THE OPPORTUNITY

The Bayshore Regional Sewerage Authority (BRSA) recognized the need to enhance the efficiency and resilience of their wastewater treatment process. With aging infrastructure and insufficient sludge management capacity, there was an opportunity to upgrade critical systems. These upgrades were aimed at improving sludge concentration, storage capacity, and flood mitigation while increasing operational efficiency and ensuring long-term sustainability. This project also presented the chance to implement modern technologies and processes to optimize energy use and environmental performance, especially following the damage caused by Hurricane Sandy.

THE CHALLENGE

The existing gravity thickening process had exceeded its useful life and was not producing the desired underflow concentration. Issues included inefficient sludge withdrawal, frequent clogging of sludge withdrawal lines due to struvite buildup, and aging mechanical systems. The concrete structure of the Concentration Tanks showed signs of deterioration, and the fiberglass dome covers were in poor condition. Furthermore, unexpected challenges during construction, such as difficulties with surface preparation, differing as-built conditions ,pipeline damage, odor control intake ductwork modifications, and unreliable sludge blanket meters, added complexity to the project.

THE PS&S SOLUTION

To address these challenges, the BRSA undertook a comprehensive rehabilitation of the sludge concentration tanks. Key solutions included: • Replacement of Mechanical Systems: Aging mechanical drive mechanisms, rakes, and effluent weirs were replaced, improving sludge thickening efficiency and preventing future system failures • Concrete and Coating Repairs: Concrete cracks and spalls were repaired, and a protective coating (Sauereisen SewerGard® No. 210X) was applied to safeguard against hydrogen sulfide and sulfuric acid corrosion. • Flood Mitigation: New fiberglass dome covers were installed to protect the tanks from future flooding, addressing the risks posed by Hurricane Sandy. • Sludge Management Improvements: The project increased sludge concentration from 1-2% to 3-5%, resulting in better sludge quality for incineration. Positive displacement pumps replaced centrifugal primary sludge pumps, reducing energy consumption by 62%. • Struvite Prevention: The struvite formation in sludge withdrawal lines was managed through a struvicide chemical solution system, ensuring efficient sludge removal and preventing pipe clogs. • Reliable Monitoring Systems: Sludge blanket meters were installed within the sludge channels of the primary settling tanks improving sludge management by enabling more precise control over primary sludge pumping and primary settling tank operations. Despite challenges during construction, including unforeseen pipeline repairs and equipment malfunctions, the project was completed with minimal cost overrun (2.9% above the bid price). The project significantly improved the treatment plant’s sludge management system efficiency, operational safety, and flood resilience, ensuring better performance in the long term.