews, and visual inspections. The data collected at this level is used to identify potential utilities, but it does not provide a definitive location of the utilities.
Best for:Initial project feasibility, site acquisition, and high-level planning.
A physical site visit to match the Type D desktop records with visible above-ground evidence, such as manhole covers and valve markers. This level provides a more accurate location of the utilities but may require additional verification.
Best for: Validating desktop records and identifying missing assets before detection begins.
Using Ground Penetrating Radar (GPR) and Electromagnetic Locators (EML) to physically scan and map the depth and route of utilities. This level provides the most accurate and precise location
Best for: Detailed design phases and prior to any ground investigation or drilling
Exposing the utility safely—often via vacuum excavation or hand-dug trial pits—to confirm its exact position, depth, size, and type. This level is the final step in the survey process.
Best for: High-risk areas where complex drilling or major excavation is planned in close proximity to services.
Commissioning a compliant utility survey is a critical step in the lifecycle of any development.
At Southwest Environmental Limited, our core expertise lies in comprehensive environmental and geotechnical consultancy. This puts us in a unique position to save you time and money.
If you already need SWEL to conduct a Phase 2 Site Investigation, drill boreholes, or take soil samples, combining this with a PAS 128 survey is highly efficient. By conducting the Type B utility detection immediately prior to our environmental drilling, we ensure our drillers—and your future contractors—do not strike any hidden services. Consolidating these services into a single contractor reduces site mobilization costs, simplifies your project management, and guarantees seamless data integration.
The below section was written by a machine.
A comprehensive PAS 128 utility survey serves as a vital preliminary step before breaking ground for any intrusive environmental investigation. By identifying active, abandoned, and unknown buried services, developers can safely proceed with a Phase 1 Desktop Study and subsequent intrusive borehole drilling. Integrating underground mapping into the early stages of a project ensures that environmental sampling, such as testing for groundwater risk assessments, is conducted without the risk of striking water mains, high-voltage cables, or telecommunication networks.
Modern utility mapping relies on a combination of Electromagnetic Locators and Ground Penetrating Radar to accurately trace the route and depth of subterranean infrastructure. This dual-technology approach is essential for achieving PAS 128 Type B compliance. The non-destructive nature of radar allows for rapid site coverage, which is particularly beneficial when preparing a site for a complex Geotechnical Site Investigation. The resulting topographical overlay provides structural engineers and architects with the precise spatial data required to design safe piling and foundation layouts.
Accurate utility data is frequently required by local authorities, highway agencies, and utility providers to satisfy planning conditions and ensure regulatory compliance. Demonstrating that a development layout avoids critical infrastructure can streamline the approval of a planning application. Furthermore, detailed underground mapping supports the development of robust construction management strategies, aligning with broader environmental compliance requirements and helping to prevent costly delays, redesigns, and health and safety incidents during the excavation phase of your project.