The case for Zinc Abatement and Containment.
Zinc Runoff and Roof Coatings:
Dodge Foam & Coatings Inc. products are effective in sealing and encapsulating galvanized metal roofs, posts and other metal concerns preventing residual zink run-off.
The trigger for environmental regulation, abatement and engineering controls is often local in nature. Proceedings of the 2008 Product Stewardship or "Green Chemistry" conference hosted by the State of Washington's Department of Ecology established two things:
1.) The State of Washington knows zinc is a problem in the Puget Sound and its estuaries.
2.) The State of Washington doesn't have the resources or knowledge of the ecosystems zinc inventory to form the basis of a state regulation on buildings.
While the actual sources of zinc may not be adequately understood the requirements and mechanisms are better understood. The EPA does have standards for zinc in storm water set at 0.117 mg/l for permitted facilities. Zinc's role in inhibiting the growth of algae limits the ultimate biologicalcensity of any body of water that has levels in the range of 300-30 ug/l with some species being impacted at the range of 10 ug/l. Zinc is especially toxic to certain mollusks prominent in the Puget Sound.
Forward thinking companies and individuals are prudent to consider this in their building and maintenance plans even though it may be some time before it becomes a matter or law. For the roofing industry the option of coating galvanized metal roofs seems to be an obvious place to start.These roofs start out with a layer of elemental zinc that erodes and oxidizes to the point that the zinc is sent into the ecosystem quite quickly, leaving the common site of a rusty metal roof. It is also known that these roofs have runoff that has much more zinc than typical urban run-off, so much so that it typically runs about 10-100 times that of the level required for storm water permits.
Coatings as a solution to Zinc runoff. Elastomeric Coatings are thick protective materials that isolate the zinc from the effects of acid rain, oxygen, heat and water. Elastomeric coated roofs do not rust even after 30 years and how no sign of zinc erosion, so we know the zinc effluent will be reduced by at least a level of 1/100th to 1/1000th compared to an uncoated roof. Furthermore most elastomeric roof coatings have the added benefit of using Calcium Carbonate, a pigment which buffers and neutralizes the effects of acid rain fallout on metal roofs.