Our old septic sys. Failed this summer & the new tank is 60 feet from the house. Old tank was 200 feet away. We now have odors apparently coming through the main dwv out the roof vents and accumulating at ground level. Would a trap in the main dwv prior to exiting the foundation work? I'm concerned about it clogging up since the slope isn't what it is like under a sink or tub.
Going broke on air freshener, Any help?

Put a thing called a running trap just outside the house maybe five feet or so... Put a clean out between the house and the running trap. The trap will stop the smell and the clean out will give you an access to unstop the trap, which hardly every happens.

Another option that wouldn't involve digging up the sewer line would to install Odor Hogs (see image) on those stinky vents. Check it out at; http://www.odorhog.ca/
Good luck, Tom