For nearly 30 years, West Yost has acted as the City of Davis’ trusted advisor for its treatment planning, design, and construction needs. West Yost has completed the planning and design for a major expansion to the Water Pollution Control Plant (WPCP). In support of the City, we have continued to provide additional services with alternative analysis and providing solutions on challenging problems, as described below:
Water Pollution Control Plant (WPCP) Facilities Planning and Design, Major Expansion and Upgrades
This wastewater facilities planning process incorporated Davis’ unique vision of combining natural treatment systems with conventional treatment processes to provide reliable effluent water quality while creating wetlands and other habitat features that have served as a showplace and resource for the region for almost 20 years.
Strategic Master Plan
As trusted advisor for Davis, West Yost contributed to the development of a Strategic Master Plan in 2005, which identified a number of major facility improvements needed to meet increasingly stringent effluent limitations for surface water discharge. These limitations included requirements for nitrification, denitrification, filtration and advanced disinfection of Davis’ wastewater.
Conaway Ranch Reuse Project Alternatives
West Yost identified and evaluated a year-round reuse alternative on the 17,000-acre Conaway Ranch site which led to a reduced-scale treatment facilities upgrade project in 2011.
Owner’s Advisory Services for $90M Design-Build Procurement for the Treatment Facilities Upgrade Project
These services involved an year-long planning effort where the vision for the treatment plant was reimagined at a reduced scale. These planning efforts included preparing a Procurement Guidance Document, a Preliminary Design Report, and a design-build procurement document. The revised vision for the treatment plant ultimately resulted in a Design-Build project that is less than half the cost of the project developed through the 2005 Master Planning effort. After assisting Davis with election of the preferred Design-Build team, West Yost provided continued support related to the design, construction and commissioning of the new treatment plant improvements. This support included evaluating the BioWIN models that were developed by the selected team to help secure the project’s successful completion. Our multifaceted approach to achieving success on this project includes providing a high-quality design-build contract to manage risk, allow for innovation, and provide the best value for Davis, resulting in a practical design that enabled Davis to meet discharge requirements by 2017 at the lowest life-cycle cost. This effort also included working with Davis to obtain the Envision Sustainability Silver rating for the upgrade project.
Recycled Water Master Plan
In parallel with the completion of the Treatment Facilities Upgrade project, West Yost was retained to develop a Recycled Water Master Plan for the use of new water supplies that are generated by the upgraded facilities. The analysis included assessing the available recycled water supply and projecting demand for both municipal landscape irrigation and agricultural irrigation applications, identifying potential reuse scenarios, comparing reuse scenarios and estimating costs for each reuse scenario.
Sampling Plan in Support of The City’s Comprehensive Plant Model
West Yost developed a sampling plan to help the City with a comprehensive plant model that could be used to assess the capacity of all the facilities.
Development of BioWIN Calibrated Model of New Nitrogen Removal Facilities
Calibration models were used to evaluate the performance of the secondary process facilities under design conditions specified in the design-build. The goal was to confirm that if the project met the secondary process facilities and if surplus secondary treatment capacity beyond the design capacity as defined by the design-build contract was available.
Struvite Study and Mitigation Measures Project
West Yost is currently completing a study to evaluate the cause and identify potential mitigation measures for struvite (a phosphate mineral) that has formed in several components of the solids treatment process system. The evaluation includes the development of a chemical equilibrium model to estimate the potential formation of struvite in the solids treatment process systems; use of the BioWin model to evaluate modifications to the MLE process to reduce phosphorus removal; and evaluation of alternatives for struvite mitigation.