Does "Subpart S - Underground Construction, Caissons, Cofferdams, and Compressed Air" Apply to You?

Subpart S provides the standards for underground construction, caissons, cofferdams, and compressed air. It also provides definitions applicable to this subpart including:

Caisson - A wood, steel, concrete or reinforced concrete, air- and water-tight chamber in which it is possible for men to work under air pressure greater than atmospheric pressure to excavate material below water level.

Bulkhead - An airtight structure separating the working chamber from free air or from another chamber under a lesser pressure than the working pressure.

Man lock - A chamber through which men pass from one air pressure environment into another.

Are employees engaged in underground construction, work in caissons or cofferdams, or use compressed air? If yes, click on the tabs below to see if they apply to you.

Subpart S - Underground Construction, Caissons, Cofferdams, and Compressed Air

Are employees engaged in underground construction?

Are employees engaged in underground construction?

This standard applies to the construction of underground tunnels, shafts, chambers, and passageways. It also applies to cut-and-cover excavations which are both physically connected to ongoing underground construction operations, and covered in such a manner as to create conditions characteristic of underground construction. Do your employees work in underground tunnels, shafts, chambers, passageways, or cut-and-cover excavations? If yes, then the standard on underground construction applies to you.

This standard does not apply to the following:

  • Excavation and trenching operations covered by subpart P, such as foundation operations for above-ground structures that are not physical connected to underground construction operations, and surface excavation: nor
  • Underground electrical transmission and distribution lines, as addressed in subpart V.

It provides requirements pertaining to access and egress, safety instruction (i.e., air monitoring, ventilation, illumination, PPE, emergency procedures), check-in/check-out, notifications of hazardous conditions at each shift, communications, emergency provisions (i.e, self-rescue, rescue teams), hazardous classifications, gassy operations, air quality and monitoring, ventilation, fire prevention and control (i.e., smoking, open flames, fuel, welding), illumination, ground support, drilling, haulage, electrical safety, and cranes and hoists.

Additional related information can be found on the A-Z topics pages for underground constructionelectrical safetyfire prevention plansmedical services and first aidpersonal protective equipmentwelding and cuttingconfined spacesnoiserespiratory protectionsilica and hazard communication and cranes and derricks.

Are employees engaged in caisson work?

Are employees engaged in caisson work?

If yes, then you need to comply with the standard on caissons. It provides requirements regarding shafts, compressed air and gauges.

Caisson - A wood, steel, concrete or reinforced concrete, air- and water-tight chamber in which it is possible for men to work under air pressure greater than atmospheric pressure to excavate material below water level.

Bulkhead - An airtight structure separating the working chamber from free air or from another chamber under a lesser pressure than the working pressure.

Additional related information can be found on the A-Z topics page for compressed air and compressed air equipment

Are employees engaged in cofferedam work?

Are employees engaged in cofferedam work?

If yes, then you need to comply with the standard on cofferdams. This standard provides requirements for controlling flooding, and providing warning signals and guardrails.

Cofferdam - An enclosure that allows for construction work in a body of water that has been pumped dry.

Do employees use compressed air?

Do employees use compressed air?

If yes, then you need to comply with the standard on compressed air. This standard covers medical attendance, examination and regulations; telephone and signal communication; signs and records; compression; decompression; compressor plant and air supply; ventilation and air quality; electricity; sanitation; fire prevention and protection; and bulkheads and safety screens. Decompression tables are found in appendix A.

Bulkhead - An airtight structure separating the working chamber from free air or from another chamber under a lesser pressure than the working pressure.

Safety screen - An air- and water-tight diaphragm placed across the upper part of a compressed air tunnel between the face and bulkhead, in order to prevent flooding the crown of the tunnel between the safety screen and the bulkhead, thus providing a safe means of refuge and exit from a flooding or flooded tunnel.

Additional related information can be found on the A-Z topics pages for electrical safetyfire prevention plansmedical services and first aid and compressed air and compressed air equipment.