Soil Retention. Drivable Grass consists of tilelike, 2-foot-by-2-foot concrete squares connected into a mat by a grid system. Landscapers can plant grass through lattice-style holes and cracks that let roots penetrate through the mat into the soil, anchoring it firmly into place, the manufacturer says. The mat’s porous nature enables moisture to filter into the underlying soil, reducing runoff while allowing water to be absorbed on site. 800.346.7995.