Balfour Beatty is constructing tertiary treatment facilities at the 343 MGD Sacramento Regional Wastewater Treatment Plant as part of the $2 billion EchoWater project.
The advanced “tertiary” level of treatment capable of treating 243 MGD is applied to secondary effluent (SE) after it undergoes biological nutrient removal (BNR). Tertiary-level filtration will better remove smaller particles and pathogens such as viruses and bacteria, and enhanced disinfection will help inactivate any remaining pathogens.
The project encompasses three major unit processes including: 1) Filter Influent Pumping Station (FIPS), 2) Granular Media Filtration (GMF) and 3) Disinfection Contact Basins (DCB).
The FIPS conveys SE from the existing SE channel to the GMF inlet structure. The FIPS includes tie-ins to the SE channel, drum screens, pump wet wells, discharge headers and flow metering.
GMF includes a Seasonal Flow Diversion Structure (SFDS), chemical mixing, granular media filters, filter backwash system, waste filter backwash (WFBW) equalization basins and backwash return pumps. GMF consists of anthracite and sand as dual media filters. The filtered effluent is mixed with disinfectant downstream and conveyed to the DCB.
The DCB components consist of disinfectant mixing, influent and effluent channels, disinfection contact basins and dechlorination.
During high flow events such as wet and winter weather, up to 100 MGD of excess unfiltered SE is diverted by the SFDS and will provide the required chemicals, mixing, and disinfection contact time to meet permit performance requirements before being conveyed to the existing effluent pump station for discharge to the Sacramento River, or distributed as reclaimed water.
Other elements of the project include an Area Control Center (ACC), substations, transformer yards, pumping stations, chemical storage and feed systems, stormwater handling and detention, civil and electrical site work and an Effluent Observation Structure (EOS).
The tertiary improvements will produce cleaner water for discharge to the Sacramento River and help protect the Delta downstream. The project also increases opportunities for water recycling, by producing highly treated water that meets water reuse determined by the California Department of Public Health, Title 22 Code of Regulations.
The EchoWater Tertiary Treatment Facility is expected to be complete by November 2022.