How to Dig a Sloped Trench French Drain

French drains are a convenient way to remove access moisture from a yard that features little to no slopes and drainage routes. A French drain consists of a pipe with holes, which are surrounded by stone or peat gravel and a filtered fabric that runs the length of the drain. French drains have a slight downgrade angle to help remove water and disperse it into an area that will not be damaged by the runoff water. The trench's downgrade measurement should be a 6-inch drop for every 50 feet.

Things You'll Need

• Shovel
• Two stakes
• String
• Measuring tape

Instructions

1. Determine the path of the French drain trench. The path should be in an area conducive to removing the most moisture or blocking water from entering an area.

2. Remove grass from around the trench area using a flat spaded shovel. Cut out 1-foot-by-3-foot grass segments and save them for use after the French drain is complete.

3. Place a wood or metal stake into the ground at the beginning and end of where the French drain will be dug. You should place the stake deep enough into the ground to allow a string to be stretched tautly from end to end.

4. Tie a string onto the stake 1 foot from the ground where the trench will begin.

5. Run the string to the opposite stake and tie it off at the correct height, which is determined by the 6-inch drop for every 50 feet of trench measurement. For example, if the string is tied off 12 inches above the ground at the beginning of the trench, stretch it 50 feet and then tie it off 6 inches above the ground at the end of the trench.

6. Dig the trench using a shovel. The depth of the trench should be between 16 inches to 3 feet deep, depending on how much moisture is in the soil that needs to be removed; the trench should be 12 inches wide.

References

• French Drain Installation Tips