Classifying soil is one of the steps that employers must follow to ensure that trenching work can be done safely. OSHA requires that employers have a competent person to determine the soil type and likelihood of a cave-in. This determines how to properly slope, bench, or shore the trench to prevent a collapse. OSHA’s soil classification video demonstrates how a visual inspection of a construction site’s soil is performed. It also shows the three most common methods for testing soil stability: plasticity, thumb penetration, and pocket penetrometer.