BP is keeping a lid on its runaway Mancondo well in the Gulf of Mexico, despite four leaks that developed in and around the well since July 14, when BP installed new shut-off valves. BP and federal emergency response officials believe the well bore is sound; they will continue tests in 24-hour increments with the valves closed. BP and federal overseers agree the “seepage” is not enough to signal a failure of the well bore, although they are watching closely. Two leaks are in equipment at the wellhead, and two others are “a few thousand feet” and two miles away,
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.