This is my second experience with this in the yard of my 3-year old house, but the first time something has fallen in (see attached picture).
The first time it happened, I noticed an 8″ diameter hole in the yard and dug around it to find an open area about 4′ in diameter and up to 6′ deep in one corner, all topped by a “roof” of sod that was 6-12″ thick. I’m lucky I didn’t drop the riding mower in there! I found one charred-looking log in the hole and assumed it was an old burn pile that had settled. So I filled that in and it’s been pretty stable in the 2 months or so since, and we’ve had a couple of heavy rains.
Now, as you can see from the picture, I’ve found another one. It’s about 20′ away from the first, and is smaller–looks to be maybe 3′ diameter and only 2′ deep or so.
Can anyone tell me what a good next step would be? Should I dig up that whole area of the yard and re-grade? I drive the truck in that part of the yard quite a bit delivering materials to the basement workshop, and don’t particularly want to bury it for good (in this case luckily she popped right out).
I’m also considering asking my builder to take a look at it, and see if maybe he’ll help with the repair out of good will. I’m assuming he doesn’t hold any legal responsibility to fix since the house is 3 years old now–is this correct?
Thanks for any responses!
Replies
I would check the county to find out if your house is built over a landfill. Or worse, a cemetery.
An underground creek/spring can cause sinkholes as well. Maybe the fill was put over an old runoff from somewhere else ?
Are there old mines in your area ?
I'd find out the cause/source of the sinkholes before I went after someone about it. And I may be wrong, but I would think that if the builder knowingly built over anything that is causing the sinkholes, he would still be responsible even now...
Rudeness is the weak man's imitation of strength. ~~ Eric Hoffer
Thanks for the replies. The lot was fairly heavily wooded until my house went in, so I'm pretty sure it's not on a landfill. I can only hope it's not a cemetery. No mines in the area. My guess is that it's probably the burn pile used to get rid of the debris from clearing the lot initially, as smslaw suggests. If that is the case, does anyone have any thoughts on how amenable the builder might be (or might be required to be) to helping fix the problem? He seems like a reasonable guy and is fairly well known in the area.
fairly heavily wooded until my house went in
Which means there could be ("could" being the operative word here) a number of both naturally occuring, and created by clearing, buried stumps. As the stumps decay, a hole forms, drive over, and you find the hole.
The 'bad' answer (opposed to 'worst,' i.e. mines, cemetaries, landfills, etc.) may be that you need an actual driveway of some type, just to know where there's no holes.
Occupational hazard of my occupation not being around (sorry Bubba)
Even heavily wooded area *could* have had some building on it in the past. An old well, or foundation (stone or wood) or root cellar from some early settlers. Even an old outhouse pit.
But if it's between the house and the road access or in the area cleared by building the house, I'd bet it was buried stumps or logs.
I found a "sink hole" on my property that turns out to be a 2nd cesspool overflow tank that I did not know I had. Wasn't on any surveys dating back to 1960's. I had the tank inspected; just needed a new slab top.
One possibility is that someone, probably the builder or developer, buried lots of stumps and/or brush instead of taking it offsite to an expensive landfill. Once the stuff rots and decomposes, it takes up less space and the ground above it settles. Organic matter makes lousy fill.
Around here burying trees on the property is illegal. I'd check around, then talk to the builder.
Personally, I'd be surprised if the builder will do anything after 3 years. Further, he may likely know less about the situation/cause than you do. If something was done wrong during the lot clearing, he may not have even been present during the process. A phone call can't hurt though.
Regrading the whole lot won't help, unless you compact the whole thing which doesn't sound like a good idea and would be rather expensive.
How about this: Get a probe rod or you could make one. It's a simple 'T' shaped tool that is maybe 4' long and made of steel or fiberglass. The "business end" is ground to a dull point. If you wanted to make one use, maybe #5 or #6 rebar. #4 would bend way too easily. Or buy one for about $20 - $30 - although they are hard to find. Real plumbing supplies might have one. There is a pic here.
Go over the entire yard (or the area that you want to drive on) with the probe rod in maybe a 2' grid pattern and check it all. Carry a can of upside down spray paint to mark the soft spots. Now, go rent a jumping-jack (gas engine driven compactor) and compact the problem areas. Have fill dirt on hand to fill the spots and compact those too.
I did end up calling the builder but that turned out to be a dead end. Matt, I think your suggestion is a great one--the soft spots seem to be covered by only 6-12" of dirt and sod, so a bar like you're describing would poke right through and make them easy to find. Judging by what the ground looks like, the affected area is probably only 30' x 30' or so, so it shouldn't take long. Thanks again everyone for all the replies!
Friend had one in his front yard that turned out to be large as a city bus. We are in Atlanta, GA. Here it's illegal to bury tree trash for that very reason. Takes 8-10 yrs for it to usually become a real problem. Friend's problem came in about that time frame. Developer came out, dug out trash, filled hole & regraded. All at no expense to friend. County was quite intereested in effort, hovering over effort like a black helicopter. In my original Atlanta haous had one in front yard that got to be depressed enough that when I stood in deepest point my knees were even w/ grade. I was waiting for it to quit & fill it in once. Finally had to fill it - took a dupm truck load to fill. Built a butterfly garden over it, rather than rassling w/ sod, which would sink again then have to be replaced, for a long time. Sold house; new owner took out garden, put in sod. Whatever cranks your tractor. Every house in my SD had one of those depressions in the front yard; mine just happened to be the ugliest.DonDon Reinhard
The Glass Masterworks
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