CONSTRUCTION OF NON-CIRCULAR SEWER REHABILITATION PROJECTS IN LOS ANGELES

摘要

The City of Los Angeles operates and maintains more than 6,500 miles of sewers ranging in size from 6-inch to 150-inch in diameter. Many of the larger diameter sewers constructed in the early 1900's were constructed of un-reinforced concrete with clay tile liners or of brick. Approximately 64 miles of sewers were constructed using non-circular pipes. Some of these sewers do not follow public right-of-way and cross under homes, businesses and other urban development. These sewers are approaching the end of their service life and need to be rehabilitated while minimizing the impact to the community. An emergency construction project is repairing 1,000 feet of an 85-year-old semi-elliptical sewer and two rehabilitation projects have recently been awarded for construction that will repair 4.5 miles of non-circular sewers. This construction begins a new era in rehabilitation of medium sized non-circular sewers in Los Angeles. The rehabilitation of 3 miles of the 60-inch by 73-inch oval brick Central Outfall Sewer (COS), 1.5 miles of the 60-inch semi-elliptical tile-lined concrete North Outfall Sewer (NOS), and 1,000 feet of 66-inch semi-elliptical concrete NOS brick sewer will use man-entry installation of a new pipe, non man-entry sliplining and man-entry cast-in-place-lining construction techniques. Sliplining will utilize recently approved materials that will maintain the non-circular shape of the sewer and minimize the reduction of capacity of the existing sewers. The cast-in-place option will construct a new PVC lined concrete pipe inside the existing sewer. These methods will provide a long-term structural repair of these 80 - 100 year old sewers. This paper will discuss the methods selected for the rehabilitation of the COS and the NOS as well as the lessons learned during the initial phases of the construction projects. This paper will also discuss future projects that will rehabilitate additional non-circular sewers utilizing both sliplining and man-entry methods.