Installing a French Drain for Yard Drainage

My office was built in August, 1984 and at that time there was a lot of undeveloped land adjoining my property so the water retention was not a problem. The surrounding land has now been fully developed and commercialized and there are lots of parking area and concrete and other properties drain on to my property. The result is a parking lake outside my office which can occur after a brief downpour. This is very inconvenient for patients who have to wade through the lake. After many frustrating attempts to get the problem solved, I decided to solve my problem myself by installing a French drain. A French drain is basically a trench filled with gravel and sand which allows the water to percolate down in to the sandy soil through the gravel and eliminate the lake. I began ambitiously one Sunday morning and about 10 hours later I had a French drain. This is not easy work and requires digging and in my case the trench was about 6 to 8 inches deep with a gradual slope and 110 feet long.

If you are going to do it yourself like I did, then follow these steps. You should first call the company in your city that checks for underground utilities to make sure you don't damage them or worse electrocute or injure yourself. In Mississippi, it is against the law to dig without calling first. You need to get a tape measure and measure out the length of your planned trench as this will help with estimating the supplies and also getting an idea of how much work you have in store for you. You need to figure out where the water will drain to and create a slope trench to eliminate the water that doesn't percolate down into your French drain and make sure the water isn't going to drain and divert the lake onto your neighbor's adjoining property. If you cannot eyeball the slope then use two pegs at either end of your planned and attach a string and measure the slope with a level and then use the string as your guide to assure a correct slope. This is something that isn't necessary if you have an obvious sloping property. I could easily see my slope so that was not necessary. You don't need much of a drop. In my case I dropped about 6 inches over the 75 feet. If in doubt, certainly an 8 to 12 inch drop over 100 feet will do the trick.

Using a shovel and a strong back or some younger helpers dig a trench about 6 inches wide and 6 to 8 inches deep depending on the slope necessary. In my case I was careful to lay back my sod so I could replace it after creating the French drain. After the trench is completed , get some porous landscape material and layer the trench with this material. I actually decided to lay 4 inch flexible pipe into my trench to help drain the water and it is not too expensive. This is not necessary for the drain to work.

Next, layer gravel or small rocks the entire length of the trench and fold the landscape material back over the gravel. The last part is to layer sand to about 3 or 4 inches over the landscape material covering the gravel.

I replaced my sod back over the finished French drain and it works surprisingly well and I don't have a standing lake for my patients to wade through anymore. There is extra added satisfaction to me knowing I did such a good job at solving the problem. This was hard work but after 24 years, I wonder why I didn't just go ahead and do it myself sooner. Of course you can rent a small backhoe if you don't want to do the digging but always call for a utility check!