Working Safely in Confined Spaces: Planning for Entry, Work & Rescue

A confined space is not simply a small work area. The combination of enclosure, restricted access and foreseeable hazards can make an incident significantly more difficult to manage than the same event in an open environment.

A worker who becomes unwell, injured or unconscious may not be able to leave independently. Access points such as manholes can make recovery difficult, while atmospheric conditions inside the space can create hazards for both the worker and anyone attempting rescue.

Confined-space planning therefore needs to consider the complete activity: whether entry is necessary, what hazards are present, how work will be controlled and how someone could be recovered safely if an emergency occurs.

Before planning a confined-space entry, consider whether the required work can reasonably be completed from outside the space. Inspection, cleaning, measurement or other activities may sometimes be possible without placing a person inside the hazardous environment.

Where entry can be avoided, many of the risks associated with confined-space work can be removed at source.

Where entry is necessary, suitable risk controls, competent personnel and appropriate emergency arrangements should be established before work begins.

Where confined-space entry cannot be avoided, control measures should reflect the hazards identified during the risk assessment. The system of work should be understood by everyone involved before entry begins.

Depending on the environment, this may include isolating services, cleaning or purging the space, providing suitable ventilation, checking atmospheric conditions, controlling access and establishing reliable communication between those inside and outside.

Workers should be competent for the task and understand both the normal working procedure and what is expected if conditions change or an emergency develops.

Emergency arrangements are a critical part of confined-space work. Waiting until an incident occurs to decide how a casualty will be recovered can expose both the worker and would-be rescuers to additional danger.

The rescue plan should reflect the access point, depth, potential casualty position and hazards within the specific space. Equipment required for recovery should be identified and available before work begins.

Where vertical entry is involved, a suitable tripod, harness and retrieval system can provide a controlled means of access and recovery where identified by the planned rescue arrangement.

Vertical confined-space access through a manhole or chamber creates a particular rescue challenge. A casualty may need to be raised through a relatively small opening and may be unable to assist in their own recovery.

A tripod creates a stable overhead anchorage above the opening, while the winch provides controlled movement of the retrieval line. The harness provides the connection to the worker.

These components need to be compatible and selected around the planned system of work. The correct configuration depends on the access point, working depth, retrieval requirements and manufacturer instructions for the equipment being used.

One of the most serious characteristics of confined-space work is that some hazards cannot be identified visually. Oxygen deficiency and hazardous gases or vapours may be present without an obvious warning.

Where atmospheric hazards are foreseeable, suitable testing, ventilation and other controls should form part of the planned system of work. Conditions may also need to be monitored while work takes place where there is potential for them to change.

Respiratory protection or emergency escape equipment should be selected as part of a competent assessment of the specific atmospheric risk.

Confined-space equipment may be safety-critical, but safe use depends on the people operating it. Workers need to understand the equipment, its limitations and how it fits into the site procedure.

Those involved in rescue arrangements also need to understand the planned recovery method and be capable of carrying it out without introducing additional uncontrolled risks.

Equipment should be inspected, maintained and used in accordance with the manufacturer's requirements and the organisation's established safe system of work.

Confined-space equipment should be selected as a result of the risk assessment and rescue plan, rather than selecting equipment first and trying to build the procedure around it.

Consider the access arrangement, working depth, foreseeable atmosphere, communication requirements, potential casualty position and method of recovery before deciding what equipment is required.

For vertical entry, this may lead to a combination of tripod, winch and harness equipment. Other environments may require different controls or additional emergency equipment according to the risks identified.