We changed condo associations over a year ago and the new association has not had the sewer line rodded. We recently had record rains and yesterday had the overflow pipe in the utility closet back up and flood the closet and part of the kitchen. My understanding is that the pipe is connected to the storm sewer and does not connect with actual sewage (human waste) However, the plumber suggested that we have the area professionally cleaned because he found 'poop' in the pipe. This seems like it would be totally against code. In the past I have found tree roots, worms and other earthly treasures but never poop. I was even wondering if someone had thrown dog poop in the storm sewer. Any comments?

Thanks!

Don't know what an "overflow pipe" is. Floor drain? Can you post a picture?

I assume that by "overflow pipe in the closet" is a washer stand pipe.
My understanding is that the pipe is connected to the storm sewer Not unless the storm drain and the city sewer system are connected.
First off I don't think the storm or heavy rain fall had anything to do with your situation. All though you didn't say, it's my bet that you have a unit over you, right? It could be roots or other trash but you have a blockage downstream from the stand pipe, (I'm surprise your plumber didn't tell you where the poop was coming from). You're getting the sewage discharge from your neighbors upstairs, The solution should be to, not only snake the sewer lines but to sewercam the line .find out where the roots are getting in and repair it.
Since this sounds like the problem's in "the common area" so the Condo Assoc. should be responsible for the expense. Good luck, Tom