Large Diameter Sliplining Works To Rehabilitate Aging Interceptor Sewers In Albuquerque

By Michael Rocco, Trenchless Manager, AUI Inc. | March 2010 Vol. 65 No. 3

On past Albuquerque jobs, CCFRPM has been used because it is a thin-wall high-strength pipe that can maintain the flow capacity of the existing line. Even in the case of a diameter step-down in sliplining, a pipe with a high flow capacity (low Manning’s value) provides the greatest recovery. Kim Paggioli, P.E. of Hobas Pipe USA, said, “Previous data reported back to us for sliplining installation show that a 0.10 Manning’s value is very reasonable to expect post rehab.”

The biggest interceptor to be rehabilitated totaled 5,234 linear feet of 78-inch RCP, which was sliplined with 66-inch diameter CCFRPM pipe. One of the most difficult jobs in this slipline process was to clean and remove all the silt from inside the old sewer pipe. AUI subcontracted the cleaning operation to Southwest Sewer Service Inc. of Los Lunas, NM. They removed more than 1,500 tons of debris that has been lying in the old 78-inch line and hauled it to the sewer plant. All of the slipline work was done under live conditions without the need for bypass pumping.

The 1,210-linear foot 54-inch sewer interceptor line was rehabilitated with a 48-inch sliplining pipe. This section was located in downtown Albuquerque, so vehicle traffic, pedestrians and business owners were all stakeholders in the construction process. Under the direction of ABCWUA’s project manager, Nancy Musinski, P.E., the work downtown went smoothly and was completed in less than a month.

No open-cut option
The 48-inch sewer interceptor, 2,209 feet long, was sliplined with 42-inch pipe. This section was originally installed in 1966 and the closed-circuit television (CCTV) inspection before the work began revealed an extremely deteriorated condition with exposed aggregate and hanging gaskets. The sewer line ran through the city of Albuquerque’s Solid Waste Yard. One segment actually ran under a service building, so open cut was not an option.

The CCTV inspection of one of the segments revealed three active sewer service lines, which were connected at depths of up to 18 feet.

During the course of the installation, a group of ABCWUA employees assembled on site to watch a demonstration of Hobas CCFRPM pipe being installed by sliplining. They were joined by representatives of AUI, Hobas and others involved in the construction from the general contractor to various subs. In addition to sliplining, the project used another trenchless rehabilitation method, cured in place pipe (CIPP).

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