[email protected] in addition to being dangerous in certain concentrations, sewer gasses and sewer gas odors from this facility must significantly diminish your quality of life. Air quality issues are complex and air quality is a difficult thing to measure, especially when it comes to determining whether the concentration of a specific odorous gas is objectionable. In Colorado, we actually have folks whose noses are “State Certified! ” I think that you should contact a local environmental engineer that specializes in air quality issues.
My Advice:
Seek the assistance of a professional in this issue.