The Rules, at-a-Glance…
Cave-ins pose the greatest risk and are much more likely to result in a worker-related fatality than other excavation-related accidents. An unprotected trench becomes an early grave for a lot of workers. The weight of collapsing soil and the speed in which it is traveling cannot be overstated.
Trench Safety Measures
As soon as a trench reaches the 5’ depth, whether it appears stable or not, the OSHA standard governing excavations becomes applicable and a protective system must be installed. The only exception is if the trench has been dug in stable rock. If shallower depth trenches show signs of instability, these must be addressed as well.
Competent Person
OSHA requires the Competent Person to perform a daily inspection of the trench and its immediate surroundings. A re-inspection is required should conditions change that could have a direct bearing on the conditions of the trench. Among other things, this individual has knowledge of the standard, knowledge of the work being performed and the ability to take prompt corrective action to ensure worker safety.
Access and Egress
OSHA standards require safe access and egress to all excavations, including ladders, steps ramps or other safe means of exit for employees working in trenches 4’ or deeper. The travel distance to reach these devices cannot exceed 25’.
General Rules
. Spoil piles must be kept, at minimum, 2 feet from trench edges
. Underground utilities must be located prior to digging
. Atmospheric Testing is required where poor air quality is suspected
. Workers are not permitted under overhead loads
. Workers must wear high-visibility clothing, when exposed to vehicular traffic
Protective Systems
Benching…means a method of protecting workers from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near vertical surfaces between levels. Benching cannot be done in Type C-soil.
Sloping…involves cutting back the trench wall at an angle inclined away from the excavation.
Shoring… requires installing aluminum hydraulic or pneumatic shoring devices to prevent soil movement and cave-ins.
Shielding…protects workers by using trench boxes or shielding devices
Tabulated Data
Tabulated Data is a mandatory component of the excavation standard. These are the installation requirements from the manufacture and/or the Registered Professional Engineer that has approved the design of the protective system being used. Tabulated Data must possess the RPE approval stamp and be present on the jobsite during installation of the system.