Key Points
- Required before any ground disturbance or excavation at industrial sites.
- Addresses invisible underground hazards: buried cables, gas mains, process piping.
- Requires utility surveys, ground-penetrating radar, and as-built drawing review.
- Digital PTW overlays excavation areas on maps of known underground services.
Definition
A Permit to Dig is a specialized work authorization required before any ground-breaking, excavation, or ground-disturbance activities are performed at an industrial site. This permit type addresses the significant risks associated with underground hazards that are invisible from the surface — including buried utilities (electrical cables, gas mains, water pipes, fiber optic lines), underground process piping, contaminated soil, unexploded ordnance in some locations, and ground stability concerns. Striking a buried electrical cable or gas main during uncontrolled excavation can result in electrocution, explosion, fire, or environmental contamination. The permit-to-dig process requires identification of all underground services through utility surveys, ground-penetrating radar, cable avoidance tools, and reference to as-built drawings. It specifies safe digging methods (hand digging near known services, mechanical exclusion zones), required protective measures, and emergency procedures for utility strikes. In complex industrial facilities, underground services are often poorly documented, making digital asset management and 3D underground mapping critical safety tools. Digital PTW systems can overlay excavation permits on facility maps showing known underground services, automatically flagging potential conflicts and requiring additional surveys when excavation is planned near documented utilities.
Related Terms
Excavation Permit
An excavation permit is a specialized work permit required before any ground-breaking, digging, trenching, boring, or drilling at an industrial site. Excavation carries unique and potentially fatal hazards including striking underground utilities (electrical cables, gas lines, water mains, fiber optics), trench collapse and engulfment, exposure to contaminated soil or ground gases, and damage to foundations. The permit process ensures all underground services have been identified, located, and protected before ground disturbance occurs. It typically requires consultation of underground service drawings, cable and pipe location surveys using detection equipment (CAT and Genny locators), marking of all identified services on the ground surface, hand digging within proximity zones, trench support systems for deep excavations, atmospheric monitoring for ground gases, and edge protection for personnel in trenches. The permit must define exact dig boundaries, maximum depth, authorized equipment types, and all safety controls. Any deviation from permitted boundaries requires stopping work and re-assessment.
Permit to Work (PTW)
A Permit to Work is a formal control process used to manage hazardous work activities in industrial environments. It ensures that work is properly planned, risks are identified and mitigated, and responsibilities are clearly assigned before work begins. The permit defines conditions under which the work can be carried out, including required safety measures, isolations, and approvals. In practice, PTW acts as the central coordination tool between operations, maintenance, and contractors to prevent accidents and conflicts between activities.
Job Safety Analysis (JSA)
A Job Safety Analysis is a structured process used to break down a task into individual steps and identify hazards associated with each step. For every identified risk, appropriate control measures are defined to reduce or eliminate the hazard. JSA is typically prepared before work begins and is often linked directly to the permit. In practice, it ensures that work is systematically thought through rather than executed based on assumptions.
Energy Isolation Permit (LOTO)
Ensures that all hazardous energy sources are isolated before work begins. This includes electrical, mechanical, and pressure energy. Proper isolation prevents accidental start-up or release of energy.
More in High-Risk Work Permits
Hot Work Permit
A hot work permit is required for activities that generate heat, sparks, or flames, such as welding or cutting. These activities pose a fire or explosion risk and require strict controls like fire watch and gas testing. The permit ensures all precautions are in place before work begins.
Confined Space Entry Permit
This permit is required for entering enclosed or restricted spaces where hazards such as lack of oxygen or toxic gases may exist. It includes requirements for gas testing, rescue plans, and supervision. These environments are high-risk due to limited escape options.
Lifting Permit
A lifting permit governs operations involving cranes or lifting equipment. It ensures load calculations, equipment checks, and safe lifting plans are in place. Poorly managed lifting can result in serious accidents.
Work at Height Permit
This permit is required when working at elevated heights where fall hazards exist. It ensures proper use of fall protection systems and safe access. Falls are one of the most common causes of injuries in industry.
Frequently Asked Questions
How does a permit to dig differ from an excavation permit?
The terms are often used interchangeably, but in some organizations, a "permit to dig" covers all ground disturbance activities (including shallow hand-digging, trenching, and drilling), while an "excavation permit" specifically covers deeper excavations where additional risks like ground collapse, water ingress, and confined space hazards apply. Some PTW systems use both as separate permit types with different risk controls.
What survey methods are used before issuing a permit to dig?
Common survey methods include reviewing as-built drawings and utility records, electromagnetic cable avoidance tools (CAT scanners), ground-penetrating radar (GPR) for detecting non-metallic services, trial holes (hand-dug to confirm utility locations), and consultation with utility owners. Multiple methods are often used together because no single technique detects all types of underground services.
Explore Our Guides
Deepen your knowledge with our comprehensive guides and expert resources.
Pirkka Paronen
CEO, Gate Apps
CEO of Gate Apps, expert in digital permit-to-work and HSEQ software.
