a modular insert for curb - inlet storm drains creates a composite collection system for trash and for oil or other hydrocarbons and related chemicals . a hopper contains a multitude of irregular , macroscopic fragments of a hydrophobic , compliant , oil - absorbent , copolymer material having high surface area . preferably , the material is formed with a binder in a novel extrusion process . the fragments absorb and retain permanently a high quantity of oil and other chemicals passing through the hopper , while permitting a high water flow - through rate . the fragments are held in place by a removable bottom plate , which allows replacement of the filtering fragments , and an internal basket . trash and debris are collected in the internal basket . the hopper is configured to be suspended in a storm drain adjacent to a curb inlet on a bracket and can be installed or serviced through a conventional manhole entry . the hopper has a side cutout that permit lateral overflow from one of the modular units to an adjacent one .