Phoenix Project #2108
In order to address immediate and long-range needs, the town of Salem, NH performed an extensive renovation & remodeling of its Woodbury Middle School. This project consisted of traditional pit underpinning for a new elevator, as well as a unique underpinning system to support a 50 foot section of existing foundation to facilitate the performance of an adjacent excavation.
Phoenix provided design and installation of a hybrid underpinning system consisting of battered drilled micropiles, 8 inch thick shotcrete, and 15 foot long soil nails. Battered piles were installed through the toe of the existing footing to a depth of approximately 17 feet. Soil was then carefully excavated to a prescribed depth and soil nails were installed through a stabilizing soil berm adjacent to the building’s face. Soil was then cut back to final wall alignment, steel reinforcement was placed, and shotcrete was applied.
This approach offered significant cost and schedule savings to the project, while at the same time maximizing the effecting excavation area (compared to a conventional soldier pile and lagging system). The entire underpinning system was installed in just a few weeks, and helped keep the client on track for the pending foundation installation.