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LANDSCAPING | GARDENING | PROBLEM SOLVING

Improving drainage problems in your landscape

If the properties next to your is higher than yours, you may have experienced excessive water on your property. Your neighbor’s property may be running down the slope and spilling onto your property. You need better yard drainage.

One option is to install a French drain. When some people speak of a “French drain,” they refer to a trench in which a drain pipe is laid. However, the traditional French drain is a drain with no pipe. The water collects in a gravel or stone-filled channel that starts from the surface of just below it. The advantage of a French drain is that is easy to construct and with the use of modern ground fabrics very efficient.

This gravel filled trench moves down through the property to a location where the water can then percolate into the soil away from foundations or large trees.

Here's How:

  1. Determine where on your property at the bottom of the slope the excess water could be re-routed. Determining such a location may end up being a matter of choosing the lesser of two evils. If water is currently spilling out at your house foundation and excessive moisture threatens to damage it, obviously almost any other spot would be preferable. The ideal French drain leach field would be an out-of-the-way area with sandy soil, through which the water could percolate harmlessly.

  2. Make sure that your drainage project does not negatively impact anyone else’s property. Check with utility companies about buried cables or gas lines BEFORE BEGINNING TO DIG.

  3. Locate an area along the slope on your side of the boundary where excavation would be easiest for your French drain (i.e., free of obstructions). Grading should be plotted out before you begin digging. You need to create a slope to carry the water down to its destination. Aim for at least a 1% grade (i.e., a drop of 1’ per 100’) for French drains. This drop in grade will get the water to go where you want.

  4. Dig a horizontal trench across the length of the slope. This is the most labor-intensive part of installing French drains. One end of the trench will head in the direction of the spot where you’ve determined the water will be re-routed (if it doesn’t quite reach that spot, you’ll have to dig a connecting ditch down to it). Trench size will depend on the magnitude of your moisture problem— and on how strong your back is! Small trenches are often dug to a width of 5”— 6” and a depth of 8”— 12”.

  5. Before applying gravel, line the trench with a landscape fabric to keep dirt out of the gravel and also allows water to pass through it back into the ground as the water moves through the gravel— one of the underlying principles that make French drains work. Shovel a coarse gravel onto the landscape fabric. Wrap the ends of the landscape fabric over the top of the gravel layer.

  6. You now essentially have a tube of landscape fabric filled with gravel. To hide it for aesthetic purposes, shovel a layer of coarse sand over it and lay sod on top. Your French drain is complete!

Construction tips:

  • Hire a surveyor if you don't think you can get the grading right for your French drain (Step 3 above).

  • A carpenter's level can be useful for approximating the grade (Step 3 above).

  • If you're not inclined to dig a French drain trench by hand, you could hire a backhoe operator. But that will jack up the cost for the French drain— not only for the digging, but for the extra gravel you'll need (since a backhoe can't dig as small a trench as can a person wielding a shovel). Another alternative is to rent a trencher. These machines cut very thin trenches.