The City of Snoqualmie’s Water Reclamation Facility (WRF) treats an annual average flow of 1.1 MGD. In 2014, Snoqualmie prepared a General Sewer Plan (GSP) that identified improvements at the WRF through 2020 to continue addressing regulatory requirements, O&M needs, and treatment objectives.
Snoqualmie selected RH2 to prepare an Engineering Report for the improvements and preliminary design for near-term improvements. The Engineering Report was completed in winter 2015 and preparation included performing treatment process assessments; preparing alternative evaluations and recommendations; and preparing total project and O&M cost estimates. A total of 6 phases of projects were identified. The City then selected RH2 to perform the design, programming, and construction phase services for the projects. Phase 1 design and construction is complete, and Phase II is currently under construction. The other phases are currently under design.
Phase 1 WRF Improvements
RH2 prepared the construction documents, estimate, and handled the permitting work including: City building and site development permits, Department of Ecology Approval, SEPA, and critical areas work. RH2 also provided bidding, construction phase services, testing and startup, O&M manual preparation and operations assistance, and SCADA programming. The WRF improvements included:
- UV disinfection system replacement for compliance with secondary and reclaimed water standards
- Standby generator replacement
- Anoxic Zone Mixer replacement
- Raw wastewater influent flow and water quality monitoring
- Non-potable water system upgrades
- SCADA system replacement and full plant control system replacement
The project was bid in 2016 and awarded to MSI Construction. The Engineer’s Estimate was $6.8 million, and the low bid was $6.02 million. The project was completed in early 2018 for a total of $5.96 million.
Phases 2, 3, and 5
RH2 prepared the preliminary design and final design for improvements to the solids handling system for the WRF and other improvements. This included an analysis of DAF vs. rotary drum thickener vs. other thickening technologies and the design of the following systems:
- Aerobic digesters and aeration system
- Solids handling – thickening, dewatering, and conveyance systems
- Trucking and haulout facilities
- Odor control
- Mixer replacement
- Grit unit replacement
- Vactor Decant station
- Operations building addition and new control center
- Existing clarifier retrofits
The project was bid in 2017 and awarded to Prospect Construction. Construction is underway and will be completed in early 2019. The Engineer’s Estimate was $11.34 million, and the low bid was $10.41 million. RH2 provided bid phase services and is currently providing construction phase services, and will provide testing and startup support, O&M manual preparation and operations assistance, and SCADA programming.
Phases 4 and 6
The remaining phase include the design of the third secondary clarifier and further evaluation of the oxidation ditch system including a potential aeration system update and conversion to a plug flow reactor. This work is underway currently.