Strike While the Iron is Hot—An “All of the Above” Approach Blends Rehabilitation and Renovation with Reactive Replacement

When an 85 year old large-diameter valve needs replacement, no one expects it to be a simple task. Typical underground valve vaults of the 1920s seldom afford easy access for replacement, and can provide their share of surprises. When the valve is one of five large diameter valves housed inside the same 1,100 square foot vault that was constructed in three distinct phases and subsequently modified over its lifetime, however, the challenges and opportunities are certain to extend beyond replacement of the broken valve alone. The city of Minneapolis, along with engineer CDM Smith and contractor PCI Roads, recently completed a project that included redesign and renovation of the entire reinforced concrete and brick valve vault. The project included structural repair and replacement (including replacement of the cast-in-place roof with sectional precast slabs that can be removed for future work), replacement of the broken valve and associated piping, and extensive rehabilitation of four other large-diameter valves inside the vault, which offered a less expensive alternative to replacement of those valves. The project is an example of utilizing the need to replace a specific component as an opportunity to think holistically and make other cost-effective improvements for the long term.