Aspects & Impacts of Porous Pavements Essay

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Short Memo: Aspects & Impacts of Porous Pavements The purpose of this short memo is to discuss aspects of use, applicability, and environmental impacts of porous pavements as gleaned from practical findings and pertinent examples. A porous pavement is one with high enough porosity and permeability to allow rain and snowmelt to pass through it, thereby reducing the runoff from a site and surrounding areas. In intensely built up areas, pavements account for more than half of all the land, and for about two-thirds of total built cover (Ferguson, 2005, 2-3). Parking lots, in particular, account for the majority of paved areas. Pervious paving materials have the capability of providing a dual purpose in parking and other areas with low to…show more content…
1999). This base serves as a reservoir for stormwater runoff where water is allowed to infiltrate to underlying permeable soils or is redirected through an overflow drain system. Filter fabric is placed beneath the aggregate subgrade to prevent fine particles from moving into the soil bed. Essentially, “porous pavement infiltrates and treats rainwater where it falls” (Ferguson, 2005, 10). The pore space and aggregate base act as rainwater retention, reducing runoff during storm events. Further, particles and pollutants are removed from the water flow through the filtration process, with the underlying soils acting as a second filter treatment area and as a water recharge basin. Use & Applicability Porous pavements are particularly functional as low-volume traffic surfaces and parking areas and have been used for over thirty years. Early installations continue to function as both parking lots and stormwater management systems. Cahill Associates (CA) designed one of the first large-scale porous parking lots for an office park in a Philadelphia suburb. The design consists of porous asphalt parking bays terraced down a hillside and connected by conventional traffic lanes. The site is over 20 years old, has not needed repaving, and has staved off sinkholes in an area prone to them. CA attributes this to even distribution of stormwater through infiltration and particularly to the aggregate reservoir below the surface. Through other projects, CA has found that
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