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Retaining wall questions

Discussion in 'Hardscaping' started by frdm12, Apr 1, 2011.

  1. frdm12

    frdm12 LawnSite Member
    Messages: 28

    I'm going to be building a allan block retaining wall in a backyard of a new construction home. Back entire lot was brought up 8-10 feet with fill about a year and a half ago. It's pretty compacted now after sitting that long, but obviously its not as compact as virgin ground and could still settle more. Any thoughts on something I should add to the base to strengthen it?
  2. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Messages: 6,601

    1. Where are you?

    2. Why "Allan Block"?

    3. 8-10 feet of fill is not "pretty compacted", as "about a year and a half" is NOT "THAT LONG". It'll take about 6-7 yrs for that to settle.

  3. frdm12

    frdm12 LawnSite Member
    Messages: 28

    yes that is my point exactly which is why I'm asking for ideas on what I should set the wall on to counter the issue.

    I'm in New Hampshire.
  4. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Messages: 6,601

    Ultimately the engineer that you have hired to engineer the wall will dictate the process and specs.

    You're going to have to go down to virgin soil. There is no magic answer :) Can't "add" anything to the base, because it's NOT the base that settles. Settlement occurs from the bottom up.

    Can't put a wall on loose fill unless it's been compacted and the soil is structural fill and has been approved. And monitored and tested by a geo-tech during the backfill process.

    This will have to be a million dollar home for a builder to do it right. Otherwise the builer will find some hack to half a$$ it, and it WILL fail.

    Even when my house was built, the builder had to dig down about 5-feet to virgin soil just to install (2) 4x4 posts for the kitchen steps...

    Last edited: Apr 1, 2011
  5. zedosix

    zedosix LawnSite Silver Member
    Messages: 2,665

    Something you forgot to add frdm, how high is this wall going to be, if its a garden wall of one or two feet, you should be ok, but if its 10' tall then "as dvs said"
  6. meets1

    meets1 LawnSite Gold Member
    Messages: 3,855

    To much fill. I have a project going right now. New house two years old. Filled up the corners and rapped around house to level out. Now were building walls. I dug all the dirt out with the skid, one wall is 8ft - levels nicely into the front yard. Geo - thru the layers of block and backfilled that today. Start next one monday.

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