What is a Confined Space Rescue

Confined space rescue is the planned recovery of a person who has become injured, incapacitated, trapped or otherwise unable to leave a confined space safely. In drainage and sewer work, the relevant spaces can include manholes, inspection chambers, wet wells, pumping stations, tanks, culverts and sections of sewer large enough for personnel to enter.

The defining issue is not simply that access is physically restricted. A confined space can contain hazards capable of causing serious injury or death, including oxygen deficiency, toxic gases, flammable atmospheres, flooding and engulfment. Rescue therefore cannot be treated as an improvised response in which another worker enters the space to help a colleague.

In the UK, confined space work is principally governed by the Confined Spaces Regulations 1997. The regulations require work in a confined space to be avoided where reasonably practicable. Where entry is necessary, a safe system of work is required, together with suitable and sufficient arrangements for rescue in the event of an emergency. Those arrangements must not rely simply on the emergency services being available after an incident has occurred.

Rescue Planning Starts Before Anyone Enters the Space

An effective rescue arrangement is established before entry begins. Once a worker is unconscious at the bottom of a chamber or inside a sewer, there may be very little time to decide how to reach them, what equipment is required or how rescuers will be protected.

The rescue plan needs to reflect the actual space and the hazards identified for that entry. A shallow chamber with vertical access presents different recovery problems from a long sewer entered through a manhole, even if both meet the definition of a confined space.

Important planning information includes:

• the location, dimensions and internal configuration of the space;
• entry and exit points;
• expected atmospheric hazards;
• potential for water, sewage or other material to enter;
• isolation requirements;
• number and location of people entering;
• communication arrangements between entrants and personnel outside;
• equipment needed to recover an incapacitated person;
• first-aid and resuscitation requirements;
• how rescuers themselves will be protected.

The means of rescue should be compatible with the access opening. It is not enough for a person to fit through a manhole during normal entry. The opening and retrieval arrangement also need to allow an injured or unconscious person to be recovered, potentially while wearing a harness and other equipment.

Vertical access creates particular difficulties because an incapacitated worker cannot climb a ladder. A planned mechanical retrieval arrangement may therefore be needed to raise the person to the surface.

Horizontal travel presents different constraints. If work takes place a significant distance along a sewer or culvert, a retrieval line from the original access point may not provide a practical rescue method. The distance, bends, changes in level, intermediate access points and physical obstacles all affect the rescue strategy.

A generic rescue statement is consequently insufficient for every confined space. The arrangement has to correspond to the entry method and foreseeable emergency conditions at the particular location.

Atmosphere and Flooding Can Make Entry Rescue Extremely Dangerous

Sewer and drainage environments can develop hazardous atmospheres for several reasons. Biological decomposition can generate gases, ventilation can be poor and substances introduced elsewhere in the drainage network can travel into the work area.

Oxygen concentration is a fundamental concern. Normal atmospheric air contains approximately 20.9% oxygen by volume. A reduction in oxygen can impair physical and mental performance and, at sufficiently low concentrations, rapidly become life-threatening.

Toxic gases are another hazard. Hydrogen sulphide can occur in sewer environments and is highly toxic. Methane may also be present under some conditions and creates a flammability concern. Carbon dioxide can accumulate and contribute to oxygen displacement.

Gas behaviour cannot safely be assessed by smell. Hydrogen sulphide is particularly important in this respect because exposure can impair the sense of smell, making odour an unreliable warning.

Atmospheric monitoring is therefore a technical control rather than a confirmation that the space “smells safe”. Depending on the risk assessment, monitoring may be required before entry and continuously while people remain inside.

Flooding deserves equal attention. A sewer that appears manageable under normal flow can become hazardous if upstream pumps start, valves are operated or rainfall increases the flow entering the system.

Isolation should therefore address foreseeable sources of inflow rather than only machinery immediately beside the entry point. Pumps, penstocks, valves and connected systems may need to be secured according to the specific installation and safe system of work.

Weather can also affect rescue conditions. In drainage networks receiving surface water, rainfall elsewhere in the catchment can increase flows at the work location. The absence of rain directly above the manhole does not necessarily mean that upstream conditions are stable.

These hazards explain why spontaneous entry by an unprotected colleague can be fatal. If the original entrant was overcome by an oxygen-deficient or toxic atmosphere, a second person entering without appropriate protection is exposed to the same cause.

Non-Entry Retrieval Is Preferable Where the Situation Allows It

A rescue that can be completed without sending another person into the hazardous space avoids exposing a rescuer to the same environment. For suitable vertical entries, this can involve a harness, retrieval line and lifting system arranged before the worker descends.

Tripods, davits and other support systems can provide an anchorage above or adjacent to an opening. A winch or retrieval device can then raise an incapacitated entrant.

The complete system has to work together. Having a tripod on site does not by itself create an effective rescue arrangement.

The worker needs to be connected in a way that allows retrieval, the equipment must be correctly positioned and the route from the casualty to the opening must remain sufficiently clear. The anchorage and retrieval system also need to be appropriate for the loads involved.

A typical pre-entry retrieval check should establish:

1. whether the entrant can remain connected throughout the work;
2. whether the retrieval line can reach the work position without becoming trapped;
3. whether the casualty can physically pass through the access opening;
4. whether internal ladders, pipes or structures could obstruct lifting;
5. whether the retrieval equipment is correctly positioned and suitable for the intended load;
6. whether personnel outside the space can operate it effectively.

Not every confined space permits non-entry rescue. A worker may move horizontally away from the access point, pass around a bend or work behind equipment that prevents direct retrieval.

An entrant may also become physically trapped rather than merely incapacitated. In those circumstances, pulling on a retrieval line could cause injury without releasing the casualty.

Entry rescue may then be necessary. This requires trained rescuers equipped for the hazards they will encounter, rather than workers entering because they happen to be nearby.

Respiratory protective equipment can become critical where the atmosphere is unsafe or cannot be confirmed as safe. The appropriate equipment depends on the identified hazard and rescue conditions. Ordinary filtering respirators do not supply oxygen and cannot make an oxygen-deficient atmosphere safe.

Rescue Capability Depends on People, Equipment and Rehearsed Procedures

Confined space rescue equipment is useful only when personnel can deploy it correctly under emergency conditions. Training therefore needs to reflect the rescue tasks that people may actually be expected to perform.

A person stationed outside the space may need to maintain communication, recognise an emergency, initiate the rescue arrangement and prevent unauthorised entry. Rescue personnel may need to operate lifting equipment, use respiratory protection or recover a casualty through a restricted opening.

Communication methods should remain effective under the actual conditions. Distance, machinery noise, underground geometry and protective equipment can make ordinary speech unreliable.

The rescue arrangement also needs to account for what happens after the casualty reaches the surface. Exposure to hazardous atmospheres, drowning, trauma or other injuries can require immediate first aid or resuscitation. Suitable equipment and competent personnel therefore need to form part of the emergency arrangement rather than being considered only after retrieval.

Equipment used for confined space rescue may include:

• full-body harnesses and suitable retrieval connections;
• tripods, davits or other appropriate anchorage systems;
• winches and retrieval devices;
• atmospheric monitoring instruments;
• communication equipment;
• lighting suitable for the environment;
• respiratory protective equipment where required;
• first-aid and resuscitation equipment.

The exact equipment list should follow the risk assessment. Carrying every item commonly associated with confined spaces does not compensate for a rescue method that cannot physically reach or recover the casualty.

Practice is equally important. A procedure that appears workable on paper may reveal practical problems when personnel attempt to move a simulated casualty through the real or representative access arrangement.

A rescue exercise can identify whether a lifting system has sufficient clearance, whether communications work from the entry position and whether the team can operate equipment while maintaining control of the access area. It can also reveal situations where the planned number of people is insufficient to perform the required tasks.

For sewer work, changing conditions need particular attention. Flow, atmosphere and access can differ between sites and can change during the same operation. The rescue arrangements therefore need to remain linked to the conditions under which entry is actually taking place, rather than being treated as a standard equipment package carried from one job to another.