How deep below the original surface should the top of the distribution pipe be placed?

• A. Below 4 inches
• B. Below 6 inches
• C. Not less than 8 inches
• D. Not less than 10 inches

Answer: (C)

The main idea is protecting underground distribution piping from surface disturbances while keeping installation practical. Placing the top of the distribution pipe at not less than eight inches below the original surface gives a reliable shield against damage from mowing, tillage, and other activities that occur at the surface, and it also helps prevent roots from easily reaching and interfering with the line. Eight inches is deep enough to provide this protection without making the trench excessively deep for installation or future service. If buried shallower, at four or six inches, the pipe is more vulnerable to damage or displacement from routine landscaping work. Going deeper, like ten inches, adds unnecessary trenching work without meaningful added protection in most cases.