The Excavation Safety Guide

Excavations and trenches pose intrinsic toxic atmosphere and cave-in hazards. Site supervisors must create safe working conditions in excavations by installing measures to prevent cave-ins, establishing regular trench inspections and giving workers an escape route if conditions abruptly become hazardous.

Exits

• The Occupational Safety and Health Administration requires construction employers to ensure that stairways, ladders or ramps are erected in trenches over 4 feet deep. Exits must be positioned so that a worker is never further than 25 feet away from one.

Protective Systems

• Depending on the soil, an excavator may slope or cut steps into trench walls at an angle that eliminates cave-in risks. Shoring protects workers through exertion of pneumatic or hydraulic pressure against a barrier to keep walls intact. Shielding involves installing a large metal chamber inside the trench where workers can labor while shielded from collapsing debris.

Inspections

• OSHA requires that a competent person, capable of identifying existing and potential hazards, be on-site to inspect trenches before every shift and after any rainfall. The inspector must be authorized to order trench evacuation and immediate correction of any hazard she detects.