Make Trench safety your job site's first priority. OSHA specifies Trenches 5 feet deep or greater require a protective system unless the excavation is made entirely in stable rock. Be sure to follow these rules on a daily basis:
Keep heavy equipment away from trench edges.
Keep surcharge loads at least 2 feet from trench edges.
Know where underground utilities are located.
Test for low oxygen, hazardous fumes and toxic gases.