Can’t have too many manhole covers
You know what they say about manholes? Nothing. Nobody gives them a second thought, let alone a third, fourth, fifth, sixth, seventh, or eighth. If you thought one manhole was enough, you’re surely mistaken according to the genius construction crew who placed eight manhole covers within six feet of each other.
All they did was create more exits for mutants to leave the sewers and terrorize us surface folk. And don’t for a second think that the TMNT will pop out of these covers to save the day. Turtles skilled in ninjitsu martial arts aren’t real, though that’d be a sight to see.