If you’re a contractor, engineer, or project manager working on Virginia infrastructure, you’ve probably heard the terms SUE Level B and SUE Level A thrown around. But what’s actually different between them — and when does your project require each level? This guide breaks it down clearly, with Virginia-specific requirements.
What is SUE? A Quick Primer
Subsurface Utility Engineering (SUE) is a branch of engineering that manages the risks associated with subsurface utility information. It’s governed by ASCE Standard 38-02, which defines four quality levels (A through D) for how accurately underground utilities are located and documented. The higher the level (A being highest), the more accurate and legally defensible the data.
The Four SUE Quality Levels
| Quality Level | Method | Accuracy | Best For |
|---|---|---|---|
| Level D | Records & maps only | Lowest — often wrong | Early planning only |
| Level C | Field surveys of visible features | Surface indicators only | Preliminary design |
| Level B | Geophysical (GPR, EM, etc.) | Horizontal ±1–3 feet typical | Design, planning, bid documents |
| Level A | Physical exposure (hydro excavation) | Exact X, Y, Z coordinates | Final design, construction, legal |
SUE Level B: Geophysical Detection
Level B uses non-invasive geophysical equipment — ground-penetrating radar (GPR), electromagnetic induction (EM), or acoustic tools — to detect buried utilities from the surface. The result is a map showing approximate horizontal location.
What Level B Gives You
- Horizontal position of utilities (±1–3 feet depending on soil conditions and depth)
- Utility type identification in many cases
- Mapping suitable for design drawings and bid documents
- No physical excavation required — non-invasive and faster to complete
What Level B Cannot Tell You
- Exact depth of buried utilities — critical for conflict analysis
- Condition, material, or diameter of the utility
- Whether a utility has been abandoned, capped, or rerouted
- Precise vertical position in 3D space
Level B Limitations in Virginia Soil Conditions
Virginia’s clay-heavy soils — common in Hampton Roads, the Piedmont, and Northern Virginia — can significantly reduce GPR penetration depth and accuracy. EM tools perform better in clay, but signal interference from dense utility corridors (common in urban cores like Norfolk, Richmond, and Arlington) reduces reliability. In these conditions, the actual accuracy of Level B may be worse than the ±3-foot theoretical spec, making Level A follow-up more critical.
SUE Level A: Physical Exposure via Hydro Excavation
Level A is the gold standard. It requires physically exposing the utility, and hydro excavation (potholing/daylighting) is the accepted method per ASCE 38. A trained technician uses high-pressure water and vacuum to safely expose the utility, then a licensed surveyor records exact X, Y, and Z (depth) coordinates.
What Level A Gives You
- Exact horizontal and vertical position — surveyed to sub-inch accuracy
- Physical confirmation of utility type, size, material, and condition
- Legally defensible documentation for engineering records and owner submittals
- Required data format for VDOT SUE submittals on qualifying projects
- True 3D conflict resolution — you know exactly where the utility is before construction
Why Hydro Excavation Is Required for Level A
ASCE 38 specifies that Level A data must come from physical exposure. Mechanical excavation (backhoes, hand digging) risks damaging the utility you’re trying to locate. Hydro excavation — pressurized water plus vacuum — safely exposes utilities without contact damage, and produces a clean opening that a surveyor can accurately measure. It’s the only method that satisfies Level A requirements at scale.
VDOT Requirements for SUE Levels in Virginia
VDOT’s Utility Accommodation Policy and Standards Manual specifies when SUE is required on state-funded projects. Key triggers:
- Level B minimum — required for design of projects with known utility conflicts in VDOT right-of-way
- Level A required — when Level B identifies conflicts within the design footprint, or when the project involves excavation within 5 feet of a known utility
- Pre-construction Level A — increasingly required by Dominion Energy and Virginia Natural Gas before granting construction clearance near their infrastructure
Many design-build and P3 contracts in Virginia now include mandatory Level A SUE provisions in the utility coordination specifications.
When to Use Level B vs Level A
Use Level B When:
- You’re in early design and need approximate utility locations for planning
- The project area is large and you need to identify which specific locations require Level A follow-up
- The contract or agency only requires Level B for design submission
- Budget constraints mean Level A isn’t feasible across the full project area — use Level B to triage
Use Level A When:
- VDOT or another agency requires it per project specifications
- Mechanical excavation is planned within 5 feet of a known or suspected utility
- The design has utility conflicts that must be resolved before construction drawings are finalized
- You need legally defensible documentation for liability protection or utility owner clearance
- Level B results show conflicts or uncertainty in a critical design zone
Cost Comparison: Level B vs Level A
Level B is faster and cheaper per location — geophysical scanning costs significantly less than physical exposure. However, the real cost comparison is against the consequence of not getting Level A when you need it:
| Level B | Level A | |
|---|---|---|
| Cost per location | Lower (surface scan) | Higher (hydrovac + survey) |
| Time to complete | Faster (no excavation) | Longer (physical exposure) |
| Depth accuracy | None | Sub-inch, surveyed |
| VDOT construction submittal | Design phase only | Construction + design |
| Legal defensibility | Limited | Full — ASCE 38 compliant |
| Utility strike prevention | Reduces risk | Eliminates risk |
A utility strike on a high-pressure gas main or transmission line costs $50,000–$500,000+ in repairs, project delays, and liability. Level A verification on a critical conflict zone typically costs a small fraction of that.
Common Project Types by Level
Projects That Typically Need Level B Only
- Preliminary road design and alignment studies
- Environmental impact assessments requiring utility corridor identification
- Large-area pipeline route planning (before route selection)
- Early-stage real estate due diligence on undeveloped land
Projects That Require Level A
- VDOT highway construction and widening in utility-dense corridors
- Municipal water/sewer main replacements near multiple crossings
- Fiber optic slot trenching through established utility corridors
- Substation and electrical infrastructure installation
- Bridge and structure foundations where utilities pass underneath
- Any project where a utility owner requires clearance before construction
Beach Hydrovac: SUE Level A Provider Across Virginia
We perform SUE Level A potholing for engineering firms, general contractors, VDOT projects, and utility companies across Hampton Roads, Richmond, Northern Virginia, and into NC, MD, and DE. Every Level A pothole includes written documentation your engineers can use for final design submittals. We coordinate directly with utility owners for clearance on Dominion, VNG, and Cox assets.