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The Importance of Subsurface Utility Engineering (SUE)

Posted on April 28, 2025 by Canadian Hydrovac Team

The Importance of Subsurface Utility Engineering (SUE)

Subsurface Utility Engineering, or SUE, is a systematic engineering process used to manage the risks associated with underground utilities. It combines geophysics, surveying, and non-destructive excavation to create a detailed and reliable 3D map of the underground environment. Hydrovac excavation is a cornerstone of the SUE process.

The Four Quality Levels of SUE

SUE defines data in four quality levels:

  • Quality Level D (QL-D): Information gathered from existing records and verbal recollections. It is the least reliable.
  • Quality Level C (QL-C): Surveying visible surface utility features (like manholes and valve boxes) and correlating them with QL-D information.
  • Quality Level B (QL-B): Using geophysical methods (like electromagnetic locators and GPR) to determine the approximate horizontal position of utilities. This is where most utility 'locates' stop.
  • Quality Level A (QL-A): The highest level of accuracy. This involves using non-destructive excavation to expose the utility at critical points to get precise horizontal and vertical position, as well as size and material type. This is achieved through hydrovac daylighting (potholing).

How Hydrovac Enables Quality Level A Data

Hydrovac excavation is the only way to achieve QL-A data without risking damage to the utility. By creating a series of small, precise test holes, project engineers can gather the ground-truth data needed to make informed design decisions. This allows them to:

  • Design new infrastructure that avoids conflicts with existing utilities.
  • Reduce the need for costly project redesigns during construction.
  • Minimize unexpected delays and change orders.
  • Greatly enhance the safety of the project for workers and the public.

Conclusion

Investing in a proper SUE program, with hydrovac excavation as the key to achieving Quality Level A data, is one of the smartest decisions a project owner can make. It transforms unknown risks into manageable information, saving time, money, and protecting lives.