Two former employees of Aggregate Industries NE Inc., Saugus, Mass., pleaded guilty on July 8 to 12 charges involving a conspiracy to deliver substandard concrete to the $15-billion Central Artery/Tunnel project. Four more employees are scheduled to go to trial this week in U.S. District Court in Boston. Gerard M. McNally and Keith H. Thomas pleaded guilty to two counts of conspiracy, five counts of mail fraud and five counts of filing false reports stemming from a 2006 indictment alleging that, between 1996 and 2005, the six defendants delivered at least 5,000 10-yd truckloads of “non-specification” concrete to the project.
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.