When should excavation be performed with assistance of supports in sewer installation?

When should excavation be performed with assistance of supports in sewer installation?

• A. When the soil is rocky
• B. When the trench is deep and narrow
• C. When the sub-surface is unstable
• D. When the weather is inclement

Answer: (C)

Excavation should be performed with the assistance of supports when the sub-surface is unstable because unstable soils can increase the risk of cave-ins and accidents during the excavation process. The use of supports helps to stabilize the walls of the trench and ensures the safety of workers. This is crucial in preventing hazardous conditions that may arise from loose or shifting soil, which could collapse under its own weight, leading to potentially dangerous situations. Performing excavation in stable conditions minimizes the need for additional support, whereas unstable sub-surfaces require extra precautions to protect the workforce and maintain the integrity of the excavation site.

Excavation should be performed with the assistance of supports when the sub-surface is unstable because unstable soils can increase the risk of cave-ins and accidents during the excavation process. The use of supports helps to stabilize the walls of the trench and ensures the safety of workers. This is crucial in preventing hazardous conditions that may arise from loose or shifting soil, which could collapse under its own weight, leading to potentially dangerous situations.

Performing excavation in stable conditions minimizes the need for additional support, whereas unstable sub-surfaces require extra precautions to protect the workforce and maintain the integrity of the excavation site.