Environmental considerations

Parking lots tend to be sources of water pollution because of their extensive impervious surface. Virtually all of the rain (minus evaporation) that falls becomes urban runoff. To avoid flooding and unsafe driving conditions, the lots are built to effectively channel and collect runoff Parking lots, along with roads, are often the principal source of water pollution in urban areas.

Motor vehicles are a constant source of pollutants, the most significant being gasoline, oil, polycyclic (PAHs), and heavy metals. (PAHs are found in combustion byproducts of gasoline, as well as in asphalt and coal tar -based sealants used to maintain parking lots.) Many parking lots are also significant sources of trash which ends up in waterways.

Treatment of parking lot pollution: Traditionally, the runoff has been shunted directly into storm, streams, dry wells or even sanitary sewers. However, larger municipalities now require construction of storm water management facilities for new lots. Typical facilities include retention, infiltration basins and percolation trenches. Some newer designs include bio retention systems, which use plants more extensively to absorb and filter pollutants. However, most existing lots have limited or no facilities to control runoff.

Alternative paving materials: An alternative solution today is to use paving surfaces, such as brick, pervious, concrete, stone, special paving blocks, or tire-tread woven mats. These materials allow rain to soak into the ground through the spaces inherent in the parking lot surface. The ground then may become contaminated in the surface of the parking lot, but this tends to stay in a small area of ground, which effectively filters water before it seeps away. This can however create problems if contaminants seep into droundwater, especially where there is groundwater abstraction 'downstream' for potable water supply.

       Landscaping

Many areas today also require minimum landscape in parking lots. This usually principally means the planting of trees to provide shade. Customers have long preferred shaded parking spaces in the summer, but parking lot providers have long been antagonistic to planting trees because of the extra cost of cleaning the parking lot.

However, parking lots represent significant heat islands and, indeed, heat sinks in urban areas. The heat from paved areas in urban zones has been shown to even have the power to change the weather locally. By providing trees or other means of shading parking lots, the heat and glare resulting from them can be significantly reduced.

  BY:MAYAANK