Tying Into Sewer Line

[samo615]

I am having my 50 clay pipe sewer line replaced. The plumbers just got to the part where the pool's overflow drains and backwash line ties in. He said he needed to put an "air trap" on there to pass inspection. Then, he said he is just going to tie it in like it was and cover it up, hoping the city inspector won't say anything.
I am not sure what to do. I want this done right but I don't want a huge additional cost to bring this up to code. Does anyone have any knowledge of the complexities of tying the pool drain in? Currently, the overflow drain pvc and backwash pvc Y together and then goes over to the sewer line, and straight down to tie in.

 

[X-PertPool]

An air trap like a sink trap? Traps are for sewer gas, I doubt you'll have gas leaking out of your filter. If it was fine before I find it doubtful that things would change just because your switching to PVC.

 

[samo615]

He had concerns for sewer water backing up into the filter if there was a clog in the line. Not sure.

 

[bk406]

He may mean an air gap? That would keep any waste water from backing up into the pool in case of a sewer backup. It would be like tying an ice machine drain directly into the stack. Cant do it, you have to use and air gap. W/o more info, hard to tell what an "air trap" means.

 

[bk406]

He may mean an air gap? That would keep any waste water from backing up into the pool in case of a sewer backup. It would be like tying an ice machine drain directly into the stack. Cant do it, you have to use and air gap. W/o more info, hard to tell what an "air trap" means.

Edit: Ok, I was posting at the same time here. Yes, an air gap. You cant tie the drain line directly into the sewer w/o a gap between the drain line and the sewer line.

 

[samo615]

OK. Air Gap makes sense. I hope this guy knows what he is doing.

 

[smccull]

Air gap is simple and cheap, there should be no huge cost associated with it - basically the pool drain will come straight up out of the ground, make a u-turn back down to the sewer line. Somewhere after the downturn the pipe needs to be cut with an airgap present above ground. Usually the pool drain line will be a fair bit smaller than the line to the sewer so that it can just shoot right into the bigger pipe.
That is all. Mainly they are ugly because you have white PVC pipe coming up out of the ground. Keeps sewer water and bacteria from working their way back up your drain and into your pool.

edit: it will also probably need a PVC p-trap as well to prevent sewer gas from getting out, but again PVC fittings are cheap.