SUE Quality Levels

Subsurface Utility Engineering (SUE) investigations are classified according to ASCE 38-02/ASCE 38-22 standards. These define the reliability of utility data based on the methods used to collect it.

Understanding these levels helps clients choose the right level of detail for their project stage — from early planning through to detailed design and construction.

• Based solely on existing utility records or verbal recollections.
• Provides a general idea of utility presence but lacks spatial accuracy.
• Useful for early-stage planning and feasibility reviews.

• Combines record data with visible surface features such as manholes, valve boxes, and hydrants.
• Improves confidence compared to Level D but still approximate in location and depth of buried lines.
• Suitable for preliminary design and identifying potential conflicts.

• Uses electromagnetic (EM) and ground-penetrating radar (GPR) to physically detect and trace utilities underground.
• Horizontal accuracy is greatly improved and utilities are mapped to a defined coordinate system.
• Commonly used for design and pre-construction coordination.

• The highest accuracy level, obtained by vacuum excavation or test pitting to physically expose the utility.
• Position and depth are measured by survey to centimetre accuracy.
• Used for high-risk areas, design validation, and construction verification.

Every project has unique risk and accuracy requirements.

Northern Link can tailor a SUE scope to your needs — whether you need Level D–B mapping for planning and design, or Level A confirmation for construction-critical utilities.