Valley Creek Wastewater Treatment Plant Repairs
The Valley Creek Wastewater Treatment Plant was built 100 feet deep into bedrock and houses a $52-million pump station. Several elements of this underground structure, including the six-foot-thick floor slab failed, partially flooding the pump station and rendering it inoperable. The slab ruptured and left a nearby wall with a two-inch crack approximately 100 feet long. Walter P Moore performed a post-failure investigation, a structural analysis using conventional and finite element methods, material testing, groundwater studies, and geophysical testing for possible sinkhole conditions. The repairs included wall/floor thickening using 25,000 epoxy grouted dowels, stabilization with 700 rock anchors, bracing for unsupported vault walls, urethane crack injection to reduce groundwater infiltration, and epoxy injection of cracked concrete. Despite the magnitude and the challenges of the repairs, the pump station was restored within three years of the failure and is fully operational.