Hazardous Atmospheres

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Hazardous Atmospheres
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Confined Spaces

• CFR 1910.146
• Any space with limited access egress not designed
  for human occupancy or habitation

By definition, NOT safe for people to enter for
any sustained period of time!
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Confined Spaces

• Transport vessels
• Storage tanks
• Grain bins
• Silos
• Wells and cisterns
• Manholes
• Pumping Stations

• Drainage culverts
• Pits
• Hoppers
• Underground vaults
• Mines
• Caves

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Confined Spaces

• 60 of all confined space fatalities are rescuers!

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Common Emergencies

• Falls
• Medical emergencies
• HAZMAT exposure
• Oxygen deficiency, asphyxia
• Explosions
• Structural, machinery entrapment

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Confined Space Hazards

• Oxygen deficient atmospheres
• Toxic/explosive chemicals
• Engulfment
• Machinery
• Electricity
• Structural concerns

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Oxygen Deficient Atmospheres

• Limited ventilation
• Decaying organic matter
• Presence of heavier-than-air gases
• O2 levels will have to be monitored before entry
• Ventilation systems may have to be set up to
  improve air exchanges

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Toxic/Explosive Chemicals

• CO2 (carbon dioxide)
• CO (carbon monoxide)
• CH4 (methane)
• H2S (hydrogen sulfide)
• NH3 (ammonia)

• Cl2 (chlorine)
• NO2 (nitrogen dioxide)
• N2O4 (nitrogen tetroxide)
• O2 (oxygen)
• Explosive dusts (grain, coal, metal)

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Engulfment

• Risk of burial in grain, sand, coal, other
  particulate solids
• Risk of explosions from finely-divided
  particulates

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Machinery

• Augers
• Mixing blades
• Motors

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Electricity

• Risk for live current, stored energy
• Safety procedures
• Blank out all power to site
• Dissipate all stored charge
• Lock-out, tag-out all switches, breakers
• Ventilate area thoroughly

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Structural Concerns

• Non-cylindrical shapes
• Space limiting support structures
• Limited light
• Restrictions on SCBA use because of space shape,
  size
• Personnel may have to resort to air lines
• Full-body harnesses may be needed in case
  emergency retrieval necessary

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Workplace Protections

• Employers must develop rescue program with
  trained personnel
• Personnel who work in/around confined spaces
  trained in hazards
• Entry controlled by permit
• Atmospheric monitoring
• PPE, retrieval equipment
• Warning signs
• Detailed hazard information available on site

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Rescuer Risks

• Greatest danger is non-permitted sites (cisterns,
  culverts, natural caves)
• Do NOT enter or allow entry unless appropriately
  trained, equipped for specific environment

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Trench Collapses
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Trench Collapses

• Most involve trenches lt12 feet wide and lt6 feet
  deep
• Cubic foot of typical soil weighs 100 pounds
• Two feet of soil on patients chest, back can
  weigh 700 to 1000 pounds!

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Reasons for Trench Collapses

• Disregard of regulations
• Improper/absent shoring
• Spoil pile too close to trench
• Water seepage
• Ground vibration
• Previously disturbed soil

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Trench Collapse Procedures

• Secure scene, perimeter
• Establish command
• Call for trench rescue team
• Interview on-site supervisor, witnesses
• Number of patients?
• Extent of entrapment/burial?

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Trench Collapse Procedures

• Unnecessary personnel, equipment away from trench
  edges
• Trench properly shored before rescue begins
• Personnel in trench wear helmets, protective
  clothing
• Use hand-tools, not heavy equipment
• Determine location of ALL underground utility
  lines on site

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Trench Collapse Procedures

• Priority--uncover patients face, chest begin
  oxygen administration
• Keep weight away from patients chest
• Lie flat, stand on planks to spread weight, avoid
  compressing patients chest
• Do NOT pull on patient at any time
• Consider crush syndrome during prolonged rescues

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Structural Collapses
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Structural Collapse Procedures

• Secure scene, perimeter
• Establish command
• Carefully size up situation
• Consider nature of occupancy, time of day to
  assess extent of problem
• Interview bystanders, rescued occupants

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Structure Collapse Hazards

• Broken water pipes
• May flood basements, other low areas
• Water may have to be shut off at meter, at
  street, or at main
• Pumping equipment may be needed to clear out
  flooded areas

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Structure Collapse Hazards

• Domestic Gas
• Risk of fire, explosion, asphyxiation in closed
  spaces
• Service may have to be discontinued at meter,
  street, or main
• Discontinuation of gas service to large area
  requires house-by-house restoration to relight
  pilot lights

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Structure Collapse Hazards

• Electricity
• All wires assumed to be energized
• Live wires handled by electric company personnel
• Electricity shut off at master switch near meter
  or fuse box or killed at pole by electric company
  personnel

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Structure Collapse Hazards

• Sewers
• Flooding
• Escaping gases (toxic, flammable)
• Risk of exposure to pathogens

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Structural Collapse Procedures

• Stage I Immediate Rescue
• Persons who can be seen, heard
• Persons trapped in voids, other areas where their
  exact location is known

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Structural Collapse Procedures

• Stage II Exploration
• Searching places where trapped persons are likely
  to be found

• Specially constructed shelters
• Under stairways
• Basements
• Near chimneys

• Spaces under partially collapsed floors
• Rooms with exits blocked by debris
• Fringe areas around explosions

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Structural Collapse Procedures

• Stage III Selected Debris Removal
• Takes place when persons are known to be missing
  but cannot be seen, heard
• Based on some combination of
• Persons last known location
• Location, condition of debris
• Direction person may have fallen in collapse
• Location of voids
• Calling and listening
• Removal of debris up to probably location of
  persons

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Structural Collapse Procedures

• Stage IV General Debris Removal
• Used if persons still missing after all other
  stages completed
• Consists of systematically stripping area
• Must be done carefully, methodically
• May require heavy equipment use
• NOT to be confused with site clean-up

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Types of Collapses

• Lean To
• Pancake
• V-Type

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Lean-To Collapse

• Sections collapse on one side, remain supported
  on other
• Produces large void on supported side
• Enter void on side where wreckage is supported
• Do not disturb debris

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V-Type Collapse

• Occurs when heavy loads are concentrated near
  center of floor
• Enter voids along walls
• Wreckage must be stabilized before trying to
  remove debris

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Pancake Collapse

• Floors collapse one of top of another onto lower
  floors or basement
• Voids are small, locations cannot be predicted
• Use call and listen method before removing
  debris