Author(s): John J. Sansalone
Linked Author(s): John J. Sansalone
Keywords: No Keywords
Abstract: Urban surface waters often contain high loads of metal elements, particulates and dissolved solids. Metal elements are a significant concern because they do not degrade in the environment and can exert severe acute and/or chronic stress on receiving waters and sediments. Numerous passive treatment strategies have been proposed to control anthropogenic constituents in urban surface waters. One novel and promising design combines the best attributes from porous pavement and infiltration trenches while functioning as a replacement for pavement underdrains. This design, known as a partial exfiltration trench (PET), intercepts and infiltrates lateral sheet runoff from pavement surfaces before it becomes concentrated gutter flow. The PET consists of an iron oxide coated sand (IOCS) media capped by a cementitious porous surface. Bench scale PET column experiments have been carried out to compare the metal element capacity of the IOCS against control media of silica sand. Metal elements investigated include Zn, Cd, Pb and Cu run separately and in mixed combination at pH levels of 6.5 and 8.0. When run in combination, Zn broke through first, closely followed by Cd; Cu and Pb were strongly retained in the columns. The IOCS capacity was greater than silica sand at a pH of 6.5 and was significantly improved when the infiltrating runoff pH was increased to 8.0 using the cementitious porous surface. Bench scale results indicate that the PET can perform satisfactorily for at least a ten year design life in a humid climate.
Year: 1997