Final Clarifiers Concrete Rehabilitation Project

The State of New Jersey’s Passaic Valley Sewerage Commission (PVSC) in Newark, New Jersey manages one of the largest wastewater treatment plants in the U.S. As one of the most extensive modern wastewater facilities on the East Coast, and the sixth largest in the country, the plant processes over 330-350 million gallons per day (MGD). This activated sludge secondary treatment facility includes miles of sewers, storm drains, access roads, process infrastructure, instrumentation, equipment, and twelve final clarifier tanks essential to its operation. 

PROJECT BACKGROUND

In 2017, a routine inspection revealed that many of the clarifiers’ concrete tank walls and baffle columns had been highly corroded over time. The 30-foot-deep tanks would need a reliable and effective protective coating solution proven to extend their service life and protect from liquid phase carbonation. PVSC began to evaluate coatings to rehabilitate the assets with the help of D&B Engineers and Architects and Corrosion Probe Inc. Corrosion Probe was tasked with conducting a rigorous, side-by-side test evaluation program using Warren Environmental’s 301-14 high performance epoxy alongside four competing products. Each coating material was required to be tested for eight to twelve months, including testing for holidays, pinholes, and adhesion. The strict testing procedures required a minimum rating of eight out of ten to meet the acceptance criteria stated. Four of the five coatings initially tested passed with a minimum rating of eight. With one product pulled from the study, only three of the five coatings tested scored the minimum rating of eight and two products were listed in the specification.  

The study yielded Warren’s epoxy as the only coating that ranked 10 out of 10 based on the ASTM D 6677 rating system. It was also the only coating applied without a resurfacing material and that could spray up to 500 mils in a single coat, setting Warren apart from the competition. With a single coat, Warren’s 301-14 was proven to extend the service life of the existing assets, enhance their existing condition, and protect them from corrosives, H2S gas, and abrasives found within the treatment system. This single coat, high build feature benefitted the owner’s project by eliminating the need for a primer or mortar while simultaneously cutting the cost and schedule with labor savings from the ease of application of Warren’s durable epoxy solutions. 

SCOPE OF WORK

In 2017, PVSC contracted Suez Advanced Solutions (now a division of Veolia North America), to rehabilitate the final clarifier tanks with Warren’s high performance, single coat system using our patented spray equipment. With a large scope, Suez Advanced Solutions needed an organized process that could be replicated in each of the clarifiers. Before applying Warren’s coating, the applicators prepared each structure’s concrete surface with high pressure blasting at 40,000 pounds per square inch (psi) to clean chlorides and buildup from the substrate. Each prepped surface was reviewed daily by the owner’s full-time corrosion inspector for quality assurance. 

The scope included twelve clarifiers, each measuring 360 feet by 120 feet, and three bays, measuring 120 feet by 120 feet. Each bay was separated by concrete baffle walls. The project also included the need to line the tank walls, baffle columns, knee walls, influent channel interior, and the influent baffle walls and floor. The walls and baffle columns were coated at 500 mils for a total of 15,400 square feet, while the influent channel interior baffle was applied at 125 mils for a total of 400 square feet, and the top five inches of the wall perimeter was lined with 250 mils of epoxy totaling 950 square feet. All assets in the scope were lined with Warren’s 301-14 high performance epoxy, and still remain in service today. To date, this project continues to reign as one of Warren’s largest applications with the magnitude of the assets coated. 

PROJECT CHALLENGES

The plant could only handle having two clarifiers offline at a time which called for detailed coordination between Suez Advanced Solutions’ applicators and PVSC’s operations staff. Daily management of operations, key processes, and safety plans were critical to the project’s success.  

The applicator crews also encountered difficult weather challenges including temperature extremes and humid conditions brought by rain events in the spring season. Luckily, Warren’s epoxy had the added benefit of proven, successful applications in various types of weather. Even in the wake of a temporary project shutdown because of the COVID-19 pandemic, PVSC’s clarifier rehabilitation project was successfully completed by the end of 2020.  

PROJECT SUCCESSES

As one of the country’s largest wastewater facilities, PVSC knew that there was no room for error in this critical rehabilitation project. Even a small mishap could have led to difficult challenges and potential disruptions in service to millions of customers. The project team succeeded by collaborating from the start, ensuring a high level of coordination and problem solving when working in the complex facility. The efficiency of Suez Advanced Solutions’ applicator crews combined with Warren epoxy’s quick cure times yielded a timely project delivery for the owner.  

When asked about Warren’s epoxy solutions after the project was completed, Michael Donne, P.E., Mechanical Engineer at PVSC, said, “I think the Warren product is an excellent product, especially for applications requiring a high buildup. And it’s durable. What also helped speed up the project was its low immersion (cure) time. With some coatings, you have to wait seven to 10 days to put something back in service. I believe Warren’s product is four to six hours.”   

With the success of the long-term study, benefits of the product, and detailed coordination of the application, the Suez Advanced Solutions and Warren team provided PVSC with the best value solution for their rehabilitation project. Warren’s epoxy will extend the service life of PVSC’s facility assets and protect them for up to 75 years.