Case Study: New Orleans Flood Protection Design Flaws Revealed During Construction (2011)

Project Overview
• Name: New Orleans Hurricane and Storm Damage Risk Reduction System (HSDRRS)
• Location: New Orleans, Louisiana
• Year: 2011
• Project Size: $14.5 billion
• Scope: Construction of levees, floodwalls, and pump stations for hurricane protection
• Lead Agencies/Contractors: US Army Corps of Engineers /

Category of the Issue, Problem, or Challenge
• Design
• Hydraulic and Geotechnical Engineering

Summary of the Issue, Problem, or Challenge
During construction of floodwalls, design shortcomings related to foundation stability and seepage control necessitated redesign and additional ground improvement works to prevent future failures.

Root Cause Analysis

• Design underestimated soil permeability and seepage forces.
• Insufficient consideration of long-term soil behavior under flood conditions.
• Lack of full-scale testing of foundation design concepts before construction.
• Limited feedback loops between construction observations and design refinements.

Impacts Due to the Issue, Problem, or Challenge
• Construction delays exceeding 9 months.
• Additional costs estimated at $35 million for redesign and ground treatment.
• Heightened public scrutiny and demand for increased safety assurances.

Corrective Actions Taken

1. Redesigned floodwall foundations with enhanced seepage control measures.
2. Introduced extensive ground improvement and drainage systems.
3. Established continuous monitoring and feedback system between field and design teams.
4. Conducted pilot tests and modeling to validate redesigns.

Lessons Learned

• Accurate hydrogeological analysis is critical for flood protection infrastructure.
• Design must anticipate long-term soil and water interaction effects.
• Iterative design-construction feedback improves system reliability.
• Pilot testing validates critical design assumptions before full-scale work.

Audit & Prevention: Project Control Questions to Ask on Future Projects to Help Control the Situation

• Are seepage and soil conditions comprehensively assessed?
• Does design incorporate long-term environmental interactions?
• Is there a formal feedback process between construction and design teams?
• Are pilot tests used to validate foundation and seepage control designs?