Horizontal drains are among the most common methods for subsurface drainage of landslide slopes. The horizontal boreholes are typically drilled using a temporary casing at a shallow angle (typically 2-3 degrees) up to depths of 1,000 feet in length. Perforated PVC casing is installed the full length of the borehole and a permanent steel casing can be installed at the exit of the drain. The drain is then sealed at the surface and can be hooked up to a drainage system to transport water way from the slope.
For more information on CJA’s expertise and services for horizontal drains please contact our nearest office location.