While finishing my basement I recently discovered the drain pipe for the stubbed in toilet was broken. I called a plumber who ran a camera through the pipe and discovered the pipe was bowed and had to be replaced. He subsequently jackhammered a trench in the basement floor. The photo below shows what it looked like after opening up the hole.

http://216.77.188.54/coDataImages/p/Groups/317/317617/folders/281179/224609147b7cf35b3127ccebfa60631acdb00000026108CauG bVy3Zi.jpg

What the plumber discovered is that the fill dirt under my basement floor had settled dramatically, as much as two feet in some areas. The pipe got weighed down by the dirt on top of it, and that pressure broke it.

While the plumber was able to replace the section of pipe, and packed dirt underneath it very well, I am concerned now about that void under the floor, and how it might effect the pipe in the future. The following picture of the trap beneath the tub shows just how severe the problem is.

http://216.77.188.54/coDataImages/p/Groups/317/317617/folders/281179/224609247b7cf35b3127ccebfa61aabac4f00000026108CauG bVy3Zi.jpg

I realize this is not stricly a plumbing question, but I figure some plumbers out there might see this on occasion and have some advice. So far the basement floor has not cracked or settled. The basement sits on a subfoundation and is located north of Atlanta, GA.

Thanks.

There are companies that specialize in jacking floors and leveling patios. That may be a place to start with filling those voids. They can't remain, the concrete will eventually move downward.

Gave useful advice, and verified my concerns.

Those voids can be located non-destructively using ground penetrating radar.

That's very good to know. Thanks.