Results of a Successful French Drain
By Beauregard Master Gardeners
A French drain system consisting of 4 inch perforated sleeved drain pipe was installed on the east end of the Beauregard Master Garden in DeRidder, Louisiana on October 27. The depth varied from 8 inches to 20 inches as a sighted laser level for gravity drainage in a South direction. Gravel was placed below and above the drain pipe along with a tight weave landscape fabric above a portion of the gravel fill.
On November 23 an overnight flooding rain occurred. Pictures were taken at 7:45 am and then at 4:30 pm for comparison. Typically rain-water would keep this garden area flooded for several days. Within 9 hours, the area around the French drain showed minimal surface water. In other parts of the garden on the west end, water holding low areas were still flooded after the 9-hour lag. The desired effect of the drain is demonstrated in the photographs.
The project was necessary to prevent fertilizer leaching, water-logging of soils, fungal and bacterial infections of planted materials, anaerobic acidification, and volatilization of sulfur and nitrogen compounds.