An excavator operator is trenching for a new sewer line on a commercial project. Soil conditions are silty clay with a high water table, and the trench is planned to be 3.5 metres (11.5 feet) deep. What specific shoring or sloping requirement must be met for this trench before workers can enter, as per general Canadian safety standards (e.g., Ontario Reg. 213/91)?

Question: An excavator operator is trenching for a new sewer line on a commercial project. Soil conditions are silty clay with a high water table, and the trench is planned to be 3.5 metres (11.5 feet) deep. What specific shoring or sloping requirement must be met for this trench before workers can enter, as per general Canadian safety standards (e.g., Ontario Reg. 213/91)?

Answer options:

• No shoring or sloping is required as long as the trench is less than 5 metres (16.4 feet) deep.
• Sloping back the trench walls to a maximum ratio of 1:1 (45 degrees) is sufficient. ✅ The trench walls must be adequately shored, benched, or sloped to a stable angle.
• Only the trench entrance and exit points require shoring.

Correct answer: The trench walls must be adequately shored, benched, or sloped to a stable angle.

Explanation: For trenches exceeding 1.2 metres (4 feet) in depth, Canadian regulations mandate adequate shoring, sloping, or benching to prevent collapse, especially in unstable soil conditions like silty clay with a high water table.