Wastewater Treatment Plant Nutrient Removal Alternatives Evaluation and Facilities Plan Project

The City of Benicia is soliciting proposals from qualified consulting firms to prepare a Facilities Plan evaluating nutrient removal technologies and alternatives to address new nutrient reduction requirements or potential water resilience needs.

The selected consultant will review existing background data, develop a whole-plant process model, identify and evaluate feasible nutrient removal and resiliency alternatives, and prepare a comprehensive facilities plan detailing findings and implementation strategies. Optional tasks may include a wastewater characterization study to refine the process model prior to design.

The project duration is anticipated to be approximately ten (10) months. All deliverables will be submitted in PDF format. The City of Benicia looks forward to collaborating with an experienced consulting firm to address this new regional challenge.

On July 10, 2024, the Regional Water Board adopted Order R2-2024-0013 that outlines waste discharge requirements for nutrients from municipal wastewater discharges to San Francisco Bay (NPDES Permit CA0038873). As part of this order, the City of Benicia Wastewater Treatment Plant’s (WWTP) effluent was required to meet an interim effluent limit of 290 kg/day of total inorganic nitrogen (TIN) starting October 1, 2024, and a final effluent limit of 120 kg/day of TIN starting October 1, 2034. The interim and final limits are for the average discharge from May 1 through September 30 of each year.

There are two potentially significant factors in Benicia that may affect the analysis of alternative means of removing TIN. There is a proposed development, the “Rose Estates Development”, that is expected to go forward, and that is expected to increase the loading to the City’s WWTP by roughly 0.5 MGD that may be slightly more concentrated as a result of modern water fixture building requirements. This should factor in as an addition to what is found in existing data, and any data generated on loading rates over the course of this work. There is also a possibility that the Valero Benicia Refinery will cease to be operated by Valero Refining Company. If this happens, and if another petroleum corporation does not take over operation of the facility, it will have a great impact on the City’s Water Treatment Plant and Distribution system, which may lead to a greater interest by the City to review options of direct or indirect potable reuse, or recycled water for overall water resiliency.