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Composites Get Los Angeles Ready for Rain

14 September 2008

When an almost 80-year-old, semi-elliptical sewer pipeline in Los Angeles showed signs of imminent failure, the emergency solution was a new liner of fibre-reinforced polymer (FRP) composite panels manufactured by Channeline International.

The resin formulation for Channeline’s composite production incorporated Vipel corrosion-resistant technology from AOC.

The new composite liner was part of a major emergency repair of the North Outfall Sewer (NOS) of the City of Los Angeles. The NOS was built between 1923-1929 using cast-in-place concrete to form a semi-elliptical pipeline that connected the San Fernando Valley to the Los Angeles sewer system. Clay tiles were applied to the pipe interior to form a protection layer.

A video inspection of the NOS system in 2007 revealed that the 290-foot (88-meter) long upstream section of the old, non-circular concrete sewer pipe had deteriorated. The reach included several curved alignments of about 100 feet (30 meters). With most of the clay tile protective layer missing, the potential for failure in the near future was imminent.

As a result, Channeline International Ltd. was contracted in late October to assist in the design and installation of composite liner panels on an emergency basis. Channeline manufactured the panels using a design solution based on the work of WRc, a UK-headquartered, global engineering consultancy that specializes in water and wastewater systems.

The panel cross section was semi-elliptical in shape and had a width of 47 inches (1194 millimeters) and a height of 40 inches (1016 millimeters). The panels were manufactured in a resin matrix that used Vipel technology from AOC to achieve required structural properties and long-term resistance to corrosive attack.

To make the panels, Channeline used a hand lay-up construction in which a polymer resin core was sandwiched between layers of Vipel resin-impregnated glass fabrics. The reinforcement was a combination of unidirectional fiberglass mat and chopped strand mat.

“The AOC resin met our needs to have a fairly long pot life and be able to lay up the thick laminates and core without slump or sag,” said Robert Walters, Chairman, APS Dubai, of which Channeline is a wholly-owned subsidiary. “The AOC service was generally of an exceptionally high standard. We particularly appreciated the fact that AOC export manager Steve Olle saw to it that we got what we needed when we needed it.”

The composite panel sections were shipped by mid-February 2008 from the Channeline manufacturing facility in Dubai. The panels arrived at the Los Angeles jobsite in mid-April and were installed in a matter of weeks. The panels were site-bonded together using a proprietary epoxy putty bonding agent called “Channeline 3000,” which provides exceptional high strength and a long term bond.

The bypass pumps were shut off in May to allow the full flow to pass through the newly rehabilitated system. The North Outfall Sewer was ready for the next time it pours in Southern California.






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