Oregon Wire Products
Meet or exceed Oregon Department of Environmental Quality stormwater permit benchmark for zinc using existing drainage infrastructure and adapting passive filtration methods.
Reduce total zinc at sample point to a geometric mean of <0.24 mg/L over 4 consecutive sample events.
Approximately 2.4 acres of totally impervious surface of which about half consists of buildings with a mixture of metal and composite roofs. Buildings have galvanized gutters and downspouts connecting to main storm drainage pipe through cast iron underground pipelines. The remainder of the site is paved with asphalt and includes four concrete loading docks. A total of seven catch basins drain the paved area with each loading dock having one catch basin at its lowest point. All catch basins are connected to the same main drainage pipe and a sampling manhole has been installed at the edge of the property. All the roof runoff and the pavement drains connect upstream of the sample manhole and the combined flow is analyzed and the result submitted to the permit regulatory agency.
Company management had implemented a program of frequent parking lot sweeping and pressure washing of roofs and gutters along with moving all identifiable zinc sources under cover. They also deployed non woven fabric catch basin filters throughout the site. These measures brought the levels of suspended solids down to acceptable limits but left the zinc levels at >5.0 mg/L. Beginning in March, 2007, they replaced the non woven fabric filters with CleanWay® catch basin filters and in February 2008, began to install MetalZorb® metals removal filtration elements in the catch basins which showed the highest concentration of zinc.
Through adapting a strategy of adding MetalZorb where zinc was highest, coating one of the metal roofs and keeping to an adaptive maintenance schedule, the permit requirement of four consecutive samples with an average zinc content of <0.24 mg/L has been met and a waiver of further testing in the remaining permit cycle has been achieved. For more information, call 800.723.1373.