Construction Health and Safety Technician (CHST) Practice Test

Excavation cave-in protection is always required when what conditions are met?

1. The excavation is less than five feet deep.

2. The excavation is greater than five feet in depth and comprises clay or silt.

3. The excavation includes solid rock.

4. The excavation mainly comprises sandy soil.

The correct answer is: The excavation is greater than five feet in depth and comprises clay or silt.

The requirement for excavation cave-in protection is based on the depth and the type of soil involved in the excavation work. When an excavation exceeds five feet in depth, it poses a significant risk for cave-ins, particularly when the soil is classified as clay or silt. These types of soil can provide minimal support and are more susceptible to collapsing, especially under the weight of machinery or adjacent structures. Regulatory guidelines, such as those from OSHA (Occupational Safety and Health Administration), clearly state that protective measures must be in place for excavations that are deeper than five feet, especially in soil conditions that are not stable. Clay and silt do not resist collapsing very effectively when disturbed, making it critical to implement safety measures to protect workers from potential cave-ins in those scenarios. In contrast, excavations that are five feet deep or less typically do not require protective systems, as the risks associated with cave-ins are significantly lower. Additionally, solid rock provides a stable foundation and support, reducing the likelihood of cave-ins, while sandy soil may present its own risks but often requires specific considerations based on other factors, making them less straightforward in terms of protection requirements.