Water Reclamation Facility Phase 3 Improvements

Purpose

The Water Reclamation Facility (WRF) Phase 3 Improvements will increase sewer treatment capacity, enhance performance, and replace critical components that are nearing the end of their expected service life.  State regulations require that when wastewater flow and loading to a facility reaches 85 percent of the design capacity, the City must begin the planning process for modifying the facility to increase capacity. In addition to these capacity requirements, many of the WRF components have been operating continuously for the past 25 years and are nearing the end of their expected service life. Both the 2012 General Sewer Plan (GSP) and the recent 2021 GSP identified the need to begin the planning process and increase the WRF capacity. 

Description

The WRF Phase 3 Improvements will upgrade aging components with new equipment sized to handle future sewer flows and loads projected through the year 2040.  In addition, the Phase 3 improvements will increase efficiencies and delay the need to build a third clarifier. Phase 3 of the WRF Improvements include major improvements at the Kimball Creek Lift Station, headworks, oxidation ditches, and solids handling facility which are described below.

Kimball Creek Lift Station

The Kimball Creek Lift Station is the largest lift station in the City.  During periods of low flow conditions the lift station creates excessive flow cycling and spikes at the WRF which results in treatment inefficiency and excessive wear on equipment.  This project will replace one of the three pumps with a smaller baseflow pump operated on a variable frequency drive (VFD) to smooth out the flow to the WRF. This project will also upgrade the original 1997 electrical gear with modern controls to allow for the WRF to communicate directly to the lift station.  These improvements will increase efficiency throughout the WRF and delay the need for a building a third clarifier.

Headworks

The WRF headworks improvements will improve capture of rags and grit. The headworks serves as the first line of defense at the WRF and protects downstream process equipment from expensive damage. The improvements include a new perforated belt screen and vortex grit system.

Oxidation Ditches

The oxidation ditches will receive the majority of the Phase 3 improvements. The ditches will be retrofitted with partitions into a series of smaller tanks outfitted with oxygen diffusers, mixers, and monitoring equipment to provide operators with greater process control and treatment efficiency. The project will increase capacity of the facility by 25%, replace aging equipment, and provide cost saving performance enhancements including more energy efficient oxygen transfer and delaying the need for a third clarifier.

Solids Handling Facility

The solids handling facility improvements will increase the facility capacity to meet loads projected through the year 2040. The improvements will include installation of a new jet aeration system and two chopper recycle pumps.  These capacity improvements are necessary to service the Snoqualmie Casino Hotel expansion. The improvements are fully funded by the Snoqualmie Tribe under the 5^th Amendment to the Agreement between City of Snoqualmie and the Snoqualmie Tribe for the Sewer Services.

Timeline

Construction will begin summer 2023. Construction of the new blower building, headworks improvements, and solids handling improvements is expected to occur over the next year.  The Kimball Creek Lift Station will be retrofitted during summer 2024. Following completion of these tasks, the oxidation ditches will be retrofitted in phased succession. The new treatment process will begin startup during winter 2024 and construction completion is expected during summer 2025.

For more information about City of Snoqualmie wastewater treatment facilities and future project, please visit www.snoqualmiewa.gov/559/Water-Reclamation-Facility