Installing A French Drain

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woodsy
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Installing A French Drain

Post by woodsy » Sat Feb 15, 2014 5:43 am

This spring I will be installing a French drain to eliminate a drainage problem I have at my cabin. This drain will not be next to any type of foundation. After watching several installation videos I still have a few questions that I hope you can help me with.
1-Should I use a sock to cover the perforated pipe? I have seen it with and without, those that don't use it claim that the sock can clog over time and also creates another barrier for water to flow thru. Those that do use it claim it will keep out silt and other debris. I will be using landscaping cloth on the bottom of the trench, adding gravel, then pipe, then gravel to the surface no soil on top of the gravel.
2- At the end of the pipe where the water drains to, what do you do there? In my situation where the pipe will end the water that has drained will not cause any problems. I was thinking of digging out a small area say 3'x3' and filling it with gravel for some sort of drainage pool at the end of the pipe. Or do I just leave the pipe be and not worry about the end, it is sandy soil. My main concern I guess would be when the water reaches the end of the pipe and has nowhere to go but into the soil it would start backing up into the perforated pipe and perhaps filling the pipe in with silt from that end.
Thank You for any advice you can give me.
Steve

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Shannon
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Re: Installing A French Drain

Post by Shannon » Sat Feb 15, 2014 9:09 am

#1 A sock is highly recommended, by most people. The problem like you said is that over time it may become restricted. If you have no sock dirt still more easily enters the pipe and eventually plugs it also. My feeling is the sock is better because it keeps dirt out of the pipe so even if it gets a little restricted water should still find its way into the pipe and away. The gravel around the pipe acts as pre filter so that really helps as well. Final conclusion ..... Use the sock.

#2 As you suggested I would dig at least a 3' x3' hole filled with gravel. The pipe is generally drained into a pit and pumped into the sewer system but I'm assumming that your cabin is likely not on a city sewer type system but only a holding tank so you do not want storms filling up your tank.

Great questions , thanks for coming here with them , and I hope my answers were of some help.
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keif_sanderson
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Joined: Wed Oct 01, 2014 8:52 am

Re: Installing A French Drain

Post by keif_sanderson » Wed Oct 01, 2014 9:18 am

Hi Steve, I just finished french drain install and thought I'd add a little o what Shannon has already said. I had to pull out a previous owner's handiwork because he'd butchered it. First off, I would skip the black corrugated line and go with PVC. It is easier to install (at the proper grade), flows more water easily, and lasts longer. Also, it is easier to clean out many years down the road should the sock eventually fail. This brings me to my second recommendation: add a 90 degree elbow at the top of your drain to use as a clean out. The odds are you'll never need it, but you are already there, and the next owner/generation will appreciate it. Lastly, if you don't have the grade on your property to simply let the drain open to air, make sure your ground/hole is permeable enough to take whatever you are throwing at it. Otherwise you may need to have a massive hole (for it's increased surface area available for drainage, or run a pump to move the water further way. I recommend using a plastic barrel in the dry-well. Size the barrel according to how much water you are expecting to drain (35gal, 55gal, etc.) and drill a BUNCH of small holes around the sides and bottom(small enough that your washed stone can't get in, don't drill the top). Dig your well twice the diameter of the barrel (probably a safe bet unless you live in a clay pit), and line it with landscape fabric, leaving enough fabric sticking out of the hole to fold back over and completely cover your excavation (more on that later). Add some washed stone to the bottom, add your tank to the middle and connect your drain, and then fill in the remainder of the hole (outside and over the barrel) with washed stone. Leave the barrel empty to maximize its capacity to accept water. I would stop 3-4 inches from the surface, fold your landscape fabric completely over the top to seal it up, and then put dirt/sod/mulch or whatever over the top.

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Shannon
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Re: Installing A French Drain

Post by Shannon » Wed Oct 01, 2014 4:26 pm

Sounds like good advice, I would add that I'm sure you drilled a series of holes in the PVC to accept ground water , did you also put a sock over it?
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