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Does the quality of fill dirt matter?

For example, in my application, I need to fill an area where I'm planning to have a gravel patio. I picked up a yard of dirt from a local supply place and, upon coming come, I discovered that contained a few broken cinder blocks and is full of sod, and generally looks to me more like soil that dirt. I expect dirt to look more like clay than soil.

In any case, will this potentially cause problems if I use it to try to raise the level for the patio?

Dirt

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  • Does the title of this question? Did everone think this was a confusing? Sep 26 '20 at 1:31
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If you were pouring a slab over this -- and required decades of stability -- you might need to worry about your fill. Organic matter and other debris that will break down over time is appropriate for topsoil but not for fill.

Your project is going to be less sensitive to settling. You should compact your fill well as you place it. It looks like you have way less than a cubic yard in your photo, so you can easily do it with a hand tool, like a tamping bar or a lawn roller (see equipment rental yards for the roller.) Make more than one pass of fill-compact-more-fill in the deepest area. A few inches at once should compact well with a small lawn roller and won't take all day!

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    The organic matter thing is key. Many non-organic materials are just fine, but if it's going to decompose and compress you'll have problems.
    – isherwood
    Sep 25 '20 at 18:16
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    Absolutely. But since Wynne's project is a gravel patio, any amount of settling can be easily corrected by raking and if necessary, adding a little more gravel, over the years. Dirty fill won't be a problem in this circumstance. Sep 25 '20 at 18:26
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The cinderblock chunks are not a big deal, they just speak to the source of your "dirt" "fill", "not particularly 'clean' fill" or whatever you want to call it.

But sod will break down (into "loam" - nice garden soil) and will shrink as it does. At minimum you should separate out all the sod you can identify and use it for that purpose, if you have a garden. It is NOT good "fill."

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The type of material you use for the base of a patio or slab maters.

Can you fill voids or bring up to grade (minus gravel depth) and compact with dirt/soil. Yes, with some kinds of dirt/soil, if you are compacting it properly BUT you still need the correct substrate on top of that for the patio.

Typically that is "gravel" that compacts well, I.E. D1 or crushed stone, something with sharp angled edge surfaces that lock together when compacted.

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Are you sure you want to be using soil/dirt of any kind for this purpose? It's very difficult to compact it well enough that you don't get settling down the road.

I prefer pea gravel or compacted crushed stone to provide a stable base for your patio. Sand can also be used but it can wash out if the site is not well graded.

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  • I have to raise the level by 18". You can't be suggesting using gravel for that?
    – Wynne
    Sep 25 '20 at 17:52
  • Of course I am! I can't imagine using dirt where you plan on having something build on top of it. Dirt takes years to settle and it will mess up your patio. It just cannot be uniformly compacted without going to extremes. Have you ever seen a highway construction crew with a truck dumping tons of lime in front of a fleet of compactor/rollers? They are trying to compact DIRT.
    – jwh20
    Sep 25 '20 at 18:07
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    @Wynne The 18" info would be pertinent info to include in the question. There are many types of "fill" you can use that compact well. You still need the proper substrate on top of that.
    – Alaska Man
    Sep 25 '20 at 18:13
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If, as you say, you only need to raise the level by 18", the thing to do is to separate out as much of the sod and "topsoil" as you can, then fill the area in 4 or 5 "lifts", compacting after each using a hand compactor (unless you want to rent a power compactor). Put the broken cinder blocks towards the bottom.

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