Oak Park is laying down brick streets on two two-block stretches this summer at 700-800 South Humphrey and 900-1000 South Wenonah. The village will assess the results before offering bricks elsewhere in the village.
The village is using brick, said Village Engineer Jim Budrick, because it is “a more historical material that we used in the past.”
But there are other kinds of pavers being used at several places in the Chicagoland area, such as the Unilock Ecoloc being used by Dominican University in River Forest and the Morton Arboretum in Lisle. These permeable pavers have high maintenance costs, but may be better for the environment and would likely reduce flooding in basements.
According to Oak Park architect Michael Iversen, 85 percent of rainwater that hits brick pavement flows into the Chicagoland area’s stormwater runoff system, which is connected with the sewer system. The remaining 15 percent is absorbed into the soil.
By contrast, some pavers that are more permeable allow 60 to 90 percent of water to pass into the soil through gaps in the interlocking pavement.
Because the permeable pavers reduce runoff into the sewer system, they would reduce the overload of the sewer system, which, according to Village Engineer Jim Budrick, leads to flooding in basements. Also, Iversen said, the additional water permeable pavers allow to pass through the street into the soil would help filter out pollutants.
The amount of water permeable pavers allow to pass through them, however, diminishes over time without maintenance. A 2006 study of one permeable concrete block pavement found that permeability decreases to only 50 percent after two years and less than 20 percent after 10 years.
Permeable pavers’ biggest cost, said Budrick, is “the level of maintenance that would be needed to keep them functional.”
However, the initial cost to pave a street with interlocking pavers can be as little as with asphalt. According to Interlocking Concrete Pavement Magazine, at one project in Moline the permeable pavers used there cost only $171 per linear foot for a municipal street, while asphalt costs $179 per linear foot.
But, besides regular maintenance, there are also hidden costs to permeable pavers, such as special rollers on snow plows and additional snow routes in the wintertime.
There are also other considerations besides cost.
Dawn Morse, the project manager of new construction at Dominican University, said the school used permeable pavers on its parking lot several years ago and is now using the pavers around a new building because the administration “wants to be good stewards of the environment” and it “is a much more natural way to handle rainwater” than asphalt pavement.