Rotating Pipe and Differing Site Conditions

摘要

The Central Outfall Sewer (COS) Rehabilitation Slauson to Vernon Project rehabilitated approximately one mile of the 110-year-old 57-inch by 72-inch elliptical shaped brick pipe between Slauson Avenue and Vernon Avenue in the City of Los Angeles using trenchless technology. The project was constructed for $6.8 Million by Mladen Buntich Construction Co. Inc. Through prolonged exposure to sewer gases and aging, the COS became structurally compromised and materially deformed. The steel mandrel, utilized to clean and proof the sewer, became stuck within the host pipe due to the unanticipated pipe deformation. As a result, multiple modifications were made to the mandrel to successfully complete cleaning and proofing operations. It was also necessary to remove the anti-rotation devices on the liner pipes manufactured by Channeline. The Contractor was able to install the liner pipe at a rate of approximately 1000 linear feet per day without crushing the pipe or damaging the pushing machine. Even though the pipe installation went smooth, the deformed shape of the brick sewer and the removal of anti-rotation devices caused the liner pipe to rotate through the push and emerge at the receiving pit at an angle. Construction of transitional collars were required to connect to maintenance hole structures to maintain vertical alignment at the receiving pit. In addition to the challenges caused by the different site conditions, a “squash” box was constructed to accommodate an overcrossing storm drain cutting through the COS.