West Yost performed planning and design services for two major projects at the City of Vacaville’s Easterly Wastewater Treatment Plant (EWWTP), a $100 million Expansion/Upgrade Project and a $130 million Advanced Treatment Project.
Major facilities planned, designed, and constructed included a secondary process expansion, with the addition of nitrification and denitrification, construction of tertiary filters, a chlorine contact basin expansion, flow equalization facilities to eliminate blending, administrative/laboratory/O&M facilities, and the demolition and phase out of existing facilities.
The planning work was developed in two phases and culminated in the 2010 Master Plan, which is referred to as the Tertiary Treatment Project Facilities Plan. This planning document is built off of the City’s 1996 Master Plan, also developed by West Yost, that provided a forward-thinking, flexible approach that has stood the test of time from a regulatory and facility planning perspective.
Specifically, Vacaville was faced with a decision regarding if and how the old existing plant (North Plant) should be incorporated into an expanded plant.
West Yost conducted an extensive assessment of the existing structures, which included rigorous cost estimating, to determine the capital expenditures required to bring the old facilities up to comparable performance and reliability expectations of new facilities. This thorough analysis identified a strategy for maximizing the use of existing facilities without investing significant dollars, in order to minimize unnecessary expenditures as the older facilities were phased out/abandoned over a 10- to 15-year period. A new, readily-expandable South Treatment Plant was constructed to operate in parallel with the old (North) plant, with the expectation that the old plant would eventually be abandoned with capacity replaced in the South Plant.
The 2010 Master Plan identified a comprehensive program of improvements that phased out the North Plant facilities and upgraded the South Plant facilities to meet new regulatory requirements that mandated stringent ammonia and nitrate limits, eliminated blending, and enabled compliance with dry weather filtration/Title 22 reclamation standards. The evaluation of nutrient removal facilities included developing a calibrated BioWIN model of the treatment facilities to define the capacity requirements. The blending analysis identified and compared alternatives for eliminating blending, such as providing additional hydraulic treatment capacity to accommodate peak wet weather flow conditions, equalizing flows upstream of the hydraulically-limited systems to ensure capacity is not exceeded, or to provide some combination of equalization and treatment process expansion. The recommended combined strategy resulted in the lowest-cost approach for meeting the blending elimination goals.
West Yost recently designed an acetic acid storage and feed system at Vacaville’s wastewater treatment plant. The system is being used to promote more reliable denitrification at the wastewater treatment plant. This design effort required detailed research on storage and materials requirements for various acetic acid strengths, as our engineers discovered inconsistencies in the then-current engineering recommendations. West Yost is also currently providing engineering services for the design of odor control systems at the Vaca Valley Lift Station and Easterly Wastewater Treatment Plant.
West Yost won the CWEA Redwood Empire Section, 2007 Engineering Achievement Award for this project.
Team Spotlight
Thomas Hendrey, PE
Principal Engineer II
Thomas Hendrey, PE
Principal Engineer II
“I enjoy applying science to solving problems. I am happy and prefer performing “nuts and bolts” engineering tasks all day long more than the project management end of things. I spent 20 years in the petroleum industry and when it crashed, I needed to pivot. A friend who worked in the water industry enlightened me that water is an excellent, timeless industry because it is everywhere. And I’ve learned for interesting water work you don’t need a giant firm. There are firms like West Yost which provide paths to success and provide a really nice atmosphere.
I am very proud of the work I have done over the years for Dublin San Ramon, we managed to keep a good client for a long time by giving them excellent solutions in various projects over the year including a master plan, cogeneration and digester gas, and primary clarifiers projects. A client that gives you more work because they are happy with what we have done.
Kathryn Gies, PE, ENV SP
Regulatory and Planning Practice Area Leader, Engineering Manager II
Kathryn Gies, PE, ENV SP
Regulatory and Planning Practice Area Leader, Engineering Manager II
“As a facilities planner, I help guide our clients through process of evaluating treatment alternatives and selecting the solutions that provide the most sustainable approach for their community. Helping communities select and implement effective solutions for achieving environmental protection and water reuse is so rewarding.
What I’m most proud of are the long term relationships I have with clients. I have been working with a large percentage of the clients that I work with today since I started at West Yost over 20 years ago. These long-term relationships not only make me feel like a valuable member of their team, but I also feel like a real member of their community.”