Wastewater Treatment Facility Upgrade
City of St. Helena, California

West Yost is assisting the City of St. Helena in the development of the best compliance solution for several outstanding regulatory issues associated with their 0.5 mgd Wastewater Treatment Facility (WWTF). One of the major drivers of the proposed project is the need for expansion of the currently available disposal operations, which include surface water discharge to the Napa River from December through April, and land application on property located adjacent to the treatment facility. This project has capitalized on West Yost’s understanding of and experience with wastewater permitting, and includes ongoing interaction with the San Francisco Bay Regional Water Quality Control Board.This project has involved evaluating the feasibility of several treatment processes to meet surface water discharge requirements and produce recycled water for unrestricted use. Among the alternatives evaluated is the expansion of the existing high-rate pond treatment system, supplementing the pond system with a conventional activated sludge system, or replacing the pond system with activated sludge. Sizing and locating tertiary treatment (filtration) facilities and evaluating the use of alternative disinfectants (UV compared to the existing hypochlorite system) are also significant parts of the project.