Since we are a paving company, I would think that one of our responsibilities is to keep up on the latest technologies in our industry. So, in the spirit of ingenuity and forward thinking, I’ve done a bit of research on what else is out there when it comes to applications of asphalt in many different situations. One of the most interesting things which I’ve come across is pervious asphalt and what opportunities it offers as a way to mitigate stormwater runoff. The whole idea behind pervious asphalt is that stormwater is able to drain through the asphalt surface, down through layers of stone and sand which act to filter the water, eventually reaching the water table beneath the installed subgrade, and re-entering the water table as benign, filtered water. If engineers and planners were to embrace this technology and approve the use of these materials, site developers would be able to forgo the installation of expensive, and sometimes very complicated, detention ponds and other water runoff related structures. The biggest difference between the installation of pervious asphalt and traditional is in the sub-base. Pervious asphalt requires a layering of stone, sand and fabric, all of which is required to achieve the filtering necessary to clean the water before it re-enters the water-table. This does increase the price of installation, though costs are more than offset considering that detention ponds and other runoff related structures do not need to be installed.
The technology is rather new, and does have its drawbacks. One of which being that you cannot sealcoat pervious pavement, another being that it requires some maintenance in the form of a special vacuuming in order to keep the top asphalt layer from clogging up.
The University of New Hampshire has been studying pervious asphalt and has a wealth of information on its website dealing with it. Check it out here: http://www.unh.edu/erg/cstev/
As well here’s a bit more info to take a look at: http://www.pavegreen.com/water_quality.asp