Question

water mains are buried six feet below ground. which two of the following show the primary reasons for this?
a to reduce the chance of sharp rocks damaging the pipes
b to increase the force of gravity that is pushing down
c to allow space for other pipes in the water system
d to avoid damage from the weight of the street above
e to prevent pipes from freezing in very cold weather

Explanation:

• Option A: Sharp rocks are more likely to be near the surface, so burying pipes deeper reduces damage risk.
• Option D: The weight of the street (e.g., from vehicles, pavement) can exert pressure. Burying deeper (six feet) helps avoid damage from this weight.
• Option E: Deeper underground, the temperature is more stable. In cold weather, the ground acts as insulation, preventing pipes from freezing.

Answer:

D. to avoid damage from the weight of the street above, E. to prevent pipes from freezing in very cold weather