Introduction: Installing a French Drain
If you live in a part of the world that receives a fair bit of rain, then you are probably pretty mindful of water and how it effects your property.
I live in the beautiful state of Maryland. My home is built on clay soils. And when it rains you can bet that not all of that water quickly percolates through and into the earth.
The purpose of this "how to" is to serve as a visual reference for constructing a hidden drainage ditch in your yard if you have limited standing water issues on your property.
A common term for this kind of approach is a "French Drain"
Oh disclaimer time: Before you dig ANYWHERE, make sure you contact your local utilities people. It can't be stressed enough that the danger of damaging a line in your yard is a real possibility whenever you dig (It also becomes your responsibility if you knock out your neighborhoods power, so call first then dig.) Also, do not do this procedure very close to your foundation. Check with a landscaping company if you don't want to get your hands dirty. A little bit of research and you can feel pretty confident to do this one on your own.
Alright? Let's go!
Step 1: Materials and Methods
A muddy poorly drained yard.
A cast iron constitution if you're digging this by hand.
A long length of string/rope
A line level
A couple of round point shovels
Iron tooth rake
Stones of various sizes, depending on your project you will need quite a lot of pea gravel, stones, rocks, etc. Usually come in 0.5 cu/ft bags. You can acquire a lot of stone from your local garden center. Just do your math. Length x width x Depth of your trench will be your total volume. Buy more rock than that and you'll be good to go.
Step 2: Dig, Lay Cloth, Fill Stones.
Step 1 Acquire a helper. No minion this time. You need someone with whom you may confer. You'll be determining start and end points, depths, and even a slope on this job.
I took the side of the yard to right of the tree (see image 1) as the start of the drain. From there I dug an approximate 1--2% slope across the face of my patio, around the corner and to the edge of the fence. (This by no means got me to the street! So far! I could have, but I decided to drop a small stone well under my stepping stones. You basically dig 2-3 feet down and fill that hole with stones. This will allow the water to percolate down through the soil at this point very quickly and serves as the outlet to the drain.)
Use your lines, line level, and helper to establish your drain's direction and slope. Remember, however many feet your trench is going, is how much deeper the end of your trench will be.
Take a step back and do the math. Be sure that you're not going to be 4 feet underground. If that is unavoidable you may need to do a more extensive project than this guide provides. (Check this one out)
The trench should be about 6 inches in width and sloping to 2 ft in depth (depending on your distance, remember we're doing 1-2% slope, so for every 10 feet you'll drop ~2.5 inches. (Go here if you want more info)
Once it is dug, Get your water out and your bucket or hose. Test your drain. Ensure that the water is flowing in the right direction and at the appropriate speed. open up any stuck areas. Clear the trench of excess sticks and roots (there will be LOTS). Once it's running the way you like, you're ready for cloth and stones.
Landscaping cloth should be cut into small manageable lengths and widths. It should be much wider than your trench because you'll need to fold it over to cover the stones with them later. You need to remember that the cloths should be overlapped in such a way that the running water will not run under the cloths.
Essential: Lap your cloths so that they look like house shingles in the direction of water flow, think of how a fish scales look.
If the water direction is ----------------->
At this point you could also include a small 2-3 inch PVC pipe with holes drilled into it along its' length. The stones provide the channel and the support for the drain, but the inclusion of a pipe here will improve the efficiency of your drain quite a lot. I did not use a drain pipe, it was more than I needed for this job. See the previously linked "how tos" if you'd like more information.
Once you've laid out all your cloths, start filling with stones. Put the big ones in first and then cover the bigger ones with the pea gravel. Take your time. Make sure you've got even coverage.
Be nice to your helper on this one. Rocks are heavy.
Step 3: Cover, Soil, Seed.
Now, you've gotten your stones down to the end. You've filled in your small stone well. You're ready to cover the stones with the remainder of your landscaping cloth and can put the topsoil down.
Topsoil? How will the water get to our drain? Because topsoil will allow the water to percolate down to your drain much better than the previous soil that was there. Also, by putting down topsoil, we can plant grass. Plants are excellent at keeping the soil aggregates from agglomerating. (Alternatively, if you want to go hog wild here, you can put in a gravel walk way which will be an added boon to your drain and will hide all this work. If that's your plan, stay tuned, I will be posting of of those really soon.) If not, continue:
Cover your drain with topsoil and seed the heck out of it.
Water your new grass every day or so, depending on the weather. Once the grass starts coming in, your drain will perform even better. Check my before and after pictures. It's a fun project and it requires a bit of strength and thought.
Thanks for checking it out. Good luck on your project !