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CTP Electrical Distribution System Replacement


The City of Tacoma’s Central Wastewater Treatment Plant (CTP) treats over seven billion gallons of wastewater annually and serves thousands of customers in Tacoma and its surrounding areas, including the City of Fife, the Town of Ruston, the City of Fircrest, and portions of Pierce County.  The CTP’s existing Medium Voltage (MV) electrical distribution system provides power throughout the facility and is approaching 40 years of age.  The industry standard for MV cables is 20-30 years of age.  This facility’s MV cables are past their expected service life and have spent many years submerged and exposed to moisture in underground utility vaults. 


During the winter of 2013, a failure occurred within the MV distribution system which caused an immediate outage to multiple parts of the plant.  The CTP survived that outage without significant damage, but a power loss during a severe storm event could cause devastation similar to a natural disaster resulting in hundreds of millions of gallons of untreated sewage reaching Puget Sound. This project will replace the entire 15 kilovolt (kV) electrical distribution system at the City of Tacoma’s Central Wastewater Treatment Plant. 


The project is scheduled for construction in 2020 and 2021.  The completed project will build more than 3,000 lineal feet of concrete encased reinforced duct bank, install over 20 miles of electrical cables, construct a 3,400 square foot building for storing and operating the new electrical equipment, and install a new 15-kV switchgear comprised of 41 circuit breakers.  It will provide redundant and reliable power to the entire facility.  The planning level cost estimate for the entire project is $30-$35 million.


The facility borders the Puyallup River and treated wastewater discharges into Commencement Bay and Puget Sound.  The Puget Sound is a natural resource for the entire Northwest area of the State of Washington with international significance:  supporting tourism, wildlife, sports and recreation, food sources, cultural importance, and international shipping through the Ports of Tacoma and Seattle.  This project is regionally significant to provide wastewater treatment to maintain and improve the quality of water in the Puyallup River Estuary, Commencement Bay, and Puget Sound.   Providing reliable power to the Central Treatment Plant helps Tacoma do its part preserving Washington’s beautiful natural resources.


Bids were opened on May 19th, 2020. Six bids were received, and a contract was awarded to Prospect Construction, Inc. (Puyallup, WA) on July 27, 2020. Notice to Proceed was issued on August 10th, 2020 and construction is expected to last until the summer of 2022.



Design: 2018-2019


Public Bid Period: March to May 2020. 


Construction: 2020-2022


The project will be partially funded by a loan from the United States Environmental Protection Agency Water Infrastructure Finance and Innovation Act (WIFIA). This loan is for up 49% of eligible project costs and will not exceed $20M. The project will be partially funded by a loan or loans from the Washington State Department of Ecology Water Pollution Control Revolving Fund. The extent of the funding is not yet known because loan applications are still in process.



The City of Tacoma Environmental Services Department is managing the project.  For questions or concerns regarding this project, please contact the City’s Project Manager, Max Drathman at (253) 502-2276.


Tacoma Aerial of treatment plant