Heavy Metal Retention within a Porous Pavement Structure

Porous pavements with reservoir structure for infiltration of runoff from parking spaces and residential streets offer the opportunity to dispose water without using additional space in urban areas. However, pollutants in urban runoff endanger soils and groundwater, when pollutant retention in the structure is not sufficient. Porous pavement structures with four different subbase materials were tested in rigs. Additional tests were carried out in a pilot-scaled test bed. The pavements consisted of porous concrete blocks. All structures were loaded by sprinklers with synthetic runoff at pH 5, spiked with dissolved heavy metals. In most of the structures metal concentrations in effluent do not reach German limits for seepage water after simulation of 50 years. If porous pavements are planned and constructed carefully, groundwater seems not to be endangered by trace metals in the road-runoff.