Filter Point Linings with filtering points (drains) provide an erosion resistant, permeable concrete lining for ditches, channels, canals, streams, rivers, ponds, lakes, reservoirs, marinas, and protected port and harbor areas. Filter Point Linings have a cobbled surface and a relatively high coefficient of hydraulic friction in order to achieve lower flow velocities and to reduce wave run-up. The filter points provide for the relief of hydrostatic uplift pressure, increasing the system’s stability.
Filter Point Linings are generally used in lieu of stone rip rap or slope paving due to their lower cost and higher performance. Filter Point Linings have greater stability than conventional slope paving because of several factors – they can mitigate uplift pressure from ground water, reduce hydraulic uplift of flowing water by slowing channel velocities, and conform to soil contours during installation to reduce the potential for underscour.
Filter Point forms are woven from multifilament and textured yarns. The double-layer fabric is joined by interwoven filter points on controlled centers to form a lining with a deeply cobbled appearance. The spacing of the filter points determines the lining’s thickness and weight, while the specially designed filter points relieve hydrostatic pressure and reduce applied stress to the fabric during pumping. Filter Point Linings are available in a wide range of thicknesses.