What Does Capillary Fringe Mean?
The capillary fringe is defined as the moisture saturated zone directly above the water table and below the boundary of saturation. The capillary zone is located in the vadose zone and its height varies depending or soil property and type. The capillary action (tension) that creates the rise is a negative hydraulic force that exceeds the force of gravity.
Trenchlesspedia Explains Capillary Fringe
In trenchless construction, determining the location of the water table is of utmost importance. Trenchless construction that takes place below the water table runs the risk of excessive water ingress.
The capillary fringe is usually the first indication that the water table is nearby. This provides contractors with a reliable indication of the depth of the water table so as to commence drainage activity. However, caution must be exercised since it is not possible to drain the capillary fringe via seepage drainage. In addition, placing the drainage only down to the capillary fringe does not lower the elevation of the water table.