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Rehabilitation of a Hydraulically Limited Sewer 30-Feet Deep Under Interstate-5
Author: Robert K. Lee, P.E.1, and Patty M. Nelson, P.E.2; 1 Brown and Caldwell, Portland, OR; 2 City of Portland Bureau of Environmental Services, Portland, OR
Date: 4/912
Preprint, North American Society for Trenchless Technology (NASTT) No-Dig Show 2012, March 11-15, 2012, Nashville, TN

With a planned expansion to an upstream pump station, the City of Portlandís Bureau of Environmental Services, Oregon (City), determined that portions of their 60-year old Burlingame Trunk sewer were undersized and hydraulically limited. In designing a replacement sewer to increase size from 30-inch to 48-inch, the City discovered that more than 1100 linear feet of existing sewer was located under the ramps to Interstate 5, and another 350 linear feet was a perpendicular crossing, 30-feet below the Interstate. New sewer pipeline installation within the Interstate ROW, even with trenchless methods, was prohibitively expensive. However, the City realized that the steep slopes provided the additional required capacity, if a thin enough cured-in-place pipe was utilized to minimize the loss of inside diameter. a reinforced or composite cured-in-place pipe was utilized that provide limited loss of inside diameter. Laser profiling was performed and the Contract Documents were developed to ensure the pipe met the hydraulic demands and design life according to the Cityís requirements. Construction begain in late summer 2011. This paper discusses the CIPP process with a focus on the capabilities of the composite materials, its abrasion resistance requirements when examining peak flow velocities of 20 feet per second, project constraints related to the shutdown of ramps, and CIPP test results, and lessons learned during construction.