Utility mapping involves precisely identifying and digitally recording the locations of underground utilities. These maps provide a complete view of subsurface infrastructure, helping ensure safer excavation and more efficient maintenance by reducing unnecessary digging and minimizing the risk of utility strikes and accidents.
Designers and contractors rely on survey drawings (electronic and hard copy) to make critical excavation decisions. When survey crews pull utility data from 811 paint marks or outdated municipal records without defining the data’s reliability, they’re not just cutting corners. They’re introducing massive liability and project risk that can cost lives, delay timelines, and expose firms to serious legal consequences.
It should also be noted that in many instances marking an 811 request as ‘survey only’ is treated as low priority and may take longer for the locator to mark the site. To protect public safety and project timelines, licensed professional land surveyors must coordinate effectively with Subsurface Utility Engineering (SUE) teams, strictly adhere to ASCE 38-22 quality levels, and produce clear CAD deliverables that leave zero ambiguity for the design team.
Take a deeper dive into utility mapping with our continuing education course, Land Surveyors and Utilities.
Understanding ASCE 38-22: The Quality Level Framework
The ASCE 38-22 standard provides the definitive framework for communicating the reliability of underground utility data to project stakeholders.
Its core innovation, which was introduced in the original 2002 edition and refined in the 2022 update (the most current edition as of this date), is the Utility Quality Level: a professionally judged value assigned to each buried utility segment that defines the relative, nonquantifiable uncertainty of that utility’s existence, location, and attributes.
The intent, as the standard states, is to allow “the project owner, engineer, and constructor to develop strategies to reduce risk or, at minimum, to allocate risk due to existing subsurface utilities in a defined manner.”
Here’s how the four levels break down.
Quality Level D (QL-D)
Information derived entirely from existing utility records and oral history. This is the starting point — utility company records, municipal as-builts, verbal accounts from facility managers.
It’s the most basic level available and is highly unreliable for design purposes. As the course puts it, these are “typically unreliable sources.” This is a good way of referring to this information as most ‘’as-builts” are NOT based on field surveys prepared and reviewed by a professional surveyor.
Quality Level C (QL-C)
Surface-visible utility features—manholes, valve boxes, cleanout covers—are physically located in the field, surveyed, and correlated with QL-D records. When records and visible features don’t agree, discrepancies must be resolved.
This is where a standard topographic survey becomes an important part of the process.
Quality Level B (QL-B)
Subsurface utilities are designated using surface geophysical methods — ground-penetrating radar (GPR), electromagnetic (EM) locators, terrain conductivity, pipe and cable locators, and others.
Paint marks are placed on the ground surface; flags or stakes are set at 50-foot intervals (or closer if conditions and utility congestion dictate), and those marks are tied in by the survey crew, processed into the project database, and shown on the survey drawing.
The result is two-dimensional horizontal positioning of the utilities relative to the property boundary and other visible improvements. According to ASCE 38-22, the interpreted position must be tied to the Project Survey Datum with an accuracy of 0.2 ft (60 mm) horizontally.
Quality Level A (QL-A)
Utilities are physically exposed via non-destructive excavation (potholing or vacuum excavation), allowing precise 3D measurement by the survey crew. Under ASCE 38-22, QL-A requires the utility to be tied to the Project Survey Datum with accuracy of 0.1 ft (30 mm) vertically and 0.2 ft (60 mm) horizontally. Material type, size, condition, and other attributes are recorded on-site.
Critical point for surveyors: A standard topographic survey—even a thorough one—typically only achieves QL-C or QL-D without direct SUE involvement. As one McKissock course states plainly: “the exact location of underground features cannot be accurately, completely, and reliably depicted” without excavation.
Even ground penetrating radar or physically probing the utility is subject to errors caused by site conditions, soil type, and other factors. The cost of a proper SUE investigation is nothing compared to the cost, and danger, of damaging a fiber optic cable or high-pressure gas line.
Coordination Strategies: Aligning Field Pickups with SUE Markings and Records
Seamless coordination between survey crews and SUE technicians prevents critical data loss between field designation and office drafting. This is where many projects quietly fall apart—not in the field, but in the gap between what the SUE team did and what the survey crew picked up.
Use the following strategies to promote successful coordination with SUE teams.
Time Your Field Pickups Immediately After SUE Marking
Paint marks fade. Chalk washes out in rain. Flags get run over by traffic or removed by property owners or mowing crews.
A survey crew arriving days after a SUE designation campaign may be picking up ghost marks from a prior, completely unrelated utility locate—perhaps from a previous 811 ticket for a neighboring excavation that was never removed. If your crew surveys those old flags without questioning their origin, you’ve just introduced QL-D-level data into what the client thinks is QL-B work.
An optimum situation is to have the survey and SUE teams onsite concurrently. An alternative is to have a SUE team that is properly trained and experienced as a survey field crew to tie in the markings as they are completed.
Establish a Common Control Network Early
Both the SUE investigators and survey crews must work on the exact same coordinate system and datum from day one. Under ASCE 38-22, all QL-B designations must be tied to the Project Survey Datum.
If the SUE team is working on a local assumed coordinate system and the survey crew is using a state plane grid, or any other coordinate datum, the resulting depiction of utility locations will be misaligned at every station. This isn’t a minor QA/QC issue — it’s a design-level error.
Reconcile Field Data Against Utility Records While Still on Site
Don’t wait until you’re back in the office to compare QL-B designations against QL-D record drawings. If a gas main shown in utility records doesn’t appear in the geophysical results, that’s a conflict that needs to be resolved in the field—not flagged in a submittal review note three weeks later.
ASCE 38-22 specifically calls for correlating QL-B information with existing utility records and resolving discrepancies as part of the SUE process.
Project sites are not static; they are dynamic and constantly changing as new improvements and utilities are installed. If the two teams are not working together on the site, the survey crew should be provided with the SUE location information so they can compare it to what they find onsite.
Yet another cross check to avoid issues down the road.
Deliverables and CAD Standards: Presenting Data for Designers
Your final deliverable must explicitly communicate the reliability of every utility line shown. A designer who can’t tell the difference between a QL-D record line and a QL-A pothole location is flying blind—and if they make an excavation decision based on that ambiguity, the professional liability flows upstream to you.
ASCE 38-22 addresses this directly. The standard defines SUE Deliverables as sealed documents that include a Utility Report with accompanying Utility Drawings showing all utilities at their achieved Quality Levels. “Achieved” is the key word—the level you can actually certify, not what was hoped for.
In some instances, the PE in charge of the SUE team will sign the survey plat – specifically stating they are only certifying to the SUE portion of the drawing while the PLS will certify to the remainder of the information shown.
This type of cooperation provides the client with yet another level of confidence that the professionals they hired are competent and thorough in their work.
Practical implementation in CAD:
- Use distinct line types, layer names, and colors for each Quality Level. QL-A should be visually unmistakable from QL-D. Don’t rely on annotation alone, as designers scan drawings fast. Color and line type communicate reliability at a glance.
- Embed metadata and attribute tables in Civil 3D. For each utility segment, tag the source: “Record Drawing — City of Springfield Water Dept., 2009,” “SUE QL-B GPR Designation — surveyed 4/2/25,” “QL-A Pothole — vacuum excavated, 3.2 ft depth to top of pipe.” This isn’t bureaucratic overkill. It’s the information a designer needs to make a responsible decision. There is a saying, ‘too much information is just enough,’ and never is this truer than in this scenario.
- Include robust general notes and disclaimers on the plan set. Notes should explicitly state which portions of the utility depiction are record data only, which are geophysically designated, and which are vacuum-excavated and verified. Make clear that the survey does not constitute a full SUE investigation (unless it does), and that subsurface conditions beyond what is depicted remain unknown.
The basic deliverable package under ASCE 38-22 includes a CADD file or GIS file showing utility information in plan view for QL-A through QL-D, and in plan and profile view for QL-A locations. That profile view matters—it’s the only way a designer can visualize clearance between a proposed storm drain and a confirmed gas main.
Avoiding Scope Gaps: Where Survey Ends and SUE Begins
Clear contracting and upfront communication define the boundary between a surveyor’s liability and a SUE provider’s responsibility. This is where projects—and professional reputations—most often run into trouble.
As with any collaboration between professionals, communication and cooperation are the keys to success. The design engineer, SUE, and surveyor should have a clear understanding of the needs for the project and clearly defined—in writing—areas of responsibility.
Consider a common scenario: a developer hires a survey firm for a “utility mapping survey” ahead of a mixed-use redevelopment project. The proposal scope says, “locate and depict existing utilities.”
The developer reads that as geophysical scanning. The surveyor reads it as calling 811, picking up the marks, and showing them on the topo. When excavation begins and a telecom conduit bank is struck 4 feet from where it was shown, both parties are pointing at the proposal language.
That ambiguity is entirely preventable with clear scope definition. Specifically:
- Define who interprets geophysical signals. Surveying QL-B paint marks is not the same as performing the geophysical designation that produced them. A survey crew tying in flags placed by a utility owner’s locator is capturing someone else’s judgment — not performing SUE. ASCE 38-22 is explicit that QL-B requires interpretation by a qualified professional using appropriate geophysical methods, not simply locating existing ground marks.
- Educate clients on what a topographic survey does and doesn’t provide. As the standard language used in ALTA/NSPS surveys states, the survey can show utilities based on “observed evidence,” 811 markings, and records provided by utility companies—but accurate three-dimensional location of underground utilities requires the skills of a SUE team, including a registered SUE professional, providing QL-A services. Put that language in your proposals and require the client to sign the proposal stating that they understand and accept the terms of the contract. Put it in your notes. Say it at the kickoff meeting.
- Use proposal language that explicitly references ASCE 38-22 quality levels. Rather than “utility mapping,” your scope should state: “Surveyor will locate and depict surface utility features (manholes, valve boxes, risers) to QL-C accuracy and will tie in 811 One-Call markings as QL-D or QL-B per their designation source. No geophysical designation or potholing is included in this scope unless separately contracted.”
Conclusion
Buried utility mapping only works when the deliverable intent matches the field execution. A survey plan that mixes QL-A pothole data with QL-D record lines—without clear labels—isn’t more informative than a plan that shows nothing. It’s more dangerous because it creates a false sense of confidence.
By coordinating closely with SUE teams, applying ASCE 38-22 quality levels rigorously to every utility segment in your CAD files, and setting clear scope boundaries in your proposals and contracts, you protect the public, protect your license, protect your client, and give designers the foundation they need to make informed decisions.
Want to learn more? Enroll in McKissock’s land surveyor CE courses, including Land Surveyors and Utilities, to deepen your understanding of utility rights, the SUE process, and your obligations as a licensed professional working around buried infrastructure.
