Reducing Zinc in Stormwater: What’s Working in the Northwest?September 17, 2014
PPRC has just released a short video documenting some of the ways businesses are successfully reducing zinc pollution in their stormwater. Why the focus on zinc? Because a number of Northwest businesses are discharging concentrations that lie above state benchmarks for this metal.
Zinc comes from diverse industrial sources. “It’s a tricky one to chase around and capture,” says Al Cairns, Environmental Compliance Officer at the Port of Port Townsend. Businesses are looking for both proven and innovative solutions to solving their zinc problems. And that’s where PPRC comes in. Our video shows three kinds of solutions: source control, Low Impact Development, and other filtration options.
We emphasize source control as the most cost-effective solution that businesses can employ. As Lisa Rozmyn, of the WA Stormwater Center, says: “Preventing pollutants from reaching the stormwater in the first place is far less costly than trying to remove them once there.” Rozmyn lists a few fundamental source control solutions, such as diligent lot sweeping, cleaning stormwater systems, and keeping metal-containing materials under cover. (For a more detailed look at administering effective lot sweeping, check out our Emerging Stormwater Best Management Practices: Street and Surface Sweeping. And for a more detailed look at other good “house-keeping” measures, check out our Stormwater Manual for Sports Facilities, coming soon…)
Other source control measures require re-thinking the materials and processes used at an industrial site. We focus on one change that businesses can make relatively quickly, and from which they can derive immediate benefits. This is coating galvanized roofs. Because galvanized roofs typically leach high concentrations of zinc, coating roofs with non-zinc paint can dramatically reduce a businesses’ zinc runoff. (For a more detailed look at the effectiveness of roof coating, check out our Emerging Stormwater Best Management Practices: Addressing Galvanized Roofing.)
An increasingly promising solution for businesses of all sizes is use of Low Impact Development (LID) or “green infrastructure,” which simply means altering a site’s landscape to allow natural filtration of pollutants. Marc Daily, of the Puget Sound Partnership, says that LID solutions succeed in more ways than one: “They’re approaches that help businesses achieve their regulatory mandate in a way that’s lighter on the landscape, a little more attractive to look at, and costs them less money. So it tends to be a win all the way around.” We demonstrate the vast environmental and economic improvements that an LID installation made at one shipping business, Totem Ocean Trailer Express (TOTE). At TOTE, a series of raingardens completely eliminated the contaminants draining to the Sound from one of the lot’s outfall pipes. Such improvements helped TOTE reduce its metal runoff to levels below the region’s tight regulatory curve.
Last, we focus on the potential of filtration technologies that offer targeted reduction as part of a businesses’ stormwater plan. While filtration systems are typically the most expensive options – after source control and LID – we show an affordable and versatile filtration solution currently in trial at Port of Port Townsend. The Port is using biochar as part of filtration mixture that has proven extremely effective at filtering metals in lab environments. The port is using this media in a below-grade sand filter as well as in rain-barrel totes that catch runoff from rain gutters. (To learn more about biochar’s positive potential as a filtration media, check out our Emerging Stormwater BMP: Biochar as Filtration Media. Also, to learn more about reducing zinc runoff in boatyards see our Emerging Stormwater BMP: Mitigating Zinc in Boatyards. For all of our stormwater resources, and a collection of other useful regional resources, check out our full page on Stormwater Pollution Prevention.)
We made an effort to focus on pollution prevention solutions that make both environmental and economic sense for businesses. Because zinc pollution comes from so many different sources, businesses need an arsenal of viable solutions.
We at PPRC hope you enjoy the video and our other stormwater resources. Please let us know what you think. What other solutions are proving successful? What potential solutions, or aspects of solutions, would you like to know more about? And what other resources would you like to see to help prevent stormwater pollution?
– Communications Manager,