Name of Facility: Oro Loma/Castro Valley Water Pollution Control Facility
Population Served: Approximately 190,000
Established: Oro Loma Sanitary District was founded in 1911. Construction for the Oro Loma/Castro Valley Water Pollution Control Facility was completed in 1950.
Average Daily Capacity: 20 mgd Dry Weather Capacity, 106 mgd Wet Weather
Advanced Secondary – Modified LudzackEttinger Nitrification/Denitrification Process. Influent flows are nitrified and denitrified, achieving average annual Total Inorganic Nitrogen loads of <10 mg/L and average annual effluent TSS of <5 mg/L. Digester (3.2 million gallons), Cogeneration System (720 watt) with 2 Waukesha Engines, Grease Receiving Facility, Solar Drying Fields (20 acres), Wetland Treatment Basin, and Horizontal Levee Demonstration area.
“The District has maintained an exceptionally high compliance record, achieving over 18 years of continuous NPDES Permit Compliance until 2023, boasting one of the lowest known sewer collection and treatment rates in California, alongside its innovative practices.”
In 2020, the conversion from activated sludge to secondary nutrient removal was successfully achieved. The operations staff reached a total inorganic nitrogen (TIN) concentration of less than 10 mg/L. Credit goes to the Operations team, whose performance results have significantly exceeded design targets, despite the challenges posed by the pandemic.
In 2021, the first full-scale sidestream treatment unit, which facilitates ammonia reduction from Belt Filter Press filtrate, was implemented west of the Mississippi, utilizing an innovative process. Furthermore, an ongoing research partnership with UC Berkeley and Valley Water is currently evaluating the treatment of reverse osmosis concentrate within the District’s Horizontal Levee System. Addressing the treatment of concentrates from water purification presents a considerable challenge for our industry; consequently, collaboration with UCB is pivotal in advancing scientific understanding related to concentrate treatment in natural systems.
The Horizontal Levee Demonstration, established in 2015, has functioned as a living laboratory. A comprehensive $50 million program is in progress to replace 40 miles of collection system piping, representing 15% of the overall system, from 2017 to 2027.5. Additionally, the implementation of a computerized competency-based training module for new hires is underway, which will help maintain ongoing operational knowledge. Beyond these recent advancements, the District has made substantial strides in reducing its energy footprint through the integration of solar energy, fats, oils and grease (FOG) receiving systems, and biogas-based cogeneration systems.
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