Excess rain or other exceptional conditions may cause temporary flooding on your backyard due to oversaturation, but those conditions are typically fleeting and rare. If you consistently have issues with standing water or mud on your backyard, then you will need to create a drain to remove the excess water. One way to do so is to create a French drain, a gravel-filled trench that lets water flow away from your backyard and be absorbed by the surrounding ground.
Pump standing water from your backyard or allow it to dry naturally. If pumping the water, then take care that you don’t pump it to a place uphill since it will flow down to the low region you are pumping it from.
Dial 811 or get in touch with your local utility company and request a survey to mark any buried utility lines. This ensures that you won’t damage any unseen lines or pipes while installing drainage in your yard. Do not start digging until after the survey is complete and some other lines that are unseen are marked.
Dig a trench 8 to 12 inches deep and 5 to 6 inches wide which passes through the lower area in your backyard to an area of the yard with better drainage. Should you experience frequent flooding or large pools of standing water, then dig the trench around 24 inches deep and 12 inches wide.
Produce a grade within the trench if one is not present naturally. The grade must be adequate for water to flow through the trench; a 0.5 percent level will probably work, though a 1 percent or 2 percent level will see superior results. Place stakes at the start and end of your trench and run a string between them at the desired level. Insert or remove soil as necessary to coincide with the grade of this string and generate a smooth, gentle slope.
Fill the trench with gravel that’s 1/2 inch to 1 inch in size. Continue adding gravel until the trench is filled within 3 to 4 inches of the top. Water will flow easily through the gravel, enabling it to drain more easily through the filled trench than through the surrounding ground.
Cover the gravel in the trench with about 3 inches of coarse sand until the trench is even with bottom level. Avoid using fine sand or sandbox sand as it can become packed and can prevent water from flowing through to the gravel below. Dampen the sand with water, adding additional sand as essential to maintain a level surface.
Sow grass seed over the sand, covering it with straw or other natural material if necessary to maintain the grass seed moist and prevent it from being affected during germination. You may alternately place sod from the sand, though you must wash the dirt from the sod’s roots before doing so. If using sod, leave space to the sod layer when filling the trench with sand.
Eliminate any wax or alternative material remaining above the grass when the turf has formed appropriate roots and is growing well. When the grass is established it may be mowed like the surrounding turf while the sand and gravel under it permit water to drain out of the low area in your yard.