For Water Subcommittee Meeting June 23, 2025
TO: Honorable Water Subcommittee Members
APPROVAL: John Rossi, Interim Utilities Manager
FROM: Toyasha Sebbag, Assistant to the City Manager
Title
Staff request that the Water Subcommittee provide feedback on the Rialto Biosolids Handling Upgrades Project at the Wastewater Treatment Plant. (ACTION)
Body
RECOMMENDATION
Staff recommends that the Water Subcommittee provide feedback on the Rialto Biosolids Handling Upgrades Project at the Wastewater Treatment Plant.
BACKGROUND:
On March 8, 2022, the City Council (City)/Rialto Utility Authority (RUA) Board approved the Final Construction Work Authorization (FCWA) which included, among other projects, for Rialto Water Services (RWS) to complete a Rialto Biosolids Upgrade Study.
On February 14, 2023, the City/RUA Board approved the FCWA for RWS to complete the 30% design, and 60% design and preparation of a guaranteed maximum price (GMP) for Biosolids Handling Equipment.
The GMP is good until August 27, 2025. The City has contracted with Jacobs Engineering to review the costs for the project as proposed and to determine if replacing the equipment that needs rehabilitation would be less expensive. A draft of the FCWA for the construction costs and Veolia fees for this phase of the project was received last week. RWS has provided an engineer’s estimate cost of $34,910,000. Staff are currently evaluating these numbers.
ANALYSIS/DISCUSSION:
The existing biosolids handling equipment, including sludge thickeners and dewatering systems is over 30 years old, beyond its useful life, and in need of replacement. This equipment processes sludge from the aeration basins and primary clarifier, feeds it to the anaerobic digesters, and then dewaters the digested sludge for drying and off-site disposal.
The proposed scope of work includes:
(1) Replacing two gravity belt thickeners with rotary drum thickeners;
(2) Replacing existing belt filter presses with centrifuges;
(3) Performing associated site, mechanical, plumbing, and electrical work, including replacing the digester covers with new inflatable covers; and
(4) Modifying pumps and piping to support the new equipment.
This Biosolids Handling Upgrades Project would enhance operational reliability, provide redundancy, increase digester gas production, and improve sludge dewatering, which would potentially reduce hauling costs. Integration with SCADA would also support advanced monitoring, automation, and future use of Artificial Intelligence (AI) tools for process and energy optimization.
Staff will provide the Subcommittee an update on the project in anticipation of final details, including the Final Construction Work Authorization (FCWA), costs, fees, and schedules coming to the committee in July.
FINANCIAL IMPACT:
Operating Budget Impact
The proposed action is expected to have a positive impact on RUA’s Wastewater Operating Budget, as lower sludge hauling costs are anticipated.
Capital Improvement Budget Impact
Staff is waiting for RWS to provide a cash flow model to ensure funds are available for this and other capital improvement projects anticipated through June 30, 2026.