Elliot Bay Seawall Project – Working Within Strict Regulations to Provide Efficiency in Stormwater Treatment Amid a Large-scale Waterfront Construction Project

Ever wondered how to keep Seattle's waterways clean during massive construction projects like the Elliott Bay Seawall? This case study delves into the complexities of urban construction stormwater management. You'll learn how to design adaptable treatment systems that can handle ever-changing water quality and flow rates. We'll also explore strategies for navigating the permitting process with multiple regulatory agencies, mitigating risks associated with historical site contamination, and maintaining environmental responsibility throughout your project.

Full Abstract: Strict regulations and continuous adaptation were crucial for successful water management and water treatment in the dynamic Elliott Bay Seawall replacement project. Located in Seattle's bustling waterfront, this project faced challenges due to its proximity to a popular tourist area, the state's busiest ferry terminal, and sensitive marine ecosystems.

Multiple regulatory agencies with varying requirements (Washington State Department of Ecology's NPDES permit, King County Industrial Waste Program's Major Discharge Authorization, and a site-specific Administrative Order) dictated water treatment approaches. Additionally, known groundwater contamination on-site posed potential threats to dewatering efforts.
Clear Water Services addressed these complexities by designing and implementing adaptable stormwater treatment systems. Two distinct dewatering streams, each with fluctuating contaminant levels and governed by different agencies, required specific treatment trains to support high concentrations of heavy metal removal while the primary stormwater stream presented significant challenges due to extreme variations in water quality (0-4,000 NTU), flow rate (0-3,500 GPM), and strict discharge limits. Further complicating matters was the self-imposed requirement to maintain discharged water pH within 0.2 units of Puget Sound water, a vital resource for the nearby Seattle Aquarium.

This presentation utilizes the Elliott Bay Seawall project as a case study to demonstrate the importance of designing and permitting adaptable stormwater treatment systems that can accommodate changing conditions while ensuring effective communication and collaboration with various regulatory agencies. This presentation will also review flexible treatment strategies that adapt to fluctuating water quality and flow rates. The Elliott Bay Seawall project serves as a valuable case study, offering insights and strategies that can be applied to similar projects to ensure clean water and environmental protection.