Emergency CFRP Repair of the City of Sacramento 120-in. RCP Pioneer Outfall: Railroads, Levees, and Vacuum Conditions

The City of Sacramento (City) has a combined sewer system that is served by a 23 MG storage/primary treatment reservoir (Pioneer). Pioneer is connected to a 120-in. diameter reinforced concrete pipe (Pioneer Outfall) that discharges treated combined wastewater from Pioneer to the Sacramento River during extreme storm events, making this outfall a critical relief system. The Pioneer Outfall extends under a railroad and through a levee into the Sacramento River. The City reported leakage at joints during a storm event. An internal pipe inspection identified cracks, missing mortar at joints, and joint separation. Internal joint testing found four leaking joints. The criticality of the pipe and urgency of completing this repair prior to the upcoming wet-weather season challenged the design team to think "out-of-the-box" and recommend Carbon Fiber Reinforced Polymer (CFRP), a fully structural repair solution. The CFRP rehabilitation was designed to withstand vacuum pressures and railroad loading and was installed successfully in less than 2 weeks as an emergency project to return the Pioneer Outfall to normal operations for the wet-weather season.