Directing Sewer Gas at Intersection

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by jblakley, Jul 23, 2013.

  1. jblakley

    jblakley New Member

    Messages:
    3
    Location:
    Houston, Texas
    Our house originally had piping that ran the sewage from the kitchen and utility room across the house, met up with the sewage from the bathrooms on the other side of the house, and then ran to the main sewer line. Before we bought our house, the previous owner re-directed the sewer line on the kitchen/utility side of the house around the house to the backyard where the line runs to the sewer. He did not, however cap either end of the old line that ran across the bottom of the house. The old line has several cracks. We have capped the ends of the old line at the kitchen and utility room, but whenever we run water in the kitchen or utility room, gas gets pushed around the house and back to the old line and through the cracks, and our house smells awful.

    We have a plumber who has proposed that we pay approximately $5,000 to dig under our foundation to where the old line meets the bathroom line to cap that end. I'm wondering if there is an easier solution. For example, the new line from the kitchen makes a T-intersection with the line in the backyard that runs to the main sewer line. That is where the gas from the kitchen/utility room is being pushed back towards the house and old line. Is there a way to somehow direct the gas going towards a T-intersection in one direction so that the gas will run towards the main line instead of back to the house?

    Any susggestions are appreciated. We have a baby and feel it's unsafe to have her breahting in this sewer gas but we're not sure if we can afford to pay $5,000 at this time...
  2. leejosepho

    leejosepho DIY scratch-pad engineer

    You could wrap the exposed surface of that old line with fiberglass cloth and epoxy to seal it (using plenty of ventilation for a few days) for a lot less than $5000.00, but it sounds to me like you have some kind of vent problem if that old line is being pressurized enough for sewer gas to be pushed through its cracks unless the cracks are numerous and visibly open.
    Last edited: Jul 23, 2013
  3. Smooky

    Smooky Member

    Messages:
    569
    Location:
    NC
    My thought is this is where your problem is located. It would be good if you could take pictures of the drains under these sinks. Also some pictures of drains under the home may be helpful or things you think are the cause of the odor.

    As always it is a good idea to get several estimates from local plumbers.
  4. jblakley

    jblakley New Member

    Messages:
    3
    Location:
    Houston, Texas
    The pipes have been smoke tested, and it was confirmed that the gas is leaking from the old pipe. The plumber said based on the volume of smoke, the old pipe is "severely" damaged, allowing a large volume of gas to move upward into the house and attic. I am planning on contacting more plumbers. I am really wondering if you have water and gas that runs toward a T-intersection, is there a way to divert/direct the flow at the intersection so that all the gas runs in one direction.
  5. Smooky

    Smooky Member

    Messages:
    569
    Location:
    NC
    Where did the smoke come out? How does it get into the house? Are you on a slab or crawl space? Do the old pipes still carry waste water?
  6. jblakley

    jblakley New Member

    Messages:
    3
    Location:
    Houston, Texas
    We are on a slab foundation. That's one of the questions I have for the plumber - if the old piping is under the slab, how is it getting above it? When we smell it, we smell it from the vents. At some place, it is getting into the ducts in our attic...
  7. leejosepho

    leejosepho DIY scratch-pad engineer

    At least in theory and with no continual guarantee of working properly and effectively, a swing-check valve at the side of the tee where the bathrooms' drain line comes in would stop the water from the kitchen from pushing air on around into that line and on into the old one, but if that kind of patch job (with nothing negative intended against you there) were all I was planning to do, I would likely instead just vent the capped end (and maybe even add an inline vent fan) at the kitchen end of the old line so no pressure could build inside it.
    Last edited: Jul 23, 2013
  8. bluebinky

    bluebinky Member

    Messages:
    382
    Location:
    Santa Clara, CA
    Ah... the AC/heating ducts? Is your AC unit in the attic, and if so is the condensate draining directly into one of the vents?
  9. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,249
    Location:
    Cave Creek, Arizona
    Your description is somewhat convoluted so I cannot really follow the paths of the piping, but there should not be ANY connection between the new and old piping, if the old pipe was abandoned. Therefore, ANY THING flowing in the new piping would NOT "force air", especially sewer gas, out of the old piping. Either the diagnosis is faulty, or the installation is.
  10. leejosepho

    leejosepho DIY scratch-pad engineer

    He has something like this, hj:

    jblakley.png
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