1 2005 PLASTIC DEBRIS CONFERENCE DEBRIS NETS IN THE SAN GABRIEL RIVER – DESIGN AND PHYSICAL MODELING

A major storm event can mobilize waterborne pollutants from throughout our watersheds. Floating debris, including plastics, polystyrene and green waste, finds its way into our tidal waterways and beaches. It degrades the visual amenity, is expensive and time consuming to clean up, and is an environmental threat to wildlife and health. This paper presents information regarding design and physical model testing of innovative debris nets intended for installation in a concrete lined trapezoidal section of the San Gabriel River in Los Angeles County. The nets are designed to intercept debris before it discharges into the tidal sections of the San Gabriel River. The paper will describe the design philosophy behind the nets, the challenges of debris capture in high current velocity regimes and demonstrate the benefits of physical modeling as a key element in the design process. Public safety issues associated with net implementation also played a major role in the ultimate project outcome