drainage from around a retaining wall

Discussion in 'Landscape Architecture and Design' started by jayman99, Oct 13, 2006.

  1. jayman99

    jayman99 LawnSite Member
    Messages: 13

    Hey folks,

    I have a rock retaining wall that is about 7ft tall in my backyard and I plan to install a french drain to keep the water from accumulating behind the wall (on the house side of the wall). My plan is to dig down to the bottom of the wall and install a drain pipe connected to the existing weep holes in the wall and cover it with fabric to keep the dirt out. Then I plan to cover the pipe with 1" to 2" diameter gravel all the way to the surface.

    I have clay soil and want to make sure the drain does not get clogged. Should I use sand on top of the pipe to help keep out the dirt as well?

    I have included a photo so you can see what it looks like. Any help or ideas are greatly appreciated.


  2. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    I dont think that would be to smart to dig out behind wall. What is going to support it when it is dug out? The weight of the equiptment sitting there is a bad surcharge even if it is properly built.
  3. Green-Pro

    Green-Pro LawnSite Bronze Member
    Messages: 1,420

    Would have to agree with Mikes assessment. I'd also say you would be looking at a lot of headache, and a potentially dangerous situation trying to excavate this out.
  4. stumper1620

    stumper1620 LawnSite Bronze Member
    Messages: 1,889

    I agree.
    This is not really an area I'm experienced in but, I'm gonna throw this idea out there and you other guys can have at it.

    I'm thinking since its a clay area, and it really don't look like a feasible idea to dig to the bottom, why not dig down about 2 foot and put a slotted drain pipe with pee gravel covering it, take it to the end of the wall and off the drop off, seems to me being clay your water wouldn't get down past the drain anyway.
  5. huh

    huh LawnSite Senior Member
    from Lubbock
    Messages: 251

    what is up with the far end of the wall cracking and separating away and looking like it is going to fall into the lake?
  6. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    You need to bring an experienced wall builder out to the site.

    This is not something a homeowner wants to mess with.

    That said, I think I see drainoutlets on the base of the wall as is. Are you sure the drainage is failed?
  7. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    Another option would be to concrete the area from building to wall edge and slope it away to the sides no water could get behind wall then. Or im a wall builder the other option if i was called out would be tear it down and start over.
  8. AGLA

    AGLA LawnSite Bronze Member
    Messages: 1,778

    The first thing you should consider, maybe you have already, is to do everything you can to keep water from finding the back of the wall in the first place. catching roof runoff in gutters and piping it around to the front of the house is going to keep a lot of water away. Any surface grading that you can do to direct water out to the front of the house is going to help.
  9. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,586

    I do some drain work....simply hand dig a trench about a foot deep along the top of the wall. Then drop in the flex drain pipe and fill the trench up with gravel. Then dump the water out at the end of the wall. Then if some still comes thru the weep holes do the same at the bottom. It woun't take long to dig that short distance.
  10. jayman99

    jayman99 LawnSite Member
    Messages: 13

    Wow that's a lot of posts in 24 hours. Let me answer some of the responses before I ask more questions.

    Mike - Yes, I agree that using equipment to dig out the wall might cause more harm than good. I was thinking of getting some day laborers and doing it by hand.

    Stumper raises a good question. How far does water penetrate in clay soil?

    "Huh" is very observant. That end of the wall is falling because of the weight of water behind it. I'm trying to relieve that type of pressure to keep the rest of the wall from doing the same.

    "Dirty Water" - Yes, there are drain outlets at the base of the wall about every 5 feet. but I never have seen more than minimal seepage coming from any of them.

    Ok, so here are some questions I have...

    How deep does water penetrate clay soil? I guess it depends on several factors like how fast it runs off, but does anyone have a general idea?

    Mike, I know what you are saying about putting down concrete to direct the water away from the wall. Instead of using concrete, what do you think about digging down two feet and laying down plastic to route the water to a french drain? I could use six foot wide plastic to collect the water and slope it to the french drain.



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