I wondering if someone can advise me properly. We alot of rain ( approx 7 inches) in a weeks time, after this rain I noticed a 6 inch round sink hole in my driveway. This sinkhole has now expanded to 3 ft wide by 3 1/2 ft deep. The contractor responsible came to fix it and dug the sink hole by hand 6 ft down and then filled it with gravel. He stated that it was a natural spring that got to much water in it etc.... My question is what is the proper way to control this issue? since I believe the problem can occur again ( off course the builder says no way). What is the PROPER WAY to assure myself this will not happen again? THANK YOU FOR ANY ADVICE THAT YOU HAVE ON THIS MATTER
If it is indeed a sinkhole and sounds like it might be, you may well have a much larger problem brewing. I'd recommend contacting city/ county building department and ask about prevelance of sinkholes in the area in which you're located as a start. Many areas are riddled w/ underground caves and if it's a limestone formation, these can open up to swallow houses and, in an area in TN where we were, about half of a relatively new subdivision (about 20 houses were either completely lost or condemned iirc).
It's possible it was just a small spot and the corrective action may be enough and it won't come back, but if it were me, I'd do some serious investigating of the geology in my neighborhood rather than just hope it's ok...
Sometimes after determining where the extent is, they area can be stabilized by pouring concrete down to fill a relatively small void. If there happens to be a large cavern, it may be impractical to impossible.
If it's truly an underground spring, then filling it in won't solve anything - the water has to go somewhere and if it can't go there it will pop up somewhere else (maybe somewhere by your foundation???). If it were me, I'd fill it with gravel and/small rocks and see what happens next time it rains. I wouldn't sink too much cash into it until you see how it'll play out - might have just been a freak occurrance.
It depends a great deal on exactly what's going on. Is it really a spring? Or, is it a channel from an underground stream meandering over bedrock or...? The contractor would probably say "spring" no matter what it is because it's simpler for a homeowner to understand.
Our bedrock is 4-7' down under sand. We have several "lines" of sinkholes. One of them came close to swallowing our garden tractor and trailer... One line extends across the country road, and a few years ago, a sinkhole opened up in the middle (entrance hole in asphalt was only 6" across, but it was several feet deep and wide underneath the asphalt).
We understand this to be lines of water runoff thru the sand, just on top of the bedrock, slowly taking sand away with it. Eventually it breaks through.
If you're on bedrock, especially if you have very light/sandy soil, that's probably what you have. Filling with gravel and packing it will probably make the problem go away long enough for you to not care about it. This is all they did with the road.
On our property, we had a backhoe in to do some work, and given he needed to get some sand, he got it from the sink hole area, and re-leveled/graded one area of sinkholes to see if that would do the trick. After 15 some years, the sinkholes haven't recurred in that spot.
Aside from that, you might want to talk to someone in your municipality. They probably have someone who'll know your conditions well enough to make an educated guess.
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