Overview: Invisible Structures, Inc. provides surfacing and stormwater solutions that protect and enhance the environment. Since 1982, ISI has manufactured porous paving, erosion control, drainage, and stormwater storage products for easy, cost-effect, on-site stormwater management. Solutions that effectively filter out pollutants reduce runoff volumes and rates, and lower treatment costs. Grasspave2 and Gravelpave2 are the best porous paving products on the market - both creating beautiful and functional areas. Rainstore3 is an underground stormwater storage pond, which eliminates the need for real estate-consuming retention ponds.