Opinions are split on whether TransCanada's revised proposal to build the Keystone XL crude-oil pipeline from Alberta to the Gulf of Mexico will pass muster with the Obama administration. Representatives of organized labor and energy industry groups, which have long backed the $7.6-billion project, say the new plan must move forward. But environmental organizations contend the latest proposal is still not in the U.S. national interest and thus unlikely to be approved.The decision is in the hands of the State Dept., which on May 4 received the new proposal from Calgary-based TransCanada. In January, the department had rejected the company's
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.