AWARD OF EXCELLENCE: Municipal Category

Joint Water Pollution Control Plant Repair

Carson, California

Submitted by Sika Corporation

The Joint Water Pollution Control Plant (JWPCP), owned and operated by The County Sanitation Districts of Los Angeles County (Districts) is one of the largest wastewater treatment plants in the world. The pure oxygen secondary treatment process produces high quality secondary effluent; however, the process also results in an environment that is highly corrosive to both the equipment and the concrete surfaces. After approximately 16 years of service some of the concrete structures had experienced up to a 1/2 in. loss of section due to the exposure to the aggressive environment. Continued loss of section would no doubt eventually lead to attack of the reinforcing steel and ultimately structure failure.

The District began a research effort to evaluate material that would protect the concrete from further damage and provide enhanced protection for the steel reinforcement. The search ultimately lead to the evaluation of several very-dense, low-permeable, cementitious-based materials. These materials would be mechanically 'shot' onto the prepared substrate in the appropriate manner (wet or dry) and evaluated for various important physical properties including absorption, permeability and bond. A comprehensive test program was completed to evaluate the performance of the materials when applied, and to identify any project-specific concerns pertaining to surface preparation, application, testing, finishing and curing. Once the selection of the appropriate material was completed, the project specification was finalized.

The work, completed in the secondary effluent conveyance structures, could only be done when the entire secondary treatment facility was shut down. The Districts obtained special approval from the regulatory agencies to complete all repairs and return to full operation within 90 days. The Districts would be subject to substantial fines and penalties if this deadline was not met. Therefore, the selection of material and method of application were especially important to ensure a problem-free completion of the work with the highest quality and without any delays.

Owner/Project Engineer
Los Angeles County
Sanitation District
Carson, California

Consulting Engineer
Construction Technology Laboratories
Skokie, Illinois

Repair Contractor
J.F. Shea Construction, Inc.
Walnut, California

Material Supplier
Sika Corporation
Lyndhurst, New Jersey