View Full Version : Under slab sewer line repair

09-13-2004, 03:27 PM
It is starting to look like the dream home is becoming the money pit. It started with an intermittent bad smell which might have been a dead rodent. It has progressed to a less intermittent smell and a sewer camera. The sewer camera showed what appeared to be cracks in several places in the upper side of the cast iron pipe. Also perhaps some roots intruding in places and some standing water in several sections. The young man running the camera said that jackhammering up the slab and replacing the bad sections was a solution. I'm not too excited about that solution. To exacerbate the problem, I think the drain lines are located underneath the ductwork, which is cast into the slab. Surely there must be some way of coating or repairing the inside of the line. I have found references to epoxy coating on the internet but no real concrete information. No one I have talked to here in Kansas seems familiar with it.

The home was built in 1972 and I believe the drain lines are cast iron pipe. A new septic tank and lateral field were installed within the last six months. I was told that sometimes it take awhile for things to "settle down" but we have had some heavy rain and surely enough time has passed for that to happen. I have filled all P traps. The smell seems worst in the early morning near sunrise and after a rain. I presume that gas from the septic system is traveling into the house and then either finding its way through a break in the venting system or through a crack in the sewer line to the ductwork and then into the house. I removed the cap from the line cleanout outside the house so any gas could just escape before entering the house. This seems to have helped although I think it is probably treating the symptoms and not the cause. A U-type trap between the house and the septic tank has been suggested, along with a fresh air vent but again, this seems to me to maybe be treating the symptoms.

Is there any help/hope or do I resign myself to more debt and a torn up house?



09-13-2004, 04:00 PM
"The sewer camera showed what appeared to be cracks in several places in the upper side of the cast iron pipe. Also perhaps some roots intruding in places and some standing water in several sections."

I Hope that you kept a tape copy for a second and possibly third opinion...
If the camera operator knew exactly what he was looking at and determined that there are cracks/defects/roots in the piping and it is holding water, the only real fix would be to replace the line. Your septic system appears to operating normally.
A licensed plumber can perform a smoke test on the interior drainage/venting system to detect any defects.

09-14-2004, 06:24 AM
Regardless of the condition of the underfloor pipe, it is not the cause of your odors. There would not be any "pressure" to force the odors out of the pipe and then up through the soil, and finally through the floor slab. Long before this could happen the odors would exit through the roof vent pipe. More likely the vent pipe is located near an exhaust fan or other outlet on the roof, and they are being sucked into the house by atmospheric pressure changes. Spending money for a sewer camera to check for odors was not the proper step to take.

09-14-2004, 08:14 AM
Thanks to both. It looks like I may have overreacted a little in the wrong direction. Well, better to learn late than not at all. There is an opening in the roof around the hot water heater vent. I will address this problem first. If the odor problem is resolved what action is necessary with potential cracks and roots? Is that a problem that can be left to itself until or unless it worsens down the road?

I appreciate the help.

09-22-2004, 02:44 PM
A visit to the State Fair yielded some interesting information. If it becomes necessary it appears possible to fix the drain lines underneath the slab without digging everything up. A method using an epoxy impregnated fiber tube is the solution. The impregnated tube is inserted into the drain line, a bladder is inserted and inflated, pressing the fiber tube against the inside of the drain line. After a short curing period the bladder is withdrawn, the inlets into the main line are cut out and it appears a nice, lasting repair is made without jackhammering up the slab. Of course, this presumes that the lines running into the main drain line are in reasonable shape but it looks like a good solution to me.

09-22-2004, 03:49 PM
"The sewer camera showed what appeared to be cracks in several places in the upper side of the cast iron pipe. Also perhaps some roots intruding in places and some standing water in several sections."

You may be able to buy some time but this type of a repair, (epoxy coating) should be considered only temporary :(
IMO, depending on the condition of the piping, (which doesn't sound good), it may be a complete waste of money.
Get a couple/few estimates from local reputable licensed plumbers based on the video inspection of the drain piping that was done.

09-22-2004, 08:21 PM
IF the pipe is cast iron, then it would be unusual for them not to have stactites and stalagmites "growing' inside the pipe, and it would be impossible to reline it without having numerous "bumps" in the liner. And it is almost impossible to "knock" them loose so the interior of the pipe is smooth.

09-23-2004, 08:26 AM
When I have identified and replaced cast iron under slab there is almost always an odor observation from the users in addition to the drain complaint. Smell (air) is thinner than water and I've always felt it drifted up through the concrete usually at cracks in the floor.

09-23-2004, 09:32 AM
If you have cracks in the pipe and roots are growing through, the only fix is to replace this pipe. A reline will be VERY temporary and I personally think that it is a waste of money in your case.
This is a different problem than the odor. I would get a smoke test to determine if I had any breaks in the venting system that was allowing sewer gas to enter. Many times people think that they are smelling sewer gas and it is something else entirely. However, winds and atmospheric conditions can sometimes cause the odors from the roof vent to settle down i(early morning and after a rain) instead of rise up. You can buy a filter for the end of your roof vent pipe if that is the problem.
Also, did you explain the problems you were having to a plumber and let him take the steps he thought were necessary or did you just call someone and ask to get your sewer video'd? A good plumber will listen to the problems you are experiencing and suggest steps to rectify the problem(s), starting with the most likely scenario. For instance, I have no idea who suggested it, but a whole house p-trap (although they look like a U they are called p-traps) will do nothing for you, can cause other problems and are illegal in many places. There are no magic answers. Many plumbing problems are not readily apparent and take investigation to discover the cause and repair. A good plumber that you trust is your best option.
The Pipewench