The hazards associated with excavation and trenching operations are many and varied. Since cave-ins present the greatest threat of injury or death to workers, OSHA's trenching regulations contain detailed appendices on soil types, and approved methods of sloping, shoring, and the use of shields. OSHA requires that one of these methods be used in all excavations and trenches five feet or more in depth to protect employees exposed to potential cave-ins. The "registered professional engineer" is free to choose the most practical design approach for each particular circumstance, but once the design has been selected, it must meet the required performance criteria.

Every year between 100 and 400 construction workers are killed by cave-ins. Seventy-nine percent of the deaths in trenches are in excavations 5 feet to 14 feet in depth. Lack of training and safe practices are the major reasons. Most workers, for example, are unaware that a cubic yard of earth (3'x3'x3') weighs about 3,000 lbs., or about as much as a pickup truck. The result is deaths and injuries from suffocation, crushing, loss of circulation, and falling objects. Safety training in this area should emphasize the unrecognized hazards of excavation and trenching work.