Arctic Division

10" Pipe Line Constructed Across Turnagain Arm in Alaska's Cook Inlet


Associated's crews were strongly challenged by nature in laying a 10" pipe line across Turnagain Arm, near Anchorage. This dead end waterway which once frustrated the famous Captain Cook on his search for a "passage to India", has the second highest tide fluctuation in North America, reaching 38 feet at certain periods. At each low tide, our lay barge came to rest on the sea floor, dramatically halting construction. But, as the picture illustrates, we were able to see the "underwater" trench and to daily note our progress along the "right-of-way." Naturally, these extreme tidal conditions resulted in very strong currents. As the waves advanced or retreated, our lay barge required extra strong moorings to hold our position, or we would have separated from the pipe line. Despite these unusual conditions our crews successfully completed this Alaskan pipe line, too.

 

 

Associated Builds Important Segment of Trans-Alaska pipe line.

Right-of-way preparation was one of the most important phases of construction on the trans-Alaska pipe line project. Environmental requirements and governmental regulations dictated that all operations be performed from a work pad. A year before start of actual pipeline construction, tons of gravel were hauled in, spread, and leveled to grade in the construction of the work pad. An all-weather steel-girdered bridge crossing the Yukon was completed in 1976. This bridge paralleled the pipe line right-of-way, and we installed the 48" pipe line on the side of the bridge for the aerial crossing of the Yukon in the same year. Prior to completion of this bridge, we operated a 130-ton hovercraft as a ferry in the summer and as an air-cushioned transport after the river iced over in the winter. Many varied and unusual conditions were encountered during the construction of this remarkable pipe line system. Temperatures ranging from +90° F to below -60° F, permafrost, mountainous terrain with over 30 degree slopes, hard rock, dense forests, caribou migratory trails, and hibernating bears were just the more memorable problems that we faced. At the end of 1975, we had completed 60 percent of the pipelaying activities required in Section 4. During 1976 we completed all pipelaying operations including the installation of 46 miles of aboveground pipe line and 12 miles of buried pipe line. In addition to the 127 miles of 48" pipe line that we installed in Section 4 over the two-year period, we also constructed 16,154 vertical supports, 27 mainline valves, and installed 94.4 miles of insulation on the aboveground sections of the pipe line. In full operation, the trans-Alaska pipe line system will transport two million barrels of crude oil per day from the wells on the North Slope to the pipe line terminal and ice-free port at Valdez, Alaska. We are proud to have been chosen as one of the execution contractors in the construction of this great pipe line system. We are especially proud of all our personnel assigned to this project who worked long hours under very difficult conditions to establish our company as the leading contractor on the entire system. The experience that these people gained on the trans-Alaska project will be, we believe, of invaluable assistance to our company on future Arctic pipe line projects.