Concrete over old cast sewer pipe??

[heirlooms]

Help.. My 19 year old Son bought a very old house (1890's), during renovations, he wanted to pour the very small basement (17' x 25') in order to install a new furnace, he removed the old oil tank and had gas installed, he then dug out 6 inches of soil as it was contaminated with old oil. The problem is, that the large cast iron sewer pipe was only 1" below the soil, which he has now completely uncovered, its not broke, so we don't want to fix it, there seems to be a clean out valve? on top, we have no idea how to pour concrete with this obstruction? Do we pour stone around it and protect it? it runs down the center of the small space. Help, this was an easy job, we thought, if somebody could run quickly through what should be put down first, whether stone, or seal type cover etc.. thank you

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[DD_BobK]

Welcome to old house ownership. Nothing (well, almost nothing) is ever as simple or easy as it first appears.

Whenever I do a repair or restoration, I always think about the downstream consequences and the current opportunity to do a "fix" that would otherwise not be worth doing.

Without seeing your exact situation, I would consider the following as you get ready to button this back up.

vapor barrier drainage (as in french drain, if needed) future repair, replacement of pipe or drain clearing activity ....maybe cutting out the clean out and relocating?

I would consider using sand to bring the soil level back up & incorporate a vapor barrier as well. Covering the pipe with sand completely will allow you to break (or cut) through the concrete in the future and easily access it.

You probably want to minimize headroom loss and are not crazy about putting sand back in. You could just add a couple inches of sand, enough to handle the vapor barrier and then cover the pipe with a couple layers of plastic or roofing material and place the concrete right over the pipe.

The roofing or plastic will act as a "release agent" and if oyu ever need to get at the pipe, the concrete wont be adhered to it. You could also score the concrete on either side of the pipe (like ~12" wide) so that the floor cracks where you want it to.

You might consider 17 x 25 a "small" basement but in SoCal they are pretty much non-existent. :( I have an 8 x 12 utility basement (with stairway in it) & would love to have a basement like your son's.

cheers Bob

[George]

I think it would be considerably easier to replace the old pipe now rather than breaking up the concrete slab later if there should be a problem. You already have it exposed and PVC is inexpensive. Not only that you may be able to place the new pipe lower.

[clare]

That's what I'd be checking into. The cast iron WILL fail eventually, and the biggest part of the replacement job is gaining access to the pipe. You've already done the hard part- - - - .

[EXT]

You will probably not be able to lower the pipe unless you lower the sewer lateral running to the street, which could be expensive, it is the same as having a new one installed. Doing so would solve a number of problems. Or you would install a sewage pump where the lateral exits the houst in order to lower the basement line. This is the old "snowball effect", just as a snowball gets bigger rolling down a hill, renovations to old houses grow in size as the "might as well do it" factor keeps popping up.

[aemeijers]

Common situation in old commercial buildings. One cheap but PITA solution- form a trench around all or part of the pipe, and cap it with steel plate just sitting in grooves on the edge of the trench. There is one maybe 30 feet long in the basement of the 1902 wing of the building I work in. Maybe the preformed french drain channel they sell to put drains in front of garage doors would work for the trench part, if you can find it big enough. Any scrap steel or whatever would work for the lid, if you can find a cheap way to get it cut. When you need access to the pipe for inspection or repair, just drag the plates out of the way.

-- aem sends...

[Rick Samuel]

If you don't want to mess with the pipe now, put forms around it, with a lip for what ever cover you want to use. 2x6, steel

[EXT]

If this was a dirt floor, I am sure that you have no sinks or toilets in the basement. Then I would do the same thing that people who have septic tanks with a high outlet in the basement, since it is very expensive to lower the sewer lateral to the street.

Get a plumber in to cut the line where it exits the house and as high as possible in the stack just under the first floor. Rip out all the cast iron in the basement floor (sell it for scrap iron). Reinstall a plastic line from the bottom of the cut stack across the ceiling, or along a wall, somewhere out of the way, over the the exit point then down to connect with the outlet line. This will clear the floor for you to do whatever you want. Be sure to put a layer of washed gravel over the dirt and heavy poly sheet plastic over the gravel before pouring the concrete. This will keep dampness from wicking up through the floor.