Wastewater Facility Upgrade Project Wins Walsh CSEA High Hazard Award


BY CAROL EATON T


he San Jose Digester and Thickener Facilities Upgrade Project took place within the San Jose-Santa Clara Regional Wastewater Facility, which has evolved since its inception in 1956 to become the largest advanced wastewater treatment facility in the Western United States. The facility treats an average of 110 million gallons per day (mgd) with a maximum capacity of 167 mgd. Walsh Construction overcame a variety of challenges to successfully complete this technically complex upgrade project, earning it the AGC of California Construction Safety Excellence Award for “Safety on a High Hazard Project.” With a final contract value of approximately $178 million and span- ning nearly six years duration, the project’s complexity was amplified by the age of the facility, the presence of numerous hazardous materials, and its location in the center of a fully operational plant. Major scope items for this project included:


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CALIFORNIA CONSTRUCTOR JANUARY/FEBRUARY 2024


• Modifying the four existing 3.5 MG mesophilic anaerobic digesters to convert them into new thermophilic anaerobic digesters, involving an array of scope components.


• Modifying six of the existing dissolved air flotation thickener tanks. Work included demolishing portions of the existing structural concrete, electrical, piping and equipment; new structural concrete; new tank coating and covers; new equipment, piping and electrical; and new thickened sludge structure, equipment, and canopy.


• New thickened sludge equalization tanks, sludge screening building, polymer storage and feed system and odor control facility. Tis work entailed new structural concrete, equipment, piping, electrical, canopy and building finishes.


• A new 3000 linear foot pipe rack system, requiring new concrete footing, columns, and structural steel rack system, and installing new gas piping, sludge and hot water piping. • Installing a 3000 linear foot digester gas bypass system along


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