A structure for draining water
that has a high water table
, or slow percolation
, or heavy runoff
, or some combination.
For normal garden or backyard use, a narrow trench is dug approximately along the fall line of the land, or from wherever standing water collects. The trench should be deep enough that water will percolate into it naturally, ie. down to and just below the water table. The bottom of the trench should obviously be graded so it flows away from the problem area, but don't fret about a perfect grade.
Next, pea gravel is added to a depth of a couple of inches. Here's where you do your grading: run your hand along the middle of the gravel in the direction of flow, spreading gravel downstream and to the sides until the middle of the channel has water.
Take slotted, corrugated four-inch plastic pipe and wrap it with lawn wrap, a type of perforated sheeting that allows water through but not weeds or dirt. Or don't; but unwrapped pipe will clog sooner. Place the pipe in the trench, pressed into the gravel and evenly spaced on both sides.
Now fill the sides of the trench around and over the pipe with more gravel, leaving enough room to cover with dirt. Gravel to the sides and top is more important than gravel under the pipe. If you've been careful you can replace the sod you removed cutting the trench.
You now have an underground channel that drains a wide area efficiently and will not soon silt up. In the clay-ey Virginia soils around where I live, it works like a charm.
Could there be a more mundane node?
Nevertheless, there is quiet satisfaction in improving the place you live, unobtrusively and for the long run.