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.