I noticed today while in my basement a very strong sewer like smell coming from an opening in one of the vertical pvc pipes in my basement.

Any ideas why?

Do you have a floor drain? An unused tub or sink?

Hi cazgillo, there should not be an opening in a vertical drain pipe, have you removed something? Maybe a sink?

Partime is right, can you show us a picture? Drain pipes have no opening except at their termination