NOS Unit 10
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PROJECT details
Client: City of Los Angeles
Location: Los Angeles, CA
Capabilities: Rehabilitation, Value Engineering / Design Build
Services: Bypass Pumping, Sliplining, Cement Mortar Lining
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The North Outfall Sewer (NOS) has been a critical component of Los Angeles’ sewer infrastructure since 1925. Almost a century later, the NOS is found in an advanced state of deterioration with high levels of debris impacting hydraulic capacity and severe corrosion compromising structural integrity. This abstract examines the multifaceted challenges faced by the City of Los Angeles and its partners in the rehabilitation of the NOS from the 101 Freeway to Cardinal Street utilizing non-circular Reinforced Polymer Mortar Pipe (RPMP).
Originally constructed in 1930, the Unit 10 segment of the NOS features a Burns McDonnel Semi-Elliptical (BMSE) concrete sewer lined with tiles, comprising 1,426 feet of 48-inch pipe, 3,397 feet of 54-inch pipe, and a unique 39 foot “squash box” segment crossing under a 108-inch LA County Storm Drain. The alignment navigates five angle points and six curves, with about 65% of the alignment passing beneath private property owned by Union Pacific Railroad (UPRR) and San Antonio Winery, posing significant engineering challenges.
Seamless coordination was essential with various jurisdictions, including LA County, Southern California Regional Rail Authority, Metrolink, Amtrak, UPRR, LADOT, and Caltrans. Critical project hurdles included innovative design alternatives, worksite constraints, obtaining temporary construction easements, railroad and county coordination, utility relocations, odor control, sewer bypass strategies, deep excavations, supply chain, custom RPMP fabrication, and traffic control. This session highlights the strategies employed to overcome these complexities, ensuring the successful rehabilitation of the NOS Unit 10 while maintaining uninterrupted service for Los Angeles residents.
