Easterly Wastewater Treatment Plant Tertiary Project Denitrification and Filtration Improvements

Timely upgrades result in compliance with new requirements

The City of Vacaville, California, is well on its way improving its Easterly Wastewater Treatment Plant and fulfilling a time-sensitive mandate to limit the amount of suspended solids and nitrates emitted into its waste stream.

Operational 24/7, the plant treats up to 15 million gallons of raw sewage per day. To comply with the Regional Water Quality Control Board’s new discharge requirements, the City launched a multi-million dollar upgrade program with the goal of providing tertiary level treatment by 2015.

At the outset, Harris performed a biddability/constructability review for Phases 1 and 3 of the program. The team has since provided construction management services on both projects within the program, including a $22.5 million construction project to prepare the plant for denitrification and a filtration process with a construction cost of $50.5 million.

Harris' work to date on the denitrification project has resulted in holding cost changes to less than 1% for errors and omissions in the contract documents. In addition, the Harris team has provided valuable cost reduction recommendations, including the elimination of the equalization basin drain mats—resulting in considerable savings to the City of Vacaville. 

Core Elements

Harris has provided construction management services for two phases of the improvement program, which have included:

  • Aeration basin additions and modifications
  • New aeration blowers, including a new electrical building
  • Washer/compactors, perforated plate screens, sludge grinders and pumps
  • Flow equalization basins
  • Replacement biosolids storage lagoon
  • Added 2Mw standby electrical generator
  • Piping systems 
  • New filtration complex
    • Six filter basins
    • Chemical storage and injection systems
  • New clarifier and RAS pumps
  • Two new influent pumps
  • New digester boilers and associated infrastructure
  • Demolition of North Plant Systems
    • Secondary clarifiers
    • Blowers
    • Biosolids system
    • DAFTS 1&2
  • Replace roof on secondary digester
  • New DAFT
  • Replace electrical distribution system for North Plant

 Beyond the Blueprints

With time-sensitive programs like this one, every milestone matters. Harris has worked closely with the contractor every step of the way—conducting weekly schedule updates, formal monthly schedule reviews and diligent analysis of the critical path.

When the project required technical and physical changes to resolve a piping design and construction challenge, open communication between all team members enabled progress without affecting the critical path schedule.

Success of these projects is the direct result of Harris' leadership, dedication, communications, teamwork and problem solving among the key stakeholders.

The experience, expertise and commitment of the Harris team has played an important role in keeping the plant improvement program on track, on time and on budget for the City.

Meet the Team

Vern Phillips, PE

Vern Phillips, PE

Principal Engineer / Engineering


City of Vacaville


Vacaville, CA




Construction Management