Our family cottage had to be moved back from the lake bluff due to erosion several years back and they moved it over the septic tank. My Grandfather took care of refitting the drainage system after the move. There is one large (4"?) PVC drain from the toilet a branch that comes in from the kitchen sink and one that comes from bathroom sink. The large soil pipe goes directly into the septic tank. All of this is open under the cottage in a crawl space. I don't see any vent and I do notice odors under the cottage, low toilet bowl water and gurgling in my kitchen sink vent after flushing. I'm assuming this is a venting problem. We just got a new well and have been enjoying being able to flush the toilet on a regular basis, wash dishes, shave etc. (the simple things of life). So I'm assuming the increased water flow and usage has kicked up the odor and the problem.
I've read about vents that can be hooked directely to the waste pipe with a one way valve rather than go to a stack up through the roof, can you vent an entire system this way? Where would the "sewer" gas go, doesn't that need a way out into the atmosphere? Also, Could I just tap into the one big line as it enters the septic with 1 1/2 PVC and go out through the foundation up along the chimney and vent up the roof as is normally done, or am I simplifying this too much?