Posted: 7/6/2017 5:32:34 AM EDT
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I am putting in a French drain to dry out a notoriously soggy spot in the back yard. The drain will empty into the lake behind my house. I will be using the traditional perforated pipe and gravel in the areas where it's always wet, about 50ft, but I'm not sure what to do with the other 50 ft that is never wet that will lead to the lake.
My questions are does the "discharge" pipe that will be running the final 50 ft to the lake need to be solid or perforated? Do I need to fill the entire length of the pipe with gravel, or just the area with the drainage problem. IIRC the drain we paid to have put in in our old house only had gravel in the wet spot and not under the long "discharge" pipe. I hope that makes sense. Thanks for the help |
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Quoted:
I am putting in a French drain to dry out a notoriously soggy spot in the back yard. The drain will empty into the lake behind my house. I will be using the traditional perforated pipe and gravel in the areas where it's always wet, about 50ft, but I'm not sure what to do with the other 50 ft that is never wet that will lead to the lake. My questions are does the "discharge" pipe that will be running the final 50 ft to the lake need to be solid or perforated? Do I need to fill the entire length of the pipe with gravel, or just the area with the drainage problem. IIRC the drain we paid to have put in in our old house only had gravel in the wet spot and not under the long "discharge" pipe. I hope that makes sense. Thanks for the help Do your self a favor and spend the extra money and use sch40 PVC it wont collapse and can be snaked out if it ever becomes clogged. I have lost count of how many black corrugated French drains I have had to replace because the pipe collapsed |
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Quoted:
Do your self a favor and spend the extra money and use sch40 PVC it wont collapse and can be snaked out if it ever becomes clogged. I have lost count of how many black corrugated French drains I have had to replace because the pipe collapsed Quoted:
Quoted:
I am putting in a French drain to dry out a notoriously soggy spot in the back yard. The drain will empty into the lake behind my house. I will be using the traditional perforated pipe and gravel in the areas where it's always wet, about 50ft, but I'm not sure what to do with the other 50 ft that is never wet that will lead to the lake. My questions are does the "discharge" pipe that will be running the final 50 ft to the lake need to be solid or perforated? Do I need to fill the entire length of the pipe with gravel, or just the area with the drainage problem. IIRC the drain we paid to have put in in our old house only had gravel in the wet spot and not under the long "discharge" pipe. I hope that makes sense. Thanks for the help Do your self a favor and spend the extra money and use sch40 PVC it wont collapse and can be snaked out if it ever becomes clogged. I have lost count of how many black corrugated French drains I have had to replace because the pipe collapsed You'll need perforated PVC pipe, solid PVC pipe, PVC couplers (if the pipe isn't bell end), PVC cement, landscape fabric, drain sock, 3/4" washed gravel, a couple Y-fittings (for a clean-out), a couple clean-out fittings, and either a pop-up emitter or screen for the end of the run. For the wet spot, dig your trench, line with landscape fabric, add ~3" of gravel to bottom, lay perforated PVC covered with drain sock, cover with ~3" of gravel, fold landscape fabric over gravel and add another couple inches of gravel, cover with dirt and sod. For the discharge run, just lay the solid pipe. I suggest a clean-out at the beginning of the run, and every 50' thereafter. For the first clean-out, use a Y-fitting and cap the straight entrance to the Y-fitting and just use the Y-entrance and the output. |
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I know this my be a little late, but you really should create a cutoff wall at the junction of the perf/non-perf pipe. This will force the collected water into the solid pipe.
Cutoff walls are typically constructed by excavating a slot about 12" in diameter at the junction. The slot need not be thicker/wider than 6 inches. Then create a small "wall" within the slot by forming up and pouring enough concrete to fill the slot and fully enclose the junction. The gravel wrapped pipe package will come up against the cutoff wall and be forced into the solid pipe. This will ensure the best performance of the system. I've built dozens of these and it works very well. |
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Quoted:
I am putting in a French drain to dry out a notoriously soggy spot in the back yard. The drain will empty into the lake behind my house. I will be using the traditional perforated pipe and gravel in the areas where it's always wet, about 50ft, but I'm not sure what to do with the other 50 ft that is never wet that will lead to the lake. My questions are does the "discharge" pipe that will be running the final 50 ft to the lake need to be solid or perforated? Do I need to fill the entire length of the pipe with gravel, or just the area with the drainage problem. IIRC the drain we paid to have put in in our old house only had gravel in the wet spot and not under the long "discharge" pipe. I hope that makes sense. Thanks for the help Just to be clear, you mean fill the entire length of the ditch with gravel, not the pipe itself, correct? |
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Quoted:
Do I need gravel under the non perforated pipe? If your soil is silty, I would put down a layer landscape cloth around the stone. What I have done is cut large strips and lay them in the trench, with some overlap. Put in the stone, and wrap the cloth over the stone, then cover with topsoil. If you have a lot of water infiltration, the fines will load up the stone and block the drainage. Just make sure your stone or gravel is washed. You don't want any fines. |
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Do not use Sched 40 pvc pipe. Sched 40 is rigid and once its in the ground for good it is subject to all of the pressure and movement in the ground over the years. This is why you see 1" sprinkler lines get cracked over time, but it is used for sprinklers because the water is under pressure. Draining water is not under pressure. You need to be using sewer & drain pvc, which is also found at Lowes type stores, and is also perforated. 3"-4" S&D pipe will flex, you can feel it yourself. It will be better for a french drain. Make absolutely certain you do this right the first time so you dont have to dig it up.
Make sure when you're laying the pipe  that you include some sort of entry point near the beginning or periodically along the drain route so that if you have to get an auger down there you can very easily. Laying down the pipe should go like this:
1. Once your drain route is dug, lay down geotextile fabric in the trench. You can lay multiple layers of this if you want, it won't hurt anything. In fact you probably should anyway due to the weight of the rock. 2. Lay down your river rock or gravel or whatever rock you are using and level it out to get the proper declination for water drainage. 3. Fit drain sock around perforated drain pipe. Lay that pipe on top of the leveled rock. *helpful tip* When mating each section of S&D pipe, make sure you use pvc primer and cement. At Lowes they carry regular cement and a heavy duty version. Use the heavy duty one. 4. Once everything is set and you've verified proper leveling, take the fabric wrap the entire sections where there is rock/perforated pipe. Keep it wrapped by using some sort of heavy duty tape (not duct tape). 5. Bury pipe. Source: had to run about 100 linear feet of french drain myself. Dont want to do that again. |