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Project Flashback—Historical Manson Outfall Projects

In addition to the 18th Ave North Myrtle Beach Ocean Outfall project, Manson has plenty of experience with offshore ocean outfall projects.

Read below about two projects at Point Loma, CA, in the 1990s.

A concrete screed on a construction site.
The screed was developed by the Joint Venture team to place the rock and sand “roadway” underwater to support the pipeline.

Point Loma Outfall Repair Project

In February of 1992, the Point Loma Outfall in San Diego, CA, —which at the time extended 12,500 ft. into the Pacific Ocean—ruptured at a location approximately 3,000 ft. offshore at a depth of approximately 35 ft. Within five days of the rupture, Point Loma Constructors—a joint venture comprised of Manson and Morrison-Knudsen—mobilized to the site to locate the source and repair the problem. The project team discovered several 20 ft. sections— totaling 500 ft.—of pipeline missing, and a disturbed rock cover. The project team reinstalled the missing sections starting at either end of the break location and working toward the center setting new pipe. New rock cover was then placed over the pipe to protect and finish the project.

The Point Loma team worked round-the-clock to complete the project in two months, preventing long-term pollution to the area. The Point Loma Outfall Extension project received several awards including the American Society of Civil Engineers Project Award, Project Managers Institute Award, and the Excellence in Construction Award from the American Public Works Association.

Point Loma Outfall Extension Project Several months later in July of 1992, the project team returned to work on the Point Loma Outfall Extension project. This project was part of San Diego’s Clean Water Program and involved adding an additional 12,500 ft. to the outfall including two 2,500 ft. long diffuser sections which extended the pipeline nearly 5 miles offshore and in a water depth of 325 ft.

A derrick barge in San Diego, California.
The derrick barge HAAKON placing rock on the Point Loma Extension project, San Diego, CA. Photo credit: Hawkins Productions

Manson’s used derrick barge HAAKON to install the bedding for the pipeline—an underwater “roadway” consisting of rock and sand. This supports the pipeline and was placed with a specialty screed built by the joint venture. Each 20-ft.-long, 12-ft. -diameter, 73-ton pipeline section was placed using another joint venture design-built piece of equipment called a “horse.”

Pictured on the cover of Concrete Pipe News is the “horse” Manson created which lowered the outfall pipe sections into place.

The “horse” is a structural rigging tool that allows for remote-control positioning of the pipe from the barge deck above water to join and seal them underwater. With these innovative mechanical solutions, the project team completed the job nine months ahead of schedule.

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