Sewer water standing in front yard

(This is related to another thread, or, it may be)

We had the CI stack replaced on the exterior of our house last week. Now, we have a rising level of water in the front yard that is smelling more and more like sewage. It is located about 10 feet "downstream" from where they replaced the stack and about 6'-8' from the connection to the city sewer. (They went down to the main line and attached it to the horizonal line with a PVC elbow.) The plumber is returning today to take a look, but - the timing is suspicious.

Could the sawing or whatever they did have possibly jarred it loose or cracked it?!? When we first noticed the water on Saturday, it was a puddle about the diameter of a handprint. On Sunday, it was about 2-3 feet in diameter, and now it's about 4-5 feet in diameter. And mushrooms popped up over night.

Any thoughts?!? We don't want to blame it on the plumber if it's not his company's fault, but the timing just seems so suspect. Thank you.

It is possible that they cracked the line further downstream, but without having seen exactly how they went about their work, I don't see where blame can be placed. Old pipes are old pipes and any movement could have sped up what was likely to eventually happen anyway.

A lot of times while removing the old cast iron stacks a bunch of rust will wash down the line and cause a clog. I doubt the pipe is broken any further.