Removal of dissolved metals from stormwater runoff using pervious concrete

Jerin William Tilson

Due to increased development in recent years and subsequent impervious areas, an increase in peak stormwater runoff (flooding) and non-point source pollution to aquatic systems has occurred. Pervious concrete is a low impact development (LID) technique that has been shown to protect against flooding by allowing stormwater runoff to infiltrate through the concrete and into the soil. In addition, pervious concrete may be capable of providing water quality control. An investigation was conducted to test the efficacy of dissolved zinc and copper removal in stormwater runoff with pervious concrete. Short term tests were performed to determine the ability of the concrete to remove zinc and copper during first flush conditions. An equivalent of 12 mm (0.5 inches) of stormwater was applied to three pervious concrete cylinders for approximately ten minutes with hotspot zinc and copper concentrations of 500 µg/L and 100 µg/L, respectively. These concentrations are found in areas that are exposed to prolonged sitting and running vehicles. Minimum removal rates of zinc and copper were 96% and 90%, respectively. Another test was conducted on three concrete cylinders to simulate removal of typical zinc and copper concentrations (100 µg/L and 20 µg/L, respectively) deposited on roadways. The pervious concrete cylinders removed zinc and copper from the stormwater at a v minimum of 89% and 87%, respectively. Four other cylinders were subjected to additional typical concentration tests after the columns experienced long term exposure of a theoretical 15 years. Zinc and copper was removed at a minimum of 87% and 83%, respectively, after 15 events (approximately 7 years) of long term exposure, and a minimum of 86% of both copper and zinc after 24 events (approximately 12 years). To determine the long term efficacy of the pervious concrete, twelve cylinders were loaded with 30 events at concentrations forty times typical concentrations for a projected 15 years of exposure. Zinc and copper were removed at a minimum of 59% and 56%, respectively. This study indicates that pervious concrete is a viable best management practice for treatment of zinc and copper in stormwater, particularly in areas with limited space.

Removal of dissolved metals from stormwater runoff using pervious concrete

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