The round sewers

1. No orientation required: A circular lid fits in any orientation, while a square or rectangular lid must align correctly.
2. Additional reasons: Fewer corners = less wear and tear.
3. Final section: Fewer corners = less wear and tear. Then, no orientation required: A circular lid fits in any orientation, while a square or rectangular lid must align correctly.

Answer: At least three technical reasons:

1. Cannot fall through the hole: A circular cap cannot fall through its own opening, no matter how it is turned. A square top, on the other hand, could fall along the diagonal (which is longer than the side).
2. Ease of movement: The circular lids can be easily rolled, making them easy to transport and place. The square lids would have to be lifted and loaded.
3. No orientation required: A circular cap fits in any orientation, while a square or rectangular cap must align correctly.

Additional reasons:

• Uniform pressure distribution from above
• Cylindrical wells are easier to build and more structurally resistant
• Fewer corners = less wear and tear