Two weeks after an 18-in. three-phase common pipeline ruptured on Alaska’s North Slope, spewing more than 1,000 barrels of crude oil, produced water and natural gas from a 24-in. gash, cleanup workers are “trimming” the tundra by hand and with machinery in subzero temperatures to remove oil and produced water. At ENR press time, they had removed the bulk of the spilled material from the surface of the 8,400-sq-ft affected area, says Steve Rinehart, spokesman for producer BP Exploration Alaska Inc. Photo: B. Fultz, Alaska Dept. of Environmental Conservation Spilled material melts for collection with a vacuum rig. Small Bobcat-type
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.