In 2019, ECOSS and Equinox Studios co-created an “industrial strength” Green Stormwater Infrastructure (GSI) demonstration site. Prior to installing Grattix Boxes, oyster barrels and other GSI features, ECOSS sampled the stormwater to get a baseline understanding of the types of toxic heavy metals and other pollutants gathering on the roofs and pavement at Equinox Studios. Stormwater solutions filter out toxic heavy metals and other pollutants from rain water that collects on hard surfaces before entering local water bodies. These pollutants are harmful not only to aquatic wildlife, but also to the communities which border the polluted water bodies. So how have the GSI performed?
ECOSS returned to Equinox Studios in 2020 and 2021 to sample stormwater and see how the GSI impacted water quality. Although the team expected some reduction in heavy metals, the effectiveness of Grattix Boxes and oyster barrels was astounding. Here are some highlights:
- In 2020, Grattix boxes on-average reduced zinc content by 70-90% compared to 2019 water sampling before they were installed
- In 2021, Grattix boxes continued to perform, showing over 80% reduction in copper and zinc
- At one Grattix box, stormwater was filtered from 1,700 micrograms of zinc per liter to 139 micrograms per liter – over a 90% reduction!
- One downspout is connected to a Grattix Box and oyster barrel combination, reducing copper content by 88%, while zinc dropped to undetectable levels.
These types of GSI installations have helped industrial stormwater permitted businesses reduce their pollutant loads to below their permit benchmarks when maintained regularly, depending on the amount of pollutant they are managing.
ECOSS will continue to monitor these GSI installations and see how filtration power changes over time. The most recent sampling results showed that a combination of GSI systems could work synergistically to filter out heavy metals even better and is particularly useful for areas with greater metal loads. Repeated sampling will also help determine when the materials inside the GSI have to be cleaned or replaced.
Rain water that falls on and passes through the Equinox Studios site ultimately flows to the Duwamish River, which is a Superfund site and one of the most polluted water bodies in the United States. But ECOSS is showing how to mitigate some of that pollution with “industrial-strength” Green Stormwater Infrastructure.
Want to get a closer look at these stormwater solutions? ECOSS and Equinox Studios will be hosting an in-person, socially-distant, self-guided tour on April 24, 2-4pm, in celebration of Earth Day!
ECOSS clean water and environmental stewardship work was featured in the Seattle Times!