strange hole under patio

Need some ideas as to why. Last summer my uncle and I put a patio in his back yard. dug up the turf leveled it out, used a compactor to compress the material used for leveling. Placed 2x2 concrete slabs for the patio, entire surface area is 10 x 10. Recently my aunt falls into a hole that is 1’ deep under the lawn next to and goes under the patio. The dirt just dissapeared. Where did the dirt go?


How old is the home?

Was there a Water Well previously in this area?

the house was built in 1950. not sure about a well. being only 77 years and not far from the hospital i think it would have city water. although it is a good idea. Nanaimo was at one time a massive mine town perhaps the yard is falling into a mine shaft

There are places in PA that have had underground coal fires going on for decades. From time to time, a big sinkhole will open up because of that. The side benefit is that some people never have to shovel snow. Centralia, PA is one such town near me.

Familiar with that area.

Undermining from H2O Wells and Mines can not be discounted if the geography of the area indicates that the condition may be preexistent.

well if i ever think about moving ill remember Centralia, PA has underground heating, LOL. Could you imagine one day your house just falls into a firery pit

It has happened here…

If you have not experienced this type of scenario firsthand, it is extremely difficult to comprehend…


Have you got pictures or have y’all already repaired, for safety sake.

I’m going there for dinner tomorrow will take a few pics

Check for an old septic system that may have been installed before municipal services. I had that happen one one house, I sat and watched my rear lawn sink for over an hour… (I did not have paint to watch dry:mrgreen: )

Al Gore told me it’s due to global warming, the permafrost below the patio is thawing out and the soil is compacting due to the loss of ice crystallization. But, I do have a reccommendation, fill it in and see if it continues to sink. Could just be decaying vegetation buried way back. Could be an old outhouse, people are looking for these now to dig up for old bottles and such. Could be…anything. I don’t believe aliens are involved, good luck, let us know if you find a faster trade route to Hawaii.:wink:

Throw in 3 bags of ice into the hole, every day. This should slow
down the thawing action until they fix global warming. Al said it
shouldn’t take much longer until he has it corrected.

A tree stump or root was there, and since you layed the patio, a moist enviroment was created under it, which attracted termites, and they have consumed the wood. My theory

I will throw two more possibilities out there.
(1)An abandoned underground oil tank that was never decommissioned properly.
(2)An abandoned steel septic tank. That was never filled.
Both can collapse as the steel corrodes, causing sink holes.

Oil tanks will usually have a fill tube and vent pipe, unless someone cut them off, or otherwise concealed them. If it had an oil furnace in the past, it will often have the copper supply and return lines in the crawl space still, and if it is a basement home, the lines could possibly be exposed arond the furnace location.

Just some ideas to ponder…