Clogged Later Line


Old 04-06-13, 09:18 AM
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Question Clogged Later Line

I have recently discovered, I think, what is a broken or collapsed lateral drainage line in my home. It it the line that drains the washer and kitchen sink line. Starts with the washer, and the Kitchen sink taps into it. Single story home, slab foundation, built in the 1950's, Dallas County, TX. I rented a plumbing snake, manual, and worked and worked at clearing the line, starting at the vent on the roof, for the washer. I even put one of those "bladder" units on the end of a water hose and put it down the pipe. And yet still, the water backs up into the kitchen sink. I called out a friend of friend who is a plumber. And so because he found mud on the end of the snake, he thinks I have a collapsed or broken line under the house.
Fortunately or unfortunately, the general location, based upon the amount of snake, reeled out; is on the back side of the house. Now at that area, it is just where the lawn meets the house, no patio, or porch stoop. It is free and clear of any utilities. Unfortunately, it would be about 3' to 4' under the slab, and probably right under a load bearing wall.
The plumber seemed to make it sound like it was perfectly safe to dig under a slab. But, I have researched this, and frankly because of the load bearing wall, it scares me to attempt this.
I could hire a plumbing company, if I had a few grand lying around. But I have come up with what I think may be an alternative. I thought maybe I could just run another line outside the house, and tap it into the sewer line in my back yard.
So the primary questions that pop into my head are #1, what size line, #2, do I need vent stacks, and #3, what is the rule of thumb as far a grade level, or angle of slope for the line?
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Old 04-06-13, 06:34 PM
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It might be worth getting someone in who has a camera snake and can precisely locate the head. The $100-200 it costs to scope the line will probably be worthwhile so you know exactly what you're dealing with and where. Not only will you be able to see what's wrong with it, but they will be able to locate exactly where it is and where you'll have to dig. Maybe, if you're lucky, it'll just be some roots that can be cut out.

If you had to re-run the line, you could take a different path. Washers now require 2" pipe, kitchen sinks are fine with 1.5. But since you have both, you'll be running 2" pipe. Both fixtures need to be vented, but it sounds like they may be already. As for slope, 1/4" drop per 1' run is perfect, 1/8" is acceptable. PVC will definitely be the way to go.
Old 04-07-13, 10:36 AM
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new line

Ok, so if I go forth with the new line, as far as the venting is concerned.

Do I stick with 2" for the vent or can it be reduced?

Does it have to penetrate the roof, or will going just below the roof be acceptable?

Does the vent have to be directly above lateral line, or can it have a 90 degree bend, between it and the lateral line?

As in place the vent next to the outside wall, but continue past it with a 90 degree elbow into the lateral line.

I ask this because I am not sure how far down the main line, away from house, I will have to go, before I make a junction point, surely within a 3' from the house.

So the lateral line may need to start moving away from house, to avoid too much deflection in the piping.

It is approximately a 30' distance from where where I want to start, to the main line.

So I am thinking that at the point the sink will tap in I will be already be a foot away from house.

Right now I am truly just brainstorming the different possibilities. I know I will have to dig around the clean out, to find out just what the possibilities are for that location, for a tie in.

I definitely appreciate any advice or input.
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