🎓 Lesson 1 D1

Getting Started with Hazard Identification & Risk Assessment

Hazard identification is spotting anything that could harm people, equipment, or the environment during mining or blasting operations.

🎯 Learning Objectives

✓ Explain the difference between a hazard and a risk using mining-specific examples
✓ Apply the Bowtie diagram method to map one blast-related hazard to its causes and consequences
✓ Analyze a real blast site checklist to identify at least three missed hazards and justify their risk ranking
✓ Calculate risk priority numbers (RPN) using likelihood, severity, and detectability scores for three common blasting hazards

📖 Why This Matters

In 2022, 68% of fatal incidents in surface mining were linked to unrecognized or poorly assessed hazards—especially during pre-blast inspections and muck pile handling. A single missed hazard—like an undetected void beneath a drill pattern or an unmarked high-voltage line near a shot point—can trigger cascading failures. This lesson isn’t about theory—it’s about building the reflex to *see* danger before the detonator is wired.

📘 Core Principles

Hazard identification starts with context: geology, equipment, human behavior, and environment. A hazard is any source of potential harm (e.g., overhanging berm, wet boreholes, seismic activity); risk is the combination of probability and consequence if that hazard manifests. The ISO 31000 risk management framework defines risk as 'the effect of uncertainty on objectives'—here, safety, production, and environmental compliance. We use layered thinking: physical (rockfall), chemical (NO₂ fumes), biological (legionella in water tanks), ergonomic (fatigue from shift work), and psychosocial (poor communication during shift handover). Risk assessment then applies qualitative (risk matrices) or semi-quantitative (RPN scoring) methods to prioritize controls—elimination first, then engineering, administrative, and PPE.

📐 Risk Priority Number (RPN)

The RPN is a semi-quantitative tool used in preliminary risk screening to rank hazards when precise failure data is unavailable. It multiplies three ordinal scores (1–5 or 1–10) representing Likelihood, Severity, and Detectability. While not predictive, it enables rapid consensus-based prioritization during pre-blast planning meetings.

Risk Priority Number (RPN)

RPN = L × S × D

Semi-quantitative score used to rank hazards during preliminary risk screening in blasting operations.

Variables:

Symbol	Name	Unit	Description
L	Likelihood	ordinal (1–5 or 1–10)	Probability of hazard occurrence (1 = extremely unlikely, 5 = almost certain)
S	Severity	ordinal (1–5 or 1–10)	Worst credible consequence (1 = minor injury, 5 = multiple fatalities/environmental catastrophe)
D	Detectability	ordinal (1–5 or 1–10)	Ease of identifying hazard before harm occurs (1 = highly detectable, 5 = nearly impossible to detect)

Typical Ranges:

Low-risk blasting (stable granite, dry conditions): 3–12

High-risk blasting (weathered rock, proximity to infrastructure): 36–50

💡 Worked Example

Problem: A blast design includes drilling into weathered shale with known fracture planes. Assess the hazard 'premature detonation due to stray current'. Likelihood = 4 (occasional, e.g., nearby rail or power lines), Severity = 5 (catastrophic—multiple fatalities), Detectability = 2 (difficult—requires specialized metering not routinely deployed).

1. Step 1: Assign scores per standardized scale (1–5): L=4, S=5, D=2

2. Step 2: Multiply: RPN = 4 × 5 × 2 = 40

3. Step 3: Compare to typical RPN thresholds: ≥40 triggers mandatory engineering controls (e.g., grounding grid + battery-powered initiation)

Answer: The result is 40, which falls within the high-risk range (36–50) requiring immediate mitigation before blast approval.

🏗️ Real-World Application

At the Bingham Canyon Mine (Utah, USA), a 2019 near-miss involved a misaligned perimeter hole that fractured a previously undetected shear zone. Pre-blast hazard ID had flagged 'geological discontinuities' but failed to cross-reference LiDAR terrain models with historical seismic data—missing the zone’s orientation. Post-event, the team adopted a mandatory 3-layer hazard review: geotechnical map overlay + drone-based crack mapping + crew-led 'what-if' tabletop exercise. This reduced unplanned rockfalls by 72% in the next 12 months (Rio Tinto HSE Report, 2020).