[LazyPup]

Curtain drains are used to prevent water from leaching through the soii laterally.

They are often used to protect foundations or leach fields.

A trench is dug completely around the area to be protected. The depth is determined by the soil characteristics but normally 4 to 5 feet deep then a four inch diameter perforated pipe is laid in the bottom of the trench. The pipe must be laid with a minimum of 1/8 inch per foot and must be able to discharge into a drainage ditch or other area that is lower than the pipe.

The trench is then filled with pea gravel to within a few inches of finished grade, the gravel covered with a permeable membrane and the top covered with topsoil.