Rock For French Drain

Discussion in 'Landscape Architecture and Design' started by White Gardens, Nov 26, 2008.

  1. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    I know Pea Gravel is the standard for filling a trench after laying a drain pipe, but is that the best rock to use.

    I was thinking any sort of crushed/screened gravel. I've always been told that angular rocks don't pack together so tight and allow water to flow through them better.

    Any thoughts or experiences???
     
  2. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,080

    I did a french drain of the roof of a large house. I used baseball sized rocks at the bottom of a 2 ft. deep trench along the foundation. Filled it over with 1" - 1 1/2" wash stone up to, a couple inches of the top. Layed down fabric then put 2" of wash stone on top of that.

    The best results that I ever had.
    [My experience in sandy soil, so take it for what it is worth. :) ]

    BTW, in the 'v' shaped hole - Put down fabric on the foundation side of the 'v'.
     
  3. NC Greenscaper

    NC Greenscaper LawnSite Senior Member
    Posts: 446

    I usually use 1- 1 1/2 gravel, but I line the trench with fabric, fill with gravel (and corrogated pipe) in some cases), cover the top with fabric, cover that with sand/dirt, sod/seed.
     
  4. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    Well, Here's what I'm thinking.

    26-28 inches deep, 2-3 inches gravel in the bottom, 4 inch corrugated tile pipe with silt sock, and fill the trench the rest of the way with gravel.

    Do you guys still think I need to line the trench with fabric or is the silt sock take care of that for me.

    The pipe is going to carry away water from two downspouts also. And I was also thinking about using PVC pipe with holes in it next to the house where my run is straighter, and flexible pipe where I start curving it out away from the house only so that it can be rooted out someday if there is a clog.
     
  5. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    So, after driving alone for 4 hours today, I come to a conclusion that I'm going to:

    1.) Use a solid pipe 10 feet along the house so water from a downspout won't push water towards the foundation. Then turn it along the garage and turn it into either corrigated black pipe (with slits), or PVC with holes to at least the corner of the garage.

    2.) I think I am going to line the trench with fabric to help keep silt out of the drain, and also have a sock on the tile pipe for added protection.

    3.) then I think I'm going to fill it with washed gravel and fold the fabric back over to encase the drain.

    I'll post some picks later after the wife brings the camera home.
     
  6. vaham

    vaham LawnSite Member
    Posts: 69

    The silt sock only protects the pipe. If you enclose the stone in filter fabric, it's absorptive rate and transport capacity will remain fairly high over years of use. Without the fabric, especially in clay soils, over time the fine silt will infill all the voids between the stone, and when a dry spell hits, will solidify, and effectively seal off the migration route for the runoff-meaning the water does not get through the gravel to the pipe.
     
  7. EagleLandscape

    EagleLandscape LawnSite Platinum Member
    Male, from Garland, Texas
    Posts: 4,347

    yes, line the trench with fabric. we use like 3/4" rock. remember, the smaller the rock, the more water the drainage field can hold. just make sure its washed rock, and not something like decomposed granite, or crushed limestone. fines, are bad.
     
  8. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    I've been wondering about the rock. I definitivly want at least a well screened. I was also thinking no more than an inch, but closer to 3/4 will work better.

    So do I use an an angular/crushed stone, or more of a smother pea gravel style. I've been told both ways, I like the angular as it leaves more voids between the rocks, but I'm not 100% positive.
     
  9. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    Here's a few pics of the progress.

    I first had to dig out 4.5 tons of river rock. there was probably 4-5 inches of it in that small area.

    Found the old 90 year old clay drain tile. It is 2/3 the way full of silt.

    Tree roots are no fun to to trench through but the machine did well. I only had to cut a couple of them.

    The one pic of the machine next to the garage; almost slid it into the siding, but I will say, this Vermeer really handles tight spots well and had no problems driving away from a distance of a quarter of an inch next to the siding.

    More pics will come as the trench comes along.

    Metz 3.jpg

    Metz 4.jpg

    Metz 5.jpg

    Metz 6.jpg

    Met 7.jpg

    Metz 3.jpg

    Metz 4.jpg

    Metz 5.jpg

    Metz 6.jpg

    Met 7.jpg
     
  10. White Gardens

    White Gardens LawnSite Fanatic
    Posts: 6,776

    One more pic.

    Also, the trench is no less than 26 inches deep, no more than 38 inches deep and 6 inches wide.

    A 4 inch drain tile will be placed.

    Metz 8.jpg

    Metz 8.jpg
     

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