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How to Design a French Drain

When designing a french drain system, you want to start with the low points or wherever you get standing water. Other spots to start with are areas that are difficult to mow, this is where designing your french drain begins.

 

From there you will need to take your french drain to a storm drain, a ditch or a water feature. You will need to add slope to your trenches, but this is the starting point. If you try to fill in these areas you will just move the water somewhere else, once the water has been contained to an area, it’s perfect.

 

Here you can see that the grass is receding, most likely because of root rot. We ran a french drain here and now the grass will be able to grow. Underneath the filter fabric is a trench that is 14 inches by 14 inches and filled with coarse, washed rock and a pipe at the bottom. We were able to put the sod back in a few places.

 

Sometimes french drain designs require some extreme measures. We had to cut the homeowner’s driveway 24 inches. It is filled with stone right now, we will take some out when we pour concrete. We have plywood over the stone so the homeowner can continue to use their driveway until we finish.