The Performance of Block Paving With and without Geotextile in the Sub-base

Sustainable urban drainage systems are increasingly used to improve surface water quality and prevent contamination of groundwater. Permeable paving, such as the Priora block development by Marshalls Plc are commonplace in car parks, driveways and minor roads where one of their functions is to improve the quality of urban runoff. However, little is known about the water quality benefits of incorporating an upper geotextile within the paving structure. This paper reports on a pilot test programme to determine whether or not an upper geotextile layer within a permeable paving system provides water quality and hydraulic benefits. A field experiment was set up in which ten test panels of paving were constructed, each 1m x 1m x 0.5m deep. Three different categories of pollutant were applied; a suite of five heavy metals; motor oil; and street dust. The test programme comprised the equivalent application of ten years simulation of oil and metal application, carried out in 3 simulation periods. The paper presents the results from all of the tests.