Incidents in below ground structures may present significant challenges in gathering information and establishing accurate situational awareness. Therefore, it may be beneficial for fire and rescue services to liaise with local organisations or groups to maintain knowledge of below ground structures in their area.

The seriousness of the incident in a tunnel or below ground structure may not be immediately apparent and there is potential for the incident to rapidly escalate. Responding to below ground incidents may present personnel with a range of complex and unfamiliar hazards that may include:

• Long travel distances
• Complex workings and uncharted layouts
• No through access
• Compressed air workings
• Complex and unfamiliar machinery
• Highly restricted working areas

Consideration should be given to the likely resource and time requirements to establish, initiate and maintain an effective intervention and the likely development of the incident during that time. Initial considerations should include:

• Identifying any fixed installations and their status
• Identifying appropriate bridgeheads or equipment staging areas
• The position of any ventilation outlets if the products of the incident may affect people on the surface or remote from the incident
• Direction of any mechanical forced ventilation, so that safe areas for members of the public and operational bridgeheads can be provided
• Gradient of any passageway allowing run-off, liquid contamination or flowing fuel fire to spread, or the potential for inclined surface 'trench effect'
• Method of containing run-off or contaminated liquids, and their environmental impact
• Stability of the structure and its effect on the surface
• Risk of inundation of the infrastructure
• Identifying the possible spread of flood water and its predicted effects on the wider community

Tunnels

Where tunnels have public access, fire and rescue services will normally have prior knowledge and understanding of the hazards presented. There may be pre-planned arrangements for attendance and the actions to be taken in the event of an incident.

Sewers and associated below ground assets

Sewage or wastewater undertakers should have emergency procedures for their employees and subcontracted staff working in those environments. The assistance that fire and rescue services can provide will depend on the knowledge, training, skills and equipment of the individual services. It may be necessary to seek specialist assistance, such as urban search and rescue (USAR). For further information refer to Utilities and fuel: Isolate utility or fuel supply to the premises.

Operational mines

The British Geological Survey (BGS) continually monitors the location and nature of active onshore mineral workings in the UK and publishes this information in its Directory of Mines and Quarries. A number of mines are used for other purposes such as tourism and storage of documents, computer records, wine and cheese.

Under the Mines Regulations 2014, the mine operator needs to make suitable arrangements for the escape and rescue of people from the mine; this may include using safe havens in the mine.

Arrangements for rescue may include using companies that provide specialist rescue training, trained rescue staff at mines, cave rescue teams in locations such as tourist mines and, in some instances, fire and rescue services.

If fire and rescue services are requested to assist, and depending on the type of incident at a mine, first responders may be limited in their ability to deal with the situation. It may be necessary to seek specialist assistance from teams skilled in rope rescue, confined space rescue, urban search and rescue, cave or mine rescue.

Although large-scale coal mining operations have ceased in the UK, there may be hazards to people, livestock, property and the environment from:

• Collapse of mine entries and shallow coal mine workings (subsidence)
• Emissions of mine gases
• Incidents of spontaneous combustion
• Discharge of water from abandoned coal mines

The Coal Authority manages the effects of past coal mining, including subsidence damage claims that are not the responsibility of licensed coal mine operators. It deals with mine water pollution and other mining legacy issues.

At all mine and mine surface incidents, it is important to consider the need to preserve the scene for investigation purposes. Fire and rescue services need to be aware that other organisations may have to carry out their own investigations. For further information refer to Operations: Compromised investigations: Poor scene preservation.

As large-scale incidents involving mine or mine surface hazards are infrequent, fire and rescue services should carry out joint exercises with the mine operator to understand what skills and techniques may be required.

Caves and recreational below ground environments

Depending on the type of incident at caves or recreational below ground environments, first responders may be limited in their ability to deal with the situation. It may be necessary to seek specialist assistance from teams skilled in rope rescue, confined space rescue, cave rescue or urban search and rescue.

Attendance and intervention will often be led by attending cave rescue specialists, but there may be occasions when fire and rescue services have the ability and resources to assist. For example, if a person has fallen into a vertical entry point at the start of a cave system, personnel may have the rope rescue capability to immediately access and recover the casualty.

Abandoned mines

Depending on the type of incident involving abandoned mines, first responders may be limited in their ability to deal with the situation. It may be necessary to seek specialist assistance from teams skilled in rope rescue, mine rescue, confined space rescue, cave rescue or urban search and rescue.

Attendance and intervention will often be led by attending rescue specialists, but there may be occasions when fire and rescue services have the ability and resources to assist. For example, if a person has fallen into a mineshaft, personnel may have the rope rescue capability to immediately access and recover the casualty.

Armed forces and civil protection below ground structures

Some structures in use are fully occupied, while others are remote stations that are only visited occasionally. Some are only visited by staff to check or maintain equipment or to assess the security of the site. Other sites provide resilience and have only occasional use, but there are usually procedures in place to ensure the safety of those who visit.

The Defence Fire and Rescue Service may provide normal emergency response activities for all operational military establishments.

Structures in private or commercial use will be required to maintain a safe system of work for any working staff or visiting public and, depending on the use and levels of commercial security and sensitivity, will include notification and collaboration with local fire and rescue services.

Fire and rescue services should work with the establishment's management to provide additional assistance if required, to establish a structured response plan and arrange regular joint exercises and familiarisation of sites to ensure all partners have a clear understanding of the extent and limitations of their role and responsibilities.

Evacuation and rescue

Some infrastructures will contain large numbers of people, unfamiliar with their surroundings or emergency procedures. The responsibility for their evacuation in an emergency rests with the infrastructure managers; however, fire and rescue services will undertake rescues of staff or members of the public if they are in imminent danger.

Incident commanders should attempt to identify the progress and success of a managed evacuation. If it appears that people are, or may be, imminently exposed to harm personnel will need to take appropriate action. For further information refer to Operations: Evacuation and shelter.