Long Term Flow Test Apparatus (AIM 250)

The tests for permittivity and transmissivity help in comparing one fabric to another, but gives no indication of the hydraulic behaviour of the composite soil-fabric system. Under steady state and reversing flow conditions, fabric clogging or binding causes a decrease in water flow rate and corresponding increase in hydraulic head loss through the geotextile. When the potential for fabric clogging is significant, clogging resistance of filter fabrics should be evaluated to ensure adequate long term filter performance. As the clogging is highly soil dependent, soil fabric permeability test is suggested to determine the long term flow capability of a geotextile.