Unofficial Notice of Invitation to Bid (NIB)

Union Sanitary District is seeking bids from qualified and interested contractors for the following project titled, PRIMARY DIGESTER NO. 6 REHABILITATION PROJECT, identified under Solicitation ID: 800-588. Work is to be performed near 5072 Benson Rd, Union City, CA 94587, USA in Alameda County.

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General Project Description

This project involves the rehabilitation of Primary Digester No. 6, encompassing a comprehensive range of improvements. The scope includes recoating and repairing the digester cover and its anchors, demolishing the existing mixing system, and installing a new Vaughan Rotamix digester mixing system with updated piping and valves. Additional work items consist of adding surface wasting and bottom digestate withdrawal with new pumps and piping, replacing Hot Water Circulation Pumps No. 6 and 7, Sludge Recirculation Pump No. 6/7, and associated electrical and instrumentation equipment, including VFDs. Replacement of digester gas safety/handling equipment and piping, demolition of existing above-grade piping, and installation of glass-lined DIP are also required. Further tasks involve replacing MCC 26 and Panel C82102, replacing Plant Hot Water Pumps No. 1 and 2 and triple-duty valves with modifications to the plant hot water loop piping, and installing a simplex sump pump and replacing the digester cover grating and HMB4 duplex sump pump. The project also mandates the installation of digester overflow piping and modifications to Plant Hot Water piping, Heat/Mixing Buildings 1 and 2, and existing PLC -20 control panel backpanel.

General Bid Items

Quantity: - Unit: - Work Item: Recoating the digester cover.
Quantity: - Unit: - Work Item: Repairs to portions of the digester cover.
Quantity: - Unit: - Work Item: Repair of the digester cover anchors, without lifting the cover.
Quantity: - Unit: - Work Item: Demolition of the existing Primary Digester No. 6 mixing system.
Quantity: - Unit: - Work Item: Installation of the Vaughan Rotamix digester mixing system including updating the piping configuration and associated valves.
Quantity: - Unit: - Work Item: Addition of surface wasting and bottom digestate withdrawal from Primary Digester 6 with the addition of a new pump and piping.
Quantity: - Unit: - Work Item: Replacement of the Hot Water Circulation Pumps No. 6 and 7, including all electrical and instrumentation equipment and connections.
Quantity: - Unit: - Work Item: Replacement of Sludge Recirculation Pump No. 6/7, including all electrical and instrumentation equipment and connections.
Quantity: - Unit: - Work Item: Installation of VFDs and associated equipment for the new digester mixing pumps.
Quantity: - Unit: - Work Item: Installation of VFDs and associated equipment for the Sludge Recirculation Pump No. 6/7.
Quantity: - Unit: - Work Item: Replacement of digester gas safety and handling equipment and digester gas piping.
Quantity: - Unit: - Work Item: Demolition of existing above grade piping associated with Primary Digester No. 6.
Quantity: - Unit: - Work Item: Installing glass-lined DIP.
Quantity: - Unit: - Work Item: Replacement of MCC 26.
Quantity: - Unit: - Work Item: Replacement of Panel C82102.
Quantity: - Unit: - Work Item: Replacement of the Plant Hot Water Pumps No. 1 and 2, triple-duty valves.
Quantity: - Unit: - Work Item: Modifications to the plant hot water loop piping.
Quantity: - Unit: - Work Item: Installation of a simplex sump pump outside near the Heat/Sludge Control Area.
Quantity: - Unit: - Work Item: Replacement of the existing digester cover grating.
Quantity: - Unit: - Work Item: Replacement of the HMB4 duplex sump pump.
Quantity: - Unit: - Work Item: Installation of digester overflow piping.
Quantity: - Unit: - Work Item: Modification of Plant Hot Water piping and Heat/Mixing Buildings 1 and 2.
Quantity: - Unit: - Work Item: Modification of existing PLC -20 control panel backpanel.
Quantity: - Unit: - Work Item: Adequate sheeting, shoring, and bracing, or equivalent method, for the protection of life and limb in trenches and open excavation (required as a bid item per California Labor Code Section 6707).

NAICS Classification

NAICS 237110 – Water and Sewer Line and Related Structures Construction, NAICS 237990 – Other Heavy and Civil Engineering Construction, NAICS 238210 – Electrical Contractors and Other Wiring Installation Contractors, NAICS 238220 – Plumbing, Heating, and Air-Conditioning Contractors

Records and Due Date

This bid opportunity was entered into BidAmerica on February 6, 2026, and was last updated on February 26, 2026. All bids and/or proposals are due on April 7, 2026.

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All bidders are responsible for reviewing and verifying all official bid documentation directly from the issuing agency. BidAmerica aggregates public bid information for advertisement purposes for contractors and government agencies convenience. This Notice of Invitation to Bid is for reference purposes only and is not an official or complete representation of any documents issued by Union Sanitary District. BidAmerica does not guarantee the accuracy, completeness, or timeliness of any information displayed and shall not be held liable for any errors, omissions, misinterpretations, or damages resulting from reliance on this summary. Contractors must obtain all official information—including plans, specifications, addenda, deadlines, submission requirements, qualifications, and bidding conditions—directly from Union Sanitary District prior to bidding.