Case Study: Cost Overrun from Inadequate Soil Stabilization on Louisiana Levee Construction (Louisiana, 2011)

Project Overview
• Name: Louisiana Coastal Levee Strengthening
• Location: Louisiana
• Year: 2011
• Project Size: $400 million
• Scope: Construction and reinforcement of flood protection levees
• Lead Agencies/Contractors: U.S. Army Corps of Engineers /

Category of the Issue, Problem, or Challenge
• Geotechnical
• Cost Management

Summary of the Issue, Problem, or Challenge
Insufficient initial soil stabilization measures led to levee settlement and rework, increasing costs and delaying project completion.

Root Cause Analysis

• Underestimation of Soil Conditions: Poor initial soil testing underestimated compressibility and settlement risk.
• Inadequate Stabilization Methods: Chosen techniques were insufficient for local soil variability.
• Rework Requirements: Additional soil treatment and reconstruction required during construction.
• Contractor Coordination Issues: Delays in implementing corrective measures extended schedule.

Impacts Due to the Issue, Problem, or Challenge

• Cost overruns estimated at 20%.
• Project delays of up to 8 months.
• Increased risk perceptions among local stakeholders.

Corrective Actions Taken

1. Conducted comprehensive soil re-assessments and monitoring.
2. Implemented enhanced ground improvement techniques (e.g., deep soil mixing).
3. Improved contractor communication and rapid response protocols for geotechnical issues.
4. Increased contingency planning for soil-related risks.

Lessons Learned

• Thorough geotechnical investigations are vital for reliable cost and schedule estimates.
• Early detection and response to soil issues reduce rework and overruns.
• Collaboration between geotechnical experts and contractors improves outcomes.

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

• Are soil investigations sufficiently comprehensive for the project scale?
• Is there continuous soil condition monitoring during construction?
• Are risk contingencies included for potential geotechnical challenges?