Confined spaces 30th June 1998. Introduction. How bad is the threat? Confined spaces are a danger to people choosing to explore underground tunnels, silos and some abandoned buildings. Confined spaces come with their own hazards. It is important to be aware of these hazards. The main dangers of confined spaces for the urban explorer are Entrapment, Asphyxiation (suffocation) and Engulfment (getting stuck in a liquid or fine grained solid)

What confined spaces means for urban explorers

Urban explorers should be aware that places with confined entry and confined ventatlation are likly hazards for bad air and the prescence of gas. They should be aware that if they enter silos that not only do they face bad air hazards, but they can also become trapped and by grain, flour or other similar substances. Due to the lack of easy entry points, rapid evacuation may not be possible. When entering an unknown confined space for the first time, particuarly those with the posability of bad air, one person should remain outside of the space at all times to monitor those that enter. Evacuation equipment such as life line and harness around the entrant should be used. As many Urban Explorationrs can not afford walki talkis, a system of rope tug signals should be worked out such as one tug for okay, and two tugs for pull me out. All people in the group should be very clear of the signaling procedure.

Urban Explorers by our nature will take risks, but entering such places as sewers, gas tunnels and other places with known bad air is not advised. In fact I strongly advise against entering any of these places. Be aware of stratification - some dangerous gasses rise, while others settle to the floor. In reality I don't expect that Urban Explorationrs will follow all of these procedures, but they should try to do so.

The following information is a copy of some procedures I once wrote up on confined spaces strategy and policy - slightly edited. Most of it is relevant to Urban Explorers.

Defanition of Confined Spaces

Confined Space

Means a space which:

• Is large enough and so configured for an employee to bodily enter and perform work.
• Has limited or restricted means for entry and exit.
• Is not designed for continuous worker occupancy.

Permit-Required Confined Space

Is a confined space which has one or more of the following characteristics:

• Contains or has the potential to contain a hazardous atmosphere.
  
• Contains a material with the potential for engulfment of an entrant.
  
• Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls, or a floor which slopes downward and tapers to a smaller cross-section.
  
• Contains any other recognized serious safety or health hazard.

Non-Permit Confined Space

A confined space NOT containing ANY of the characteristics listed under permit-required confined spaces may be considered a non-permit confined space.

General Entry Procedures - roles

In the case of an Urban Exploration group, at least three people should be present in the team. These should consist of: An Entry Supervisor, the Entrant (person entering the confined space) and an Attendant. All of these people should be aware of the dangers of confined spaces, be aware of first aid CPR practice and have the telephone number of rescue authoraties on hand.

The Entry Supervisor should research the location and make themselves as aware as possible of any dangers - particuarly gas, engulfment and entry and exit difficulties. In event of emergency the attendant should be the one to summon help.

The Attendant should wait at the point of entry and provide communication with the Entrant. They should feed out rope attached to the Entrant and if possible, maintain communications via walki talki. They should be aware of the symptoms of confined spaces problems such as the effects of gas, engulfment and entrapment. The attendant should not enter the confined space to attempt a rescue unless they have proper respitory equipment such as a bottled air supply! There are many documented cases of somone entering a confined space to rescue someone, only to die themselves. The attendant should not ever leave the entrance of the confined space while the entrant is still inside unless their life is in immediate peril.

The Entrant is the person entering the confined space. They should ensure that a harness and life line is securely attached to themselves (a climbing harness works well as long a it can not slip off the user.). They should maintain a running dialouge with the Attendant or use rope tug signals. They should ensure that they remain within communication distance with the attendant. Remain within visual contact of the Attendant. Take adequet equipment as required such as flashlight, air tanks etc.The Entrant should immeidetly tell the Attendant if they feel any symptoms as result of exposure to haxards in enclosed spaces.

Entry procedure is as follows.

• Inform a designated competant person of confined space location and plans for entry.
  
• The members of the team should go over what they are planning to do in detail. Make sure everyone is clear on what the Entrant/Entrants plan to do. Make sure everyone is clear about signals between the Entrant and Attendant.
  
• Guard or barricade entry opening to protect the safety of pedestrians and motorists.
  
• Ventilate the space by opening the access point and using a directed fan (typical home fan will generally only ventilate the entrance but is better than nothing) for at least 10 minutes.
  
• Prior to entry, test the atmosphere with a calibrated, direct-reading instrument for a hazardous atmosphere. If a hazardous atmosphere is detected, ventilate the space and re-test. If the atmospheric hazards cannot be eliminated with ventilation, DO NOT ENTER THE SPACE.
  
• Evaluate the space for engulfment, entrapment or any other serious safety or health hazards. If any of these hazards are found, DO NOT ENTER THE SPACE.

• If the space does not contain any serious hazards or those hazards present have been eliminated, entry may occur
  
• Entrants must wear all required personal protective equipment (PPE) for the assigned task.
  Continuous monitoring and/or ventilation must be used when the unexpected development of hazardous atmospheres should occur.
  
• Entrants must be observant to the effects of hazardous contaminants and evacuate if any are detected.

• Entrants must have a means to summon assistance (i.e. two-way radio). Alternativly, Urban Explorers chould use a system of rope tug signals. Ie - one tug to give more slack on the rope, two fast tugs means pull me out fast! If in doubt about the meaning of a rope tug signal, it is better to be safe than sorry, and pull the person out.

Testing the Air

Atmospheric testing is required for the evaluation of hazards in the confined space and verification that acceptable conditions for entry into the confined space exist. At a minimum, the space must be tested for oxygen, combustible gases and vapors, and toxic gases and vapors. These items can be tested individually (oxygen first, combustibles, then toxics) or they can be tested simultaneously.

Testing for atmospheric hazards must be conducted prior to entry into a permit space to determine if acceptable entry conditions exist. Then, during entry into the space, monitoring must be conducted either continuously or periodically to ensure that acceptable entry conditions are maintained. The atmosphere must be tested at various levels in the confined space as atmospheric hazards may be found at different levels, depending on the contaminant present and the conditions of the space. If the monitoring instrument goes into alarm or fails to operate at any time during entry, the entry must be stopped and entrants removed from the space.

Monitoring equipment must be maintained according to manufacturers' specifications to ensure proper operation during confined space testing and entry. Instrument calibration must be conducted frequently and recorded to ensure equipment operation is within acceptable ranges.

Proper atmospheric testing will be one of the most important subjects covered in employee training. Employees must become familiar with the performance and limitations of their particular monitoring equipment. EH&S can assist departments on the proper selection and usage of personal monitoring equipment for confined spaces testing and entry.

Defanitions

Acceptable Entry Conditions:

The conditions necessary in a confined space to allow entry and to ensure that employees can safely enter.

Asphyxiation:

A class of dangerous gases that replace oxygen and cause unconsciousness or death by suffocation (lack of oxygen).

Attendant:

An individual who is stationed outside one or more permit spaces, who monitors the authorized entrants, and who performs all duties assigned to the attendant by the employers permit program.

Authorized Entrant:

An employee authorized by the employer to enter a confined space.

Carbon Monoxide:

A colorless, odorless, and tasteless gas that is a chemical asphyxiate. Carbon monoxide is found as the end product of combustion.

Confined Space:

Means a space which is:

• Large enough and so configured for an employee to bodily enter and perform work;
• Limited or restricted means for entry and exit; and,
• Not designed for continuous worker occupancy.

Engulfment:

The surrounding or capture of a worker by a liquid or finely divided solid (such as sand, grain or gravel) that can be inhaled to plug the respiratory system or cause death by strangulation, constriction, or crushing.

Entrapment:

The trapping or asphyxiating of a worker by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section.

Entry:

The action by which a person passes through an opening into a permit-required confined space. Entry is said to have occurred as soon as any part of the body crosses the plane of the opening.

Entry Permit (Permit):

An authorization and approval in writing that specifies the location of the confined space, and the type of work to be done. It also certifies that all existing hazards have been evaluated by a qualified person, and the necessary protective measures have been taken.

Entry Supervisor:

An employee assigned by the employer to supervise permit space entries. Responsible for determining if acceptable conditions exist in a permit space prior to entry, for authorizing entry with a permit, overseeing operations, and terminating the entry at the completion of work.

Flammable Atmosphere:

An atmosphere which poses a hazard because flammable or explosive gases, vapors, or dusts are present at a concentration greater than ten percent of their lower flammable limit.

Hazardous Atmospheres:

An atmosphere which exposes employees to a risk of death, incapacitation, injury, or acute illness from one or more of the following causes:

Flammable atmosphere. Airborne combustible dust. An atmosphere containing oxygen levels below 19.5% or above 23.5%. An atmosphere where the permissible exposure limit for a certain chemical has been exceeded and could result in exposure. Any other atmospheric condition that is immediately dangerous to life and health.

Hot Work:

Any work that introduces an ignition source into a confined space, (i.e. welding, cutting, brazing, or soldering).

Hydrogen Sulfide:

A colorless gas that, at low levels, has the odor of rotten eggs. It is a chemical asphyxiate and its smell cannot be relied upon for adequate warning.

Immediately Dangerous to Life and Health (IDLH):

Any condition that poses an immediate or delayed threat to life or that would cause irreversible adverse health effects or would interfere with Authorized Entrants abilities to evacuate the permit space unaided.

Lockout/Tagout:

The control of all hazardous energies within a system prior to performing service on the system. The ISU Hazardous Energies Control (Lockout/Tagout) Manual will assist in complying with the OSHA "Control of Hazardous Energies (Lockout/Tagout) Standard," (29 CFR 1910.147).

Non-Permit Required Confined Space:

A confined space NOT containing ANY of the characteristics listed under permit-required confined spaces may be considered a non-permit confined space.

Oxygen Deficient:

An atmosphere containing less than 19.5% oxygen by volume. Insufficient oxygen is present to sustain life.

Oxygen Enriched Atmosphere:

An atmosphere containing more than 23.5% oxygen by volume. Increases the potential for explosion or ignition of an explosive or flammable substance.

Parts Per Million (PPM):

Volume measurement of a gas concentration (parts of a contaminant per million parts of air).

Permit-Required Confined Space (Permit Space):

Is a confined space which has one or more of the following characteristics:

Contains or has the potential to contain a hazardous atmosphere. Contains a material with the potential for engulfment of an entrant. Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls, or a floor which slopes downward and tapers to a smaller cross-section. Contains any other recognized serious safety or health hazard.

Personal Protective Equipment (PPE):

Equipment that will help prevent accidents and personal injury. PPE includes hard hats, goggles, face shields, steel-toed shoes, respirators, aprons, gloves, and full body suits.

Prohibited Condition:

Any condition in a permit space that is not allowed by the permit that occurs during entry.

Purge:

To do a complete air exchange in a confined space prior to entry which is designed to remove the contaminated air and replace it with fresh air.

Qualified Person:

A person designated by the employer, in writing, as capable (by education or training) of anticipating, recognizing, and evaluating hazardous substances or other unsafe conditions present in confined spaces.

Retrieval System

The equipment used for non-entry rescue of persons from permit spaces (includes retrieval line, harness, and lifting device).

Site Survey:

The process by which the workplace is surveyed for confined spaces, identifying "permit spaces" and determining whether employees would need to enter the spaces or not.

Stratification:

Gases form layers, or "stratify" depending on weight, especially without normal ventilation in a confined space. Stratification is dependent upon the weight of the gas. This is the reason why atmospheric testing must be performed at various levels to ensure employee safety.

Ventilator:

A machine designed for moving quantities of air. This machine is used to ventilate the confined space prior and during the entry.

Sources

Most of this was modified from my own text when I worked as a health and safety officer