An excavator operator is preparing to dig a trench 2.5 metres deep in Type B soil. According to provincial occupational health and safety regulations for excavations, what is the minimum slope ratio required for the sides of the trench if shoring or other protective systems are not used?

Question: An excavator operator is preparing to dig a trench 2.5 metres deep in Type B soil. According to provincial occupational health and safety regulations for excavations, what is the minimum slope ratio required for the sides of the trench if shoring or other protective systems are not used?

Answer options:

• 1:1 (45 degrees)
• 3:4 (approximately 53 degrees) ✅ 1.5:1 (approximately 33.7 degrees)
• 1:2 (26.5 degrees)

Correct answer: 1.5:1 (approximately 33.7 degrees)

Explanation: For Type B soil, provincial regulations typically require a maximum allowable slope of 1.5 horizontal to 1 vertical (1.5:1) unless engineered protective systems are in place. This slope provides a stable angle of repose for this soil type. A 1:1 slope is for Type A soil, while 3:4 and 1:2 are generally not sufficient for unsupported Type B soil at this depth.