The six-million-gallon capacity Oak Hill tank is critical to meeting peak demands and fire flows in the Attleboro water system. When its original coating systems failed, resulting in corrosion and metal loss, and thermal stratification in the tank threatened water quality, GZA provided concept to start-up engineering services to address these issues and maintain the tank’s compliance with regulatory standards for finished water storage.
GZA’s engineering services included designing the full coating rehabilitation; retrofitting the tank for access and climbing safety; modifying the overflow system for MassDEP compliance; and removing and re-galvanizing ladders, railings and platforms. GZA oversaw the contractor’s operations during construction. GZA structural engineers also reviewed and approved the contractor’s design and welding procedures for of a temporary door sheet in the tank shell, reinforced by steel beams, to facilitate installation of a hydrodynamic tank mixing system within the tank. This innovative approach also expedited the interior surface preparation and coating application by enabling the use of aerial lifts inside the tank. Exterior coating removal was expedited by using robotic vacuum blasting followed by vapor blasting in remaining areas. Minor modifications to venting, safety systems and overflow piping were also completed at two additional City-owned tanks.
The Oak Hill tank is now protected by high-performance coating systems, and Oak Hill and two additional tanks were brought into compliance with the State’s safety and sanitary standards. The work at Oak Hill tank and the two others was completed below budget.