The Ship Canal Water Quality Project will build an offline storage tunnel to reduce the number and volume of Combined Sewer Overflows that discharge into the Lake Washington Ship Canal from Ballard, Fremont, Wallingford, and north Queen Anne. The project includes a 29-million gallon offline storage tunnel, six diversion structures for diverting influent combined sewage away from existing Combined Sewer Overflow outfalls to the tunnel, five drop structures to move combined sewage into the storage tunnel, and odor control systems.
- Partially reach compliance with the Utility’s Consent Agreement to meet state requirements.
- Protects the water quality in the Lake Washington Ship Canal by reducing combined sewer overflows (CSOs) to an average of one per year or fewer at all six CSO outfalls. The reduction in overflows is estimated to reduce pollutant discharges to the Ship Canal by an average of 84 percent per year.
- Saves Seattle Public Utilities ratepayers an estimated $66 million by financing the project with a WIFIA loan compared to a bond issuance.
- Seattle Ship Canal Water Quality Project (PDF)(1 pg, 296 K)