GREEN ROOF TRAYS INTERLOCK Columbia Green Technologies Inc.’s Advanced Vegetative Roof System is easy to install and maintain. An overlapping edge and removable vinyl rivets join the trays. AVRS trays are manufactured from recycled, 100-mil, high-molecular-weight polypropylene. The growth media is a blend of organic and inorganic compounds that retains up to 70 percent moisture. (503) 217-3010 /