A trench is being dug to install new water mains. The trench is 2.8 metres deep in Type C soil. According to OHS regulations (e.g., CSA Z275.10-12, or provincial trenching regulations), what is the minimum distance from the edge of the excavation that excavated material (spoil piles) should be placed?

Question: A trench is being dug to install new water mains. The trench is 2.8 metres deep in Type C soil. According to OHS regulations (e.g., CSA Z275.10-12, or provincial trenching regulations), what is the minimum distance from the edge of the excavation that excavated material (spoil piles) should be placed?

Answer options: ✅ At least 1.0 metre from the edge of the trench.

• At least 0.6 metres from the edge of the trench.
• The spoil can be placed directly at the edge if not too high.
• At least 0.3 metres from the edge of the trench.

Correct answer: At least 1.0 metre from the edge of the trench.

Explanation: OHS regulations typically stipulate that excavated material (spoil piles) must be placed at least 1.0 metre (or 3 feet) from the edge of an excavation. This creates a safe working clearance, reduces the surcharge load on the trench wall to prevent collapse, and prevents materials from rolling back into the trench.