The City of Ekurhuleni has procured a Specialised Rescue Vacuum Unit for Trench Rescues, to rescue patients trapped in trenches on construction sites, excavation or any similar incidents such as silos.

The procurement is based on Newton’s third law of motion which states that; “Every force has a reciprocating equal and opposite force”. The City needs to meet the challenges.

Providing services to communities involves the construction of roads, bridges, water distribution networks, sewer systems, electricity networks, buildings and the like. These also come with humongous risks, which could cost lives; trenches could collapse and bury workers underneath.

New plans outlined by the government highlight the intention to use the power of critical infrastructure to drive social and economic improvements in the country, to the benefit of the construction industry too.

Trench Collapse

The Rescue Vacuum Unit can be deployed in both dry and wet conditions. It is able to move a significant amount of soil far more quickly than more traditional methods. Cave-ins occurring at depths of 2,438m or more often result in several meters of material covering the victim.

Historically, trench rescue instruction advises rescue personnel to anticipate one hour of manual excavation for each vertical foot of soil to be excavated. For a victim suffering from trauma, restricted breathing, or blood flow, time is of the essence. Tragically, some rescuers attempting to move the soil manually in time to save a victim have resulted in using backhoes or excavators, resulting in severely injuring or killing the victim.

Using vacuum truck technology

As most industry insiders will tell you, trench collapses are nothing new, but what has changed is the technology in dealing with them. Here, vacuum trucks play a critical role. Traditional methods of uncovering an inundated trench involve the use of shovels and a bucket brigade, which in the event of a buried or partially buried worker takes up precious time and is very labour intensive. The use of heavy equipment in trench rescues is, for obvious reasons, to be avoided. In the same kinds of incidents heavy machinery like front-end loaders are being used, which risk further injuries to the victim buried under the trench.

The more rescuers at a scene also increase the risk to individuals. Technology for using vacuum trucks for trench and similar engulfment rescue operations was developed and successfully used by fire and rescue services such as the Chicago Fire Department in the USA and has become the norm for engulfment rescue operations.


Once this unit is seen as the best option to ensure rescuer and victim safety, the rescue team proceeds with standard trench rescue site preparation prior to the Rescue Vacuum Unit’s arrival. This includes setting safety zones, shoring or shielding the trench, and removing or limiting destabilizing influences such as traffic.

On arrival, the unit is slowly positioned forward or rearward of the collapsed zone at a distance from the edge of the trench equal to at least twice the depth. The vacuum and pressure hoses are then extended to the critical area.

After determining the victim’s position, rescuers identify the best place to excavate a sump, into which water and soil are washed away and vacuumed up within a few seconds, eliminating pooling or seepage into the soil. The technicians or rescue personnel activate the vacuum and pressure-jetting systems and begin to hydro-excavate the soil from atop the excavation.

When sufficient soil is removed to allow for the extrication of the victim, the technician vacuums up the residual water and wet soil. Rescue personnel then enter the trench to remove the victim, using the most appropriate means and methods.

The unit comes equipped with an air knife to loosen soil; special nozzles to ensure safe vacuuming around the patient and a rescue shield to protect the patient against a further cave in. The pressure equipment is driven from the built-in compressor on the heavy rescue unit, or from a mobile compressor.


The vehicle will be deployed for operation as soon as the final registration has been concluded with licensing as a fire and emergency services` rescue unit and training conducted to the operators.

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