French Drain and Infiltration Trench Design for High Water Table

Professional Help Needed for Complex Foundation Drainage

A homeowner with a 1980s wood-foundation house, high water table (7 ft), and wet crawl space wants to install french drains and a 10'x40' gravel infiltration trench. An engineer recommended it, but they want to avoid engineering fees. A backhoe will be on site for egress windows.

Why This Requires a Professional

Drainage around a wood foundation with a high water table involves:

• Precise slope calculations
• Soil permeability analysis
• Proper outlet design (daylight, dry well, or sump)
• Structural protection during excavation

Mistakes can lead to foundation failure, mold, or worsened flooding.

Cost-Effective Alternative

Hire a local handyman or landscaper with drainage experience—not a full engineer. They can implement the engineer's general plan at lower cost. Since excavation equipment is already on site, this is the ideal time to do it right.

Do not attempt this as a DIY project. The risk to your home is too great.