Fishbeck led the significant upgrade to modernize water pretreatment processes for the City of Grand Rapids Lake Michigan Filtration Plant. Outdated equipment and fluctuating water temperatures from Lake Michigan posed challenges. The upgrade involved strategic planning, design, and construction, focusing on replacing old equipment with advanced technology to enhance efficiency.
The plant had undergone a previous expansion in 1994, with four upflow solids-contact clarifiers and six conventional flocculation and sedimentation tanks added. However, the clarifiers could not be used to their full capacity since the city would have to run the clarifiers at reduced rates or shut them off entirely during thermal events in Lake Michigan. In addition, upon installation of the flocculation and sedimentation tanks, the equipment experienced immediate operational issues, necessitating significant and ongoing maintenance and repairs over its lifespan.
The existing four clarifier basins were rated for a capacity of 64 MGD, or 16 MGD per basin. Fishbeck developed a design concept to consolidate this capacity into just two basins while maintaining the original 64-MGD rating. This was accomplished by implementing high-rate segmentation technology, specifically inclined plate settlers, which resulted in a 32-MGD capacity per basin. This innovation significantly increased sedimentation efficiency within a smaller spatial footprint. Unlike the prior chain-driven flocculators prone to operational issues during thermal inversions, the new plate settlers consistently maintain low water turbidity, regardless of flow rate or raw water turbidity. This enables year-round operation at varying flow rates and water qualities, ensuring consistently high water treatment efficiency.
With a focus on efficiency and reduced maintenance, the original chain-driven flocculators in the conventional flocculation and sedimentation basins were replaced with direct-drive flocculators. This enhancement eliminated the need for the previous chain and sprocket system, substantially reducing maintenance requirements for the city. The new direct-drive system demands only periodic greasing and oil changes, contributing to a more streamlined and hassle-free operation.
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Fishbeck played a vital role in the project and was involved from its initial planning stages through equipment startup and commissioning. The company's involvement encompassed a comprehensive spectrum of responsibilities, from offering recommendations for enhancements across equipment, the building, electrical systems, and more during the alternative’s evaluation to providing dedicated onsite construction inspection and administration.
The outcome of the project has surpassed the owner’s expectations, particularly in terms of plant performance and reliability. Since the installation of the new equipment, the plant has encountered numerous water quality events in Lake Michigan, including thermal inversions and runoff events that increased raw water turbidity. Despite these challenges to incoming water quality, the treatment equipment has demonstrated remarkable resilience, consistently delivering high-quality water. This performance has enabled the city to successfully achieve all treatment objectives.
