What is an Excavation Permit (Dig Permit)?

What is an Excavation Permit?

An Excavation Permit is the final defensive barrier in your excavation safety system. It's the operational mechanism by which you demonstrate compliance with your "primary duty of care" under the Work Health and Safety Act 2011.

The permit functions as more than paperwork—it's a checklist of due diligence. It confirms you've obtained current utility plans, validated them on-site, assessed ground stability, and verified safe work methods are in place. The permit converts information into actionable safety controls.

Critically, an Excavation Permit differs from a Before You Dig Australia (BYDA) enquiry. The BYDA enquiry provides you with plans and archival data—it's passive information gathering. Your Permit to Dig is active authorization, verifying you've analyzed that data, validated it on-site through locating and potholing, and confirmed safe work methods are ready.

Why Excavation Permits Matter

The economic and human costs of excavation failures are staggering. Subsurface utility damage costs the Australian economy approximately $4.6 billion annually, aggregating direct repair costs, project delays, business interruption, and broader economic impacts.

Beyond financial losses, the safety risks are severe. Contact with energized high-voltage cables causes arc flash incidents, electrocution, and fatality. Breaches of high-pressure gas mains create explosion risks and mass evacuations. Trench collapses remain a leading cause of workplace fatalities due to engulfment—a cubic meter of soil weighs approximately 1.8 tonnes.

Your Permit to Dig forces a structured pause, combating the systemic "production pressure" that drives unsafe excavation practices. It ensures you apply the hierarchy of controls proactively rather than reactively.

Legal Requirements Under WHS Regulations

Your obligation to implement excavation permits stems from several regulatory sources that create non-delegable duties.

Primary Duty of Care (Section 19)

Section 19 of the WHS Act mandates that you, as a Person Conducting a Business or Undertaking (PCBU), must ensure, so far as reasonably practicable, the health and safety of workers and others. For excavation, this requires you to eliminate risks (using above-ground alternatives) or minimize them through positive identification of services.

Your Permit to Dig is the evidentiary document demonstrating you've taken "reasonably practicable" steps to manage excavation risks. It serves as your checklist of due diligence.

Regulation 304: Management of Underground Services

Regulation 304 is the regulatory linchpin. It explicitly mandates that before directing or allowing excavation work, you must take all reasonable steps to obtain current information about underground essential services. This information must be provided to workers, readily available for inspection at the workplace, and retained until work completes (or two years if a notifiable incident occurs).

"Essential services" include electricity, gas, water, sewerage, telecommunications, chemicals, fuel, and refrigerant. Your Permit to Dig cannot be issued unless current utility plans are physically present on site and communicated to the machine operator.

Victorian Notification Requirements

If you're working in Victoria, you face an additional external regulatory requirement. You must notify WorkSafe Victoria at least three days before commencing construction excavation if the excavation involves a trench deeper than 1.5 meters, a shaft deeper than 2 meters, a tunnel, or any excavation allowing person entry.

This creates dual-layer compliance: your internal Permit to Dig authorizes daily work and ensures asset protection, while your Notification of Excavation ensures regulatory oversight for high-risk geotechnical activities.

Critical Components of an Excavation Permit

Your excavation permit acts as a checklist for the hierarchy of controls. Each component addresses a specific failure mode identified in incident investigations.

Scope and Methodology

You must define the specific excavation method: mechanical excavator, vacuum extraction, hand digging, or directional drilling. Different methods carry different risk profiles—mechanical excavation requires stricter exclusion zones than non-destructive digging.

Utility Asset Register

Your permit must list every asset identified in BYDA plans and track the verification status of each. For every utility, you need to confirm whether it's identified on plan, located electronically (QL-B), positively identified through potholing (QL-A), and what the verified depth is (as-found depths often differ from plan depths).

Isolation and De-energization

Wherever possible, you should de-energize services. Your permit serves as the verification point that a Network Access Permit (for power) or gas isolation has been confirmed. If isolation isn't reasonably practicable, your permit must mandate specific controls like spotters and exclusion zones.

Geotechnical Stability and Ground Support

For trenches deeper than 1.5 meters, your permit must categorize soil type (Type A, B, or C) and specify the protection method: benching (stepping the trench walls), battering (sloping to angle of repose), or shoring (trench shields or hydraulic supports). You typically need a competent person to sign off on stability assessment before entry is permitted.

Supervisory Sign-off

Your permit is a contract between your workforce and management. It requires signatures from the applicant (supervisor requesting work), the operator (acknowledging they understand conditions and have seen potholes), the spotter (confirming their presence and role), and the authorizing officer (site manager verifying all conditions are met).

Data Quality: Understanding AS 5488 Levels

Your permit's effectiveness relies entirely on the quality of utility data you're using. Australian Standard AS 5488 classifies subsurface utility information into four quality levels based on how the data was obtained, not assumptions about accuracy.

You cannot issue a permit to dig mechanically based solely on QL-D data from BYDA plans. Most rigorous permits require QL-A validation for any asset located within the excavation zone or a specified tolerance buffer (typically 300mm to 1 meter).

This systematic upgrade of data quality shifts liability. If you dig on QL-D data and strike a pipe, you're likely negligent. If you dig on QL-A data (having potholed) and still strike an unmapped branch line, you've demonstrated due diligence.

The Permit Workflow

Your permit lifecycle ensures no safety steps are skipped through a structured sequence:

1. Preparation: Lodge your BYDA enquiry, receive plans from all asset owners, and perform a site walkover to correlate plans with visible surface features.

2. Locating (QL-B): Engage certified locators to use electromagnetic induction or ground-penetrating radar to trace utilities and mark them on the ground. This upgrades your data from QL-D to QL-B.

3. Validation (QL-A): Perform potholing using non-destructive digging on all assets within your tolerance zone. Visual exposure upgrades critical conflict points to QL-A, providing the 50mm accuracy needed for safe mechanical excavation.

4. Issuance: Review all verification data and authorize your permit for a specific timeframe—usually one shift or 24 hours.

5. Execution: Excavate with active supervision from a dedicated spotter who has authority to stop work immediately if conditions change.

6. Close-out: Inspect the site, backfill safely, and update as-built records if unmapped assets were discovered. This feedback loop improves data quality for future works.

The Role of Spotters and Supervision

The most sophisticated permit system fails if you neglect the human element. Your spotter is a mandatory control for excavation near live assets or mobile plant.

Spotter Duties and Authority

Your spotter's sole focus is observing work and communicating hazards to the operator. They must not be engaged in other tasks like laying pipe, checking phones, or reading plans while the machine is moving. "Spotting" is a full-time activity.

Your permit must explicitly grant the spotter authority to stop work immediately. If the operator ignores the spotter, work must cease. A "blind" spotter who cannot communicate effectively is a liability, not a control.

Positioning and Communication

Your spotter must stand where they have clear line of sight to the bucket and asset markers, but remain outside the swing radius and blind spots of the machine. Before work starts, your operator and spotter must agree on communication signals—hand signals or two-way radio.

Competency Requirements

In some jurisdictions and sectors (rail, power), your spotters must hold specific nationally recognized units of competency. Your operators must be competent not only in driving the machine but in "lift and swing" operations near assets. The person issuing your permit must be trained in hazard identification and your organization's specific permit procedures.

Managing Trench Collapse Risks

While utility strikes are the most frequent incident, trench collapses are the most lethal. Your Permit to Dig must address ground stability with equal rigor.

Excavation collapses happen instantly and without warning. A worker buried even partially faces immediate risk of asphyxiation and crush injuries. For any trench deeper than 1.5 meters, WHS Regulations and Codes of Practice require you to verify specific ground support systems are in place.

Your permit must confirm one of these controls: benching (creating steps in the trench wall), battering (sloping to a safe angle based on soil type), or shoring (using engineered structures like trench boxes or hydraulic struts).

Most construction sites assume Type C soil conditions (non-cohesive sand, gravel, or submerged soil) as a conservative safety measure unless a geotechnical engineer proves otherwise. Deep trenches can also become confined spaces, accumulating heavy gases or lacking oxygen. If a trench is defined as a confined space, your Excavation Permit must be accompanied by a separate Confined Space Entry Permit requiring gas monitoring and a rescue plan.

Emergency Response and Incident Management

Despite all precautions, utility strikes and ground collapses do occur. Regulation 43 of the WHS Regulations requires you to have an emergency plan in place.

Immediate Response Protocols

Your Permit to Dig should outline specific emergency responses for the assets present:

Gas strike: Immediate cessation of work. Shut down all engines (ignition sources). Evacuate upwind. Do not attempt to kink or block the pipe. Call 000 and the asset owner immediately.

Electrical strike: Your operator should ideally stay in the cab to avoid step-potential voltage gradients on the ground. If the machine is on fire and they must exit, they should jump clear with feet together and shuffle away, ensuring they don't touch the machine and ground simultaneously.

Trench collapse: Do not enter the trench to rescue (risk of secondary collapse). Use a ladder or retrieval system if available. Call emergency services immediately.

Notifiable Incidents

Any incident involving a utility strike (gas, electricity, water) or trench collapse is typically a notifiable incident under the WHS Act. You must notify your regulator (SafeWork NSW, WorkSafe Vic, etc.) immediately.

Best Practices and the "Golden Rules"

To achieve robust safety culture and avoid penalties, you should adopt these golden rules of excavation:

1. Assume plans are wrong: Always treat BYDA plans (QL-D) as a guide, not a map. Archival records are notoriously unreliable due to poor drafting, lack of updates after repairs, or reference points that no longer exist.

2. Pothole everything: If an asset is within your tolerance zone (typically 300mm to 1 meter), it must be visually exposed to achieve QL-A verification.

3. Positive identification required: Do not dig until you've physically seen the pipe. Touching it with a probe is insufficient—it could be a rock or a different service.

4. Empower the spotter: Your spotter controls the pace of excavation. If they signal to stop, work stops immediately without question.

5. Close the permit properly: Ensure your permit is signed off and site conditions are safe before leaving. This closure loop prevents isolations being left in place inadvertently.

Continuous Improvement

You should use the close-out phase to feed data back into your system. If a utility was found 1 meter away from its plan location, record this "as-found" data and submit it to the asset owner or your project's GIS team. This creates a cycle of improving data quality (QL-D to QL-A) for future works.

Penalties for Non-Compliance

The legal consequences for failing to manage excavation risks are severe and should motivate rigorous permit implementation.

Category 1 Offence (Reckless Conduct): Up to $3 million for corporations and 5 years imprisonment for individuals. This applies if you recklessly allow digging without permits, resulting in a strike that endangers life.

Industrial Manslaughter: In states like Victoria and Queensland, negligent conduct causing death can attract fines up to $16.5 million and 20 years jail. Your failure to implement a Permit to Dig system could be evidence of such negligence.

The cost of a rigorous permit system—including locators, non-destructive digging, and spotters—is negligible compared to the $4.6 billion annual cost of utility strikes and the incalculable cost of human life.

References

• Safe Work Australia, Model Code of Practice: Excavation Work, Australian Government, 2022
• Safe Work Australia, Model Work Health and Safety Regulations, Part 6.3, Regulation 304, 2022
• Standards Australia, AS 5488:2013 Classification of Subsurface Utility Information
• Before You Dig Australia, Best Practice Guide, 2022
• WorkSafe Victoria, Construction Excavation Notification Requirements, 2024
• Safe Work NSW, Work Near Underground Assets—Guide, 2023
• Standards Australia, AS 1674.1:2022 Safety in welding and allied processes—Fire precautions