retaining wall install and the ground is spongey after compaction!

Discussion in 'Hardscaping' started by Hardscaping, Sep 17, 2008.

  1. Hardscaping

    Hardscaping LawnSite Senior Member
    Posts: 359

    ok so i got a wall install it is 54 ft long and 3.5 feet high.

    so i took out the old retaining wall which was made of rail ties. once itook these out i duge the ground until it seemed solid ther was only one spot the was a bit sponey at first in the corner before compaction. once i noticed this i dug it out a bit more.

    so i fill in the area for base material of road gravel so i can compact it, once i started to compact it most areas became really spongey.

    we have had alot of rain in the last bit before the job started.

    it was si spongey that when walking on it you could see it moving under you feet.

    My assumtion is that it is still wet there and that the ground is spongey from that, now my plan is to go back tomorrow and do the wall and the base material again. take out what is in place redo it and use 50% a gravel compacted then the other %50 of the base i am going to use 3\4 clean.

    any suggestions on this situation, need them asap.
  2. bike5200

    bike5200 LawnSite Member
    from Ky
    Posts: 55

    If the ground is spongy or what I call pumping, gravel is not going to fix it. I guess you could try to dry it out. Around here they use shale to bridge it. You need to talk to a soil engineer.
  3. shovelracer

    shovelracer LawnSite Silver Member
    Posts: 2,009

    Suggestions? Take a class. There is a very small margin of moisture content in most materials that will result in proper compaction. This varies by classification. But none the less you most likely are outside the range for your application and likely are using the wrong tools.
  4. Hardscaping

    Hardscaping LawnSite Senior Member
    Posts: 359

    No need for being rude, Thanks for the input though. The moisture content is high i know this hence me saying that it has rained alot lately. I am leaving it until tomorrow to see if it hardens up. if it does then it was just the rain.

    The area is very small and compact i can only fit a jumping jack in there and have noticed that this is the wrong thing to use. I will never use one of those again.
  5. mrusk

    mrusk LawnSite Gold Member
    Posts: 3,260

    You do need to take a class. First off a wall base trench should not be tiny. It should be 2-3 feet wide. And a jumping jack is the best compactor you could use for compacted the sub base for any hardscape.
  6. Hardscaping

    Hardscaping LawnSite Senior Member
    Posts: 359

    ok so i won't use the gravel i will just use 3\4 inch to 1.5 inch crusher run stone. I am going to use a tamper on it a bit not the jumping jack, hopefully it fits.

    Basically i think what i will do, is dig it out a bit more as much as i can, resonably. Then i will fill it with the road gravel compact and then the 3\4" on the top of the road gravel for drainage. Now since this type of thing is requiring alot of extra diging like another probably 6 to 8 inches, I think that i will be ok for the block wise, but the base blocks i will just burry them a bit more.

    The question now is do i pass some of the extra cost on to the customer or do i just eat it?
  7. Hardscaping

    Hardscaping LawnSite Senior Member
    Posts: 359

    The reason why i say not to be rude is i cannot take a class right now between tonight and tomorrow. So i would be willing to take a class for this kind of thing it just won't happen before i finish this wall.

    This website is here to HELP people not tell them things that are irrelevant to helping them at the current moment.

    For example a relevant answer would be by not being rude but stating the same info.

    "Suggestions? ( now write a suggestion here ). Also would like to state that there are classes that can hel you with this type of info, so that you can know this type of thing before hand and know how to deal with it."

    The trench is 21 inches wide. but there is a deck right up to the area where the wall is going and the wall base is about 18" below the top of the deck. So you can understand why i am saying that it is tiny.
  8. mrusk

    mrusk LawnSite Gold Member
    Posts: 3,260

    Dig your trench 24" deep. Don't compact the dirt. Line the trench with fabric. Throw in 12" of 2.5" crushed stone. compact and cover the top with fabric. Then put your 6" qp base on top of that. You will be fine.
  9. Hardscaping

    Hardscaping LawnSite Senior Member
    Posts: 359

    ok when i get there i will look at it, if it is still spongey then i will dig it out and then i was thinking maybe putting 1" styro foam down ( the stuff they use on the house basements ) and then the road gravel with the fabric underneath it, 4" of gravel compacted. then i will put in 2 inches of 3\4 " crushed for drainage.

    Let me know what you think.

    Mrusk that is a good idea i will think it over and see how things work out. i will def do this if i have to dig that much out.
  10. mrusk

    mrusk LawnSite Gold Member
    Posts: 3,260

    Hardscaping I have donw thousands of feet of walls using that method.

    Don't use foam. That is the craziest thing I ever heard.

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