Pulp and Paper Industry

Sample Engagements:

Wastewater Treatment Plant Condition Assessment, Rehabilitation Design, and Construction Management:


Two 30-year old circular primary clarifiers at a Midwestern pulp and paper mill were badly deteriorated due to corrosion. The clarifiers treated municipal and pulp and paper mill waste water. The waste water was high in sulfate, chloride, and other chemical concentrations. Also, the top rims of the concrete walls were badly cracked and spalled from freeze-thaw and chloride-induced rebar corrosion. This was due to deicing salts used to provide traction for the drive carriage that rides on the wall rim. The side walls were suffering from acidic attack related to carbonation, H2S-related biogenic corrosion and Sulfur Oxidizing Bacteria (SOB), and higher chlorides.



CPI performed a detailed condition analysis, defined the corrosion mechanisms, and conducted a careful repair material and protective coatings evaluation. CPI also prepared specifications and drawings for the rehabilitation and future corrosion protection of the clarifiers, provided design engineering services, and provided resident inspection during construction.

The wall rims were rebuilt using a methyl methacrylate acrylic polymer concrete. The carbon steel launder troughs were repaired by welding and then coated with a high-build epoxy coating. The clarified water collection tubes were removed and replaced with FRP V-Notch weirs. The concrete walls and floor were repaired using specialty cementitious, non-shrink grout. All interior surfaces were lined with an elastomeric polyurethane lining. And the rake arms and center wells were abrasive blast cleaned and properly recoated with a hybrid epoxy and urethane coating system.

Customer Benefits

The clarifiers were rebuilt several years ago and continue to perform well. The project was completed two weeks ahead of schedule and on budget.


Service Areas

  • Corrosion and Materials Engineering
    • Corrosion Control/Protection Design
    • Corrosion Analysis and Material Selection Consulting
    • Failure Analysis - Mode and Root Cause Analysis
    • Cathodic Protection System Design and Evaluation
  • Structural and Mechanical Rehabilitation Services
    • Structural Design Engineering
    • Mechanical Design Engineering
    • Condition Assessment Evaluations
    • Structural Evaluation and Analysis
    • Shop and Field QC Inspection and Support
  • Mechanical Integrity and Inspection Design Services
    • Pressure Vessel and Tank Program Development and Implementation
    • Systematic Inspection Design (SID)
    • Risk-Based Inspection
    • Integrity Evaluation and Analysis
    • Fitness-for-Service Evaluations
    • Welding Consulting and Inspection
  • Coatings and Linings Engineering
    • Consulting
    • Failure Analysis
    • Project Management
    • Quality Control and Inspections
  • Project and Quality Management Services
    • Cost Estimating Services for all Construction Disciplines
    • Project Management Services, Including Planning, Scheduling, and Project Controls
    • Quality Control Inspection and Testing Services
    • Quality Assurance Program Development for New and Rehabilitation Construction
    • Quality Assurance Program Auditing and Oversight Services
  • Training Services
    • Alloy Selection for Corrosive Environments
    • Solving Corrosion and Materials Problems for Plant Engineers
    • Welding Essentials for Plant Engineers
    • Brick and Tile-Lined Equipment Inspection and Repair
    • FRP Essentials for Pulp and Paper Mills
    • Concrete Restoration and Protection
    • Quality Assurance for Capital Projects

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