Construction of two new aeration basins and retrofit of four existing basins to provide denitrification of 15 MGD of secondary effluent. Upgrades included new Nueros Turbo Blowers that allow the City of Vacaville, CA to meet new energy efficiency requirements. Additional improvements included a new 200,000 SF equalization basins, new Huber plate screens and washer compactors, a 2 MW emergency generator, and SCADA upgrades. We carefully developed the sequence of construction to minimize operational impact to the plant while still improving schedule.