The Occupational Safety and Health Administration's guidelines for trenching are primarily found in the Code of Federal Regulations, Title 29, Sections 1926.650 through 1926.652.
Trenching Versus General Excavation
Trenching regulation is lumped together with regulations for general excavation, although trenching is a specific kind of excavation that creates a hole deeper than it is wide with a maximum width of 15 feet.
Encumbrances
All encumbrances above and below ground such as power or telephone lines must be removed prior to the beginning of trenching or otherwise avoided during excavation.
Ladders, Stairways or Ramps
In trenches more than 4 feet deep, a ladder, stairway or ramp needs to be placed at least every 25 feet along the trench.
Hazardous Environments
When a trench is in an environment containing an atmosphere of less than 19.5 percent oxygen or containing an otherwise hazardous atmosphere, proper precautions must be taken as described in the Code of Federal Regulations, Title 29, Section 1926.50 of Subpart D and Section 1926.107 of Subpart E.
Cave-ins
Protections from trench cave-ins as described in Title 29, Section 1926.652 of the Code of Federal Regulations are required unless the trenching is done in entirely stable rock, or if the excavation is less than 5 feet deep and there is no sign of a potential cave-in.
