SPU Basin 111 CSO Compliance Analysis

Principal, Tony Dubin, worked with Seattle Public Utilities to estimate the current frequency of CSO events and annual discharge volume to the Duwamish 111 outfall. The Duwamish CSO basin contains eight CSO weirs that discharge to a large diameter drainage pipe and a tidally influenced section of the Duwamish River. Adding complexity, water levels in the SPU system can also be influenced by the County’s Duwamish pump station. Because flow rates can be difficult to monitor within CSO structures, the model validation analysis focused on monitored depth data to refine the model hydraulics. In addition to reporting CSO frequencies and volumes, Tony provided SPU with hydraulic context and lessons learned that will help inform SPU’s future CSO control decisions in the basin.

Services: Modeling