Are you experiencing drainage problems with your lawn, garden or house foundation? A French drain may be the answer. The basic concept of a French drain is, water always flows down hill by the easiest route. A slightly sloped trench filled with gravel, and a perforated pipe will divert underground water away from the effected area. The ideal French drain leach field would be in an out-of-the-way area with sandy soil that the water can percolate harmlessly.
Determine the area where excess water is coming from. Find an area on your property where you can build your French drain field by creating a gentle slope. The size and length of your trench will depend on your property size, distance of drain and pitch needed.
Make sure drainage does not adversely affect your neighbor. Check city or county codes before digging. Call the local utility company for the "Safe Dig" phone number. They will send someone out to make sure you are not going to damage any underground cables, water or sewer lines.
Plot trench lines before digging. A gradient of 1 percent allows a drop of 1 foot for every 100 feet in length. Use tape measure to find the distance for your trench. Pound two stakes in the ground to mark the beginning and the end of the trench. Tie string tightly to the first stake and run it to the second stake tying it loosely. Use a string level to make sure you have the line level then tie it tight.
Start digging the trench and check often to make sure you are achieving the proper grade. If the trench drain is 100 feet long and the gradient is 1 percent you should have a 6-inch depth at fifty feet. The width of the trench will depend on the amount of water you are dealing with. A small trench would be 5 to 6 inches wide.
When the trench is completed line it with landscaping fabric and add a 2-inch gravel base. Insert the four- to 6-inch perforated drainpipe then overlap the fabric. Add 4 inches of gravel and several inches of sand. Replace some of the dirt you removed, rake it smooth and plant grass seed.