Established in 1982, Invisible Structures, Inc., offers a variety of products to meet National Pollutant Discharge Elimination System (NPDES) Phase II requirements. Grasspave is a living turfgrass alternative to asphalt and concrete for traffic bearing surface applications. It combines recycled raw materials, sound structural engineering and efficient production and installation techniques with proven horticultural methods. Gravelpave is designed to contain fine gravel while preventing particle migration and rutting that have been traditionally associated with gravel driveways, roads, parking lots and pathways. It is a true porous pavement, reducing runoff, preventing non-point source pollution and providing urban heat island mitigation.