Environmental assessment of a permeable pavement system used to harvest stormwater for non-potable water uses in a building.

The objective of this work is to present and to apply a method to environmentally evaluate a permeable pavement system used to harvest stormwater for non-potable water uses in a building. Two pavement systems were compared through life cycle assessment (LCA). The first system consists of a permeable pavement; in this case, the stormwater filtered by the pavement is used for non-potable water purposes in a building. The second system consists of a flexible pavement (impermeable), with no stormwater harvesting, and with conventional water supply in the building. The method was applied in a case study in a public building in southern Brazil. Water consumption surveys were made and the potential for potable water and electricity savings in the building were estimated. In the inventory, input and output data related to each stage of the life cycle of the systems were gathered and quantified. In the impact assessment, it was found that, for both pavement systems, the most significant damages were related to the implementation and end-of-life stages. The permeable pavement system presented a lower potential for environmental impacts in most midpoint categories evaluated, and also lower overall potential impact in the endpoint approach. The results also showed that the categories with the greatest environmental impact for both systems were fine particulate matter formation and global warming. The method proposed can be used as a basis for guiding planning and decision-making to improve water infrastructure management through stormwater harvesting in urban centres.