Maybe your Problem is some Trees that got buried when your Place was first cleared.It takes Years before they decay.Another Reason is a underground spring.

Another far off thought.. Any old coal mines in the area? I grew up in southwest PA. There were quite a few old mines that colapsed. May be WAY off base.

Good suggestions. The buried trees are a possibility, as this area was forested once upon a time. A spring - I wish, but don't think it's likely. Wouldn't there be water around that area? There is none. I don't think there was ever any coal mining done in this area, the very north central part of Indiana.

So I take it you don't think a failing septic system is a possibility?

Thanks for your responses.

we are now haveing the same problem as Perenneal Woman, we were digging a ditch along the back of our yard for a low wall and once we hit the low spot a ton of water came gushing out. it was definetly septic and as we dug a little further found the leach field pipe. There was a big rock in front of the exit of the pipe and the fluid was going to the least path of resistance, which was up. we have a septic company coming out next week to find the other pipes, if there are any....it seems there were no regulations 34 yrs ago when house was built. so there might not be any other pipes leading out of the tank. BAD for me!!! i wish you luck and hope its just a blocked pipe and not time for a new system.

Perennial_Woman, did you ever find out what was causing that area of your yard to sink?

Pluckey, what did the septic company say about your system?

Paul

No, Paul, nothing has happened. There has never been any water around that area and I've not had any problems with interior plumbing. No emergencies, so I will just bide my time.

This fall I have filled in that area very well, and will seed (grass) it before winter. If by spring it appears to be sinking again, I will call my plumber.

A friend who is more knowledgeable about septics than I said even if it's settling, that doesn't mean it's failing.

We shall see . . . . . Thanks for asking.

Do you know the history of your land? Do you think it could be an older septic system, maybe from a previous house long ago, that just got forgotten/abandoned there?
I don't plan to use a septic system, just a sawdust compost toilet and a greywater wetland myself.
Hope it stops sinking!
Eric in Japan

This is unlikely I know, but old graves sink also. We used to live near an old abandoned graveyard, about half the graves were unmarked, but you could still see where the earth fell in. A large animal like a horse or a cow could cause a hole when it finished decaying and the sides fell in. Unlikely I know.

Much more likely is something like an old well that was covered over and sunk back in, or maybe an abandoned root celler?

Or maybe it really is your septic field.

You might want to call a septic person in just to take a look, and to locate your septic field if you are not sure where it is.

Or, it could just be a sinkhole. Those happen quite often and with little obvious reason.

Let us know if you find out what caused it.

I'd vote for a developing sinkhole, if you're in a 'karst' region. I find new ones developing throughout my pastures every year.
Another possibility to consider is the possibility that when your house was constructed, the builder had a big hole dug where they dumped all the construction debris, then filled in over it. I've got that situation at my house, a big, sunken area in the side yard, where they piled and (partially) burned the construction debris, then when we had the yard graded, it was covered over, but over the past 10 years, settling has occurred, so I've got a big depression that will require repeated fillings.

Didn't realize there has been activity on this thread.

Eric, I don't know the history of this land. I've been here 11 years and the house was built about 1950. It's about 1/4 mile from the St. Joseph River, so I'm sure this has been a populated area for centuries.

I don't know if it's an older septic system. I guess there are many possibilities. And yes, Eric, I give peas a chance. ;o)

Madspinner, the depression was too perfectly round to be a grave, I think. An abandoned well would be round though, wouldn't it? I don't have any septic system problems, so I don't think it's that.

I filled and seeded it with grass and it's blended in with the remainder of the lawn now. But, I will continue to watch it.

Lucky P, what's a karst region? And this is definitely not a new construction, so I don't think that's the problem.

Interesting to think about what or who was here before.

Hey there,
A karst region would be one where there is limestone bedrock that due to the groundwater begins to dissolve. This causes the soil above it to collapse giving you a sinkhole. Since you say the sinking area isn't wet it could be that the area being dissolved is relatively deep - that would still allow for a sinkhole to develop without a wet surface. Do you know if there have been other sinkholes in your area? Your spot being round is consistent with a sinkhole.

However, since the area is adjacent to your septic system, that is suspicious. I suppose if the conditions were right, a septic field could even initiate a sinkhole forming.

Just some thoughts. Best wishes!!

With a shovel you could dig a small hole approx. a 16" down.
You will find out if it is septic related. If it is septic related you should know, especially if you have well water!
If it were me I would investigate the septic especially if I or my neighbors had well water.

Another possibility could be field drain tiles. If it had been farmed before the house was put on the land. Right after WWII farmers were given money to upgrade fields and to buy farm equipment. A broken field tile will look almost the same. We had a field tile break in our front yard. When it rains do you see water come out of it or look like your grass was "floating" after a hard rain?

My neighbor's gravel driveway has a spot in which a hole just keeps developing. Not big, but he dumps big rocks in it and after awhile they just go down. A man that works for the state showed me a place in the freeway near here that he says has accomodated something like twenty, ten yd. dump truck loads of rock over the years. They have a permanent warning sign of a dip in the road. I don't know what caused these things.
G

I'd be afraid if it were an old well or septic that the cover had collapsed and create a hazard of someone falling in some day (many articles of children falling in one of those!); could you dig down and see if the soil is wet down there or the digging gets easy?

I grew up in IN and am a little familiar with some of its geological history. The state of IN has been almost completely underwater about 13 different times over many millenia. There are layers of rock, water, rock, water, etc. as a result. Our geography teacher from Jr. High had told us that sinkholes are quite common in the region because of its unique geological properties. I wouldn't be surprised if that is the situation. I would also be very wary, suspect an old well, cistern, etc. that could have collapsed. Please be very careful.