After a long steady rain, we get a sewer gas odor in our downstairs den. The odor seems to originate from the crawl space under that part of the house (which is inaccessable). I can also smell it to a lessor degree in the attic above that part of the house (probably coming up the walls).
The problem seems to have begun right after our street was completely torn out and replaced as part of a city-wide street and infrastructure replacement program.
Our plumbers doubted that it was related to the rain and thought it might be a dead animal, but that theory has been eliminated since the odor has always occured after a good rain for the past three years!
What could cause this odor? Any suggestions on a course of action? Could it be related to the street program or is that just coincidence?
Dunbar is on the right track. One thing I want to ask do you have combination storm & Sanitary sewers there, that could explain why you smell it more when it rains. The sewer gets over loaded and forces the smell into your pipe and if the pipe leaks you smell it more, have the smoke test are water test done.