There are many benefits to installing French drains beneath the soil on your property. They efficiently remove rainwater, snow melt, and groundwater from the property or out into the middle of the yard and are highly effective at protecting foundations, sidewalks, and landscaping from damage.
Properly planning and excavating the trench for a French drain is critical. While the depth must be sufficient to collect the maximum amount of rainwater possible, the slope is even more important. If the trench is not sloped properly, then it will struggle to efficiently drain the water that seeps into it. For residential properties, this typically requires a 1-2% slope for every 100 feet of length. The excavation process is expedient and requires little preparation because of the trench's shallow depth and simplicity of design.
French drains consist of a pipe, typically between 4"- 6" in diameter, that is placed on top of a bed of gravel within a shallow trench that is frequently about 18" deep. The bottom of the pipe is perforated to allow moisture to seep into the ground. Once the pipe is in place, it is sometimes covered with a layer of gravel. The gravel can either be covered with larger rocks or with topsoil and sod. In fact, much of the design of a French drain depends largely upon the layout of the property and the aesthetic the property owner wants to create.
French drains are very efficient at diverting large quantities of water. The water can be diverted into ponds, irrigation tanks, rainwater collection barrels, or directly into the storm drain. In most cases, a 4" pipe will be more than sufficient to drain water and prevent the landscape from turning into a swampy mess. When properly excavated and installed, a French drain provides a reliable and efficient method of removing water from a landscape. The simplicity of their design means they are inexpensive to install and easy to maintain as the years pass by.