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Council authorizes design services to add baffles to Marshall Street Water Reclamation clarifiers after storm-related solids loss
Summary
The council authorized design and construction services to install Stanford-style baffles in four secondary clarifiers at the Marshall Street Water Reclamation Facility to reduce solids carryover during storm events that had previously clogged filters.
City council approved a contract March 3 to design and construct improvements to the Marshall Street Water Reclamation Facility’s four secondary clarifiers aimed at reducing solids carryover during high-flow events.
Background and problem: Public Utilities Director Rich Gardner told the council that during recent storms solids were carried out of the clarifiers into downstream filters and, in some cases, into bypass discharges. The city is seeking to retrofit each secondary clarifier with peripherally installed Stanford-style baffles to lengthen hydraulic residence time near the clarifier periphery and reduce solids carryover.
Technical approach and procurement: The council authorized AECOM to provide engineering design, bidding and construction support for the clarifier upgrades. AECOM’s work will include detailing baffle attachments and modifications to clarifier hydraulics; the overall construction cost was described as a conservative estimate in the millions, with staff characterizing the estimate as below $4 million and noting the work is intended as an intermediate solution until planned plant consolidation and decommissioning in 6–10 years.
Why it matters: Director Gardner said the baffles are a relatively simple, proven retrofit to reduce the risk of downstream filter blinding and the need for emergency bypasses during storms. Councilmembers asked about expected service life (staff estimated 10–20 years for fiberglass baffles) and confirmed the improvements would be removed if the Marshall Street plant is later decommissioned as part of system consolidation.
Outcome and next steps: Council gave consent to proceed with AECOM’s engineering services; staff will return with construction bid documents and a more detailed budget as the design is completed.
Ending: Councilmembers endorsed the measure as a pragmatic step to reduce near-term operational risk while the city pursues longer-range consolidation plans.
