sewer gas smell


We recently had our basement redone,, a new slab poured and new underground sewer drawings installed. Traps were installed for all new fixture locations.
The work was completed about 2 months ago.. and more recently.. we have been smelling sewer gas. It seems to occur primarily when our washing machine is running. My concern is that we did not install a laundry tub for lack of room. The washing machine drain empties directly into a pipe that sticks above the floor 1" , is trapped below the slab,, and runs down into the sanitary. I'm concerned the pressure of the washing machine is sucking the vents dry.. any suggestions? Thankyou in advance.
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Sounds more like the water pressure is siphoning the trap dry, vents are supposed to be dry. Try extending the tube up 2-3 feet from the floor so that your not pumping water directly into the trap under pressure. Make sure you have an adequate air gap around the drain tube so that it drains more by gravity than by the pressure of the washer pump. Verify your trap is not broken and draining from the bottom after you use it (look inside with a flashlight, usually you can see the water surface if there is no bend first)

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If the trap is vented properly it will not siphon dry. That said, anything is possible without actually laying my eyes on the situation itself. However, if you think it is tied to the washer drain, try this: When the washer is actually draining, check the area for smell. As soon as the washer is finished pour a couple of quarts of water slowly down the drain that is 1" above the floor. Check again for smell. Let us know if either or both circumstances result in sewer gas smell. Also, is the sewer effluent discharged via sump pump?
Bob Wheatley
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BTW, I always try to put my washer box into a 2 inch p-trap that dumps into a 2 inch san tee. I vent my washer and use 2 inch and use p-trap, never a problem and it all fits in wall nicely and can be snaked very easy.

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Agreed. And we would also "normally" expect that the standpipe from the trap would not be 1" above the floor and would probably tie into a washer box that is at least 36" above the floor to the flood rim. My guess is that if someone put the trap below grade that they probably were not compelled to adhere to neither standard codes or practices.
Bob Wheatley
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Bob Wheatley wrote:

Without checking, I believe the IPC requires a minimum standpipe of 24" before the trap.
MM
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Without checking, is the IPC a real code? :>)
Bob Wheatley
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Bob Wheatley wrote:

No, it's the Internet Pretend Code.
MM
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Did the plumber ever come back and install a standpipe and trap?? I find it hard to belive the trap would be under the cement in the slab. The instalation you have described to us here is not complete and or not up to code.
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Truth is.. I was the one who instructed the plumber to put the trap beneath the slab... I was arguing with him over some other issues and chose this issue to stand my ground.. now I look back and realize iim going to have a heck of a time cleaning the thing out.. im considering breaking up the conc myself and moving the trap to a point above conc.. but I will definitely follow the advice of extending the pipe to 2' above ground.. perhaps a wider pipe to ensure that the machine isn't blowing out the trap that is currently there.
One of the notes above mentioned a "washer box",,, what is that?

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Here ya' go..... Typical residential type box: https://secure.smoothcorp.com/2/item_268820/Oatey/Oatey/Washer-Box-With-Valves/item.html
Set the top of the box at about 42" and you'll be good to go. This is designed to go "inside" a wall but I am unsure if that is possible because it sounds like you have multiple issues going on here. Although I must admit that I find poetic justice with you predicament. I guess you know that you got what you deserved, right?
And BTW, back in the 70's we used to commonly put the trap and standpipe on the inside or outside of the wall and simply use an 1/8 bend (45) at the top in lieu of the washer box.
Bob Wheatley
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