By Brian Clark Howard
Normal pavement doesn't allow rainfall to penetrate through to the groundwater level, where it is naturally filtered and surface pollutants are removed. Instead, rainfall pools or flows from our patios directly into storm drains, carrying those surface pollutants, like oil and gas and the occasional lost BBQ chicken wing, into local streams, lakes and rivers. Enter pervious pavement, a type of pavement that allows water to seep down through the natural filter of the soil, where it replenishes the groundwater that many people rely on for drinking water. This type of pavement is effective in removing high rates of zinc, lead, nitrogen, phosphorous and sediments, as well as reducing flooding, erosion and ice buildup. Various types of pervious pavement are now available: poured-in-place pervious asphalt, poured-in-place pervious concrete, block and concrete modular pavers and grid pavers. Drawbacks: Cold climates can require extra maintenance, and heavy clay soils can limit its usefulness.