Alan I suspect that is part of the problem. This addition wasn't done very well. I have no idea if it was permitted or not, but I would suspect not :eusa_doh:It's on a slab, and I don't think that there was any additional venting added.It may be affecting the new addition the most because the way the drain lines were run or connected to the rest of the house, what size and pitch, and how vented. Is it a non-permit, homeowner, addition??? Is it on a slab or do you have a crawl space where you can go see for yourself?
Dave,
We had a "Poo Pumper":lol: come visit us when we lived in Buncombe Co. They used a small radio transmitter which looked like a large capsule, flushed it down the toilet and went outside with a receiver and located the tank. They triangulated the location of the access with long steel rods and dug one ~20X20" hole. The transmitter was floating right on top of the poo along with other "Lost" items. I was making beer regularly at the time and declined their special yeast. Everything was ok in the tank as a result of regular infusions of dregs from my fermenter.
Moral: Make more beer! A batch a week keeps the Poo Pumper away.:tinysmile_tongue_t:
A couple thoughts:
Depending on the age of the house, the county may have a copy of the septic installation permit. In Johnston Co. the Health dept. has the septic/leach field as-built drawings. But they have them recorded under the original owners name, I am the third owner of the house and can't find any records of who was the original owner.
Also, if there is only one vent, it can get clogged, especially if there was any high ground water situations (you mentioned water running through or around the workshop last year). Toilet paper, especially the soft fluffy type, can float for a while. If the water level goes up too much, it can float up into the vent pipe and cause a paper mache type plug. My brother had this problem, however his symptom was slow drainage, not gurgling. If you snake the line and it seems clear, also try snaking down from the roof vent (If you can do it safely).
Good luck
Go
Mark would there be a vent on the septic tank itself? I have looked down the roof vent for as far as I could see with a flashlight looking for a possible clog. I should try snaking it.
Dave
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You might also consider keeping a mesh bag of pennies in the tank of each toilet. The copper should help inhibit the growth of roots into your field lines.
J