COS Rehabilitation Project Case History

摘要

The Central Outfall Sewer (COS) in southwest Los Angeles is one of four major outfall sewers serving the Hyperion Service Area and conveying wastewater to the Hyperion Treatment Plant. This section of the COS was constructed between 1904 and 1908 out of brick and has a 57-inch-wide by 72-inch-tall elliptical configuration (City of LA, 2009, 2010). In the late 1940s an effort was made to rehabilitate portions of the sewer that had experienced corrosion issues. However, ongoing severe corrosion in the years that followed brought continued deterioration of the sewer to the point at which much of it was structurally deficient. The decision was made to embark on a full rehabilitation of approximately 5,200 linear feet of the line between Slauson Avenue and Vernon Avenue in the Mid-City area of Los Angeles. The project also required that the work be done in the wet, along with the abandonment of nine existing maintenance holes (MHs), internal reconstruction of lateral connections, and construction of four new maintenance holes. This paper examines the unique challenges of rehabilitating a live nonround sewer located in a dense urban environment and how they were successfully addressed. These challenges included choosing the correct type of lining material, accessing the sewer, and unexpected inconsistencies that were discovered during construction.