b'DESIGN AND ENGINEERINGFOUNDATION REPLACEMENT UTILIZING HELICAL PILESThe existing transformer at a Minnesota substation was overloaded, and the 4 kV equipment was aged and deteriorating. The project requested by the client was an electrical upgrade involving the replacement of the existing 69-4.16 kV transformer with a new 69-23.9 kV transformer. During initial site visits, however, the foundations for an existing substation box structure were clearly in severe need of repair, reinforcement or replacement due to concrete deterioration and poor soil conditionsadding time and complexity to the project scope. A design to mitigate clashing with existing foundations and underground cables was required, and the entire project needed to be completed while the equipment mounted on the structure was energized.The unique conditions led Ulteig to use a technology somewhat rare for the utility industry in our region: helical piles. In the construction phase, while installing the helical pile foundations, other challenges were encountered, including navigating around underground cables, temporary shoring of structure with energized equipment, temporarily relocating major equipment to install the helical piles, winter construction during the 2019 Minnesota polar vortex, and spring flooding toward the end of construction. The use of helical piles was a critical factor in allowing Ulteig to successfully navigate around all the challenges, delivering a finished project that will provide safe and reliable energy for the community well into the future.21'