Sump pump liner install, back-fill with concrete?

[andyeverett]

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.

[Mikepier]

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.

[Jim Elbrecht]

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.

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 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.

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

Jim