Sinkhole activity and organic laden sand/muck
Sinkhole activity and organic laden sand/muck
(OP)
I live in Palm Harbor, Florida and have recently had a ground subsidence study performed prior to beginning an extension project.
Thet did soil samples with hand auger borings, 2 deep Stendard Penetration Tests and a GPR ( ground penetrating radar).
Findings were: sinkhole activity and burried oraganic laden sand/muck materials with organic contents varying from 15% to 52% by dry weight.
Recommendations: a grouting program estimated by the contractor at between $67,000 and $83,000.
The report notes that "subsurface grouting will not mitigate the sand/ muck problem and that subsequent distress could occur ( and likely will) even after a properly implemented grouting program has been completed."
My question: how serious is this? Do I continue to live here? How significantly does this affect my property value?
Will a lender finance this house? What shold I do? Do I need to speak with an attorney for possible claim against the builder? HELP!
Bill Lichter
Palm Harbor, Florida
727-787-1031
Thet did soil samples with hand auger borings, 2 deep Stendard Penetration Tests and a GPR ( ground penetrating radar).
Findings were: sinkhole activity and burried oraganic laden sand/muck materials with organic contents varying from 15% to 52% by dry weight.
Recommendations: a grouting program estimated by the contractor at between $67,000 and $83,000.
The report notes that "subsurface grouting will not mitigate the sand/ muck problem and that subsequent distress could occur ( and likely will) even after a properly implemented grouting program has been completed."
My question: how serious is this? Do I continue to live here? How significantly does this affect my property value?
Will a lender finance this house? What shold I do? Do I need to speak with an attorney for possible claim against the builder? HELP!
Bill Lichter
Palm Harbor, Florida
727-787-1031





RE: Sinkhole activity and organic laden sand/muck
I'm not sure how large your residence is, but the muck problem is likely worse than the sinkhole subsidence issue. It certainly has a higher probability of being an issue with your house, though you are in a known, active sinkhole area.
It sounds as though you have had a geotechnical investigation done that was carried a bit further than typical, since you had the GPR done. Did they estimate the anticipated settlements? Has there been any fill placed on the site? If so, how much? Is this a one-story structure? Was the investigation done for you or your contractor?
I would suggest you go back to your geotechnical engineer and ask him to get a bit more specific in his evaluation/recommendations. If that is not successful, then perhaps you should approach your builder and offer a buy-back before you pursue litigation.
Start doing your homework. If you pursue litigation, it will be expensive, so try to do as much of the grunt work yourself as possible. Look at your contract with the builder. They often exclude things such as this from their liability.
Good luck.
Ron
RE: Sinkhole activity and organic laden sand/muck
I didn't see this dealt with above, but if you're thinking about spending that kind of money, you ought to price how much driven piles would cost. It may cost more than your estimation for grout, but it would definately last longer, and help to secure your property value.
I know a family that had this done, and I could find out what it cost them, if you are interested in that route.
-Jeff
RE: Sinkhole activity and organic laden sand/muck
Driving piles into this type of structure can create problems with the poor quality limestone in his area. It tends to have many solution cavities and the top surface of the limestone is at various subsurface depths and has an irregular profile.
Another issue Bill has to deal with is disclosure. He is required to disclose items such as this for real estate transactions, so he is in a position that he must take some action to mitigate or seek remedy from his builder. Neither is a great choice.
RE: Sinkhole activity and organic laden sand/muck
Van anyone comment on this?
Bill
RE: Sinkhole activity and organic laden sand/muck
Underpinning will likely be required but it will not address slab displacement anywhere in the middle of the house. You will likely have to have a remediation scheme that addresses both. Yes, underpinning is feasible and common in your area.
RE: Sinkhole activity and organic laden sand/muck
RE: Sinkhole activity and organic laden sand/muck
Grouting is probably you best bet in muck/sand. Be sure they don’t do too high pressures. Sometime the contractor will do this because they get paid by the yard. This can lift the house and cause a lot of collateral damage. Hopefully it will displace the muck and density the sand making your home more stable. However, like the engineer said, “there is a chance it may not work”.
The only other remedial action I may suggest in addition to grouting is chemical injection to upper surface soils. Grouting is typically terminated 10 ft below ground surface if most bearing of the foundation is 3B below the footing (B-footing width). Many times these soils can density. Chemical injection in the 10 ft would help this as wall as alleviate further raveling activity in this critical zone.
RE: Sinkhole activity and organic laden sand/muck
After "a properly implemented grouting program" of the moderate cost of US$ 67000 to 83000, some "distress" will nonetheless be likely to occur!!!
Which is the depth to the buried, karstified limestone formation?
Is there any way to ascertain with reasonable expense the distribution and location of major cavities, if they exist at all underneath the structure?? and tranfer the structure load to the bedrock without the problems previously mentioned by Ron?
RE: Sinkhole activity and organic laden sand/muck
RE: Sinkhole activity and organic laden sand/muck
then we have a real "bad karma" situation, I fully appreciate now Bill's concern!