If a worker has to go into the excavation to compact the granular fill, what are the steepest side slopes allowed under the Occupational Health and Safety Act?

If a worker has to go into the excavation to compact the granular fill, what are the steepest side slopes allowed under the Occupational Health and Safety Act?

• A. Side slopes no steeper than 1 horizontal to 1 vertical unit
• B. Side slopes 2 horizontal to 1 vertical
• C. Side slopes 3 horizontal to 2 vertical
• D. Side slopes 4 horizontal to 3 vertical

Answer: (A)

In excavations where a worker must enter to work, the sidewalls must be kept fairly level to prevent collapsing soil. Granular fill (like sand or gravel) is cohesionless and can fail suddenly when disturbed, so it requires a relatively gentle slope to stay stable. The steepest allowed is a one-to-one ratio, meaning one horizontal unit for every one vertical unit, which is a 45-degree slope. This provides enough stability to reduce the risk of a cave-in while someone is inside the excavation. Slopes that are steeper than this (for example, options like two horizontal to one vertical, or other gentler-looking ratios) are not permitted for granular fill when workers are inside, because they are more prone to instability. If work must continue inside such an excavation, protective measures like shoring or trench boxes should be used in addition to the slope limits.

In excavations where a worker must enter to work, the sidewalls must be kept fairly level to prevent collapsing soil. Granular fill (like sand or gravel) is cohesionless and can fail suddenly when disturbed, so it requires a relatively gentle slope to stay stable. The steepest allowed is a one-to-one ratio, meaning one horizontal unit for every one vertical unit, which is a 45-degree slope. This provides enough stability to reduce the risk of a cave-in while someone is inside the excavation.

Slopes that are steeper than this (for example, options like two horizontal to one vertical, or other gentler-looking ratios) are not permitted for granular fill when workers are inside, because they are more prone to instability. If work must continue inside such an excavation, protective measures like shoring or trench boxes should be used in addition to the slope limits.