Meeting the state’s stormwater runoff standards are a regular and often expensive challenge for businesses, but two employees at the Port of Vancouver developed a cheap and natural solution.
With all the roofs, metal boxes, fences and truck traffic at the port, the agency has plenty of sources of zinc and copper runoff, which is harmful to aquatic life. Zinc is everywhere — in sunscreen, tires, chain-link fences and metal roofs — and the heavy rains of Western Washington means it frequently winds up in animal habitats.
“You’re sort of a victim of materials,” said Port Environmental Manager Matt Graves. “Zinc is in everything.”
According to state rules, stormwater runoff should contain no more than 117 zinc parts per billion and just 14 copper parts per billion. Copper interferes with a fish’s ability to sense predators or nearby spawning grounds. Fish are very sensitive to zinc; at toxic levels it binds to their gills and causes them to suffocate.
“The amount of zinc you’d get in a bottle of water is even too high for fish,” said Port Environmental Program Manager Mary Mattix.
To correct the problem, the port looked at buying a treatment system a few years ago, but those cost thousands, require regular maintenance and many only cut zinc levels by half. After a lot of brainstorming, Graves and Mattix designed and built a compact and cheap filtration system that cut the port’s zinc levels by 90 percent to 95 percent and resulted in a similar decline in copper levels.
The Grattix, as they named it, is built into a 325-gallon food-safe plastic tote and collects rooftop runoff from the galvanized metal roofs on port buildings. At the surface, water pours onto big river rocks, a few plants and hardwood mulch. Then the water runs through layers of soil, sand, and layers of variously sized rocks until it drains out though a perforated polyvinyl chloride, or PVC, pipe. The plants use the zinc and copper in photosynthesis, and the port benefits by having cleaner stormwater.
Going to ground
For aesthetics they wrapped the tote in a wooden exterior.
The port has about 20 Grattixes in place around the port and plans to build about a dozen more this year. Each Grattix costs between $200 and $900.
The first model was built in 2009 and only recently is starting to show elevated levels of zinc and copper, suggesting it’s reached peak saturation. The heavily saturated materials will be sent to a landfill. But the team says first they’ll examine the materials and possibly tweak the layers to improve filtration effectiveness or duration for future models.
The Grattix was so successful they took the design out of a box and put it in the ground. Using the same principles, two roughly 2-acre filtration fields treat stormwater from a 50-acre terminal and a 58-acre light industrial area.
Rather than trying to market or patent the design, Graves and Mattix have shared the invention as much as possible, holding demonstrations at the port property, speaking at various events and posting their designs online.
“We’ve hit the road on these and given a lot of talks,” Mattix said. “People are hungry for this type of resource.
