A French drain is a popular way to manage excess water in yards, and it has been used for over 150 years. It is a trench filled with gravel and a perforated pipe surrounded by landscape fabric to prevent soil, roots, and other debris from clogging the pipe. French drains require a lot of precision during installation but the benefits of having them cannot be overemphasized. For instance, it prevents soil erosion, keeps wetlands, and basements dry, and prevents foundation damage.
Step 1: Planning
Before starting the installation of a French drain, you need to plan. Planning involves deciding on where to install the drain and the size of the trench. You need to consider the area where the water originates, and the landscape's current slope and drainage system. You will also need to check if there are any buried pipes, utilities, or septic systems in the area. Planning of the installation is crucial as it eliminates the possibility of making mistakes during the installation process.
Step 2: Excavation
After planning, the next step is excavation. You need to dig a trench that should be at least 8-12 inches in width and 18-24 inches deep. The size of the trench will depend on the volume of water that needs to be drained, so it's necessary to decide on it with precision. Besides, the trench should slope at an angle of 1 inch for every 8 feet to facilitate the movement of water. To keep the trench straight, you can use stakes and string lines.
Step 3: Adding Gravel
Once you've dug the trench, you need to add gravel to the bottom. The gravel used should be clean, angular, and of the right size, which ranges from 0.5 inches to 0.75 inches. It's essential to have the right size of gravel because smaller ones are likely to fill up with fine particles from the soil and lead to clogging. You should lay about 2-3 inches of gravel at the bottom of the trench. Afterward, you will need to compact the gravel using a tamper tool, which is a robust, flat material used to flatten loose soil.
Step 4: Adding Perforated Pipe
After compacting the gravel, you will need to lay the perforated pipe on top of it. The pipe should have holes on its sides, and it should be positioned with its perforations facing down. You should align the pipe to follow the slope of the trench, and it should be connected to a drainage outlet or a collection box at the end of the drain line. Once you have installed the pipe, it should sit at the same level as the gravel at the bottom of the trench.
Step 5: Adding More Gravel
Once you have installed the pipe, you need to add more gravel on top of it to cover it fully. You should use only clean gravel to avoid clogging the perforations on the pipe. The gravel should cover the pipe entirely, and you should compact it using a tamper tool.
Step 6: Landscape Fabric
After adding the gravel to cover the entire trench, you will need to place a landscape fabric on top of the gravel. The landscape fabric helps to keep soil, dirt, and debris from getting into the gravel and clogging the pipe. It should be at least six inches larger than the trench on all sides, and it should be folded over the gravel and perforated pipe. You should then stake down the ends of the landscape fabric using landscape pins to keep it in place.
Step 7: Finishing Up
The final step of a French drain installation involves backfilling the trench with soil. You can use the soil you removed during excavation to fill the trench. It's crucial to compact the soil carefully to prevent any sinkholes from forming. Also, the final layer of soil should slope away from the trench to facilitate drainage.
Conclusion
In conclusion, the installation of a French drain might sound like a daunting task, but it's not. It's a simple process that, when done correctly, can help solve drainage problems. Planning, trench excavation, adding gravel, installing the perforated pipe, and adding more gravel, as well as landscape fabric, are crucial steps in the installation process. The final step of backfilling the trench should be done with precision. A well-installed French drain can last for several years without needing repair.
