Case Study: Discovery of Contaminated Soil Causes Site Remediation and Delay in California (2019)

Project Overview
• Name: San Francisco Bay Bridge Eastern Span Replacement
• Location: San Francisco, California
• Year: 2019
• Project Size: $6.5 billion (entire span)
• Scope: Bridge replacement with extensive foundation and approach work
• Lead Agencies/Contractors: California DOT (Caltrans) /

Category of the Issue, Problem, or Challenge
• Geotechnical
• Differing Site Conditions
• Environmental

Summary of the Issue, Problem, or Challenge
Unexpected contaminated soils discovered during foundation excavation required extensive environmental remediation, halting construction.

Root Cause Analysis

• Incomplete pre-construction environmental site assessments.
• Lack of soil sampling in historical industrial use zones.
• Insufficient integration of environmental and geotechnical investigations.
• Contract lacked clear risk allocation for contaminated soil remediation.

Impacts Due to the Issue, Problem, or Challenge

• Delay of 9 months due to environmental cleanup and regulatory approvals.
• Significant cost increases from remediation, disposal, and health monitoring.
• Community and regulatory scrutiny on environmental compliance.

Corrective Actions Taken

1. Expanded environmental site assessments with comprehensive soil testing.
2. Developed remediation plans in compliance with environmental regulations.
3. Implemented health and safety protocols for workers and nearby residents.
4. Revised contract terms to clarify responsibility and cost-sharing for contamination.

Lessons Learned

• Integrated environmental and geotechnical investigations are critical.
• Early identification of contamination prevents costly delays.
• Contracts should address environmental risk allocation clearly.

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

• Have environmental contaminants been assessed in site investigations?
• Are remediation and disposal plans developed prior to excavation?
• Are contract terms explicit on environmental risk responsibilities?