Manhole Cover ‘Floats’ In Dance-Like Movement

Someone caught video of a manhole cover in Phoenix, Arizona and saw a definite opportunity for a beat. What, exactly, is going on down there?

The storm drain system normally has a lot of air in it. When the system suddenly carries a lot of water, as it has during intense downpours in Arizona lately, the water pushes the air against the covers.

That’s a lot of pressure, because those covers are heavy.