Utility Locating and Ground Disturbance JHA (Job Hazard Analysis / Activity Hazard Analysis)
Updated 2026-06-23
A Utility Locating and Ground Disturbance JHA (Job Hazard Analysis / Activity Hazard Analysis) is the plan that keeps any dig from striking a buried utility — preventing the electrocution, explosion, flooding, and service outages that follow when a crew puts a tool or a bucket into a live line they did not know was there. Every ground disturbance, from a fence post to a deep excavation, carries the risk of hitting buried electric, gas, water, sewer, or communication lines, and the locate-and-verify process is the control that stands between the dig and disaster. This guide walks through building a Utility Locating and Ground Disturbance JHA that names the utility-strike, electrocution, and explosion hazards and assigns the locate, potholing, and tolerance-zone controls that hold up in the field.
Why utility locating and ground disturbance needs its own JHA
Any disturbance of the ground — digging, drilling, boring, driving, trenching, grading — can strike a buried utility. The consequences are severe and varied: striking an electric line electrocutes; striking a gas line releases gas that can explode; striking water or sewer floods and contaminates; striking communication lines causes outages. Buried utilities are invisible, their locations are often poorly documented, and the only reliable defense is a disciplined process of locating, marking, verifying, and excavating carefully around them. Because this process applies to every ground disturbance regardless of its size, and because the consequences of skipping it are catastrophic, it deserves a dedicated JHA.
Breaking utility locating and ground disturbance into steps
The steps for a Utility Locating and Ground Disturbance JHA follow the process from notification to exposure:
- Notify the one-call/811 center before any ground disturbance
- Allow the required time for utility owners to locate and mark
- Review marks, drawings, and records for all utilities in the area
- Confirm all expected utilities are marked before disturbing
- Pothole (hand or vacuum excavate) to expose and verify utilities
- Maintain the tolerance zone around marked lines
- Excavate or disturb carefully, with continued awareness
- Support and protect exposed utilities during the work
Each step carries a hazard, and the locate notification and the potholing to verify are where strikes are prevented.
The hazards step by step
Striking a buried utility
The core hazard is the strike itself, and what is hit determines the consequence — electrocution from power, explosion from gas, flooding from water, contamination from sewer, outages from communications. The controls are the foundation of damage prevention: notify the one-call center (811 in the US) before disturbing the ground, wait the required time, and confirm all utilities have been located and marked. No mechanical excavation begins near a marked utility until it has been verified.
Failure to locate and incomplete marks
Strikes happen when the locate was never called, when the marks are incomplete (private or unregistered utilities are often unmarked), or when the crew digs before the locate is confirmed. The controls are always calling the locate, recognizing that one-call may not cover private lines (which may require a private locator), reviewing site drawings and records to catch utilities the locate missed, and never assuming the absence of a mark means the absence of a utility.
Striking lines within the tolerance zone
Even with accurate marks, the exact location and depth of a buried line is uncertain, so a tolerance zone around the mark must be treated as occupied. The controls are maintaining the tolerance zone (a defined horizontal distance on each side of the mark) within which mechanical excavation is prohibited, and potholing — hand or vacuum excavating — to physically expose and confirm the utility's exact location and depth before mechanical equipment works near it. Seeing the line is the only certainty.
Hazards from exposed utilities
Once exposed, utilities must be protected from damage and from causing harm. The controls are supporting exposed lines so they are not damaged by soil movement or equipment, protecting them from the ongoing work, and treating exposed electric and gas lines with particular care.
A simple Utility Locating and Ground Disturbance JHA structure
| Step | Hazard | Control | Standard |
|---|---|---|---|
| Notify one-call | Unlocated strike | Call 811 before disturbance, wait required time | OSHA 1926.651(b) |
| Confirm marks | Incomplete locate | Verify all utilities marked, check private lines and records | OSHA 1926.651(b)(2) |
| Maintain tolerance zone | Strike near mark | No mechanical digging in the tolerance zone | OSHA 1926.651(b)(4) |
| Pothole to verify | Strike from uncertain location | Hand/vacuum excavate to expose and confirm line | OSHA 1926.651(b)(3) |
| Excavate carefully | Strike during dig | Careful digging near lines, continued awareness | OSHA 1926.651(b)(4) |
| Protect exposed lines | Damage / harm | Support and protect exposed utilities | OSHA 1926.651(b)(4) |
Locate, then verify by seeing the line
A Utility Locating and Ground Disturbance JHA comes down to a two-part discipline: locate, then verify. The locate — calling one-call, waiting the required time, and confirming the marks — is the first control, but marks are approximate and may be incomplete. The verification — potholing to physically expose and see the line before mechanical excavation works near it — is what turns an approximate mark into a known location. The tolerance zone bridges the two: within it, only careful hand or vacuum excavation is allowed, because the line could be anywhere in that band. A JHA built on locate-then-verify, with the tolerance zone enforced and the line exposed before machine digging, controls the strike hazard that every ground disturbance carries. The principle is simple: you do not dig mechanically toward a utility you have not seen.
From the field: what actually goes wrong
In fourteen years across federal, heavy civil, and industrial projects, utility strikes follow a small set of failures, all preventable. The first is never calling the locate, or digging before it is confirmed — schedule pressure pushes a crew to start before the marks are complete, and they hit a line that would have been marked. The locate call and the required wait are not bureaucratic delays; they are the first line of defense, and skipping them is how the worst strikes happen. The second failure is trusting the marks too much — marks are approximate, private utilities are often unmarked, and old records are unreliable, so a crew that digs mechanically right on a mark can still hit the line because its exact position and depth were uncertain.
The control that prevents the serious strikes is potholing — physically exposing the line by hand or vacuum excavation before any machine digs near it. On the projects I have run, the rule is that you do not put a bucket toward a utility you have not seen with your own eyes, and within the tolerance zone of any marked line, only hand or vacuum excavation is allowed until the line is exposed. The strikes I have seen come down to crews who skipped the locate, trusted incomplete marks, or dug mechanically in the tolerance zone without potholing first. The JHA that enforces locate-then-verify, the tolerance zone, and potholing before mechanical work is the one that keeps the dig from becoming an electrocution or an explosion.
The bottom line
A Utility Locating and Ground Disturbance JHA names the utility-strike, the electrocution, and the explosion hazards with specific controls — calling one-call before any disturbance, confirming complete marks, maintaining the tolerance zone, and potholing to expose and verify lines before mechanical excavation. Every ground disturbance risks a buried-utility strike, and the consequences are catastrophic. The JHA built on locate-then-verify is the one that keeps the bucket out of the live line.
Frequently asked questions
What is the first step before any ground disturbance?
Notify the one-call center (811 in the US) before disturbing the ground, and wait the required time for utility owners to locate and mark their lines. This applies to every ground disturbance, from a fence post to a deep excavation, and skipping it is the most common cause of serious utility strikes.
Do locate marks guarantee where the utility is?
No. Marks are approximate, and the exact horizontal location and depth of a buried line are uncertain, which is why a tolerance zone around the mark must be treated as occupied. Private and unregistered utilities are also often unmarked, so the marks may be incomplete.
What is potholing and why is it required?
Potholing is hand or vacuum excavating to physically expose and confirm a utility's exact location and depth before mechanical equipment digs near it. It is the only way to turn an approximate mark into a known location — the principle is that you do not dig mechanically toward a utility you have not seen.
What is the tolerance zone?
A defined horizontal distance on each side of a utility mark within which mechanical excavation is prohibited, because the line could be anywhere in that band. Within the tolerance zone, only careful hand or vacuum excavation is allowed until the line is physically exposed and verified.
Related JHAs
- Excavation and Trenching JHA — excavation after utilities are located
- Underground Utility Installation JHA — installing new utilities near existing ones
- Site Clearing and Grubbing JHA — ground disturbance during grubbing
- Pile Driving Operations JHA — driving into ground with buried utilities
Written by Mustafa Tok, CSP, ASP, CHST — OSHA Authorized Outreach Trainer with 14+ years of international construction safety experience across federal, heavy civil, and industrial projects.