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S424 BMPs for Roof / Building Drains at <br /> I Manufacturing and Commercial Buildings <br /> Description of Pollutant Sources: Stormwater runoff from roofs and sides of manufacturing and <br /> Icommercial buildings can be sources of pollutants caused by leaching of roofing materials, paints, <br /> caulking,building vents,and other air emission sources. Research has identified vapors and <br /> entrained liquid and solid droplets/particles as potential pollutants in roof/building runoff.Metals, <br /> Isolvents,acidic/alkaline pH, BOD, PCBs,and organics are some of the pollutant constituents iden- <br /> tified. <br /> I Ecology has performed a study on zinc in industrial stormwater.The study is presented in Sugges- <br /> ted Practices to Reduce Zinc Concentrations in Industrial Stormwater Discharges(Ecology,2008). <br /> The user should refer to this document for more details on addressing zinc in stormwater. <br /> IPollutant Control Approach: Evaluate the potential sources of stormwater pollutants and apply <br /> source control BMPs where feasible. <br /> IApplicable Operational Source Control BMPs: <br /> . If leachates and/or emissions from buildings are suspected sources of stormwater pollutants, <br /> Ithen sample and analyze the stormwater draining from the building. <br /> • Sweep the area routinely to remove any residual pollutants. <br /> I . If a roof/building stormwater pollutant source is identified, implement appropriate source con- <br /> trol measures such as air pollution control equipment,selection of materials,operational <br /> changes, material recycle, process changes, etc. <br /> 1 I/ Applicable Structural Source Control BMPs: <br /> I <br /> . Paint/coat the galvanized surfaces as described in Suggested Practices to Reduce Zinc Con- <br /> centrations in Industrial Stormwater Discharges(Ecology, 2008). <br /> IApplicable Treatment BMPs: <br /> Treat runoff from roofs to the appropriate level.The facility may use Enhanced Treatment BMPs as <br /> I described in III-1.2 Choosing Your Runoff Treatment BMPs. Some facilities regulated by the Indus- <br /> trial Stormwater General Permit, or local jurisdiction, may have requirements than cannot be <br /> achieved with Enhanced Treatment BMPs. In these cases, additional treatment measures may be <br /> I required.A treatment method for meeting stringent requirements such as Chitosan-Enhanced Sand <br /> Filtration may be appropriate. <br /> I <br /> I <br /> 1 <br /> 2019 Stormwater Management Manual for Western Washington <br /> Volume IV-Chapter 7-Page 592 <br />