Confined Spaces in Construction

Understanding Confined Spaces

What Is a Confined Space?

A confined space has three key characteristics:

• Large enough for a worker to enter fully and perform work
• Not designed for continuous occupancy
• Has limited or restricted means of entry or exit

Examples in construction include:

• Manholes
• Sewers
• Storm drains
• Water mains
• Crawl spaces
• Attics
• HVAC ducts
• Storage tanks
• Pits and excavations
• Utility vaults

Permit-Required Confined Spaces

A confined space becomes permit-required when it has one or more of these hazards:

• Contains or has potential to contain a hazardous atmosphere
• Contains material that could engulf an entrant
• Has an internal configuration that could trap or asphyxiate an entrant
• Contains any other recognized serious safety or health hazard

Difference Between General Industry and Construction Standards

• Construction standard (29 CFR 1926 Subpart AA) applies to new construction, alteration, and repair
• More detailed coordination requirements for multiple employers
• More specific provisions for controlling hazards
• Different requirements for residential construction

Identifying and Evaluating Confined Spaces

Competent Person Responsibilities

• Must identify all confined spaces at worksite before work begins
• Determine if spaces are permit-required
• Test and monitor the space as needed
• Evaluate hazards of the space
• Specify necessary precautions
• Verify testing is conducted by qualified person

Common Confined Space Hazards

Atmospheric Hazards

• Oxygen deficiency (less than 19.5%)
• Oxygen enrichment (more than 23.5%)
• Flammable gases or vapors
• Toxic air contaminants
• Carbon monoxide
• Hydrogen sulfide
• Methane

Physical Hazards

• Engulfment by materials
• Entrapment by converging walls
• Mechanical hazards (moving parts)
• Electrical hazards
• Falling objects
• Extreme temperatures
• Noise and vibration
• Limited visibility

Other Hazards

• Limited communication
• Difficult rescue
• Structural collapse
• Uncontrolled energy sources
• Insects, animals, or reptiles
• Bacterial hazards from sewage
• Drowning

Testing and Monitoring

• Test atmosphere in this order:
  1. Oxygen content
  2. Flammable gases and vapors
  3. Toxic air contaminants
• Test at various levels (top, middle, bottom)
• Test before each entry
• Continuous monitoring during work
• Calibrate instruments according to manufacturer specifications
• Document all test results

Entry Procedures and Requirements

Permit System

• Written permit signed by entry supervisor
• Identifies the space to be entered
• Purpose and date of entry
• Duration of authorization
• List of authorized entrants and attendants
• Hazards of the space
• Control measures to eliminate or control hazards
• Acceptable entry conditions
• Testing results with tester's initials
• Rescue procedures and equipment
• Communication procedures

Roles and Responsibilities

Entry Supervisor

• Knows hazards and symptoms of exposure
• Verifies tests, procedures, and equipment
• Terminates entry as needed
• Verifies rescue services are available
• Removes unauthorized individuals
• Ensures acceptable conditions maintained

Authorized Entrants

• Know hazards, including signs, symptoms, and consequences
• Use equipment properly
• Communicate with attendant
• Alert attendant of hazards
• Exit immediately when ordered or upon recognizing danger

Attendant

• Remains outside space during entry
• Maintains count of entrants
• Monitors conditions inside and outside space
• Communicates with entrants
• Summons rescue when needed
• Prevents unauthorized entry
• Performs non-entry rescue if possible
• Never enters the space

Equipment Requirements

• Testing and monitoring equipment
• Ventilation equipment
• Communication equipment
• Personal protective equipment
• Lighting equipment
• Barriers and shields
• Ingress/egress equipment (ladders, etc.)
• Rescue and emergency equipment

Controlling Hazards

Ventilation

• Most common method to control atmospheric hazards
• Must be continuous unless unfeasible
• Direct air to work areas
• Don't recirculate contaminated air
• Provide at least 10,000 cfm for most spaces
• Allow sufficient time before entry
• Verify effectiveness with testing

Isolation

• Locking out electrical sources
• Blanking or blinding piping
• Misaligning or removing sections of lines or pipes
• Double block and bleed system
• Machine guarding
• Blocking or disconnecting mechanical linkages

Personal Protective Equipment

• Respiratory protection appropriate for hazards
• Chemical-resistant gloves and clothing
• Eye and face protection
• Head protection
• Hearing protection
• Fall protection if needed
• Never substitute PPE for engineering controls

Rescue and Emergency Services

Types of Rescue

• Self-rescue: Entrant recognizes danger and exits
• Non-entry rescue: Retrieval from outside the space
• Entry rescue: Trained rescuers enter space

Retrieval Systems

• Required unless they increase risk or won't help
• Full body harness with retrieval line
• Wristlets only if harnesses create greater hazard
• Mechanical retrieval device for vertical spaces deeper than 5 feet
• Attachment point outside space

Rescue Service Requirements

• Respond in timely manner
• Equipped for specific space hazards
• Trained in first aid and CPR
• Practice rescues annually
• Know hazards they may face
• Proficient with rescue equipment

In-House Rescue Teams

• Properly equipped for all confined spaces
• Trained to perform assigned rescue functions
• Practice rescue at least once every 12 months
• Trained in basic first aid and CPR
• All members current in certifications

Training Requirements

Who Needs Training

• All workers involved in confined space work
• Entry supervisors
• Authorized entrants
• Attendants
• Rescue team members
• Testing/monitoring personnel

What Training Must Cover

• Hazards of confined spaces
• Control methods
• Duties of each role
• Entry procedures
• Permit system
• Equipment use
• Rescue procedures
• Emergency response

When Training Is Required

• Before first assignment
• Before change in duties
• When new hazards arise
• When procedures change
• When performance shows deficiencies
• When regulations change

Alternative Procedures

When Alternative Procedures Apply

• Only hazard is atmospheric
• Ventilation alone controls the hazard
• Monitoring verifies safe atmosphere
• Entry through limited or restricted opening

Required Steps

• Eliminate hazards before entry
• Continuous forced air ventilation
• Periodic atmospheric testing
• Written certification procedure
• Entrants can exit quickly
• No work that introduces hazards

Special Considerations

Hot Work in Confined Spaces

• Requires special permit
• Additional ventilation requirements
• Fire watch
• Specialized PPE
• Continuous monitoring
• Remove flammable materials

Sewer Systems

• Continuous monitoring required
• Flow control/isolation needed
• Protection from biological hazards
• Specialized rescue procedures
• Protection from vehicle traffic above

Construction-Specific Hazards

• Newly created spaces change conditions
• Multiple contractors working in/around spaces
• Changing conditions during work
• Materials being introduced
• Power tools creating additional hazards
• Temporary electrical installations

Communication and Coordination

Multi-employer Worksites

• Host employer provides information about spaces
• Controlling contractor coordinates entry operations
• Entry employers follow permit procedures
• All must communicate hazards to each other
• Debrief after entry operations

Information Exchange Requirements

• Location of permit spaces
• Hazards identified
• Precautions taken previously
• Classification of spaces
• Documentation of decisions