Ask The Expert

Q: Can pervious concrete pavement replace traditional storm water collection systems?

A: In larger scale applications, the rainwater diversion, collection, and temporary storage capabilities of pervious concrete pavements can often supplement, or even eliminate, traditional means of stormwater management. Many subdivisions have been successfully designed with pervious concrete streets in place of long lengths of drainage piping and land grabbing detention ponds, reducing environmental impacts.

As an example, the city of Shoreview, Minn. was faced with the need to replace deteriorating asphalt streets within a subdivision bordering Lake Owasso. There were signs that stormwater runoff from existing pavement was contaminating the lake water, so city officials investigated three options to better manage and treat stormwater.

One option involved repaving with asphalt, and installing catch basins and underground piping leading to a treatment tank, which would remove contaminants prior to allowing discharge into the lake. A second option, also with asphalt paving, would require catch basins connected to perforated piping to allow the runoff to infiltrate into the surrounding sandy soils. Although this was the least expensive option, providing adequate 10-year storm storage capacity would require more land area than was available.

The third option, which the city selected, was pervious concrete with a rock storage layer. At only a 10% premium compared to traditional methods with asphalt, stormwater could freely drain through the pavement layer to be temporarily stored in the underlying gravel. The existing sandy soils were ideal for infiltration, and all discharge to the lake was eliminated. As an added benefit, site excavation was reduced, lessening potential damage to the root structure of many well established shade trees in the neighborhood.

For more information on pervious concrete pavements, search "pervious concrete" on the PCA website, www.cement.org. The National Ready Mixed Concrete Association site, www.nrmca.org can also provide more information on this long lasting, cost effective, and more environmentally responsible stormwater management technique.