I've lived in this place for 21 yrs. When I first moved in, there was a
huge indentation in the back yard, approx. 30'50'x8" deep. I brought in 40
yards of topsoil to fill the spot in. My yard isn't flat, but has a slight
slope all the way around.
About 6 yrs. ago, I brought in another 10 yards, because of a the dip
Now, I have the same area of 30'x50, but it's about 24" deep. It's looks
like a sinkhole!
All utilities including sewer run out front, so I kind of figure it's not
As a side note, about 10 yrs. ago, there were some properties about 20
miles from here, which the houses fell into some old mineshafts. The shafts
were never charted, so no one knew they were even there. Because of this, I
had mine insurance added as a rider to my policy.
It's now gotten to the point of getting me spooked.
Who do I contact, or what's the first steps, getting in touch with the
There's any number of things it could be. Could simply be a poor
infill job on a bit of swampy ground, or an old basement that
wasn't backfilled properly.
It's not unusual for a depression to reappear after filling. The
dirt you add to get rid of it compacts down. It's particularly
evident in "new" driveways in rural areas, where surprising
amounts of rock fill are sometimes needed to make it approximately
stable, and every so often you have to add more until it finally
Our area is _very_ fine sand over relatively shallow bedrock with
marshy areas. There's one road over 100 years old that _still_
has to be raised several feet every time it's repaved. The white
oak logs they laid down in the late 1800s to keep it from
sinking are finally rotting out...
We have "lines" of sinkholes (usually no more than 4' wide
and 6' deep) running across our property, some of which
are completely covered with vegetation, others that have
only tiny holes at ground level. A certain caution is required
driving the tractor near them....
You'd expect the compacting down to lessen each iteration tho...
This depression appears to be increasing each iteration
significantly... That's not good, and needs to be investigated.
Contact your local govt. They _should_ have maps of such
things and might be able to tell you what was there, but
more importantly, they'll have the contacts with the
appropriate agencies and can advise you what to do/who to chase.
It may just be that the infill was too fine, and is sitting
on top of bedrock with a horizontal water flow along the
bedrock washing it away. This is what our sinkholes are...
Digging it out, laying loads of gravel, and then recovering
with the dirt might be what it needs.
Age and Treachery will Triumph over Youth and Skill
If'n it were my house, I'd call my town hall first. Not because I'd
think it was their fault, but because they would send someone over for
free to take a look and advise. I don't know if all towns or cities
would do this, but my town is pretty good at keeping us happy and
ensuring that property issues are handled before things get out of
hand. Can't hurt to drop that dime.
From my experience in two different houses:
1) A sewer pipe 5 ft down has a hole and every spring when the soil gets
saturated it flows down the pipe to the tune of 1 inch settling per year.
Village needed to be called.
2) I live in a forest and I can only presume that when they leveled the lot
for the house they laid the big trees down in a bunch and leveled the lot
over them. They are 3 ft down. I am talking 2 ft diameter trees. Every year
I have to find 3 inches of soil to fill the hole in as they decay. The
house is 40 yrs old and it still settles . I had some well work done with a
back hoe that found them.
OK, what's the topography - flat land, on the side of a hill, base rock
chalk/ limestone? Others have made comment about the possibility of
sewers (could be an issue in a chalky/ limestone area). Water mains?
Unlikely in that the supplier is likely to note a loss resulting in two
foot of soil loss in 6 years, (at least here in the UK).
How old is the property? My first thought when I read the start of your
thread was former mining - which you referred to later on. What do you
know of the former use of the area?
Just thoughts; not a solution I'm afraid.
Southern Indiana and Kentucky have that happen pretty often, in hilly
country. Underground water flow makes caves by dissolving limestone. If
a hole pokes up to the dirt layer, it can carry dirt away with it. Most
of these are rather tiny, of course, and the caves too small for human
exploration. But some of them are huge. Cheap developers have been known
to put subdivisions on top of a layer of fill, on rotten substrate like
this. So, sometimes people get a hell of bonus room in the basement.
I can not think of the name (word) these companies use. But when you
buy property, they handle the titles, or deeds, or abstracts
(whichever you use in your area). Anyhow, I had to go by my local one
some years ago, over a property line dispute. When I got there, it
was late in the day and the guy was going to be leaving in a half
hour, and said he was just sitting around since his work was done for
the day. I asked him for the measurements of this "line", and he
printed a map and wrote in the measurements. While he was doing that,
I was looking at a map on the wall that showed all the property owners
and creeks and elevations around my place. When he finished my map
copy, I asked him about the creek behind my farm, and where it goes.
Little did I know that I'd get to see an entire map of the whole creek
all the way to a large river, some 30 miles away. He told me about a
hidden spring that is located under the county's equipment parking
lot, which was capped and fed into culverts, and these culverts go
under an entire nearby small town. He told me it first appears behind
one of the restaurants in town, then goes back into culverts, and come
out again by a gravel company. It was extremely interesting, and I
think he was glad to have someone to talk to before leaving for the
day. He told me about some of the iron and other metal deposits in
the region and that there was actually a mine in this town in the
1800's, which was later filled in, and that is where the small lake
came from in the town parks, and that lake is fed by these culverts.
I would have never known any of this.
Anyhow, that is the place you need to go. Look for a company that
advertises land abstracts, or something like that. They know most
everything about the land.
It'd have to be a hellaciously huge cistern or septic tank to
cause a 30' by 50' depression. Short of some sort of abandoned
municipal-sized water supply/sewage treatment I don't think so.
I can't think of scenarios where a residential-sized unit could
cause an indentation much larger than, say, 10'x10'.
Age and Treachery will Triumph over Youth and Skill
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