Aggregate over moist soil/clay

Discussion in 'Hardscaping' started by knineteen, Nov 11, 2010.

  1. knineteen

    knineteen LawnSite Member
    Posts: 2

    In the process of installing 2 inch thick concrete pavers...15x15, for a walkway. I'm using 4-6 inches of 3/4' processed gravel on top of a landscape fabric.

    It rained heavy 3 days ago and I had 2-3 inches of standing water in my excavated area. I drained the water 2 days ago and today, in certain areas, the soil is still mushy. There's no free standing water however I can clump the soil in my hand like a snowball and throw it. It's mostly dirt however there appears to be some clay mixed in.

    I plan on doing this job in 2 the soil will have 4.5 full days to dry (temps around 50f, no rain in the forecast). If it's still wet like it is now, is it advisable to continue with the project? Is there anything I can do to accelerate the drying time? Any other recommendations?
  2. WGrnd21

    WGrnd21 LawnSite Member
    from NC
    Posts: 73

    throw some lime, or kitty litter on the soil and it will absorb the water and speed up drying time. I would not proceed with the job untill the soil has dried more.
  3. knineteen

    knineteen LawnSite Member
    Posts: 2

    Is there a certain technique I want to apply using litter? Throw it on, spread it, leave it for a day and sweep it up?

    I started over excavating the wettest and squishiest areas and will use spare soil/gravel mix that I have available...but I can only do so much given the timeline.
  4. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    better just hold off and wait till May and do it right....

  5. Tim R.

    Tim R. LawnSite Member
    Posts: 87

    If it's real bad, you will need to pull out the soggy soil. Instead of using landscape fabric I would advise a good woven geotextile fabric to ensure those clay fines won't work their way up into your base gravel.
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  6. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,417

    we just built a wall in clay soil territory.

    It rained a week ago. And I'd guess that the soil still has 70% moisture from the rain. I really don't see it drying out till late spring at this point. Where as the soil on my land at home was dry 48 hrs later (0% clay content).
  7. sgallaher

    sgallaher LawnSite Senior Member
    Posts: 265

    You need to make sure that you dig out all that is necessary. You may have to use 10" OF 3/4" crush instead. A few extra dollars in stone is better than having to re-do the whole thing.
  8. JimLewis

    JimLewis LawnSite Fanatic
    Posts: 6,841

    First of all, I feel your pain. I live in Oregon. We sort of have the monopoly on rain and clay soil. We're dealing with this very problem that you explain for a good 8 months out of the year. If we waited for it to dry out completely, we'd only be able to work maybe 3 or 4 months out of the year. Fortunately, it doesn't happen every time we do a job, even in the wet season. Usually, once we excavate down, the soil that is left is still pretty hard. So we're good to go. But we still end up having to deal with the very problem you describe several times throughout each year.

    What we've learned to do is first to work in some larger aggregate gravel INTO the clay soil. So we'll bring in an inch or two of larger like 1" size gravel and lay it down on the clay. Then we start working it INTO the clay, either by hand with a tamper or with a plate compactor, if possible. Once we get the gravel pushed down into the clay, we add some more. Eventually, you get enough gravel worked into the clay below that it begins to drain and harden up. Once it hardens up, we add a layer of straight gravel on top of this clay/gravel mix. Once we get a good inch of gravel on TOP of the clay/gravel mix and it's not mushy anymore, THEN we proceed with our normal process, which is to install some of the woven geotextile fabric and then our 4" base of rock, compact, then sand, then pavers.

    Another trick is to use tarps before and during the job. If we are doing a job and we know it's going to be really rainy before we start - we will go over a week or two before and install tarps over the whole area to keep it dry. This helps a lot. And same thing DURING the job. Whenever we leave the jobsite (if rain is in the forecast) we tarp up the whole area again to KEEP it dry.

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