Industrial Stormwater Treatment on a 200-Acre Container Terminal

Treating industrial stormwater at marine port container terminals requires a multidisciplinary approach and site-specific solutions, and the Terminal 18 (T18) Stormwater Improvements Project exemplifies this. T18 is located within the Harbor Island Superfund site in Seattle, Washington, and is one of the largest container terminals in the Pacific Northwest. Washington has one of the most stringent permit requirements in the country for common stormwater contaminants of copper and zinc. Subsequent to a third-party lawsuit, the terminal operator and the state entered into an agreement in 2015 for the terminal operator to implement stormwater treatment to meet industrial permit discharge requirements. The agreement required stormwater treatment be constructed by 2020 in three phases. This required strategically implemented best management practices, well-informed treatment selection, and an alternatives analysis balanced to meet regulatory and site operator requirements. Following construction to date, the active treatment systems installed have generally met benchmarks while some passive treatment systems installed have produced mixed results, requiring focused adaptive management through troubleshooting and modified operations and maintenance schedules. Phase 3 is currently in design for construction in summer of 2020.