ASCE UESI CI 38-22 Guide: On-Site Data Collection for Utility Mapping

For field engineers, survey crews, and construction managers, inaccurate or missing underground utility information isn’t just an inconvenience—it’s a primary cause of project delays, budget overruns, and catastrophic safety incidents. The American Society of Civil Engineers (ASCE) Utility Engineering & Surveying Institute (UESI) developed CI 38-22, “Standard Guideline for Collecting and Managing Subsurface Utility Data for Design and Construction,” to provide a unified, actionable framework for this critical pre-construction activity. This guide translates that standard into practical, on-site steps to ensure your utility data is reliable, consistent, and ready for field use.

What is ASCE UESI CI 38-22 in Practice?

In real-world terms, CI 38-22 is your project’s rulebook for the “find it before you hit it” phase. It is not a design specification but a procedural standard that defines how to gather, verify, classify, and deliver information about what’s buried underground. On-site, you encounter it when:
* A survey crew conducts a Subsurface Utility Engineering (SUE) investigation.
* A project manager reviews utility conflict matrices during excavation planning.
* An inspector verifies that potholing or vacuum excavation results match the as-built drawings before authorizing deep excavation.

Its core purpose is to fill the operational gap between vague, often outdated record drawings and the precise, physically verified data needed for safe and efficient construction. It systematizes the process to prevent the all-too-common scenario where a backhoe operator relies on a faded utility sketch and strikes a live gas line.

On-Site Problems Solved & Project Scope

CI 38-22 directly addresses costly field problems:
* Preventing Utility Strikes: The #1 safety and financial risk on any excavation project.
* Eliminating Rework: Avoiding redesigns and work stoppages when unexpected utilities are encountered.
* Reducing Contingency Budgets: Providing higher-quality data reduces the unknown, allowing for more accurate bidding and scheduling.
* Settling Disputes: Creating a clear, standardized record of pre-construction conditions to resolve conflicts between owners, contractors, and utility companies.

This standard is critical for virtually all horizontal construction projects, including roadways, bridges, site development, pipeline corridors, and public transit systems. It is widely mandated by U.S. state Departments of Transportation (DOTs) and is a best-practice requirement for most public works and large-scale private developments.

Core Technical Requirements: The Quality Level Framework

The operational heart of CI 38-22 is its four-tiered Quality Level (QL) classification system. This is not just paperwork; it’s a communication tool for field teams to understand the reliability of the data they are using.

* QL-D (Quality Level D): Information from records only. This is your starting point—existing plans, sketches, and verbal recollections. On-Site Rule: Treat QL-D data as “unverified.” Never base excavation or drilling decisions solely on this. It is for preliminary planning only.
* QL-C (Quality Level C): Records plus above-ground survey. This involves correlating record data with visible above-ground features (manholes, valve boxes, poles) and surveying their locations. On-Site Verification: Data is more precise horizontally but depth and exact horizontal position remain unconfirmed. Use for surface planning and conflict screening.
* QL-B (Quality Level B): Records, survey, and geophysical methods. This is where field verification begins. Technicians use tools like ground-penetrating radar (GPR) and electromagnetic locators to detect and mark utilities. Key On-Site Action: All QL-B data must be gathered by qualified technicians using calibrated equipment. Marks are painted on the pavement/ground. This is the minimum level for detailed design and most bidding purposes.
* QL-A (Quality Level A): Precise horizontal and vertical exposure. Also known as “potholing” or “daylighting,” this involves non-destructive excavation (e.g., vacuum excavation) to physically expose the utility and record its exact 3D coordinates. Critical Safety Control Point: This is the only level that provides verified depth. QL-A is mandatory for final design at critical conflict points and for guiding excavation machinery in the immediate vicinity of high-risk utilities (gas, high-voltage electric, fiber optics).

On-Site Implementation & Compliance Workflow

Your field implementation should follow this phased approach:

1. Project Scoping & QL Assignment: During pre-construction planning, designate required Quality Levels for different project areas. High-impact zones (e.g., trench crossings, foundation locations) need QL-A or QL-B.
2. Field Investigation Execution:
* QL-B Work: Ensure locators follow a systematic process: review records (QL-D), perform site reconnaissance (QL-C), then use appropriate geophysical techniques. Verify they are marking all detectable utilities, not just the target type.
* QL-A Work: Supervise test hole excavations. Key steps include:
* Calling 811 or your local one-call system before any digging.
* Using non-destructive excavation methods.
Measuring and recording the invert* (bottom) of the pipe/conduit, not the top.
* Photographing the exposed utility with a scale and ID tag.
3. Data Delivery & Use: The investigating firm should deliver a standardized topographic map showing all utilities, classified by QL, with a report explaining methods and limitations. Field crews must have these maps on-site during excavation. The color-coding for utility types (e.g., red for electric, yellow for gas) per the American Public Works Association (APWA) standard must be used and understood by all operators.

Who Uses This On-Site and the Risks of Ignoring It

Primary Users:
* Project Engineers/Managers: To specify QL requirements in contracts and interpret data for design.
* SUE Field Technicians & Surveyors: To execute QL-B and QL-A investigations correctly.
* Construction Superintendents & Foremen: To plan excavation sequences and set up work zones based on verified utility locations.
* On-Site Inspectors: To verify that excavation permits and plans are supported by appropriate QL data and that field markings match the delivered plans.

Risks of Non-Compliance:
* Safety Catastrophe: Striking a high-pressure gas line or energized electrical cable.
* Massive Cost Overtuns: Project shutdowns, emergency repairs, fines, and redesign costs.
* Service Disruptions: Cutting fiber optic lines or water mains, leading to public impact and liability claims.
* Legal Liability: Failure to follow the recognized standard of care (CI 38-22) can be used as evidence of negligence in litigation.

Real-World Application & Common Misconceptions

Scenario: A crew is preparing to install deep foundations for a new bridge abutment. The QL-B plan shows a suspected 12-inch water main running parallel to the work zone. Following CI 38-22, the supervisor mandates QL-A verification at three points where the foundation piles will be driven. Vacuum excavation exposes the line, revealing it is 2 feet deeper than the QL-B estimate and 18 inches off in alignment. The foundation design is adjusted on-site, avoiding a certain strike and major service outage.

On-Site Misconceptions to Avoid:
1. “QL-B is ‘good enough’ for excavation.” False. QL-B does not provide verified depth. Excavating based solely on QL-B near critical utilities is a high-risk practice. QL-A is required for mechanical excavation within the tolerance zone of a utility.
2. “We called 811, so we’re covered.” Misleading. 811 (call-before-you-dig) is a legal requirement that gets member utilities to mark their facilities. It is typically only at QL-C or QL-B level. CI 38-22 governs a more comprehensive, engineering-grade investigation that finds all utilities (including abandoned lines, private laterals, etc.) to a higher degree of accuracy for design and construction purposes.

By implementing the structured, quality-driven processes of ASCE UESI CI 38-22, field teams transform subsurface utility mapping from a guessing game into a managed, engineering-controlled activity. It provides the definitive checklist for turning buried hazards into known, avoidable objects, ensuring projects proceed safely, on schedule, and within budget.