Backfilling walls

Discussion in 'Hardscaping' started by lawnkid, Mar 31, 2007.

  1. lawnkid

    lawnkid LawnSite Senior Member
    Posts: 935

    Question for you expert retaining wall guys. What is NCMA specs for backfilling a retaining wall? There is a wall approximately 8' in height going up around my area by another contractor where it's being backfilled with 411( 2" less with screenings) or what some guys call modified 2-A and compacted. I always thought it was spec to backfill with clean 57's and compact for proper drainage. I've always been taught to use clean 57's. Can walls be backfilled with 2-A and compacted or is this guy asking for a blowout???? I'll try to snap some pics later today.
     
  2. McKeeLand

    McKeeLand LawnSite Senior Member
    Posts: 681

    it is supposed to be backfilled like you said with 3/4 clean stone. he may be back-filling the over dig in the reinforced soil area with 2a and 3/4 alone the back of the wall. it would be hard to tell if it was 3/4 12" out from the back of the wall and then 2a the rest of the way with out looking close at it.
     
  3. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929

    It is perfectly acceptable to backfill the grid zone w/ modified stone or select backfill, but your 1' drainage zone directly behind the wall must be a free draining stone (57's, 2B)

    Chris
     
  4. Mike33

    Mike33 LawnSite Bronze Member
    Posts: 1,649

    Or only 6" with a solid block accordingly to NCMA, which i think would be a real joke. 8' wall Hmm, I would have 3-4' of clean stone (57's) take a lot of pressure off of that wall. But thats how i do them every one has there theory.
    Mike
     
  5. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929


    Mike, I think you mean 6" if it's a hollow core block filled with stone. 1' for solid block. I think!

    Chris
     
  6. Mike33

    Mike33 LawnSite Bronze Member
    Posts: 1,649

    Your exactly right i had it ass backwards. I spent 9 hours of honey do today worse than working.
    Mike
     

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