Basic Flood & Drain System
- Drainage problems are often caused by lower layers of soil that are so dense and tightly packed that they don't let much water pass. Non-porous rocks in that lower layer can also cause drainage problems. A simple solution is to dig deeply into your garden soil, about 18 inches or more. As you dig, constantly turn the soil over. Fill in holes with organic matter or coarse sand to make the soil a bit more drain friendly. You can cover the whole area of your garden this way. Late fall is the best time to turn the soil, since winter's snow and ice will do much of your work for you in breaking up soil clods.
- Double digging is a method to increase drainage in the garden soil. The technique is an old one, and also requires you to dig about 20 inches into the ground. Dig a deep trench, about a foot across, and roughly the length of your garden bed. By digging far deeper than is normal for a home gardener you'll break up the second layer of dirt. Build a second trench next to the first one, using the dirt from the first trench to fill in the second. This process mixes and tears up soil that, in general, is too dense to drain well.
- If you're still struggling with drainage problems, more “artificial” methods might be necessary. The big issue is figuring out how your lawn slopes. Most of the time it's obvious, and any trench-digging should follow the slope. The trenches should be dug along the easiest route to the lowest part of the yard. The trenches may be able to empty into the public sewer system — check with your locality to be certain -- or into a buried tank at the lowest part of the yard. Much of that “runoff” soil is rich in nutrients and should be recycled.
- Trenches should follow simple, straight lines and empty into the lowest part of the lawn. The trenches are usually about 10 inches deep, and the floor is lined with gravel. A pipe with a diameter of at least 4 inches should be placed within it, partially filled back in with gravel, and the rest with soil.