Concrete over old cast sewer pipe??

Posted by heirlooms on October 19, 2009, 11:36 am

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

-------------------------------------

Posted by DD_BobK on October 19, 2009, 1:03 pm

On Oct 19, 8:36=A0am, trying2fndu_at_hotmail_dot_...@foo.com (heirlooms)
wrote:

> 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
> -------------------------------------

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

Posted by George on October 19, 2009, 1:08 pm

heirlooms wrote:

> 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
>
> -------------------------------------
>
>
>

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.

Posted by on October 19, 2009, 2:41 pm

wrote:

>heirlooms wrote:

>> 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
>>
>> -------------------------------------
>>
>>
>>

>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.

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- - - - .

Posted by EXT on October 19, 2009, 4:16 pm

> heirlooms wrote:

> > 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 -------------------------------------

> 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.

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.

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