Ballard Pump Station

Review Status

On January 19, 2017, we reviewed the concept design phase for the Ballard Pump Station project. At this meeting we approved, 6-3, the concept design with several conditions and recommendations. We will review this project again during the schematic design phase.

Project Description

The Ballard Pump Station is a part of the Ship Canal Water Quality Project (SCWQP), a joint project between Seattle Public Utilities (SPU) and King County, to improve water quality in NW Seattle. The project includes a 2.7 mile tunnel for collecting, storing and treating stormwater runoff, four drop structures to provide access to the tunnel, and a pump station. The tunnel will be in the right-of-way for most of its path through Ballard, Fremont, and Wallingford neighborhoods. Currently, sewage and stormwater from Ballard, Fremont, Wallingford, and the northern portion of Queen Anne flow into the combined sewer system, which is directed to the West Point Treatment Plant in Magnolia. During heavy rain events the pipe system is designed to release combined sewage overflow (CSO) into the surrounding waterbodies via several outfalls. On average, there are over 160 CSO events, which results in the discharge of approximately 50 million gallons of polluted stormwater into adjacent waterbodies annually. When fully implemented the project is designed to reduce the frequency of CSO events to 1 per year at each outfall location based on a 20-year moving average. The proposed storage tunnel will temporally store 15 million gallons of CSO during heavy rain events. The stored combined water will then be sent to the West Point Treatment Plant via existing pipes.

The Ballard Pump Station will be located at the northwestern terminus of the storage tunnel, between 24th Ave NW, Shilshole Ave NW, Ballard Terminal Railroad, and two existing parking lots. The pump station will include an above ground structure that is approximately 40 feet in height as well as an underground drop structure that has an approximate depth of 100 feet. The drop structure connects to the SCWQP tunnel and houses the pump stations equipment. The station will pump stored CSO from the tunnel, and it will be conveyed to the West Point Treatment Plant.

January 19, 2017