This 425,000 square feet residential building near the Purdue University campus in West Lafayette, Indiana, includes 15 stories of residential units over first floor retail space and three below-grade parking levels. Outdoor amenity spaces on the second, 14th and 16th levels include features such as an outdoor kitchen, plantings, a pool and spa, and gathering spaces. All levels use post-tensioned concrete flat slabs supported by concrete columns and shear walls. Due to the depth of the excavation required and the limited space on the site, the PE team worked closely with the contractor, owner and architect to study alternative ways to achieve adequate earth retention during construction and a permanent earth retention and basement wall solution for the life of the building. The team ultimately selected steel sheet piling with soil nails to serve as the temporary earth retention system, utilizing the same steel sheet piling as the permanent exposed basement walls for the below-grade levels.