Unknown Utilities Are Not Failures; They Are Findings

In subsurface utility engineering (SUE), few moments generate more concern than the discovery of an unknown utility. Whether identified during Quality Level B (QL-B) designation or exposed during Quality Level A (QL-A) test hole operations, undocumented utilities are often viewed as a gap in prior information or a breakdown in the process. In reality, these discoveries represent one of the most valuable outcomes SUE can provide.

From a SUE perspective, the goal is not simply to confirm what is already documented, but to uncover what is not.

Why Unknown Utilities Exist

Unknown utilities are not always just anomalies. They are a reflection of real-world subsurface conditions. Legacy infrastructure, incomplete records, undocumented modifications, and abandoned facilities all contribute to an environment where uncertainty is expected.

In practice, this can include active pipelines not shown on records, abandoned utilities that were never removed, or even previously known features, such as rail infrastructure, which have since been buried and no longer match documented conditions.

Even on well-documented projects, a complete picture of subsurface conditions is rarely achievable through records alone. This is not a limitation of SUE; it is the reason SUE is required.

The Value of Discovery

The purpose of SUE, as defined within American Society of Civil Engineers Standard 38-22, is to reduce uncertainty and manage risk associated with existing subsurface utilities.

Identifying an unknown utility during design allows the project team to evaluate potential conflicts, coordinate with stakeholders, and make informed decisions before construction begins when adjustments are still manageable.

In practice, we have seen unknown utilities ranging from pipelines to telecom and water infrastructure that significantly influence design decisions when identified early. Left undiscovered, these same utilities would have resulted in construction delays, emergency coordination, or field conflicts.

Documentation and Communication

Proper documentation is essential when unknown utilities are identified. These features should be:

• Clearly depicted within project deliverables

• Classified in accordance with ASCE 38-22 quality levels

• Supported by field observations and professional judgment

It is important not to overstate attributes such as ownership, size, or material when they cannot be verified. At the same time, the presence of the utility must be communicated clearly enough to support design decisions and coordination.

From a SUE perspective, clarity is more valuable than assumption.

Shifting the Narrative

Unknown utilities are often initially viewed as problems. In practice, they should be recognized as opportunities to reduce risk.

Across many transportation projects expectations are shifting, but there is still work to do. Unknown utilities should not be framed as deficiencies in the investigation, but as indicators that the investigation is doing exactly what it is intended to do.

When communicated effectively, the conversation shifts from:

• “Why wasn’t this known?”

  to

• “How do we address this now, before it becomes a construction issue?”

Key Takeaways

• Unknown utilities are an expected condition, not an exception

• Their identification is a primary objective of SUE

• Early discovery reduces construction risk, cost, and schedule impacts

• Clear, balanced documentation is critical

• How findings are communicated directly influences how value is perceived

Closing Perspective

As the SUE profession continues to evolve, our role extends beyond locating utilities. We are responsible for improving how uncertainty is understood and managed across projects.

Unknown utilities are not failures of the process; they are evidence that the process is working as intended.