Well a RinkWorks joke just popped up. It asked why manhole covers are round. But the answer was wrong. The correct answer is because manholes are round. OK, maybe there is more than one correct answer.

Did you know that manhole covers recently have been made of recycled plastic? Look for the words, "Not for traffic load." You can walk across a plastic manhole cover and not fall into a storm drain, but driving a truck across one is not recommended. That's why they are used on sidewalks but not streets.

And now you know what happens to those used two-liter soft drink bottles.
Howard