Runoff and pollution abatement characteristics of concrete grid pavements

Problems of water quaIity and quantity have forced many communities to redefine their approaches to local stormwater management. New approaches--alternatives to the conventional means of piping a problem downstream--focus on maintaining predevelopment runoff levels by increasing opportunities for runoff infiltration, by controlling runoff velocities and volumes, and by reducing nonpoint pollutants. Concrete grid pavements have potential as a technology capable of performing these functions, but they have not yet been evaluated to the satisfaction of officials who must endorse or implement stormwater management strategies.

This research measured, in a laboratory setting, runoff volume and pollutant load reductions associated with three types of grid pavements. A concrete slab was used as a control. Reductions in pollutant concentration and mass in water that percolated through the grids in the pavements were also measured. Runoff from the surface of the pavements and from water within the soils beneath the pavements was analyzed for phosphorus, nitrogen, organic carbon, chromium, lead, and zinc.

Results show that the grid pavements greatly reduced runoff volume, as compared to the concrete slab. The masses of 10 pollutants found in the runoff from this slab were much greater than those in the runoff from the grid pavements. The soils beneath the grid pavements acted effectively in removing significant quantities of pollutants from the water that infiltrated into them.