An unstable and weak slime-like foundation was the primary factor behind the Dec. 22, 2008, catastrophic failure of a coal-ash pond at Tennessee Valley Authority’s Kingston plant near Knoxville, Tenn., says a root-cause analysis released last week by AECOM Technology Corp. TVA hired the firm after the accident to determine why dikes holding coal-waste slurry failed, flooding 300 acres around the plant and the Emory River with 5.4 million cu yd of coal ash. Photo: TVA Spill cleanup could cost $1 billion. Los Angeles-based AECOM’s analysis determined the dikes’ angle and setbacks, increased loads because of recent high fill and
The market is generally healthy and steadily growing, and margins are up for large specialty contractors. Further, advances in design tools and owner demand for collaboration are giving subcontractors a seat at the table early on in projects.