In my basement along the outside wall is a trench, about 1" lower then the floor and about 3" wide which goes all around the perimeter of the basement and ends up at the bottom of the Main Stack.The main stack comes down to a Tee with 2 thirds of the tee poured into the basement concrete. So the stack is tied into the top of the tee which is visible, then in the concrete on one side of the tee is hooked into the drain that runs out to the road into the town sewer system all in the concrete, but on the 3rd part of the tee is always open and about 2-3" lower then the trench i mentioned along the basement wall. So i'm always getting sewer gas out of that one side of the tee but can't plug it since i get water in the basement during heavy rains and if i plugged that tee, the basement would flood. I'm just wondering what i can do in this situation, and i don't want to dig that pit deeper and add a sump pump and plug the tee. If they make some sort of plug that lets water in but no air out thats what i would want to do, any suggestions?