A plumber is installing a new building sewer line from a commercial building. The trench depth is 2.5 metres, and the soil is sandy. What is the minimum recommended cover for a building sewer pipe under a driveway susceptible to vehicular traffic?

Question: A plumber is installing a new building sewer line from a commercial building. The trench depth is 2.5 metres, and the soil is sandy. What is the minimum recommended cover for a building sewer pipe under a driveway susceptible to vehicular traffic?

Answer options:

• 600 mm
• 900 mm ✅ 1200 mm
• 1500 mm

Correct answer: 1200 mm

Explanation: According to the National Plumbing Code of Canada (NPC), the minimum cover for a building sewer pipe under a driveway subjected to vehicular traffic is typically 1200 mm (1.2 metres) to prevent damage from frost and weight. A cover of 600 mm or 900 mm would be insufficient in this scenario, while 1500 mm is generally not a minimum code requirement.