The City of San José Demonstrates Flexibility and Resolution to Accomplish Yard Piping Repairs Safely and Quickly

Submerged and buried assets such as piping, basins, and channels are costly to replace, difficult to inspect, and can catastrophically fail. The digester and thickening facilities upgrade (DTFU) project at the San José-Santa Clara Regional Wastewater Facility (RWF) involved isolation of approximately 2,000 linear feet (LF) of primary effluent (PE) and settled effluent (SES) reinforced concrete pipe (RCP) 78-, 96-, and 87-in. by 136-in. in diameter. During construction, they discovered holes with visible voids and soil at the crown of the 78-in. pipe. The adjacent wye junction structure also showed signs of severe corrosion within the interior top slab. This raised concerns about the neighboring 96- and 87-in. by 136-in. PE pipes, and ability to make future connections as designed. An emergency inspection of additional PE/SES pipes was initiated by the RWF. Flexibility, advanced planning, and proactive communication resulted in obtaining meaningful and actionable condition assessment data in a safe manner, without causing major disruptions to RWF operations. Crown corrosion was observed within all pipes from three inches of loss crown material to voids at the crown extending up to 22-in. into the soil above. This emergency project concluded with the replacement design of 200 LF of 78-in. PE/SES pipe, 10 LF of 87-in. by 136-in. pipe, 16 LF of 96-in. pipe, and wye junction structure with the other rehabilitation work deferred.