Pervious Concrete


Drive-thrus, gas stations, parking lots and driveways catch the most oil and grease. Roads are next. They also collect heavy metals from engines and catalytic converters, and harmful components from rubber tires. When it rains, the rainwater mixes with these substances and thus they become large polluters.

Most rain events produce one inch or less of rain. Too many impervious surfaces short-circuit nature’s design, preventing the earth from getting the water it needs, by diverting it into storm sewers, streams and other bodies of water. We needlessly waste a precious commodity because that first inch and a half of rain becomes loaded with these pollutants from roads, parking lots and driveways. It is often more toxic than sanitary sewer water.


The asphalt pavement above, left; holds oil and grease drippings. The pervious concrete above, right; with its porous surface traps oil and grease as well as metal particles. The run-off enters the drainage system polluting streams, canals and Tampa Bay or oceans.


Other particle pollutants should be removed from pervious or impervious pavements by periodic vacuuming.

Oil and grease left on asphalt will attack it and eventually cause erosion. The heat of sunlight will soften and damage the surface. Also the drippings and other pollutants will be carried on shoe soles into buildings and into vehicles.

Oil or grease caught by pervious concrete will have any volatile components boil off in the sunlight. Remaining carbon compounds will usually be converted into non pollutant carbon compounds by microbial action. Where heavy deposits occur, microbial compounds may be applied to the pervious surface and washed in. Other debris will be captured by the pervious surface. (Please see references at end of this and other sections.)


Two types of vacuum devices. One by Billygoat is hand operated. The other used on larger parking lots and streets, made by Elgin is truck mounted.