Case Study: QC Breakdown in Bridge Deck Waterproofing on Portland Bridge Project (Oregon, 2016)

Project Overview
• Name: Portland Bridge Replacement
• Location: Portland, Oregon
• Year: 2016
• Project Size: $620 million
• Scope: Replacement of bridge decks with waterproofing membrane installation
• Lead Agencies/Contractors: Oregon Department of Transportation (ODOT) /

Category of the Issue, Problem, or Challenge
• Quality Control
• Materials
• Structural

Summary of the Issue, Problem, or Challenge
Waterproofing membrane applied with improper surface preparation and inconsistent thickness led to leaks and premature deterioration.

Root Cause Analysis

• Inadequate inspection of surface cleanliness and moisture levels prior to membrane application.
• Lack of standardized application thickness monitoring.
• Insufficient training and supervision of applicators.
• Poor documentation of QC checks during application phases.

Impacts Due to the Issue, Problem, or Challenge

• Delay of 4 months due to membrane removal, surface re-preparation, and re-application.
• Additional costs for materials and labor.
• Increased risk of corrosion and deck damage if uncorrected.

Corrective Actions Taken

1. Developed detailed surface preparation and application checklists.
2. Introduced non-destructive testing to verify membrane thickness and adhesion.
3. Enhanced applicator training and supervision programs.
4. Established thorough QC documentation procedures for all membrane work.

Lessons Learned

• Surface preparation is as important as membrane quality.
• Monitoring application consistency ensures long-term performance.
• Training and documentation support better QC outcomes.

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

• Are surface preparation standards strictly enforced and verified?
• Is membrane thickness monitored and tested?
• Are applicators trained and supervised adequately?