When elevations slope towards foundations, water ponds or over saturates supporting soils. Swales or drains are sometimes required to move excess water away from the slab.
A French drainage system consists of a trench being dug approximately 4 feet deep. And then complied with a perforated 4″ PVC pipe, gravel and a permeable wrap to go around the pipe.
Because ground water that travels under a slab foundation can cause the foundation to go up and down repeatedly, it can cause foundation problems. The french drain can be used to collect and channel ground water to keep it from going under the home.