Howdy guys,
I think I have a real odd one here! my house was a regular 70's split level, which was added too with an ground floor extension with a full basement. there has been water leaking out from beneath the stairs connecting the sub basement to the split level basement for as long as we've been in the house. The previous owners carved a channel in the concrete and and that directs the the water into a sump pump. Now because of higher than should be radon levels and because I thought it might be a good idea to actually figure out what was leaking I cut a hole in the stairs and took a look at our leak. What I found was a two foot wide by two and a half foot high hole where concrete should be but isn't. The concrete just seems to have melted away or was never there at all and the exposed bedrock underthe split level basement is right there to be poked out and leak water out of.
Now my question is can I just construct a form and fill that in with some kind of concrete and adhesive? this is a really weird situation its not like I can dig out from under my splitlevel basement to put a waterproof barrier on the exterior side of this concrete stairwell it's literally under my house! Any ideas would be greatly appreciated. Thanks

If the picture above isn't working take click this link. https://www.dropbox.com/s/5j9o0c96ix..._0011.JPG?dl=0

 

Yes, filling the hole with concrete would be a good idea, compared to what's there now. But first determine if the existing concrete that forms the border of the hole is reasonably sound. If it happens to be soft and crumbly, adding new concrete won't be much of a repair, as the existing material around the new concrete will continue to deteriorate. Since you haven't shared with us where you live, I can't begin to offer any possible causes for the deterioration.

And keep in mind that concrete by itself isn't waterproof--you'll need to apply a sealant for that to happen.

 

what's the pic ? laid stone/brick surrounded by conc ? read your post 3x but still not clear as i view the pic,,, as bdge said, conc's porous,,, iirc, it doesn't become wtrproof til it reaches 5,000psi,,, IF i had a better understanding, i'd probably suggest an impermeable membrane rather than conc due to the radon issue

 

Howdy again, So to clarify a few things I live in Northern New Brunswick. The material behind the concrete is, I think, shale bedrock that is under the first level of the basement. I tested the concrete around the edges of the hole and it is quite solid.. no give or flaking at all.
Are there spray on impermeable membranes that I could apply to the bedrock before sealing the whole thing off with concrete?

 

ykw ? saw something on tv & its now in apron/vest stores,,, have you seen the guy who hustles membrane in a can ? gutter interiors, boat bottoms, etc,,, think that's worth a try !