_Utility quality levels are a statement about evidence, not a ranking of effort. Each level says what was actually done to produce the information on the drawing — and the single most consequential boundary is the one between designating a utility and verifying it._

The standard, and what changed in 2022

The controlling document is ASCE/UESI/CI 38-22, Standard Guideline for Investigating and Documenting Existing Utilities. It replaced the 2002 edition, which had been titled Standard Guidelines for the Collection and Depiction of Existing Subsurface Utility Data — the retitle was deliberate, meant to convey the scope more directly. 1Jump to source 12Jump to source 2

The 2022 revision retains the four-level framework and adds substantial commentary and examples, new and revised definitions, and provisions drawn from twenty years of use. Notably for anyone specifying deliverables, it adds material on utility attributes and on collecting and recording the depths of utility features and segments. 2Jump to source 23Jump to source 3

ASCE published a companion standard at the same time: ASCE/UESI/CI 75-22, Standard Guideline for Recording and Exchanging Utility Infrastructure Data, which addresses how utility data moves between CAD and GIS environments. 2Jump to source 2 If your deliverable has a data-exchange requirement, that is the standard to point at.

Check your spec language: If your specification still cites ASCE 38-02, it is citing a superseded edition. That is worth a redline on the next revision of your boilerplate.

The four levels

Level Evidence behind it What it will not tell you
QL-D Existing utility records and verbal recollection — the most basic level, drawn from sources that are typically unreliable. Whether the utility is actually where the record says, or whether it still exists.
QL-C QL-D information correlated with a survey of visible above-ground features: manholes, valve boxes, meters, pedestals, risers. The route between the visible features, or anything with no surface expression.
QL-B Surface geophysics — electromagnetic locating, GPR, terrain conductivity, pipe and cable locators — used to designate the horizontal position of subsurface utilities. Precise position or depth by direct evidence; the utility has not been seen.
QL-A The utility exposed at a specific point and surveyed. Commonly cited precision is on the order of 0.1 ft vertical and 0.2 ft horizontal. Anything about the segment away from the test hole.

What produces each quality level. 1Jump to source 13Jump to source 34Jump to source 4

The levels are progressive rather than alternative. A project typically begins with QL-D records, incorporates QL-C observations, advances to QL-B geophysical investigation across the corridor, and applies QL-A verification at the specific locations where a conflict actually matters. 4Jump to source 4

The boundary that matters most

Between QL-B and QL-A there is a change of kind, not merely a change of accuracy.

QL-B is designation. A surface geophysical method has responded to something consistent with a utility, and a locator has interpreted that response and marked a position. It is real evidence, gathered on site, and it is far better than a record — but nobody has seen the pipe.

QL-A is verification. The utility has been exposed, usually by vacuum excavation, and its position, depth, size and material have been observed and surveyed. 4Jump to source 4

That distinction drives what a designer can responsibly do with the data. Setting a design invert against a QL-B depth estimate, or writing a clearance dimension to two decimal places from a designation, imports an uncertainty that the evidence does not carry. If a specific vertical clearance governs the design, that location needs QL-A.

What we deliver: This is also why our footer states that utility designation is Quality Level B per ASCE/UESI/CI 38-22 unless otherwise stated. A private locate delivers designation. It becomes verification only when the utility is exposed and surveyed.

Writing the scope

Specify per segment, not per project

A single quality level applied across an entire site is nearly always either wasteful or inadequate. Quality levels attach to utility segments. A realistic scope reads more like: QL-B across the full corridor, QL-A at the four locations where the proposed storm crosses existing dry utilities, QL-C elsewhere.

Say what the deliverable contains

  • Which quality level applies to each segment, shown on the drawing rather than buried in a report.
  • What was investigated and what was not — including areas where access or site conditions prevented investigation.
  • Whether depths are recorded, and by what means, given that the 2022 edition specifically addresses depth recording. 2Jump to source 23Jump to source 3
  • Utility attributes required — material, size, condition, ownership — since these are also addressed in the 2022 revision. 2Jump to source 2
  • The data exchange format, referencing ASCE 75-22 where CAD/GIS interoperability matters. 2Jump to source 2

Budget the test holes where the risk is

QL-A costs more per point than any other level, which is the argument for placing those points deliberately. The general pattern used in subsurface utility engineering practice is to use the cheaper, broader levels to find the conflicts and the expensive, precise level to resolve them. 5Jump to source 5

Common scope defects

  • Citing a superseded edition of the standard.
  • Requesting “SUE” with no quality level specified, which leaves the level to the low bidder.
  • Requiring QL-A across a whole corridor when a handful of crossings drive the risk.
  • Accepting a deliverable that shows located utilities but does not show investigated-and-found-nothing areas — the two are not the same statement.
  • Treating the quality level as a warranty. It describes the evidence gathered; it does not promise that nothing else is buried there.
View 5 numbered sources

Sources

Every numbered claim above traces to one of these. Links go to the publisher of record.

  1. ASCE/UESI/CI 38-22 — Standard Guideline for Investigating and Documenting Existing Utilities — American Society of Civil Engineers — https://ascelibrary.org/doi/book/10.1061/9780784415870
  2. Newly updated ASCE 38-22 utility engineering standard and new companion standard ASCE 75-22 now available — ASCE Civil Engineering Source — https://www.asce.org/publications-and-news/civil-engineering-source/society-news/article/2022/07/newly-updated-asce-38-22-utility-engineering-standard-and-new-companion-standard-asce-75-22-now-available
  3. ASCE 38-22 — How the Update Fills the Gaps Left by 38-02 — T2 Utility Engineers — https://t2ue.com/news-and-events/asce-38-22-how-the-update-fills-the-gaps-in-38-02/
  4. Understanding SUE Levels for Construction Projects — Safe Site — https://safesitellc.com/understanding-sue-levels/
  5. Subsurface Utility Engineering — U.S. Federal Highway Administration, Utility Program — https://www.fhwa.dot.gov/programadmin/sueindex.cfm

Sourcing and limitations

This guide is original writing by High Desert Scan & Locate, LLC. It cites third-party statutes, standards, codes and publications, all of which remain the property of their respective owners. We describe them in our own words and do not reproduce their text. Standards published by bodies such as ASTM, ACI, ASCE/UESI/CI and PTI are available from those publishers; where one governs your work, obtain the current edition and read it. The published source controls; our paraphrase does not, and an edition cited here may since have been revised or superseded.

No representation or warranty. This material is provided "as is." We make no representation or warranty, express or implied, as to its accuracy, completeness, reliability or currency. It is accurate only as of the review date shown, if at all. Laws, rules and standards change, and we do not undertake to update it.

Not professional advice. Nothing here is legal, engineering, surveying or safety advice, and reading it creates no professional or client relationship. It is not a substitute for a site-specific scope, and it does not clear any area for excavation, cutting or coring.

Company names, product names and trademarks are used for identification only and do not indicate affiliation, sponsorship or endorsement. We receive no compensation for any mention.

Corrections: info@highdesertscan.com. See our Editorial policy, sourcing and attribution.

Private utility locating supplements, and does not replace, public one-call (811) notification. Utility designation is Quality Level B per ASCE/UESI/CI 38-22 unless otherwise stated. GPR interprets subsurface conditions; it does not expose them. Results are interpretations of conditions present within the requested area on the service date, and depend on target material, depth and site conditions.