_Two locate reports can show the same marks and mean very different things. The difference lives in the parts people skip: the quality level, the coverage statement, and the method behind each mark._

The first thing to find: the quality level

Under ASCE/UESI/CI 38-22, utility information carries a quality level per segment: QL-D from records and recollection, QL-C adding surveyed surface features, QL-B from surface geophysics, QL-A from physical exposure and survey. 1Jump to source 1 A report that doesn't state its level is asking you to guess how much to trust it — and a report that states one level for a whole site is usually painting too broadly, because levels attach to segments, not projects. 1Jump to source 1

The practical reading: a QL-B line is a designation — real field evidence, interpreted, not seen. Design decisions that hinge on exact position or depth at a specific point want QL-A at that point, which means a pothole, and no GNSS receiver upgrades a designation past that boundary. 1Jump to source 1 Our quality levels guide for scope writers goes deeper.

The most valuable sentence: the coverage statement

A professional deliverable says what was investigated, with what, and where the methods could not answer. That last part is not filler. "The north six feet was under standing water and was not scanned" changes what the blank space on the drawing means: not empty, but unexamined.

So read the blank areas with the coverage statement in hand:

  • Covered, and nothing found — the methods used detected nothing there. Meaningful — and still not proof of absence: every method has non-detectable targets. 2Jump to source 23Jump to source 3
  • Not covered — no statement at all. Treat exactly like ground that was never visited, because it wasn't.
  • Covered, inconclusive — the honest middle. Something prevented a clean answer; the report should say what.

A report with hits only and no coverage or exclusions reads clean and tells you the least. If you receive one like that — from anyone — ask for the coverage statement before you excavate against it.

Method-per-mark, and why it matters

Each locating method fails differently: electromagnetic locating misses non-conductive lines with no tracer wire, radar loses depth in conductive soils, records lie at QL-D. 1Jump to source 12Jump to source 23Jump to source 3 A mark labeled with its method inherits that method's blind spots, and two methods agreeing on the same line is materially stronger evidence than either alone. 3Jump to source 3 Our own job documentation states which method produced each mark for exactly this reason — and when you read anyone's report, "how do you know?" is a fair question for every line on it.

Depth figures deserve their own caution: they are calculated estimates resting on assumptions the ground can violate, which is a whole guide in itself. A depth on a report is planning information. It is not a clearance to work above.

Dates, marks and expiry

The report's field date is part of its meaning: it describes conditions within the covered area on that date. Ground gets reworked; new lines go in; grade changes. And the public-side marks on the same site run on statutory clocks — in Texas, an excavator whose start slips past 14 days from the original notice must re-notify 4Jump to source 4; in New Mexico, reaffirmation is requested every ten working days. 5Jump to source 5 Private marks have no statute, but paint has weather, and the durable record is the photographs and the report — or, where the job included mapping, the georeferenced file. If significant time or site work has passed, treat the old report as history and re-scope.

A short checklist for the receiving end

  1. Quality level stated, per segment? 1Jump to source 1
  2. Coverage statement present — investigated areas, exclusions, inconclusive zones?
  3. Method identified for each mark?
  4. Depths flagged as estimates, with their basis?
  5. Field date on the document, and marks photographed?
  6. For mapped deliverables: coordinate system, datum and correction source stated? (ASCE 75-22 exists precisely to standardize how utility data is recorded and exchanged between systems. 1Jump to source 1)
  7. Anything the report recommends verifying — and has anyone scheduled that verification?

A report that passes that list can be relied on for exactly what it claims. That is the point of it — and it's the reason the limits section is the most professional page in the package, not the small print.

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 (and companion ASCE/UESI/CI 75-22) — American Society of Civil Engineers — https://ascelibrary.org/doi/book/10.1061/9780784415870 Quality level definitions, per-segment application, and the designation/verification boundary; 75-22 for data exchange.
  2. ASTM D6432-19 — Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation — ASTM International — https://www.astm.org/Standards/D6432.htm
  3. Combining EM, GPR and Magnetics for a Complete Locate — Sensors & Software — https://www.sensoft.ca/blog/combining-em-gpr-and-magnetics-for-a-complete-locate/
  4. Excavator FAQs — Texas One Call requirements and safety — Texas 811 — https://texas811.org/excavator-faqs/
  5. New Mexico Utility Damage Prevention and Excavation Safety — New Mexico 811 — https://www.nm811.org/

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.