Final answer:
OSHA requires a competent person to perform a visual test and at least two manual tests on a soil sample. These tests, conducted by a soil scientist or a trained professional, help determine the safety of the soil for trenching and excavation operations, ensuring worker safety.
Step-by-step explanation:
The Occupational Safety and Health Administration (OSHA) requires that a competent person performs specific tests on soil samples to determine their safety for the purpose of trenching and excavation operations. According to OSHA standards, a competent person should perform a visual test and at least two manual tests on a soil sample to classify its type. The visual test includes examining the soil for any signs of vibration from sources such as traffic or heavy machinery. Manual tests may include the plasticity test (checking for cohesiveness), the dry strength test (checking for dry soil that crumbles easily), and the thumb penetration test (assessing ease of penetration). Other tests, such as the pocket penetrometer test or torvane shear test, can also be used as additional manual tests if necessary.
A soil scientist plays a significant role here by analyzing and determining the soil characteristics which are essential for making appropriate safety recommendations. The analysis helps in understanding the physical properties of the soil, potential hazards, and ensuring worker safety during construction activities