How long for dirt to settle?

   / How long for dirt to settle? #1  

snooks

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Virginia, IL
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YM2500
I tore down a house about 3 years ago. I used my Yanmar 2500 with loader to fill in the basement after removing brick and concrete. The house was on a hill and therefore I was able to dig a road/ramp on the lower end of the basement to make it easy to get loads of dirt into the basement. Since the house sat on a hill, I used surrounding top soil (Central Illinois black dirt) to fill the hole and to lower the elevation of the lot. Since I have done this I have notice some settling, but not a lot. I would like to build a slab foundation over this area. How long should I wait? Would it be better to dig the dirt back out and tamp in sand? Maybe go ahead and put in a basement? Please help.
 
   / How long for dirt to settle? #2  
I would expect if this is an area that can freeze, as well as get 'rained' on, then in three years it has settled all it's going to.
However, if not saturated with rain, not been frozen and thawed, and/or a high clay content, it will likely not be stable for a slab that will stay put.
One can make a floating slab that will have a lot of reinforcing in it, and use the fiber concrete, that probably will just stay together on top of any moving soil beneath.
 
   / How long for dirt to settle?
  • Thread Starter
#3  
yes it does get rain and does freeze. Most of the dirt was black top soil and not much clay. I spread it pretty thin and drove over it as well as pressing it in with the bucket. Like I mentioned, in three years I really only have one low spot where its settled and it really isn't that much. To be honest I had expected it to settle more than it has. I'll see what others might add, but like you I think a little more reinforcement should do the trick. Thanks for the input...
 
   / How long for dirt to settle? #4  
You've asked a question without an answer. Disturbed soil can take decades to regain compaction on it's own. How deep is the hole, what type of soil, how clean is it, does it have any organic material are all questions that nobody knows without digging it out and filling it properly.

What you really need to be asking is how do you build on disturbed soil that wasn't properly compacted. A floating slab is one alternative, but to do one right is fairl complicated. Piers dug down to a solid base is another method.

On the jobs I did in California, we had to reach 98% compaction to pass the inspection to build on top of fill. This takes allot of heavy equimpent designed to do this. Here in Texas nobody seems to care, Just lay your fill in layers and drive over it a bunch and your fine. Crazy, but it just goes to show how impossible to answer your question is.

Good luck,
Eddie
 
   / How long for dirt to settle? #5  
</font><font color="blue" class="small">( yes it does get rain and does freeze. Most of the dirt was black top soil and not much clay. )</font>

That's usually bad news.

Black topsoil can take forever or longer to compact.

I would dig that puppy out and fill it with red fill sand. It's pretty cheap. Fill it wider than you need just to be sure. If you have time, fill it to within 1 foot of full, wet it down until water stands on top, then finish by rounding it off to shed rain. Let it dry and settle for several months and you have a foundation that is virtually incompressible.

A little off the main topic, but in my opinion, limestone is the best foundation material for soggy soil areas. Dig 2-3' deep and several feet wider than the foundation, fill with 1" crushed limestone 1 foot at a time. Fill with ag lime and repeat. (Ag lime is just fine limestone, and will almost make concrete out of the limestone).
 
   / How long for dirt to settle?
  • Thread Starter
#6  
Wow, a lot of good input. Thank you. They say basements are low cost square footage, maybe I should bite the bullet and incorporate a basement. I hate the thought of digging it out to simply fill it again. The basement could be open on the back side and could have a garage door installed. Who couldn't use more garage area? Decisions, Decisions.........
 
   / How long for dirt to settle? #7  
In Ohio we used clay & misc material to fill in a old basement, that was mid 80's. it is still settling some each year it takes a couple truck loads to KEEP it level. that is the problem depending on the material it may not settle much for years then a good freeze and down it goes ... I wouldn't want that UNDER my home at all... just my 2 cents worth. compaction is in 6" lifts using native material and or less... this spot had some left over debris from the destruction (from fire) which was left on site and burried to get rid of it. that wood/leftovers was or is what is setteling the most for sure as it rots. in the last ten yrs I bet we have put in 3 or 4 feet of fill into the old hole. it is down about 12" in the center again after about 4 years of setting since the last fill..

Mark M
 
   / How long for dirt to settle? #8  
I had a slope that had an unknown pedigree for compaction. I had to have it dug out and put back in a foot at a time. Here is the Cat excavator with the poker it took to get it compacted at 95% (required, it came out at 98%). This is decomposed granite here in California. I dug a trench for a water line on the back hill in native soil and after I filled in the trench, it settled an uneven 2 to 3 inches all along the trench. You'd think undisturbed soil would be fairly compacted, but here it wasn't.
 

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   / How long for dirt to settle?
  • Thread Starter
#10  
That would be a great Chistmas present. Ask your wife if I can have one too....... /forums/images/graemlins/cool.gif

After all the great input, I went out and placed some stakes in the yard to see where I might want my new building. It is possible to have the footprint of the new building to be outside of the old basement. So it appears I have two safe choices 1) have a crawl space or 2) dig a basement under the new building. If I go with a crawl space and I place my footing within a foot or two of the old basement fill, does anyone see a problem with that? Footing would probably be 4 feet below ground. Just curious. Thanks
 
 
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