Northwest Water Reclamation Facility Clarifier #4 Rehabilitation

This project involves the rehabilitation of Clarifier #4 at the City of St. Petersburg’s Northwest Water Reclamation Facility (NWWRF). The work includes removal and replacement of the existing clarifier mechanism, which has reached the end of its service life, as well as replacement of both submerged and non-submerged components. The project is necessary to ensure the continued performance and reliability of the plant’s secondary treatment process, and to reduce the risk of mechanical failure that could impact operational compliance.

In addition to mechanical rehabilitation, the interior vertical masonry wall surfaces and associated metal supports will be cleaned, prepared, and recoated with a high-performance protective coating system. Surface preparation will be performed in accordance with current SSPC standards, followed by installation of a Tnemec epoxy system designed for long-term performance in aggressive wastewater environments. This will improve corrosion resistance and extend the life of the structure.

The project also includes an owner-directed contingency allowance to address any unforeseen structural or surface repair conditions identified during construction. All work will be coordinated with plant operations to ensure minimal disruption to ongoing treatment processes. Manufacturer involvement, qualified application personnel, and strict quality control procedures are included to ensure that installation meets specification standards and delivers long-term asset protection.

Clarifier #4 is one of several key secondary treatment units at the Northwest Water Reclamation Facility (NWWRF), and has been in continuous service for several decades. While routine maintenance has extended its operational life, the main mechanism and associated components now show signs of wear, corrosion, and performance decline. The interior coating system on the clarifier walls and supports has also deteriorated, leaving structural elements vulnerable to further degradation.

This project represents a critical opportunity to restore the structural integrity and functionality of the clarifier while implementing high-performance materials that will reduce long-term maintenance needs. Incorporating a proven coating system, combined with OEM-level mechanical replacement and modern QA/QC standards, is expected to significantly extend the service life of this asset.

A successful project outcome will not only ensure treatment reliability and regulatory compliance, but will also minimize the need for near-term corrective repairs. The City is looking for a contractor who understands the operational importance of the clarifier and can execute the work efficiently with minimal disruption to plant processes.