Model based prognosis of contaminant leaching for reuse of demolition waste in construction projects

In this study, groundwater contamination from recycled demolition waste in road constructions is assessed using predictions of leachate concentrations. Numerical transport simulations are performed for three scenarios ( a parking lot, a noise protection barrier, and road), and using a number of characteristic subsoils of Germany, to estimate the breakthrough of different contaminant classes at the groundwater table. conservative tracer breakthrough times (BTT) primarily depend on subsoil hydraulic properties, for organic pollutants K-OC and subsoil OC are the controlling parameters. Significant concentration reductions from dispersion only occur when source concentrations decrease prior to contaminant breakthrough. if source concentrations remain high for long periods relative to peak BTT, concentration breakthrough is undamped. accounting for biodegradation reduces breakthrough concentrations significantly. For the "noise protection barrier" and "road" scenarios, capillary barrier effects cause the seepage water to partially bypass the recycling material. accounting for this bypass flow and spatial averaging across the constructions reduces concentrations by about 30-40 %.