August 2011
Flood Protection System Beats Schedule
The results are in. Data from instruments installed within a big New Orleans levee has allowed the contractors to exceed ambitious schedule-compression goals. The team successfully employed a novel design based on miles of wick drains and geotextile fabrics. The system is achieving soil consolidation and strengthening faster than predicted.
“We're comparing theory to reality in performance,” says Richard Varuso, deputy chief of the U.S. Army Corps of Engineers' geotechnical branch in New Orleans. “Whenever you validate theory versus performance, the engineering community learns something.”
The amount of geotechnical data compiled from the levee reach known as LPV 109 already is informing the design of other projects, including plans to raise a 32-mile stretch of non-federal levees in Plaquemines Parish.
A conventionally built earthen levee comparable to LPV 109 would require a decade of incremental lift placements, separated by long pauses for natural soil compression. By using an elaborate wicking and drainage system rigged with instruments to report soil movement and consolidation within and below the structure, engineers fine-tuned the schedule with lead contractor Archer Western Contractors Ltd., Atlanta. They shaved work duration at sites along the 7.54-mile-long project to 45 to 60 days compared with the targeted 90 days.[read more]