Working Safely Around Underground Utilities (Before You Dig)

About this course.

Striking an underground service is so dangerous because the services buried beneath a worksite carry energy and essential resources — electricity, gas, pressurised water, sewage and telecommunications — that can kill or seriously injure a worker in an instant and can disrupt whole communities if damaged. Unlike a hazard you can see and plan around, an underground service is hidden, and the first sign of a problem is often the strike itself. That combination of high energy and low visibility is what makes underground utilities one of the most serious excavation hazards, and it is why the whole discipline of "before you dig" exists: to remove the guesswork before a tool or machine goes into the ground.

Consider what each type of service can do if struck. Electricity cables are perhaps the most immediately lethal. Contact with a live underground cable — whether by an excavator bucket, a hand tool, or even a person — can cause electrocution, severe burns, arc flash and blast. Electricity does not need the worker to touch the conductor directly; energy can arc, and the surrounding ground and equipment can become live. A single contact can be fatal. Gas mains and services present the risk of fire and explosion: a damaged gas line can release flammable gas that may ignite from a spark, a nearby ignition source, or the strike itself, causing an explosion or fire that endangers not only the worker but everyone nearby. Gas can also accumulate in trenches, pits and confined spaces, creating an explosive or asphyxiating atmosphere. Water mains, often under significant pressure, can rupture violently, injuring workers, rapidly flooding and undermining an excavation (which can trigger a collapse and trap workers), and washing out the ground. Sewer strikes release contaminated material with serious health and environmental consequences and can be costly and unpleasant to remediate. Telecommunications cables, including fibre-optic and copper networks, may not carry the same immediate injury risk, but severing them can knock out phone, internet and data services — potentially including connections that emergency services, businesses and critical facilities rely on — with major disruption and cost.