About 5 years ago after we moved into our house, we noticed a hole (about 8" diameter) in the middle of the back yard. We didn't think much of it. Maybe a hole that a groundhog dug. Now this hole has gotten significantly bigger (20" diameter). We are worried that maybe there is a pipe that has broken underground. The grass around it is worn and there is evidence that a lot of water has flowed out of the hole. Who do we contact about this? Would the City have anything on record that would identify what pipe this is?