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Ribbon Cutting Held for Wastewater Treatment Plant Upgrade

On Wednesday, October 24, 2018 the City of Davis held a ribbon cutting ceremony for the upgrade of the Wastewater Treatment Plant Tertiary Upgrade project. The construction process for the upgrade took almost 4 years but it was completed on time and within the $95 million budget. The plant upgrade is the largest capital improvement project that the City of Davis has ever built. Dedication speakers included: Davis Mayor Brett Lee, City Manager Mike Webb, Public Works Director Bob Clarke, Wastewater Division Manager John Alexander, City Engineer Dianna Jensen and Assistant Public Works Director Stan Gryczko.

The design-build team of AECO/WM Lyles and its subcontractors were lauded for their successful project partnership with the city during the project. A former City of Davis engineer, Michael Lindquist, was acknowledged for his vital contributions to the early project planning. The city’s Wastewater Treatment Plant staff were congratulated for their work in keeping the original water treatment plant processes running during the time that construction was occurring to create a totally new treatment plant system. The plant operators also had to learn how to operate the new treatment processes while keeping the old plant working.

The planning for upgrading local wastewater facilities began in 2001 when the Central Valley Regional Water Quality Control Board initiated new water discharge limits. Between 2005 and 2009 alternate upgrade plans and designs were discussed. After one original project estimate of $219 million was presented, the Davis City Council directed staff to review other less costly options that would still meet the Water Quality Board’s requirements for effluent limits.

With the assistance of UC Davis professors George Tchobanoglous and Ed Schroeder, wastewater treatment design experts and city staff came up with a wastewater management plan that was accepted by the city council. The project plan was to include: headworks, primary sedimentation, biological treatment (activated sludge), secondary sedimentation, filtration and disinfection processes in addition to temporary storage ponds.

On April 19, 2011 the city council selected the preferred project alternative and the design-build construction approach. The city project management team developed specifications and in July 2013 a Request for Qualifications was released for potential bidders. A Request for Proposals was released in October 2013 and on June 24, 2014, the Davis city council approved AECOM/WM Lyles a Joint Venture as the design-build team.

The new upgraded facility has allowed the city to move from a land-based treatment of sewage with an average treatment time of 40 days to an activated sludge system with an average treatment time of 23 hours while significantly improving effluent quality. The new system treats an average of 4.5 million gallons a day.

The upgraded Wastewater Treatment Plant has also earned the Envision Silver Award for sustainable infrastructure from the Institute for Sustainable Infrastructure.

Mayor Brett Lee stated that, “We now have a modern, efficient plant that produces the highest quality water effluent required in California and will serve the city for many years”.

Pictures from the Ribbon Cutting Ceremony:

Officals cut the ceremonial ribbon
City and County elected officials, City staff, Design and Construction Team members, and others cut a ribbon to dedicate the improved wastewater treatment plant. (photo City of Davis/Robert Schulz)

tour group listens as guide explains treatment process
Wastewater Treatment Plant Lead Operater Chris Mosier describes the treatment process to a group of visitors touring the upgraded treatment plant. (Photo City of Davis/Robert Schulz)

A tour group looks at one of the new basins for treating wastewater. (photo City of Davis/Robert Schulz)

tour group looks into treatment basin
A tour group examines the treatment plant outfall, where treated wastewater enters the Willow Slough Bypass. The upgraded treatment plant produces water that is significantly cleaner, benefitting wildlife and downstream users. (photo City of Davis/Robert Schulz)

aerial photo of treatment plant
Aerial view of the upgraded facility. (photo AECO WM Lyles)

For more information, please contact the City of Davis City Manager’s Office at 530-757-5602 or

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