Wastewater Treatment Plant Upgrade

The City is working on major upgrades to the wastewater treatment plant (WWTP).  The primary purpose of this work is to prevent combined sewer overflows (CSO) into the Skagit River.  Reduction in CSO events will improve water quality and meet requirements of a Washington State Department of Ecology (DOE) consent decree.

Other important purposes of the upgrades are to (1) increase the capacity of the plant to meet the needs of the City's growth during the next 20 years and (2) change the method of disinfection and odor control from the use of gaseous chlorine to a more environmentally benign process.

The work to accomplish these goals has been organized into two major project phases (Phase One and Two) estimated to total more than $45 million in cost.  The scope of Phase One will increase the plant capacity to approximately 20 million gallons per day (mgd) and eliminate gaseous chlorine processes as the primary method of disinfection.  The design of Phase One is complete and construction is expected to begin this summer and be completed by 2008.  The project is located at the existing plant site so that inconveniences to the public during construction should be very minimal.  The total estimated cost of Phase One is $25.7 million.

Phase Two of the plant upgrade project may be needed to increase the capacity of the plant in order to meet DOE consent decree requirements and serve the City's growth.  The second phase is expected to be in service by 2014.  The total estimated cost of Phase Two is approximately $23 million.  However, there is a good chance that the Phase One project and completion of other planned wastewater system improvements will delay or offset the need to construct the Phase Two project.