Hydraulic Testing of Plastic Filter Fabrics

The hydraulic characteristics of nonwoven filter filters were investigated using a laboratory permeameter to simulate a soil/fabric subsurface drainage system. By utilizing information of discharge, pressure, permeability, and filter properties, conclusions were drawn concerning the correlation between the soil and the plastic filters. In sands with large concentrations of fine particulate, the migration of the fines was minimal, and the soil controlled the hydraulic response of the system regardless of the filter fabric used. In fine soil where the water velocity is greatly reduced, bacterial activity within the soil can cause erroneous results. Some design criteria are developed for the use of plastic filter fabrics.