Should I take the risk?

[Pack Rat]

I have a hard choice to make. In order to put a shop in my backyard part of the slab
would have to be poured over my sewer line.
It's the line that runs from my house to the city sewer. It was put down in the mid 50's and is clay tile.
I had the location marked out and a camera run through the line. It is in remarkably good shape.
A clear run with good drainage and no broken or lifted tiles.
I could possibly run a new line to the other side of my lot, but it would be very costly.
My neighbor is a plumbing contractor and he said people poor slabs over sewers all the time.
The part of the slab over the sewer would be at it's deepest part.
Should I take the risk and put the slab down and hope for the best,
or relocate the sewer before beginning the build? What are your thoughts and experiences?

 

[Richard Cranium]

go a head and pour your slab, If you ever have a problem, then reroute your line. You would most likely go with pvc anyway.

 

[nh_yota]

They can also re-line it without having to dig it up, if needed.

 

[bwringer]

I find it very hard to comprehend how on Earth (under Earth, actually) a 60+ year old tile drain line in the midwest is still in great shape.

But, you've done your due diligence with the camera. Guess you got lucky! If you feel it'll outlast you, then why worry about it?

If there is a problem in the future, would it be possible to leave the old line in place and route a new line around the driveway?

 

[nh_yota]

I find it very hard to comprehend how on Earth (under Earth, actually) a 60+ year old tile drain line in the midwest is still in great shape.

But, you've done your due diligence with the camera. Guess you got lucky! If you feel it'll outlast you, then why worry about it?

If there is a problem in the future, would it be possible to leave the old line in place and route a new line around the driveway?

Most sewer line damage is caused by tree roots infiltrating the line, so it really depends how many trees are located near the house.

 

[Pack Rat]

They can also re-line it without having to dig it up, if needed.

That depends on the extent and kind of damage that needs repair.
I'm concerned about damaging the sewer when they tamp down the crushed stone under the concrete.

 

[nh_yota]

Does your house have a basement or is it slab-on-grade?

 

[SweetD]

Mine is run under the garage foundation, with exterior clean-outs on either side, and one in the garage floor. It's PVC and about eight years old.

 

[T_R]

I wouldn't with 60 year old clay.

If it was modern materials, I would.

 

[gregtwojeeps]

Roll of the dice really and how long do your figure on living at this place ? If it were my going to stay in it 10 years + house, I would consider just going ahead and replacing the clay tile with PVC. Cheaper now than later. No one thinks about how bad it is when their home sewer system fails, especially if you have a wife. Makes for a VERY unhappy time...until it gets fixed and the failure of a sewer usually happens at the worse time...holidays, heavy work schedules, bad weather... you name it. Just been there ..done that ..five months ago. All JMO

 

[slow]

Why not run a line a few feet (10?) parallel to the existing line available as a replacement if the clay line fails down the road. I cannot imagine 40-50 feet of PVC would add much to the cost of the project, unless it caused drastic changes to the foundation requirements. Just install at close to the correct depth to allow it to work in the future if required.

 

[Pack Rat]

Does your house have a basement or is it slab-on-grade?

My house has a foundation but the floors are a slab instead of crawl space.
The sewer line comes out of the back of the house and runs to the city sewer at the back of the lot.
For the last 20 years I would have the line cleaned out every year to remove roots.
I got lucky once already. The line went diectly under a large maple tree.
Two years ago I had the tree cut down and the stump ground out with no damage to the line.

 

[gregtwojeeps]

My house has a foundation but the floors are a slab instead of crawl space.
The sewer line comes out of the back of the house and runs to the city sewer at the back of the lot.
For the last 20 years I would have the line cleaned out every year to remove roots.
I got lucky once already. The line went diectly under a large maple tree.
Two years ago I had the tree cut down and the stump ground out with no damage to the line.

So if the tiles are pours/cracked enough to have had a lot of roots break through them... your tile may not be in as of good of condition as one thinks. JMO

 

[theoldwizard1]

They can also re-line it without having to dig it up, if needed.

They did this on This Old House. I don't remember how, but it saved thousands of dollars.

 

[bczygan]

Your new slab will be over the line where it is shallowest. It is deepest at the sewer main.

I would be tempted to dig and replace at least the portion you will be building over, and put a couple of clean outs in it, inside and out. You're going to be digging there anyway.

Bill

 

[homebuilt burner]

We had ours relined. They dug a small hole (10x10) close to the street. Then slid pvc drain line inside of the clay both directions with a rubber seal ring on the end towards the house. Not expensive and solved all the problems.

I'd build over it.

 

[My Old Tools]

I would replace that section with PVC and tie back into the old stuff on each end if you want to keep it. But , I would really just replace the whole thing with PVC right where it is and pour the slab.

 

[dw1]

So if the tiles are pours/cracked enough to have had a lot of roots break through them... your tile may not be in as of good of condition as one thinks. JMO[/QUOM

My daughter bought a house a year ago, I just dug her sewer pipe up, I pulled out about a 42" long rootball, luckily she didnt have a basement and it was only 36" deep, it was 6" terra Cotta pipe, these looked to be about 2' long, so it had plenty of joints. (For roots to get into) Hoepfully she will be good to go for a long while, I didnt want to pay for or do the whole thing. A friend also suggested that I could slide 4" SDR pipe inside the 6" Clay Pipe. I only replaced about 6' of pipe, but did add a cleanout.

 

[Pack Rat]

So if the tiles are pours/cracked enough to have had a lot of roots break through them... your tile may not be in as of good of condition as one thinks. JMO

The annual clean out prevented roots from growing large enough or accumulating enough to do damage.
When the camera was run down thu it a few weeks ago there were no roots seen.
No cleanout needed this year. The contractor said no lining or repair was needed.
Except for a very little bit of water in the bottom of the pipe it was dry, so dainage was good.

 

[Falcon67]

Having lived with a clay line that crossed two yards and part of a street, if possible I would replace the section under the slab with schedule 40 or 80 PVC drain pipe. It's easy to cut the clay and use a rubber adapter to mate the sections. We did that at the old house whe the under house lines were updated. The main run worked well even as old as it was, just needed rooting out every 2-3 years. But it's easy to crush, which is what happened when a city contractor worked on the street. Backed up next door first, then us and a 120' rooter could not find the end. They had to dig up the street and found a 20' diameter "sand septic" created by the street work LOL. Oops.

 

[HoosierMark]

why not assume you have the slab over it and it fails, what will the cost of a new line be? Now while you have equipment there, what will the cost be to at least replace the line near and under the new slab? Now you can determine aproximately how much money you are risking. fix it now or fix it later, but my bet is that you are going to fix it sometime.

 

[eastbaysubaru]

How costly is "very costly"? I would be inclined to replace it now while it's that much less expensive. Relining an old clay pipe when it fails (which it will at some point) is certainly a possibility though it would still be considered a "bandaid".

If it did collapse partially (hopefully not completely) when the slab was poured or the building was finished, relining the line may not be an option because of the reduced diameter of, along with the compressed earth surrounding, the collapsed pipe. Cutting up a fresh slab would be a painful proposition, especially considering you've given consideration to replacing the sewer line preemptively. An ounce (or roughly $3-5K in this case) of prevention is worth a pound of cure or so they say.

-Brian

 

[uppster]

I would replace it if it's not too far out of your budget

 

[techlaf]

I just did this for 25' from front of house to street connection. Rented a sizable excavator delivered with diesel for the day $425. I got a big one because I had substantial roots to rip through, but asked for a 12" bucket with teeth. I really didn't need anything wider.

Replaced all the 4" cast iron waste pipe with 4" Schedule 40 PVC. That stuff is stout and it came in 20' sections so I'm not worried about roots getting in the joints.

I also added a clean out in the front which I did not have. Rental, PVC pipe, fittings, supplies , and $500 to a retired plumber to help me and I'm just over $1K. No way would I leave that old stuff in there, but I wouldn't hesitate to build over it once modern PVC is under there.

 

[CJ7VFR]

So if the tiles are pours/cracked enough to have had a lot of roots break through them... your tile may not be in as of good of condition as one thinks. JMO

The annual clean out prevented roots from growing large enough or accumulating enough to do damage.
When the camera was run down thu it a few weeks ago there were no roots seen.
No cleanout needed this year. The contractor said no lining or repair was needed.
Except for a very little bit of water in the bottom of the pipe it was dry, so dainage was good.

I believe what he is referring to is that if you had to have tree roots removed from the inside of the piping before, in order to clear it, then the roots have already created some damage to the pipe where they broke thru to the inside and the pipe may not be as strong as originally thought.

Jim

 

[Big Bad Dad]

Your new slab will be over the line where it is shallowest. It is deepest at the sewer main.

I would be tempted to dig and replace at least the portion you will be building over, and put a couple of clean outs in it, inside and out. You're going to be digging there anyway.

Bill

me too.