Solving a Soggy Backyard: French Drain System for Double-Sloping Yards with Underground Springs

Question: My backyard is a tall slope that runs both right-to-left and back-to-front, and we're not at the highest point of either slope. An underground spring beneath several neighborhood streets keeps my yard—especially the back—a sopping, muddy mess almost constantly. Even the top of the slope stays muddy. Is there any way to dry it out, even a little?

Answer: Install a Grid of French Drains

This is a labor-intensive but straightforward fix. Dig a system of trenches 12 inches deep and 12 inches wide, running parallel to the slope contours. Space them about 5–10 feet on center. Connect these lateral drain lines at the ends or down the center to a main trench that leads around the house to a lower area of the yard or a storm drain.

Lay 4-inch perforated pipe in the trenches, connect the pipes to the main drain line, and cover the perforated pipe with gravel. Lay filter fabric over the gravel (cut into 12-inch strips from wider rolls), then backfill with soil. Tamp lightly—don't over-compact. Ensure all lines maintain a minimum 2–3% slope for drainage.

Important: Don't create a drainage problem for neighbors by concentrating discharge at a property line. If possible, tie the drain line into a storm drain, swale, ditch, or other conveyance that won't harm others.

Materials cost should stay under $500; professional installation typically runs $1,000–$1,500. Most supplies are available at local home stores. For fittings and specifications, see ndspro.com.

Best of luck!