A Laboratory Examination of Pollutants Leached from Four Different Pavements by Acid Rain
Part of a series of studies on the effects of pervious and impervious pavement on urban runoff, this chapter describes a laboratory investigation of pavement leachate. Previous literature is reviewed and the leaching processes described. To determine the effect of free-draining porous pavement as an alternative to conventional impervious surfaces, independent of traffic and land-use, four types of pavements were installed in the engineering laboratory at the University of Guelph. They were: asphalt, interlocking concrete blocks, and two versions of an infiltrating concrete paving stone. Real (acid) rainwater was collected and used in the laboratory. Runoff volume, pollutant load, and the quantity and quality of pollutants in water percolating through these pavements under different simulated rainfall durations and intensities, were studied.
Results are compared to data collected from four similar test pavements in the university's parking lot. In this present study, the only contaminants of interest were phenols, pH, zinc, iron and oils and grease, as most contaminants originated in the rainwater. It was found that pH of rain is a significant factor, with asphalt having the least buffering, and that infiltrating pavers reduced both runoff and contaminants most, while asphalt produced most of both.
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