I will install a sump pump liner and will dig a hole near a stone wall
foundation. My concern is that the hole might weaken the foundation a
bit. I have insurance for such things but want to take no chances. If
I back fill the space around the sump pump liner with concrete then
any effects of the hole weakening the foundation will be eliminated by
the concrete shell surrounding the plastic liner?

I was considering using extra gravel in the concrete to make it more
porous near the bottom so that water could seep in.

Thanks for your thoughts.

On Nov 16, 7:40*pm, andyeverett wrote:
I will install a sump pump liner and will dig a hole near a stone wall
foundation. My concern is that the hole might weaken the foundation a
bit. I have insurance for such things but want to take no chances. If
I back fill the space around the sump pump liner with concrete then
any effects of the hole weakening the foundation will be eliminated by
the concrete shell surrounding the plastic liner?

I was considering using extra gravel in the concrete to make it more
porous near the bottom so that water could seep in.

Thanks for your thoughts.

Assuming this isn't merely an unimportant outbuilding, and that
structural integrity and code compliance are important, it might be
wise to consult a professional engineer to get a proper set of working
plans for your permit. Not doing so would mean a denial of any damage
claims by your insurance company in the event of a foundation failure.
It doesn't matter who does the work (in many communities) if it is
permitted and inspected.
Old stone foundations often had no footings and must be treated as
potential problems. Your area could surprise you with an earthquake,
just as happened in Oklahoma. Your engineer likely will have some
common sense and effective ways to mitigate the possibilities of
failure.

Joe

Joe

On Nov 16, 8:40*pm, andyeverett wrote:
I will install a sump pump liner and will dig a hole near a stone wall
foundation. My concern is that the hole might weaken the foundation a
bit. I have insurance for such things but want to take no chances. If
I back fill the space around the sump pump liner with concrete then
any effects of the hole weakening the foundation will be eliminated by
the concrete shell surrounding the plastic liner?

I was considering using extra gravel in the concrete to make it more
porous near the bottom so that water could seep in.

Thanks for your thoughts.


Usually in practice you don't want to make the hole in the ground less
than 8" away from the foundation wall. This is so you will not hit the
footing when you dig the hole. Note this is for a standard 8"
foundation block wall with 16" footing. If you have a stone wall and
its more than 8" thick, you might want to stay farther away.
Usually you make the hole in the ground about 4-6" more in diameter
than the liner, and also about 6" deeper.Then you pour 3/4" gravel in
the hole till the liner sits flush with the floor, and backfill around
the liner with more gravel. Then you finish off the final 3" with
concrete and make it flush with the floor. You don't want to put
concrete surrounding the liner as this will prevent water to get to
the pit. Also make sure you drill several 1/2 " holes in the pit to
allow water to get in easy.
Doing it this way will not weaken the structure.

Check out videos on youtube, there are several videos on how to
install sump pump liners.

andyeverett wrote:

I will install a sump pump liner and will dig a hole near a stone wall
foundation. My concern is that the hole might weaken the foundation a
bit.

A valid concern. I managed to lose 40' of foundation wall by
digging a trench to promote drainage. The week before I was
getting ready to backfill with drains and gravel we got the most
intense 3 hours of rain we've had in 50 years. With a mighty
'thwump!' about 40tons of stone landed in my basement. The good news
is, once the stone foundation was out of the way, I got to dig the
floor down a couple more feet, replace the stone with block on a
proper footing, and am left with a much better situation. [including
drainage to daylight with no sump pump.

I have insurance for such things but want to take no chances.

Not likely. The first contractor I called guessed at $40K for my
job, but said he doubted my insurance would cover it. He was right.

I spent $10K, a few favors, and a couple [big] buckets of sweat-- and
a little blood.

If
I back fill the space around the sump pump liner with concrete then
any effects of the hole weakening the foundation will be eliminated by
the concrete shell surrounding the plastic liner?

If it was me, and I couldn't tear out the foundation and do it right--
I'd keep at least 4-5 feet away from that foundation with any holes.


I was considering using extra gravel in the concrete to make it more
porous near the bottom so that water could seep in.

Aside from not working, messing with the mix in concrete is not a good
idea.

Jim