 Bioretention basins are however, sensitive to any materials that may clog the filter media.Basins are often used in conjunction with gross pollutant traps (GPTs or litter traps, include widely used trash racks), and coarser sediment basins, which capture litter and other gross solids to reduce the potential for damage to the vegetation or filter media surface.Infiltration trenches are shallow excavated structures filled with permeable materials such as gravel or rock to create an underground reservoir.