A highwall inspection checklist is the structured walk of an excavated wall that confirms it still matches its design and shows no sign of instability: crest, face, benches, toe, water, geological structure, blast damage, monitoring and exclusion zones, each checked against a stated standard with a clear trigger for escalation. Its job is to let the person inspecting decide, on the day, whether the risk to people working near that wall is acceptable.
This guide sets out what Queensland and New South Wales law requires, how highwalls actually fail, and a complete field checklist grouped by section with “escalate if” triggers you can map to your own TARP. The checklist is generic. Your site’s geotechnical design and ground control management plan set the numbers.
Why highwall inspections matter
Highwalls rarely fail without warning. They crack at the crest, bulge or ravel on the face, seep at the toe, or show movement on radar and prisms hours or days before a failure. The inspection exists to catch those signs while there is still time to pull people and plant back.
The Queensland inspectorate’s highwall failures safety bulletin (Mines safety bulletin no. 145, January 2015) describes a section of wall that toppled roughly 33,000 tonnes of material into a pit, partly burying an excavator and a truck and injuring three workers. The inspectorate interpreted it as a complex full-face topple, most likely triggered at or near the toe, where the face was cut by a thrust fault nobody had detected. That is the pattern the checklist is built to interrupt: a structural feature, a toe condition and people in the drop zone, all at once.
What the law requires
Queensland coal
The Coal Mining Safety and Health Regulation 2017 puts the requirement in plain terms. Section 117 requires a surface mine to have a standard operating procedure for working on spoil dumps and near excavated faces, and that procedure must provide for inspecting and monitoring the spoil dumps and excavated faces. Section 102A requires a surface mine to have principal hazard management plans that provide for, at least, ground or strata failure.
Sections 106 and 107 set the open-cut examiner’s part. The OCE must inspect the surface excavation before activities start and periodically as the safety and health management system requires, to decide whether the level of risk is acceptable. Before inspecting, the OCE must read the latest OCE report in the mine record and acknowledge that in writing. If the risk is unacceptable, the OCE must make it safe immediately if practicable. If not, the OCE must notify exposed people, barricade the area, stop coal mining operations there and withdraw people, and, if it is still not safe at the end of the shift, report it to their supervisor and the next shift’s OCE.
The 2015 bulletin is guidance rather than law, and it predates the 2017 Regulation, but its recommendations still hold. It asks each mine’s safety and health management system to provide for slope stability radar (or similar) as a continuous control, with TARPs and site-specific alarm thresholds, to manage activity at the bottom of an excavation as well as the top, and to provide for an acceptable level of risk where an OCE cannot inspect the top of a highwall.
New South Wales
Under the Work Health and Safety (Mines and Petroleum Sites) Regulation 2022, ground or strata failure is a principal hazard. Schedule 1 lists the matters that must be considered in developing controls for it, including local geological structure, hydrogeology, the collection and interpretation of geotechnical data including monitoring of excavations, blasting, the stability of slopes, scaling, and monitoring of areas where controls are in place.
The Resources Regulator’s slope stability assessment fact sheet for surface coal is a useful mirror of what an inspector will look for: walls excavated to design and cleared of loose material, drill and blast completed to design, and indicators of failure identified so people can be separated from the hazard.
Before you walk the wall
A good excavated wall inspection starts at the desk. Read the previous inspection and the last OCE report for the area. Check the current TARP level for each wall domain, any open hazards, and what the monitoring has done since the last shift. Know what changed: a new blast, a rain event, a dig cut deeper into the toe, a crew now working closer to the face.
Then inspect from both the top and the bottom where you safely can. Crest cracking is only visible from above; toe heave and seepage are only visible from below. Where the crest cannot be accessed, that is itself a finding, and the bulletin asks sites to provide for exactly that case.
Reading the wall: the warning signs
These are the highwall failure warning signs the checklist below is organised around.
- New or opening crest cracks, especially cracks parallel to the crest, with vertical offset, or that were not there last shift.
- Face changes: bulging, ravelling, fresh spalls, open joints, or blocks that have visibly moved.
- Loose material and rockfall on benches, and catch benches that have filled and lost capacity.
- Water: new seepage, wet patches at the toe, ponding on the crest or water running into cracks.
- Structure: faults, shears, bedding or joint sets dipping out of the face, particularly where they daylight near the toe.
- Toe condition: undercutting, heave, over-digging past design, or softened material.
- Blast damage: back break past the design crest, cracking behind the face, or overhangs.
- Monitoring: accelerating movement, radar alarms, or monitoring that is down.
The highwall inspection checklist
Use this as the basis for a site form. The “escalate if” column describes the kind of observation that should move the wall up your TARP; your geotechnical engineer sets the actual triggers and levels.
| Check | What good looks like | Escalate if |
|---|---|---|
| 1. Setup | ||
| Previous inspection and OCE report read | Read and acknowledged; open actions known | Open actions from last shift not closed or handed over |
| Current TARP level for each wall domain | Known and matches the signage and radio briefing | Level unknown or different from what crews were told |
| Access to crest and toe | Both inspected, or a documented alternative in place | Crest cannot be inspected and no alternative control applies |
| Changes since last inspection | Blasts, rain, dig progress and new crews noted | Significant rain or blast since last inspection not yet assessed |
| 2. Geometry against design | ||
| Batter angle and bench height | Consistent with the current design | Steeper or higher than design |
| Bench width | At design width along the length inspected | Bench narrowed or lost |
| Toe position | Dug to the design toe line, no over-dig | Toe undercut or dug past design |
| 3. Crest | ||
| Tension cracks | None, or existing cracks marked and unchanged | New crack, crack widening, or vertical offset across a crack |
| Crest windrow or bund | Intact and at site standard height | Damaged, breached or missing |
| Surface water at crest | Drains away from the crest | Ponding at crest or water entering cracks |
| Plant and people near crest | Outside the marked crest standoff | Plant or people inside the standoff |
| 4. Face | ||
| Face profile | Clean, even face with no bulging | Bulging, new slumping or changed profile |
| Loose rock and overhangs | Scaled; no loose blocks or overhangs | Loose or hung-up material above a work area |
| Ravelling | No active ravelling | Continuous small falls, or ravelling increasing |
| 5. Benches and catch capacity | ||
| Catch bench condition | Clear, with capacity to retain rockfall | Bench full or spilling |
| Rockfall evidence | No fresh rockfall | Fresh rockfall reaching the pit floor or a work area |
| 6. Geological structure | ||
| Faults and shears | Mapped and as expected in the design | Unmapped structure exposed, especially near the toe |
| Joints and bedding | No adverse sets dipping out of the face | Adverse set daylighting, or blocks moving on a joint |
| 7. Water | ||
| Seepage on face or toe | Dry, or known seepage unchanged | New seepage, increased flow or discoloured water |
| Pit floor drainage | Sump and drains working | Water ponding against the toe |
| 8. Toe | ||
| Toe condition | Firm, no heave, no undercut | Heave, softening, or undercutting |
| Work at the toe | Within the approved dig plan and standoff | Working inside the drop zone without approval |
| 9. Blast damage | ||
| Back break | Within design allowance | Crest broken back past design |
| Post-blast cracking | No new cracking behind the face | New cracks behind the crest after a blast |
| Drilled or loaded holes | No holes in a wall section showing movement | Loaded shot in a wall showing cracking or movement |
| 10. Monitoring | ||
| Radar coverage | Covering the active wall, online and alarming correctly | Radar offline, not covering the work area, or alarming |
| Prisms and other instruments | Readings current and within trigger values | Readings overdue, missing or accelerating |
| 11. Exclusion zones and signage | ||
| Exclusion zones | Barricaded and matching the current TARP level | Zone missing, breached or out of date |
| Signage | Current, legible and at every entry point | Missing, wrong level or contradicting the radio briefing |
| 12. Outcome | ||
| Risk acceptable to continue | Decision recorded and signed | Not acceptable: make safe, withdraw, barricade, notify |
| Actions and handover | Owner and due time for every action; next shift told | Any unsafe condition not handed over |
Linking findings to the TARP
A checklist that records a crest crack but does not say what happens next is a record, not a control. Most sites run a ground control TARP with levels that step from normal conditions through heightened monitoring, restricted access and full exclusion. The inspection is where those levels are triggered, so each “escalate if” item should point to a TARP descriptor, not to free text.
For example, a new crest crack might trigger increased inspection frequency and a geotechnical review, while a widening crack with radar movement might trigger withdrawal from below the wall. Writing those links into the form removes the judgement call at 3 am. For the wider design of trigger action response plans in a digital form, see our guide to a digital TARP for mining.
Where highwall inspections go wrong
- Top or bottom only. The inspection is done from the pit floor because the crest road is inconvenient, and crest cracking is missed.
- Tick box drift. The same wall passes every shift until the form stops being read. This is the trap described in why general checklists create a false sense of safety.
- No location. “Crack on east wall” cannot be found again by the next shift. Findings need a position, a photo and a marker.
- Monitoring treated as separate. Radar alarms sit with one team and field observations with another, and nobody sees both at once.
- Weak handover. A condition found late in shift is not carried into the next OCE’s inspection, which is exactly what section 107 requires.
Spoil and dump faces fail differently and need their own form; the companion spoil dump inspection checklist covers them. Where the highwall inspection is also verifying a critical control such as the crest standoff or radar coverage, the critical control verification checklist shows how to record that properly. Quarry faces have their own quarry face inspection checklist.
Keeping the wall, the monitoring and the inspection in one place
The recurring problem with highwall inspections is not the form. It is that the form, the radar, the crack map and the TARP status live in different places, so the person deciding whether to send a crew under a wall is assembling the picture from memory and radio calls.
HazView puts them on one map of the site. A wall can be held as a hazard with a geotechnical TARP rating and an area state, and the inspection is attached to that hazard, so the history of every walk sits with the wall itself. TARP levels can be carried in the answer options, so the outcome is derived from what the inspector found, and a non-conforming answer can open an escalation section. Radar and other sensors show on the same map, and cracks, loose rock and seepage are pinned with photos. The checklist is completed offline at the wall and syncs when the device is back in reception, and forms are converted like for like from the site’s existing paper version first. Geotechnical teams can see how this works on the HazView page for geotechnical engineers, or book a demo to walk through it with your own wall domains.
For how this form fits alongside the other statutory and operational inspections on site, see the overview of mine site inspections in Australia.
Related guides
- Mine Site Inspections in Australia: What the Law Requires, What to Check and What a Defensible Record Looks Like
- Choosing Inspection Software for an Australian Mine Site: A Buyer’s Checklist
- Going Paperless on a Mine Site: Digital Inspections That Hold Up
- Quarry Face Inspection Checklist for Australian Quarries
- All Inspections & Checklists guides
Frequently asked questions
How often should a highwall be inspected?
In Queensland coal, the OCE must inspect before activities start in or around the excavation and then periodically as the mine’s safety and health management system requires. The frequency is set by the site. Many sites inspect active walls every shift and more often at elevated TARP levels.
Who carries out a highwall inspection?
In Queensland coal the statutory inspection of the surface excavation is the open-cut examiner’s duty. Geotechnical engineers typically carry out separate, more detailed wall inspections and set the triggers the OCE works to.
What are the main highwall failure warning signs?
New or widening crest cracks, bulging or ravelling on the face, fresh rockfall, new seepage, toe heave or undercutting, adverse structure exposed near the toe, and accelerating movement on radar or prisms.
Is a highwall inspection the same as a spoil dump inspection?
No. Section 117 of Queensland’s coal regulation covers both spoil dumps and excavated faces in one procedure, but the failure mechanisms and checks differ, so most sites keep separate forms.
What should happen when an inspection finds an unacceptable risk?
In Queensland coal, section 107 requires the OCE to make it safe immediately if practicable. If not, notify exposed people, barricade the area, stop operations and withdraw people from it. If it is still not safe at the end of the shift, report it to your supervisor and the next shift’s OCE.